The line at 11:51 " if it was not for their efforts...Chernobyl would have been the last chapter..." is just a figure of speech to honour the valiant efforts of the people who gave up their health and life in the process of clean up. It has been brought to my notice by many viewers, that some are using this line to undermine the importance of Nuclear energy and instilling fear about the hazards of going nuclear. I want to stress that nuclear energy is one of the cleanest energy, burning fossil fuel kills more than 3 million people each year, which means by the time you read till here, 5 people are already dead due to fossil fuel emission, and by the time you have completely watched this video 74 people would have lost their lives due to fossil fuels. Nuclear energy gets a bad name because of the explosion and theatrics associated with it. It grabs the headlines, you see people die and people make great mini-series on them. On the other hand, fossil fuels are silent killers, they are dull, lack the bravado and no one is interested to watch a video on them. Hence this video. Read more about the "What are the safest and cleanest sources of energy?" on ourworldindata.org/safest-sources-of-energy.
as an other comparsion: flying is the safest way of travel. the chace of you dying in a car accident on the way to the airport is higher than dying in a plane crash. it has even more similarities as flying is using forces of nature, just like nuclear power plants do. fun fact to anyone condeming nuclear energy: your plane stays only in the air due to air pressure from beneath the wings, the power output of the turbines is NOT enough, to overcome earth gravity! so you are basically in the faith of nature while flying. however, it works perfectly fine for 99,999% of the times, because people have figured out a shit-ton of stuff. nuclear energy can be safe just as flying is, but only if we do the required thinking. the tradegy of chernobyl teaches us that it is NOT the nuclear power that is unsafe, it is what people do. by that, i not only mean the operators -- who do have their share in the accident. but also the way how the soviets handled their tech and the knowledge about it. the positive void coeffiect was known but was not allowed to be known. the problem is not the nuclear power (this is just a part of nature that we can use), but the human interaction with it. make it safe and you have save power plants just as you have safe air planes!
The only video (and I've seen many, believe me) that explains the reason of the graphite tips at the lower end of the control rods. Everyone was talking about the design flaw of the RBMK reactor, having graphite tips on the control rods but noone explained why were there at the first place. Bravo, well done !
Well they weren't so much "tips" in the guest place. Light water is a weak neutron poison so having long graphite displacers (almost as long as the control rods themselves) take the place of the removed control rods, improves reactivity and thus efficiency. So while the graphite displacers DID contribute in a large way to the explosion of Chernobyl Reactor 4, there was a logical design reason for them to be there.
11:42 "... of thousands of brave souls who came together to save humanity by sacrificing their health...". A co-worker of mine was a Russian citizen at the time. The army came and took his younger brother right off the farm to work on the initial clean up. He told me that his brother was one of those whose job it was to run up to the gaping hole, throw a few bricks back in, and run away, fast. My friend was in college at the time so they didn't take him. But he never saw his brother again as he died following his service.
RBMK reactors _were_ cheaper to build and operate, but they weren't _"famous"_ for being cheap. Also, uranium enrichment doesn't "convert" U-238 _into_ U-235. Only U-235 is fissile with thermal neutrons, so it is extracted from natural uranium then added to the uranium which will become fuel, so as to _increase_ its concentration of U-235 (enriching it). U-238 will only fission under fast neutron bombardment.
The uranium enrichment would effectively produce Plutonium, after a couple of intermediate steps. I haven’t confirmed the following information in official sources, but I’ve heard from one of the Chernobyl liquidators who came to my university and gave a talk, that in the Chernobyl’s 4th reactor there was also some quantity of Plutonium (something like 90 kg). Apparently, they used RBMK reactors to also produce weapon-grade Plutonium, by enriching U238.
@@ilyakopyl Nope, uranium enrichment in no way produces plutonium. Plutonium is produced (most often) by irradiating natural U238 by strong neutron flux. That happens in reactor. First reactors (Chicago pile, Hancock, Windscale...) were military, and intended just only to produce plutonium. Later, many reactors were made dual purpose, both for electricity and plutonium production. But these goals were partially incompatible, since good electricity production needed long runs between fuel changes, which made the isotope composition of produced plutonium unwanted high content of Pu240 ev. Pu238, while desired was as high content of Pu239 as possible = but that was only when fuel was irradiated for only short time like a week or two. So, one possible solution was to separate function of moderator (one of best is pure graphite) and coolant (which is for technical reasons best water), which is done by using pressure tubes, where is put fuel and flows coolant, and around them is graphite (no pressure, no water). By doing so, you can fuel (change old fuel rods for new ones) the reactor while it is even running (no shutdown needed) and you can leave fuel rods in how long you need/want (or even some short time others normally long). All that is making the reactor quite simple (in comparison to other types), cheap (no big pressure vessel, using only slightly enriched uranium) and as bonus you can easilly produce good quality plutonium if you want it (well, around y.1985 both SSSR and USA had quite enough fissile materials (both U235 and Pu239) so it was never more so important, remember there were still runing some old school reactors solely for Pu creation, no electricity, and methods of uranium enrichment were also more advanced). So, every reactor creates/contains plutonium, there is just bigger amount but worse quality (up to the level that makes its use for weapons impossible) after longer time of fuel rods stay in reactor. The disadvantage of RBMK (and principially all graphite/tubes reactors with water as coolant) is less stability so it is harder to control (but its still possible!). RBMK adds to this not good construction of control rods, and then you keep telling your people (also to operators!) that it is Super Safe (while it's more the opposite, compared to other from that time)... All things together, they create the damn unlucky combination and with bad luck, sht happens :(
The RBMK- reactors that are still in operation today don´t have graphite tips at their control rods endings any more. So the system still works without it, but when you pull out the control rods it takes more time to heat the water into steam and to power the generators. The saftey shutdown push button also was changed into a turn switch key that makes the handling more easy and save too. The control rods now are moving back into the reactor in a faster speed when turning the kill switch.
No, they have a longer connection rod between the neutron absorber and the moderator: the Graphite's lower end can't get further up than the absolute bottom of the core.
Let's stop calling them graphite tips, they are water displacing graphite rods that are supposed to accelerate the reaction when the control rods are out. The issue was that they didn't extend all the way to the bottom of the core so when the power surged it started displaced coolant and accelerated the reaction at the bottom of the reactor. The simple fix was just to extend the displacers to the bottom of the core, the reactor would still have melted down but it wouldn't have exploded.
@@abrahamedelstein4806 I don´t know if we are talking about the same thing. The RBMK that are in operation today have three types of control rods. The third typ of control rods have no graphite endings or water displacing graphite. And that are the control rods that enters the core when you switch the emergency shutdown button A3-5. The emergency shutdown control rods at the chernobyl power plant had those water displacing graphite control rods.
@@derwildewesten6700 ALL control rods drop when the SCRAM button is hit. That a few of the post renovation rods don't graphite tips doesn't chance the fact that all the old ones still do. It's an integral part of the RBMK concept, it can't just be removed. The new control rods you mention have replaced fuel channels, all the old control rods and their functions are unchanged except for getting longer.
@@derwildewesten6700 The control rods you refer to are the 32 short control rods that get inserted upwards from the bottom of the reactor. This is also where the power excursion began on that fateful night in 1986. The core of the RBMK is so big that it is almost completely decoupled in some places. The bottom is like its own little reactor down there and the sensors couldn't register what was going on at the time of the accident. These short rods help keeping the power distribution under control in the lower section of the core. The insertion speed at the time of the accident when they had to start from their upper limit stops was around 18 seconds, which is a skeletal rate of descent in nuclear reactor terms. The control rod servos have since been replaced by faster ones and the control rods now move in gas while the outside of the channels is cooled by a thin layer of water between an inner jacket and the Zircaloy tube of the channel.
This is the most comprehensive and above all the easiest video to understand how and why it happened. I've looked at many videos about Chernobyl incident but this is the most helpful to me. Thanks ! From South Korea
The withdrawal of rods that led to violation of the minimum operating reactivity margin is an absurd accusation that was made by authorities. Because, the thing is, RBMK reactor control instruments WERE NOT providing any real time information on the Operating Reactivity Margin (ORM). In the instructions from the designers of reactor, ORM was not even considered as that important safety parameter, it was calculated by SKALA computer in the different room, with 5 minute delay. And it was actually calculated incorrectly at low power. Reactors designers, such as Nikolay Dollezhall and top soviet officials are to blame, Dyatlov was a scapegoat.
While you are correct with most of your statement, it was known that there was a group of 30 or so control rods that was labeled "the Untouchable Group" because they were to be in the core AT ALL TIMES (Grigori Medvedev; Chernobyl Notebook). They withdrew these as well.
This, for me, is the first-ever explanation given in general engineering terminology I understand to point directly to the cause of failure. A positive coefficient of overheating, or in laymen’s terms, ‘runaway’, seems inconceivable to design into a nuclear reactor but yes, indeed it was and for the reasons given here for the first time. Many instances of positive heat coefficient exist in engineering, generally to enhance efficiency of performance. Turbocharged engines come to mind, and their spectacular failures brought solid solutions. But a blown up motor and a blown up country are not the same. Soviets took the ultimate risk using RBMKs, one even that was fully understood, and paid an enormous price. You may have jumped the shark slightly with your concluding comment about the end of humanity, but thankfully, I can’t prove that thesis. The contributions of the recovery workers are truly species-defining. Their names should be front of mind for us all.. Thank you very much for this video.
I would point out that enrichment doesn't convert U-238 to U-235, the 238 is simply separated and discarded. This is actually where much of so-called depleted uranium is, the leftover 238 from enrichment. This is also what the concern a few years ago was with Iran having centrifuges... Since those centrifuges are used to enrich uranium, possibly to weapons grade.
RBMK stands for Channel-type Reactor of High Power output. The reactor itself wasn't that "cheap": it had a very sophisticated pipe conduit system which required a lot of qualified personnel to maintain. In addition fuel could be reloaded without stopping the reactor: a reloading device would simply attach itself to fuel channel, equalize the pressure and replace fuel assemblies.
Great video! I saw lot of videos about Chernobyl, but this is the first I saw that gives some details, and one of two which explain WHY there are these "graphite tips". Thank you for all the effort! I don't understand WHY it has not millions of views?
The word "tipped" or "tips" used in most of the sources is really missleading. Actually those "tips" are long rods that are almost as long as the absorbing part. The "almost" turned out to be a really bad design decision.
Best clip on Chernobyl accident, brief and to the point. It seems this reactor was very sensitive and unforgiving and had to be handled with extreme care. The day of the accident, as the clip shows, the electrical power output section was calling out for more power while the test was being carried out. That is absolutely ridiculous. Had they waited or let the grid import or export from somewhere else then this accident could have been avoided.
This video answered for me a lot of the questions of the reasoning behind the tests. Other videos do the deep dive into the exact science of nuclear fission. It seems to me that part of the critical operating component of this type of reactor is continuous water circulation through the reactor. The loss of water flow for one minute put it into a safety condition. So, the tests were conducted to simulate loss of power to the pumps and test the freewheeling of the generator to provide sufficient operating power for the pumps until the diesel generators were placed on line. In other videos, it was mentioned that the ECCS (emergency core cooling system) were disabled for the test, but did not contribute to the accident. Well ok, so what exactly is its function.
The very short answer to that is: Thy are reactor emergency system components (pumps, valves, heat-exchangers, tanks, piping etc.) that are specifically designed to remove residual heat from the fuel rods in the event of a failure of the normal core cooling system (i.e. a pipe breaks/ a pump seizes). They are designed to safely shut down a nuclear reactor, take it subcritical and keep it there indefinitely if need be. Depending on the reactor type ( PWR, BWR etc.) high pressure injection (HPI), low pressure injection (LPI), and core flood tanks (CFTs) are all part of the ECCS. The water used can be laced with high levels of boron to keep the reactor from going critical again. They ran the Unit 4 reactor for 9-11 hours with the ECCS physically disconnected, which is beyond insane. If anything would have happened (apart from the accident that is) the reactor would have been deprived of one of its most important core safety systems. For them to even consider running the reactor this way, shows the complete lack of safety culture in the Soviet Union at the time. To my knowledge you cannot manually disable the ECCS system on modern day reactors without it automatically scramming and staying that way until all safety parameters are met.
U-238 (even number) is called fertile because it absorbs neutrons without fission while U-235 (odd number) is fissile. The word "converted" is misleading. It is more appropriate to say that U-238 is converted to Pu-239 which is fissile after absorbing neutrons. This process goes much faster in breeder reactor.
I argue this and say it is a design flaw. I understand the reason for the graphite tips. in the end. Water will slow reaction down so the graphite is used for sustainability. But what was never though of is if you were in an point where you were making to much power. By adding rods to slow it down. As soon as the graphite enters. For those moments you are making even more power. That is a safety design flaw. In an over speed or or over power condition. Exactly what happened to the reactor. You are only going to increase power more before removing power. Hence the explosion that happened,
@@WhatTheScience exactly! Somewhere in the beginning slides of this presentation it was claimed U 238 was converted into U 235, that's why I mentioned this.
Anyone interested in Chernobyl, read Adam Higginbotham sbook Midnight in Chernobyl. He spent 10 years interviewing everyone that was there that night and survived to tell their story. Absolutely fantastic book and gives insight to everything that happened that night. Also talks about how the town was built and the nuclear plant going up.
This ,,Midnight in Chernobyl" book is good, but unfortunately based on Grigorij Medvedvev's book ,,The truth about chernobyl", when it comes to describing what happened in the control room that night. Dyatlov behavior is exaggerated, many workers of power plant questioned how dyatlov is decribed in the book, and what Medvedvev wrote is generally not that credible. HBO show was also based on this medvedvev's book. In reality the RBMK would have blown sooner or later, Dyatlov was mainly unlucky. Dyatlov had very good points when he was defending himself, and actually a lot of his points correspond with official report of the international atomic energy agency. In reality they haven't broke that much rules and contributed that much to disaster, it was reactor that was so unstable at low power but have not provided enough instrumentation and signals to show its dangerous state. Plus designers of reactor such as Nikolay Dollezhall hidden the faults from operators to protect their careers, instead of making them clear. I recommended reading those. Technical publications, but you need to deep into details in order to understand faults of the reactor and situation dyatlov was put into by system, instead of just exaggerating how dyatlov contributed to disaster. Good reactors do not explode because of a harsh boss making SLIGHT mistakes. www.neimagazine.com/features/featurehow-it-was-an-operator-s-perspective/ www-pub.iaea.org/MTCD/publications/PDF/Pub913e_web.pdf
@@cytrynowy_melon6604 Did you read Midnight in Chernobyl? He did not base it another book. He actually defended Dyatlov . He went to great lengths that most of what happened wasn’t Daytlovs fault. He interviewed everyone who was in the control room that night many times. He does chapters of the cover up on the many faults on the RBMK 1000 reactors. The HBO mini series was good but full of bull crap.
A few major problems: 8:33 The xenon was not burned away at all. Xenon is dispersed in proportion to the power of the reactor, which at 200MW would take almost 24 hours. What actually happened is that the bottom of the core was not poisoned very much at all, in comparison to the central and upper portions. This is called a 'doubled humped power distribution' or 'core decoupling.' In fact, there was so much xenon that the reactor remained poisoned by it even *after it exploded*. Not even 33,000 MW of thermal power could disperse the xenon! 9:01 The power spike occurred *after* AZ-5 was pressed, not before. You and your audience may think that this was a minor detail, but it is as absurd as saying that the WTC caught on fire *before* the airliner crashed into it on 9/11. AZ-5 was pressed in calm circumstances, and any increase in reactor power was no more than 10% of the initial 200 MW. The IAEA INSAG-7 explicitly states that the power levels remained stable at 200 MW until the explosion. 3 seconds after AZ-5 was pressed, power was 530 MW. Every time a RUclipsr makes this mistake, Dyatlov gives whisker cancer to 10 kittens. Until you fix these errors, you should include a disclaimer that this video takes place in the HBO cinematic universe, not our own.
I'm an engineer, but by no means a nuclear engineer. My understanding is that, by the time just before the turbine is shut down for the test start, power was -200MW, and the only things keeping reactivity in check were coolant (water) and xenon, as almost all control rods were removed. By shutting down the turbine, circulation of water was cut off, thus making the water already inside the core start to heat up, forming steam bubbles (voids) in the bottom of the reactor, which lead to an increase in reactivity due to the positive void coefficient (more steam=less water= less neutron absorbtion=neutrons running widly=more fission=more temperature=more steam... and so on). In this moment, I am wildly assuming the bottom part of the core got so hot, it burnt xenon 135 away, thus leading to an even more drastic increase in reactivity which lead to a power spike. Noticing this increase in power, the operators engage AZ-5, wich leads to a denotation beacuse the tips of the boron carbide control rods were made of graphite, which increased reactivity, thus leading to ANOTHER skyrocket power spike. So my questions are the following: 1. Why do you say xenon was not burned away? I mean, it was keeping things in check before the operators decided to power down the turbine. A very viable explanation is that as the turbine stalled, xenon had to be burnt away in order for the core to have an increase in reactivity in a xenon poisoned state 2. The reason the operators engaged AZ-5 was because they noticed an spike in power after a "stable" 200 MW thermal output. If this weren't the case, they wouldn't have engaged AZ-5 as they had forcibly agreed to start the test at 200 MW. So, it seems there was, in fact, a power surge before AZ-5 was engaged. A second, additional power surge happened after pressing AZ-5, due the graphite tips. So, what do you mean when you say the power surge happened after? Because I see 2 power surges. I'm just trying to fully understand what happened, and I may be wrong in my assumptions. Thank you for your time!
@@andthorn3145 Cheers, I am also not a nuclear engineer or anything close to it. However, the IAEA's INSAG-7 report is written in clear enough language that any reasonably technical person can understand it. Being able to read the Russian primary sources and related analysis also helps, because their explanations are clearer and additional background information is available there. The fascinating (and frustrating) thing about Chernobyl is that there are so many competing explanations of the disaster. The first version is the one which you roughly described in your post, as presented to the world at Vienna in 1986, and which was endorsed by the IAEA's INSAG-1 report. Only one problem... it was a huge pile of clever lies! That's why the IAEA had to go back to the drawing board in 1992 to correct the record. And because they don't like looking like fools and chumps, their new report is rather cagey when it comes to pointing out what was false in INSAG-1. And it hardly matters, because by that time a huge amount of myths had grown up around the disaster, and are still being repeated by well meaning folks such as the authors of this video. If it isn't already obvious, the purpose of the lies was to put all the blame onto the plant operators, so that the world would not find out that renowned Soviet scientists had designed an enormously unsafe reactor. For instance, the scenario you described is only possible if the control room staff were completely incompetent and unacquainted with reactor physics 101. In reality, the chief engineer and several of his subordinates had an awful lot of experience, expertise and respect. The fact of the matter is that they were completely unaware of the danger they were in. For instance, according to the operating instructions, the void coefficient was NEGATIVE. This is equivalent to being told that the natural gas in your home is not flammable: such a belief will catastrophically change your behavior when a pipe starts leaking! Without a positive void coefficient, no sort of accident could have occurred. The IAEA's INSAG-7 report clearly states that there was no increase of reactor power during the turbine rundown test. This simple fact unalterably transforms the whole narrative of the accident. There was only one power surge and AZ-5 caused it. Furthermore, INSAG-7 never even mentions the possibility of Xenon burning away in the final moments before the power surge, and I actually do not know where this myth came from. Not even the inaccurate INSAG-1 report contained such a thing. It is the equivalent of fan fiction for Western physicists. After all, 200 MW is only 6% of optimal reactor power, so there is not enough fission going on to make any meaningful difference in xenon concentrations, except on a timescale of many hours. Now in the final 36 seconds before AZ-5 was pressed, coolant supply did slowly decrease due to turbine rundown. This caused an increase in steam quality (void coefficient) in the lower portion of the core where there was relatively little xenon in the first place. As a result of rising reactivity at the bottom of the core, automatic control rods moved downwards, and although INSAG-7 notes that the reason for pressing AZ-5 remains unknown, the best theory is that the operators noticed this movement of automatic rods. Then Akimov remembered that the reactor should have shut down automatically when the turbine test began, and did the only logical thing: a scram. It is very clear from eyewitness testimony that the button was pressed in calm circumstances, and that there was no power surge. The diagnostic printouts indicate a thermal power of 200MW according to one sensor, while the other sensor recorded that power had increased by 15-30 MW. That is not even close to a power surge, and the rise was not rapid enough to trigger any alarms or warnings. All such reactor parameters were within normal limits at this time.
@@MinSredMash In challenging some of the points made by Andres above, you keep referring to INSAG-7. However, I can't find any passages within that report that support some of the rather strong claims you make. Also I find some of those remarks puzzling from the perspective of physics. For example, in your initial post you say that the xenon was not dispersed and the core remained poisened even after the explosion. First of all, to say that the core remained poinsened after the explosion seems nonsensical to me. After the explosion(s) the core was open and one of the first things that came out of it were the highly volatile bits like its gas inventory. So what do you base your assumption on that the core was poisened even after the explosion, when all the xenon already escaped into the atmosphere? Then you claim that the xenon was "not burned away at all". 135-Xenon absorbes neutrons. As it does so, it becomes the more stable 136-xenon. So whenever there are neutrons to absorb, this process will take place. What happens is that after some time, there is an equilibrium between newly produced 135-xenon (produced in the decay of iodine) and the conversion of 135-xenon to 136-xenon through absorbtion. Whenever there is a change in reactivity (i.e. more or less neutrons to go around) this equilibrium is disturbed and needs some time to adjust. So when reactivity goes up, there are more neutrons for 135-xenon to absorb, so there will eventually be less of it (i.e. it "burns away" with higher reactivity). To say that "the xenon was not burned away at all" is therefore misleading since its burned away all the time. I guess what you mean is that since you claim the power output remained stable at 200MW thermal, not enough xenon was burned away to shift the equilibrium. This brings me to another of your key claims, namely that the power output remained stable at 200MW thermal until AZ5 was pressed. Where do you find support for that claim? INSAG-7 states in its conclusions that "It is not known for certain what started the power excursion that destroyed the Chernobyl reactor. Some positive reactivity is likely to have been generated from the growth in voids as the coolant flow rate fell. Addition of further positive reactivity by insertion of the control and safety rods that had been fullywithdrawn during the test was probably a decisive contributory factor." (p.23 point 4) This explicitly contradicts your own claim. After they brought the reactor to 200MW thermal and seeing that they couldn't bring it any further than that, they decided to run the test which means that they tried to operate the circulation pumps with the power of the spinning down turbine. As a result the flow of coolant to the reactor decreased which means the water at the bottom of the reactor was getting hotter and turned into steam. This water could then no longer function as a neutron absorber, but since the graphite moderator keeps slowing down neutrons, reactivity goes up. Why should it remain stable as you say? What do you think kept the reactivity in check with the water gone and the control rods out (and you even claim that there was no 135-xenon poisoning at the bottom)? So even on your own account of events, there must have been an increase in power before(!) they pressed AZ5. You claim that pressing AZ5 was the single cause of the power spike. I don't see this diagnosis supported anywhere. INSAG-7 ranks it as "a decisive contributory factor" that added further positive reactivity. Then you reply to Andres above that "the scenario you [i.e. Andres] described is only possible if the control room staff were completely incompetent and unacquainted with reactor physics 101. In reality, the chief engineer and several of his subordinates had an awful lot of experience, expertise and respect." I don't see why Andres version is only possible on the assumption of highly incompetent staff. All it takes is for the staff to make some ill informed critical decisions (which they evidentially did). The INSAG-7 itself states that "The weight given in INSAG-1 in 1986 to the Soviet view presented at the Vienna meeting, which laid blame almost entirely on actions of the operating staff, is thereby lessened. Certain actions by operators that were identified in INSAG-1 as violations of rules were in fact not violations. Yet INSAG remains of the opinion that critical actions of the operators were most ill judged. As pointed out in INSAG-1, the human factor has still to be considered as a major element in causing the accident." (p.24, point 6) INSAG-7 "lessens" the weight of the blame that was put on the operating staff by INSAG-1. However, it still remains that critical actions were "most ill judged". So the events were possible not because the control room staff were "completely incompetent and unacquainted with reactor physics 101" as you say. But rather it was possible because of the "lack of safety culture" (as repeatedly stated in the INSAG-7), design flaws and lack of information available to operating staff, as you yourself correctly point out afterwards.
@@KH-hn2cn You are correct that "not burned away at all" is an overstatement. However, at 200 MW so little xenon could be dissipated in under 60 seconds that this phenomenon is completely irrelevant to the disaster. Note that INSAG-7 does not mention it at all. So presenting burning as xenon as a factor disturbing the equilibrium of the reactor is simply incorrect. Plant safety officer Nikolai Karpan conducted calculations on the morning of April 26, determining that the reactor would remain poisoned until evening. Xenon is heavier than air, so it could stay in the reactor pit and the central hall, and continue to form after the explosion, as I understand it. When the reports say that the gas inventory of the reactor was released, they cannot determine that this release was instantaneous and into the upper atmosphere, rather than the plant grounds. Your next points can be answered by a short quote from INSAG-7 page 65: "During the rundown of turbo generator No. 8 there was no increase in reactor power. This is confirmed by the DREG program..." There you have it. No increase in power until AZ-5 was pressed. I'm not sure how you could read the report and drawn any other conclusion than that. Also, it appears you have confused reactivity with thermal power. The downward movement of the automatic control rods was compensating successfully for the additional reactivity in the bottom of the core (caused by the inadmissably high void coefficient of reactivity, which was withheld from the operators). I never said there was no xenon poisoning in the bottom of the core, just much less of it. Again, information taken directly from the report. INSAG-7's conclusion that the operator's decisions were ill-judged is a subjective conclusion, contained in a report dedicated to more objective information. The authors have great authority in establishing matters of fact, but their subjective conclusions are as subject to critique as any other professional opinion. For instance, the most important "ill-judged" decision was in raising power after the drop, but this was not prohibited by any regulations and the ORM was still within parameters after power was stabilized at 200 MW. The report also ignores the fact that the test program actually allowed for lowering reactor power below 700 MW during the rundown period itself. INSAG's criticism of the operators is severely undercut by another passage where it is revealed that the same accident could have taken place without any violations of the rules, because the ORM could not be adequately calculated before it dropped below limits without any operator input. I think we both understand the politics of mishaps and disasters. If something goes seriously wrong, you will get the book thrown at you if your shoelaces were untied, whether that has any direct impact on the accident or not. Lastly, you need to take into account the humiliation of the IAEA after the Soviets hoodwinked them with the INSAG-1 report. The international section of INSAG-7 is full of very politick and understated corrections, trying to minimize the change in course and conclusions. In my view, the operator's decisions were fairly well-judged in the context of the information *they had at the time*. In other words, for the reactor as described in the documentation, which had a negative void coefficient, ORM which only changed very slowly, and an APS that was always effective. True, they did not abandon the test when difficulties arose, but that would have been a purely speculative decision to avoid purely hypothetical hazards whose existence was unknown. In the prevailing safety culture of the time, this is a highly unreasonable expectation. Commentators with hindsight have used the operators as punching bags so others can learn from their experience and draw lessons from it, but this does not engender a fair assessment of their performance in context.
it is said that the 2000t heavy sealingplate on top of the reactor was 10(!) seconds in the air. Go out and throw a tennisball straight up in the air and count how long it takes for it to come back again. Imagine how much power you would ned to keep that ball 10 seconds in the air and then try to imagine the power that is needed to do the same with a 2 Mio Kilogramm heavy steelplate!!
Brilliant presentation of the causes and sequence of events that led to the Chernobyl catastrophe. I recommend this to my process safety management students as part of the background information for their root cause analysis assignment into this incident where they are asked to analyse this incident against the 14 Process Safety Management elements.
In case you’re interested in my lecture on Chernobyl detailing key issues to guide students in doing their assignment: ruclips.net/video/ZeRD2xgZAzE/видео.html
Sono completamente ignorante in materia; ho cominciato a guardare il video di Ethan Chaleff, ma era troppo tecnico. Voi mi avete finalmente fatto capire cosa sia successo. Grazie
Thanks for the vid-great detail. Reason for Graphite tipped control rods was usually explained as being cheaper vs. their functionality of increasing reactivity while being removed-reverse of this was the final straw too.
After watching this video, i can say, that i have a complete understanding of the sequence of the the events and the "mechanism" that have lead to the explosion. Thank you about the video. It was complete, and worked fine for me !
Thankyou, very clearly and well explained, but your final statement about it nearly destroying humanity is definitely mistaken and could seriously mislead some people.
So basically, because of the steam voids in the coolant water, the reaction gets out of control really quickly, more power spikes=more steam, more steam= more power spikes. Hopeless fatal design
Xenon in the core slowed down the reaction. Water in the core slowed down the reaction. Control rods in the core slowed down the reaction. Because of all this, when they tried to lower power to 500 Mw at Dyatlov's instruction (the test was supposed to be run at 700 minimum), instead the power crashed and the reactor stalled. Control rods were removed, accelerating the reaction. The test was started, slowing down the flow of water through the core. Water began to boil in the core, accelerating the reaction. Power spiked hard. The xenon burned off, and power spiked even further. More water boiled, and power spiked even higher. The operators attempted to SCRAM. In pretty much any other circumstance, this would have been the right thing to do. It's hard to think what else they _could_ have done in this situation. Unfortunately, in this precise configuration, it meant that some of the parts of the core that were filled with steam were now filled with graphite, so the power spiked even further - and then the control rods jammed. There was nothing that could be done to prevent the reaction from running away until it destroyed the reactor.
@@Werrf1 What they could have done is to increase water flow to reduce steam in the reactor and then carefully and slowly insert a few control rods and then a few more. And even then it would have been a very delicate operation without damaging the core but likely it wouldn't have been the disaster it became. But realistically they were not even aware of the situation enough to take the right steps. The flawed design of the control rods was already known at that time but never communicated to the plants that use it.
@@seho8722 Several western countries, including the US also had similar graphite-mediated, water-cooled reactors. What made the RBMK-1000 reactor different were 1) it's scale. it had a much larger core than similar reactors in the west. and 2) the graphite tips on the control rods, which was used due to the soviets using lower quality (less enriched) fuel. The real problem was massive human failure.
good video for most parts, but the end "one of the dealiest human made disasters", "would have been humanities last chapter", etc. is totally bullshit. Chernobyl wasn't even close to many other deadly disasters that humanity has caused itself and without any further measures, it wouldn't even have been the end of ukraine, let alone humanity.
Please do share your views on the new video, and if you liked it share it with your friends and subscribe to my channel to get informative videos like this.
What gets me in all this, is that any sane person would still, after this disaster that very well couldve wiped out all of humanity on earth, would continue to seek and use nuclear energy. I understand the "modern" methods employed in todays nuclear plants are so called safer, but still the same fears and concerns arose with japans Fukushima plant disaster. Any sane person would immediately call for its ban world wide, because its not a matter of how its going to happen but rather when. After all, Chernobly is not over, its only been covered, and sooner or later be it by nature or by man it will never remain covered forever.
It looks pretty, but it is missing voice. I would like to offer you free voice overring "don lafontaine" style for any videos involving anything nuclear :)
You were motivated by the fear of risking your own ambitions. You know who you are, Your behavior was cowardly & pathetic and you will-as we all will-ultimately be held accountable
Hopefully this is NOT knit picking ... I've watched a lot of videos that say conducting an experiment ... and then others that say conducting safety checks ... as I understand it was more on the side of experimentation than a safety check ... considering a lot of key safety systems were turned off ... that WOULD HAVE STOPPED the whole thing ... not ONLY were the personel not adequately trained as (I understand) the lack of experience was a HUGE factor as well ... my main point is as (a different type of an example) is you DO NOT fill a room with an unknown gas and then light a match to see if it will ignite ... shutting safety systems off ... inexperienced personnel ... a known flawed reactor and a head man in charge that was almost inexperienced as the crew under him ... ALL OF THAT TOGETHER is like using gasoline to put out a fire
I wouldn't blame him entirely, the entire design of this is a JOKE. The only real mistake was removing so many control rods...not sure what they were thinking there.
@@johnspence8141 A chimpanzee manager was dictating orders in contrary to what the real engineers were telling him not to do. Let us, however, not be so hard on chimpanzee managers because they have orders from 'up above'. Maybe that was why so many control rods were missing, but blame the engineers, chimps rule. Are you a lawyer or a financier?
At 3:58 onwards, you say that water acts as a neutron (N) absorber and, since the water turned to steam, there was less N absorbance leading to a positive feedback. Yet, in modern reactors the water acts as a moderator, not an absorber. Thus, the less available water should have a negative feedback. Can you explain the apparent contradiction in the designs? Thanks.
Heavy water is used in modern reactors, which is a moderator. Whereas the RBMK reactor in question used normal water. www.nrc.gov/reading-rm/basic-ref/glossary/heavy-water-d2o.html
What The Science Not according to this guy who describes a light water reactor (LWR): ruclips.net/video/bCbms6umE_o/видео.html It is all so confusing!!
LWR uses ordinary water as a moderator, but RBMK used graphite as the primary moderator and water was mostly used as coolant not as a moderator. Ordinary water absorbs more neutron than heavy water, so for LWR to work we need highly enriched uranium. Highly enriched uranium makes up for the neutrons lost by absorption by light water. But RBMK used less enriched uranium which means if we use ordinary water it will absorb neutrons more than it can moderate. Hence it acts more as a neutron absorber in RBMK because the fuel rods are less enriched.
What The Science Ok, thanks. Now, can I ask the question about fast and slow neutrons? Why do fast neutrons have less ability to split the atom than slow neutrons? Yet, atomic bombs use fast neutrons and no moderator, as far as I know....
Fast moving neutrons has less probability to hit an atom, than slow moving neutrons, hence we need moderators. Nuclear weapons work in a different way as compared to reactors. Please watch the video to know more ruclips.net/video/QxJOmesOopA/видео.html
Well, there are many good and important facts told, but also way too many untrue ones. You cannot turn U-238 into U-235 and this isn't called enrichement. Also you don't want U-235 for it's higher radioactivity (which it has because of it's shorter half life) but for it's ability to beeing splittable, just like Pu-239 or U-233. Some other facts were plain wrong which is sad to see in a video that is otherwise made quite well.
Hands down the best video of what actually happened in the reactor! And beautiful flow for even illiterate to actually understand the mechanics of accident. Well done, i love it. I have watched every single video on youtube but this one takes the cake.
Oh sweet u got back to me. Yea i believe your rite. Great vid i also concur that it is currently the only vid that helped me get the details down. My brain says thank you💥💥💥💥💥
It was used metaphorically, not entire human race, but europe would have seriously affected. Also if the feed water tanks had exploded, then it would have been very serious.
@@WhatTheScience what would have happened if nothing was done to stop the contamination, no Boron dumping, No Cover over the reactor, just the reactor left open to the atmosphere?
Oh no... This video was doing so well right up until the last slide. There's literally NO WAY that Chernobyl would've been the last chapter of the human race. Why would you say something so silly? Even most professional anti-nuclear activists don't say things so over the top. If you actually look into the details of how weak a carcinogen radioactive fallout is and compare them to the dangers of particulate air pollution. Then you'll quickly see that a coal power plant in NORMAL operation does more harm than the worst estimates of Chernobyl.
@@WhatTheScience Well you should've said that, rather then something that does nothing but feed radiophobic alarmism. That kind of poetic turn of phrase is the reason people are gripped with fear over what EVERY scientific study has shown is literally our safest energy source. For example the Fukushima accident could not have harmed anyone with radioactive fallout, most of the surrounding area didn't even become more radioactive than Denver on a normal day. But because of the deeply UNSCIENTIFIC fear of radiation a needless evacuation was order. That evacuation all by itself destroyed the local economy, upended a hundred thousand lives and killed at least 1,500 people from the needless stress of moving around after a tsunami. NONE of which needed to happen, but they belived it needed to happen because the word radiation has become a synonym for apocalypse. Which is silly, radiation is normal and easily managed. But it's to be excepted when people have heard nothing but 50 years of poetic nonsense about nuclear energy and NONE of the science. Considering the name of your channel I'd have hoped you'd focus more on the science. More people die falling off roofs installing solar panels every year than died from Chernobyl. Saying a slightly above average industrial accident could've been the end of humanity undermines every effort to learn about the topic. More science less sensationalism please.
The line at 11:51 " if it was not for their efforts...Chernobyl would have been the last chapter..." is just a figure of speech to honour the valiant efforts of the people who gave up their health and life in the process of clean up. It has been brought to my notice by many viewers, that some are using this line to undermine the importance of Nuclear energy and instilling fear about the hazards of going nuclear.
I want to stress that nuclear energy is one of the cleanest energy, burning fossil fuel kills more than 3 million people each year, which means by the time you read till here, 5 people are already dead due to fossil fuel emission, and by the time you have completely watched this video 74 people would have lost their lives due to fossil fuels.
Nuclear energy gets a bad name because of the explosion and theatrics associated with it. It grabs the headlines, you see people die and people make great mini-series on them. On the other hand, fossil fuels are silent killers, they are dull, lack the bravado and no one is interested to watch a video on them. Hence this video.
Read more about the "What are the safest and cleanest sources of energy?" on ourworldindata.org/safest-sources-of-energy.
as an other comparsion: flying is the safest way of travel. the chace of you dying in a car accident on the way to the airport is higher than dying in a plane crash. it has even more similarities as flying is using forces of nature, just like nuclear power plants do. fun fact to anyone condeming nuclear energy: your plane stays only in the air due to air pressure from beneath the wings, the power output of the turbines is NOT enough, to overcome earth gravity! so you are basically in the faith of nature while flying. however, it works perfectly fine for 99,999% of the times, because people have figured out a shit-ton of stuff. nuclear energy can be safe just as flying is, but only if we do the required thinking. the tradegy of chernobyl teaches us that it is NOT the nuclear power that is unsafe, it is what people do. by that, i not only mean the operators -- who do have their share in the accident. but also the way how the soviets handled their tech and the knowledge about it. the positive void coeffiect was known but was not allowed to be known. the problem is not the nuclear power (this is just a part of nature that we can use), but the human interaction with it. make it safe and you have save power plants just as you have safe air planes!
The only video showing what actually happens in the reactor! So many others were just talking about unimportant stuff. Well done sir
Thank you George
Look for ethan chaleff or scott manley on youtube, then. Both do it even better.
Came here to say the exact same thing. If the scientists of the era wanted their questions answered this video would be a great resource
There's been a discussion on RUclips for years from an MIT professor, and he showed everything as well.
Scott Manley has the best video, this is just old news.
The best explanation on the disaster I found on RUclips! Thank you, great job!
Thank you Sarah
The only video (and I've seen many, believe me) that explains the reason of the graphite tips at the lower end of the control rods.
Everyone was talking about the design flaw of the RBMK reactor, having graphite tips on the control rods but noone explained why were there at the first place. Bravo, well done !
I think s so dude
That’s correct. I even searched the web looking for the answer and nothing.
This is common knowledge.
common knowledge is in short supply, you can definitely help by sharing this video.
Well they weren't so much "tips" in the guest place. Light water is a weak neutron poison so having long graphite displacers (almost as long as the control rods themselves) take the place of the removed control rods, improves reactivity and thus efficiency. So while the graphite displacers DID contribute in a large way to the explosion of Chernobyl Reactor 4, there was a logical design reason for them to be there.
The most important thing to realise is that the cause of that event was not construction flaws, it was human error.
11:42 "... of thousands of brave souls who came together to save humanity by sacrificing their health...". A co-worker of mine was a Russian citizen at the time. The army came and took his younger brother right off the farm to work on the initial clean up. He told me that his brother was one of those whose job it was to run up to the gaping hole, throw a few bricks back in, and run away, fast. My friend was in college at the time so they didn't take him. But he never saw his brother again as he died following his service.
🙏
RBMK reactors _were_ cheaper to build and operate, but they weren't _"famous"_ for being cheap. Also, uranium enrichment doesn't "convert" U-238 _into_ U-235. Only U-235 is fissile with thermal neutrons, so it is extracted from natural uranium then added to the uranium which will become fuel, so as to _increase_ its concentration of U-235 (enriching it). U-238 will only fission under fast neutron bombardment.
The uranium enrichment would effectively produce Plutonium, after a couple of intermediate steps.
I haven’t confirmed the following information in official sources, but I’ve heard from one of the Chernobyl liquidators who came to my university and gave a talk, that in the Chernobyl’s 4th reactor there was also some quantity of Plutonium (something like 90 kg). Apparently, they used RBMK reactors to also produce weapon-grade Plutonium, by enriching U238.
@@ilyakopyl Nope, uranium enrichment in no way produces plutonium. Plutonium is produced (most often) by irradiating natural U238 by strong neutron flux. That happens in reactor. First reactors (Chicago pile, Hancock, Windscale...) were military, and intended just only to produce plutonium. Later, many reactors were made dual purpose, both for electricity and plutonium production. But these goals were partially incompatible, since good electricity production needed long runs between fuel changes, which made the isotope composition of produced plutonium unwanted high content of Pu240 ev. Pu238, while desired was as high content of Pu239 as possible = but that was only when fuel was irradiated for only short time like a week or two.
So, one possible solution was to separate function of moderator (one of best is pure graphite) and coolant (which is for technical reasons best water), which is done by using pressure tubes, where is put fuel and flows coolant, and around them is graphite (no pressure, no water). By doing so, you can fuel (change old fuel rods for new ones) the reactor while it is even running (no shutdown needed) and you can leave fuel rods in how long you need/want (or even some short time others normally long).
All that is making the reactor quite simple (in comparison to other types), cheap (no big pressure vessel, using only slightly enriched uranium) and as bonus you can easilly produce good quality plutonium if you want it (well, around y.1985 both SSSR and USA had quite enough fissile materials (both U235 and Pu239) so it was never more so important, remember there were still runing some old school reactors solely for Pu creation, no electricity, and methods of uranium enrichment were also more advanced).
So, every reactor creates/contains plutonium, there is just bigger amount but worse quality (up to the level that makes its use for weapons impossible) after longer time of fuel rods stay in reactor.
The disadvantage of RBMK (and principially all graphite/tubes reactors with water as coolant) is less stability so it is harder to control (but its still possible!). RBMK adds to this not good construction of control rods, and then you keep telling your people (also to operators!) that it is Super Safe (while it's more the opposite, compared to other from that time)...
All things together, they create the damn unlucky combination and with bad luck, sht happens :(
The RBMK- reactors that are still in operation today don´t have graphite tips at their control rods endings any more. So the system still works without it, but when you pull out the control rods it takes more time to heat the water into steam and to power the generators. The saftey shutdown push button also was changed into a turn switch key that makes the handling more easy and save too. The control rods now are moving back into the reactor in a faster speed when turning the kill switch.
No, they have a longer connection rod between the neutron absorber and the moderator: the Graphite's lower end can't get further up than the absolute bottom of the core.
Let's stop calling them graphite tips, they are water displacing graphite rods that are supposed to accelerate the reaction when the control rods are out. The issue was that they didn't extend all the way to the bottom of the core so when the power surged it started displaced coolant and accelerated the reaction at the bottom of the reactor.
The simple fix was just to extend the displacers to the bottom of the core, the reactor would still have melted down but it wouldn't have exploded.
@@abrahamedelstein4806 I don´t know if we are talking about the same thing. The RBMK that are in operation today have three types of control rods. The third typ of control rods have no graphite endings or water displacing graphite. And that are the control rods that enters the core when you switch the emergency shutdown button A3-5. The emergency shutdown control rods at the chernobyl power plant had those water displacing graphite control rods.
@@derwildewesten6700 ALL control rods drop when the SCRAM button is hit. That a few of the post renovation rods don't graphite tips doesn't chance the fact that all the old ones still do. It's an integral part of the RBMK concept, it can't just be removed. The new control rods you mention have replaced fuel channels, all the old control rods and their functions are unchanged except for getting longer.
@@derwildewesten6700
The control rods you refer to are the 32 short control rods that get inserted upwards from the bottom of the reactor. This is also where the power excursion began on that fateful night in 1986. The core of the RBMK is so big that it is almost completely decoupled in some places. The bottom is like its own little reactor down there and the sensors couldn't register what was going on at the time of the accident. These short rods help keeping the power distribution under control in the lower section of the core.
The insertion speed at the time of the accident when they had to start from their upper limit stops was around 18 seconds, which is a skeletal rate of descent in nuclear reactor terms. The control rod servos have since been replaced by faster ones and the control rods now move in gas while the outside of the channels is cooled by a thin layer of water between an inner jacket and the Zircaloy tube of the channel.
This is the most comprehensive and above all the easiest video to understand how and why it happened.
I've looked at many videos about Chernobyl incident but this is the most helpful to me.
Thanks !
From South Korea
Welcome Foxtrot
Best explanation video on YT about what happened in Chernobyl.
The withdrawal of rods that led to violation of the minimum operating reactivity margin is an absurd accusation that was made by authorities. Because, the thing is, RBMK reactor control instruments WERE NOT providing any real time information on the Operating Reactivity Margin (ORM). In the instructions from the designers of reactor, ORM was not even considered as that important safety parameter, it was calculated by SKALA computer in the different room, with 5 minute delay. And it was actually calculated incorrectly at low power. Reactors designers, such as Nikolay Dollezhall and top soviet officials are to blame, Dyatlov was a scapegoat.
While you are correct with most of your statement, it was known that there was a group of 30 or so control rods that was labeled "the Untouchable Group" because they were to be in the core AT ALL TIMES (Grigori Medvedev; Chernobyl Notebook). They withdrew these as well.
This, for me, is the first-ever explanation given in general engineering terminology I understand to point directly to the cause of failure. A positive coefficient of overheating, or in laymen’s terms, ‘runaway’, seems inconceivable to design into a nuclear reactor but yes, indeed it was and for the reasons given here for the first time.
Many instances of positive heat coefficient exist in engineering, generally to enhance efficiency of performance. Turbocharged engines come to mind, and their spectacular failures brought solid solutions. But a blown up motor and a blown up country are not the same. Soviets took the ultimate risk using RBMKs, one even that was fully understood, and paid an enormous price.
You may have jumped the shark slightly with your concluding comment about the end of humanity, but thankfully, I can’t prove that thesis. The contributions of the recovery workers are truly species-defining. Their names should be front of mind for us all..
Thank you very much for this video.
Excellent detailed technical / chemical explanation of the complex series of events and all of the components that were involved.
Damn boy ! That was a excellent explanation. Very impressed by animation and you earned one sub :D
Thank you Surya
I would point out that enrichment doesn't convert U-238 to U-235, the 238 is simply separated and discarded. This is actually where much of so-called depleted uranium is, the leftover 238 from enrichment.
This is also what the concern a few years ago was with Iran having centrifuges... Since those centrifuges are used to enrich uranium, possibly to weapons grade.
RBMK stands for Channel-type Reactor of High Power output. The reactor itself wasn't that "cheap": it had a very sophisticated pipe conduit system which required a lot of qualified personnel to maintain. In addition fuel could be reloaded without stopping the reactor: a reloading device would simply attach itself to fuel channel, equalize the pressure and replace fuel assemblies.
What is the name of the music used?
Mist, odonis odonis
Great video! I saw lot of videos about Chernobyl, but this is the first I saw that gives some details, and one of two which explain WHY there are these "graphite tips". Thank you for all the effort! I don't understand WHY it has not millions of views?
The word "tipped" or "tips" used in most of the sources is really missleading. Actually those "tips" are long rods that are almost as long as the absorbing part. The "almost" turned out to be a really bad design decision.
This video should be taught in schools! Well done sir.
It is taught in schools. For example look up the MIT professor discussing it to a class full of people.
Hi, can i ask u how to make the illustration pict for the animation? I need to make it for my english task. Thank you
I have learnt watching this ruclips.net/p/PLYfCBK8IplO4X-jM1Rp43wAIdpP2XNGwP
best explanation I have seen....just moving pictures and simple facts...thankyou
Best clip on Chernobyl accident, brief and to the point. It seems this reactor was very sensitive and unforgiving and had to be handled with extreme care. The day of the accident, as the clip shows, the electrical power output section was calling out for more power while the test was being carried out. That is absolutely ridiculous. Had they waited or let the grid import or export from somewhere else then this accident could have been avoided.
Thank you for watching!
This video answered for me a lot of the questions of the reasoning behind the tests. Other videos do the deep dive into the exact science of nuclear fission. It seems to me that part of the critical operating component of this type of reactor is continuous water circulation through the reactor. The loss of water flow for one minute put it into a safety condition. So, the tests were conducted to simulate loss of power to the pumps and test the freewheeling of the generator to provide sufficient operating power for the pumps until the diesel generators were placed on line. In other videos, it was mentioned that the ECCS (emergency core cooling system) were disabled for the test, but did not contribute to the accident. Well ok, so what exactly is its function.
The very short answer to that is:
Thy are reactor emergency system components (pumps, valves, heat-exchangers, tanks, piping etc.) that are specifically designed to remove residual heat from the fuel rods in the event of a failure of the normal core cooling system (i.e. a pipe breaks/ a pump seizes). They are designed to safely shut down a nuclear reactor, take it subcritical and keep it there indefinitely if need be. Depending on the reactor type ( PWR, BWR etc.) high pressure injection (HPI), low pressure injection (LPI), and core flood tanks (CFTs) are all part of the ECCS. The water used can be laced with high levels of boron to keep the reactor from going critical again.
They ran the Unit 4 reactor for 9-11 hours with the ECCS physically disconnected, which is beyond insane. If anything would have happened (apart from the accident that is) the reactor would have been deprived of one of its most important core safety systems. For them to even consider running the reactor this way, shows the complete lack of safety culture in the Soviet Union at the time. To my knowledge you cannot manually disable the ECCS system on modern day reactors without it automatically scramming and staying that way until all safety parameters are met.
What music did you use?
I use free music available in RUclips studio, it is available on side bar under > Other features > audio library > Mist.mp3
3:42 You say "stream generation'' twice. Is that supposed to be "steam generation'' or was that intentional?
It is a typo, should be 'steam generation'
it's a pity that neither Lenya nor Sasha will be able to watch this video and understand what really happened
The best explanation Ever!
Thank You!
Thank you!
Nope, he copied so many way better people.
U-238 (even number) is called fertile because it absorbs neutrons without fission while U-235 (odd number) is fissile. The word "converted" is misleading. It is more appropriate to say that U-238 is converted to Pu-239 which is fissile after absorbing neutrons. This process goes much faster in breeder reactor.
I argue this and say it is a design flaw. I understand the reason for the graphite tips. in the end. Water will slow reaction down so the graphite is used for sustainability. But what was never though of is if you were in an point where you were making to much power. By adding rods to slow it down. As soon as the graphite enters. For those moments you are making even more power. That is a safety design flaw. In an over speed or or over power condition. Exactly what happened to the reactor. You are only going to increase power more before removing power. Hence the explosion that happened,
Also if I may U 238 is not converted into U 235.. but the concentration of U 235 is raised through an enrichment process.
Percentage composition of U235 is increased by the process of isotope separation.
@@WhatTheScience exactly! Somewhere in the beginning slides of this presentation it was claimed U 238 was converted into U 235, that's why I mentioned this.
Yes there is an error in the video
Anyone interested in Chernobyl, read Adam Higginbotham sbook Midnight in Chernobyl. He spent 10 years interviewing everyone that was there that night and survived to tell their story. Absolutely fantastic book and gives insight to everything that happened that night. Also talks about how the town was built and the nuclear plant going up.
I too recommend it
WELL THE SAME BS AS HBO???
WILL DARE TO ASSUME...
This ,,Midnight in Chernobyl" book is good, but unfortunately based on Grigorij Medvedvev's book ,,The truth about chernobyl", when it comes to describing what happened in the control room that night. Dyatlov behavior is exaggerated, many workers of power plant questioned how dyatlov is decribed in the book, and what Medvedvev wrote is generally not that credible. HBO show was also based on this medvedvev's book. In reality the RBMK would have blown sooner or later, Dyatlov was mainly unlucky. Dyatlov had very good points when he was defending himself, and actually a lot of his points correspond with official report of the international atomic energy agency. In reality they haven't broke that much rules and contributed that much to disaster, it was reactor that was so unstable at low power but have not provided enough instrumentation and signals to show its dangerous state. Plus designers of reactor such as Nikolay Dollezhall hidden the faults from operators to protect their careers, instead of making them clear. I recommended reading those. Technical publications, but you need to deep into details in order to understand faults of the reactor and situation dyatlov was put into by system, instead of just exaggerating how dyatlov contributed to disaster. Good reactors do not explode because of a harsh boss making SLIGHT mistakes.
www.neimagazine.com/features/featurehow-it-was-an-operator-s-perspective/
www-pub.iaea.org/MTCD/publications/PDF/Pub913e_web.pdf
@@cytrynowy_melon6604 Did you read Midnight in Chernobyl? He did not base it another book. He actually defended Dyatlov . He went to great lengths that most of what happened wasn’t Daytlovs fault. He interviewed everyone who was in the control room that night many times. He does chapters of the cover up on the many faults on the RBMK 1000 reactors. The HBO mini series was good but full of bull crap.
A few major problems:
8:33 The xenon was not burned away at all. Xenon is dispersed in proportion to the power of the reactor, which at 200MW would take almost 24 hours. What actually happened is that the bottom of the core was not poisoned very much at all, in comparison to the central and upper portions. This is called a 'doubled humped power distribution' or 'core decoupling.' In fact, there was so much xenon that the reactor remained poisoned by it even *after it exploded*. Not even 33,000 MW of thermal power could disperse the xenon!
9:01 The power spike occurred *after* AZ-5 was pressed, not before. You and your audience may think that this was a minor detail, but it is as absurd as saying that the WTC caught on fire *before* the airliner crashed into it on 9/11.
AZ-5 was pressed in calm circumstances, and any increase in reactor power was no more than 10% of the initial 200 MW. The IAEA INSAG-7 explicitly states that the power levels remained stable at 200 MW until the explosion. 3 seconds after AZ-5 was pressed, power was 530 MW.
Every time a RUclipsr makes this mistake, Dyatlov gives whisker cancer to 10 kittens. Until you fix these errors, you should include a disclaimer that this video takes place in the HBO cinematic universe, not our own.
Thank you for the notes!, I appreciate the time that you have spent watching the video and explaining the things that I have missed.
I'm an engineer, but by no means a nuclear engineer.
My understanding is that, by the time just before the turbine is shut down for the test start, power was -200MW, and the only things keeping reactivity in check were coolant (water) and xenon, as almost all control rods were removed.
By shutting down the turbine, circulation of water was cut off, thus making the water already inside the core start to heat up, forming steam bubbles (voids) in the bottom of the reactor, which lead to an increase in reactivity due to the positive void coefficient (more steam=less water= less neutron absorbtion=neutrons running widly=more fission=more temperature=more steam... and so on). In this moment, I am wildly assuming the bottom part of the core got so hot, it burnt xenon 135 away, thus leading to an even more drastic increase in reactivity which lead to a power spike.
Noticing this increase in power, the operators engage AZ-5, wich leads to a denotation beacuse the tips of the boron carbide control rods were made of graphite, which increased reactivity, thus leading to ANOTHER skyrocket power spike.
So my questions are the following:
1. Why do you say xenon was not burned away? I mean, it was keeping things in check before the operators decided to power down the turbine. A very viable explanation is that as the turbine stalled, xenon had to be burnt away in order for the core to have an increase in reactivity in a xenon poisoned state
2. The reason the operators engaged AZ-5 was because they noticed an spike in power after a "stable" 200 MW thermal output. If this weren't the case, they wouldn't have engaged AZ-5 as they had forcibly agreed to start the test at 200 MW. So, it seems there was, in fact, a power surge before AZ-5 was engaged. A second, additional power surge happened after pressing AZ-5, due the graphite tips. So, what do you mean when you say the power surge happened after? Because I see 2 power surges.
I'm just trying to fully understand what happened, and I may be wrong in my assumptions. Thank you for your time!
@@andthorn3145 Cheers, I am also not a nuclear engineer or anything close to it. However, the IAEA's INSAG-7 report is written in clear enough language that any reasonably technical person can understand it. Being able to read the Russian primary sources and related analysis also helps, because their explanations are clearer and additional background information is available there.
The fascinating (and frustrating) thing about Chernobyl is that there are so many competing explanations of the disaster. The first version is the one which you roughly described in your post, as presented to the world at Vienna in 1986, and which was endorsed by the IAEA's INSAG-1 report. Only one problem... it was a huge pile of clever lies! That's why the IAEA had to go back to the drawing board in 1992 to correct the record. And because they don't like looking like fools and chumps, their new report is rather cagey when it comes to pointing out what was false in INSAG-1. And it hardly matters, because by that time a huge amount of myths had grown up around the disaster, and are still being repeated by well meaning folks such as the authors of this video. If it isn't already obvious, the purpose of the lies was to put all the blame onto the plant operators, so that the world would not find out that renowned Soviet scientists had designed an enormously unsafe reactor.
For instance, the scenario you described is only possible if the control room staff were completely incompetent and unacquainted with reactor physics 101. In reality, the chief engineer and several of his subordinates had an awful lot of experience, expertise and respect. The fact of the matter is that they were completely unaware of the danger they were in. For instance, according to the operating instructions, the void coefficient was NEGATIVE. This is equivalent to being told that the natural gas in your home is not flammable: such a belief will catastrophically change your behavior when a pipe starts leaking! Without a positive void coefficient, no sort of accident could have occurred.
The IAEA's INSAG-7 report clearly states that there was no increase of reactor power during the turbine rundown test. This simple fact unalterably transforms the whole narrative of the accident. There was only one power surge and AZ-5 caused it. Furthermore, INSAG-7 never even mentions the possibility of Xenon burning away in the final moments before the power surge, and I actually do not know where this myth came from. Not even the inaccurate INSAG-1 report contained such a thing. It is the equivalent of fan fiction for Western physicists. After all, 200 MW is only 6% of optimal reactor power, so there is not enough fission going on to make any meaningful difference in xenon concentrations, except on a timescale of many hours.
Now in the final 36 seconds before AZ-5 was pressed, coolant supply did slowly decrease due to turbine rundown. This caused an increase in steam quality (void coefficient) in the lower portion of the core where there was relatively little xenon in the first place. As a result of rising reactivity at the bottom of the core, automatic control rods moved downwards, and although INSAG-7 notes that the reason for pressing AZ-5 remains unknown, the best theory is that the operators noticed this movement of automatic rods. Then Akimov remembered that the reactor should have shut down automatically when the turbine test began, and did the only logical thing: a scram. It is very clear from eyewitness testimony that the button was pressed in calm circumstances, and that there was no power surge. The diagnostic printouts indicate a thermal power of 200MW according to one sensor, while the other sensor recorded that power had increased by 15-30 MW. That is not even close to a power surge, and the rise was not rapid enough to trigger any alarms or warnings. All such reactor parameters were within normal limits at this time.
@@MinSredMash In challenging some of the points made by Andres above, you keep referring to INSAG-7. However, I can't find any passages within that report that support some of the rather strong claims you make. Also I find some of those remarks puzzling from the perspective of physics. For example, in your initial post you say that the xenon was not dispersed and the core remained poisened even after the explosion. First of all, to say that the core remained poinsened after the explosion seems nonsensical to me. After the explosion(s) the core was open and one of the first things that came out of it were the highly volatile bits like its gas inventory. So what do you base your assumption on that the core was poisened even after the explosion, when all the xenon already escaped into the atmosphere?
Then you claim that the xenon was "not burned away at all". 135-Xenon absorbes neutrons. As it does so, it becomes the more stable 136-xenon. So whenever there are neutrons to absorb, this process will take place. What happens is that after some time, there is an equilibrium between newly produced 135-xenon (produced in the decay of iodine) and the conversion of 135-xenon to 136-xenon through absorbtion. Whenever there is a change in reactivity (i.e. more or less neutrons to go around) this equilibrium is disturbed and needs some time to adjust. So when reactivity goes up, there are more neutrons for 135-xenon to absorb, so there will eventually be less of it (i.e. it "burns away" with higher reactivity). To say that "the xenon was not burned away at all" is therefore misleading since its burned away all the time. I guess what you mean is that since you claim the power output remained stable at 200MW thermal, not enough xenon was burned away to shift the equilibrium.
This brings me to another of your key claims, namely that the power output remained stable at 200MW thermal until AZ5 was pressed. Where do you find support for that claim? INSAG-7 states in its conclusions that
"It is not known for certain what started the power excursion that destroyed the Chernobyl reactor. Some positive reactivity is likely to have been generated from the growth in voids as the coolant flow rate fell. Addition of further positive reactivity by insertion of the control and safety rods that had been fullywithdrawn during the test was probably a decisive contributory factor." (p.23 point 4)
This explicitly contradicts your own claim. After they brought the reactor to 200MW thermal and seeing that they couldn't bring it any further than that, they decided to run the test which means that they tried to operate the circulation pumps with the power of the spinning down turbine. As a result the flow of coolant to the reactor decreased which means the water at the bottom of the reactor was getting hotter and turned into steam. This water could then no longer function as a neutron absorber, but since the graphite moderator keeps slowing down neutrons, reactivity goes up. Why should it remain stable as you say? What do you think kept the reactivity in check with the water gone and the control rods out (and you even claim that there was no 135-xenon poisoning at the bottom)? So even on your own account of events, there must have been an increase in power before(!) they pressed AZ5. You claim that pressing AZ5 was the single cause of the power spike. I don't see this diagnosis supported anywhere. INSAG-7 ranks it as "a decisive contributory factor" that added further positive reactivity.
Then you reply to Andres above that "the scenario you [i.e. Andres] described is only possible if the control room staff were completely incompetent and unacquainted with reactor physics 101. In reality, the chief engineer and several of his subordinates had an awful lot of experience, expertise and respect." I don't see why Andres version is only possible on the assumption of highly incompetent staff. All it takes is for the staff to make some ill informed critical decisions (which they evidentially did). The INSAG-7 itself states that
"The weight given in INSAG-1 in 1986 to the Soviet view presented at the Vienna meeting, which laid blame almost entirely on actions of the operating staff, is thereby lessened. Certain actions by operators that were identified in INSAG-1 as violations of rules were in fact not violations. Yet INSAG remains of the opinion that critical actions of the operators were most ill judged. As pointed out in INSAG-1, the human factor has still to be considered as a major element in causing the accident." (p.24, point 6)
INSAG-7 "lessens" the weight of the blame that was put on the operating staff by INSAG-1. However, it still remains that critical actions were "most ill judged". So the events were possible not because the control room staff were "completely incompetent and unacquainted with reactor physics 101" as you say. But rather it was possible because of the "lack of safety culture" (as repeatedly stated in the INSAG-7), design flaws and lack of information available to operating staff, as you yourself correctly point out afterwards.
@@KH-hn2cn You are correct that "not burned away at all" is an overstatement. However, at 200 MW so little xenon could be dissipated in under 60 seconds that this phenomenon is completely irrelevant to the disaster. Note that INSAG-7 does not mention it at all. So presenting burning as xenon as a factor disturbing the equilibrium of the reactor is simply incorrect. Plant safety officer Nikolai Karpan conducted calculations on the morning of April 26, determining that the reactor would remain poisoned until evening. Xenon is heavier than air, so it could stay in the reactor pit and the central hall, and continue to form after the explosion, as I understand it. When the reports say that the gas inventory of the reactor was released, they cannot determine that this release was instantaneous and into the upper atmosphere, rather than the plant grounds.
Your next points can be answered by a short quote from INSAG-7 page 65:
"During the rundown of turbo generator No. 8 there was no increase in reactor power. This is confirmed by the DREG program..."
There you have it. No increase in power until AZ-5 was pressed. I'm not sure how you could read the report and drawn any other conclusion than that. Also, it appears you have confused reactivity with thermal power. The downward movement of the automatic control rods was compensating successfully for the additional reactivity in the bottom of the core (caused by the inadmissably high void coefficient of reactivity, which was withheld from the operators). I never said there was no xenon poisoning in the bottom of the core, just much less of it. Again, information taken directly from the report.
INSAG-7's conclusion that the operator's decisions were ill-judged is a subjective conclusion, contained in a report dedicated to more objective information. The authors have great authority in establishing matters of fact, but their subjective conclusions are as subject to critique as any other professional opinion. For instance, the most important "ill-judged" decision was in raising power after the drop, but this was not prohibited by any regulations and the ORM was still within parameters after power was stabilized at 200 MW. The report also ignores the fact that the test program actually allowed for lowering reactor power below 700 MW during the rundown period itself. INSAG's criticism of the operators is severely undercut by another passage where it is revealed that the same accident could have taken place without any violations of the rules, because the ORM could not be adequately calculated before it dropped below limits without any operator input.
I think we both understand the politics of mishaps and disasters. If something goes seriously wrong, you will get the book thrown at you if your shoelaces were untied, whether that has any direct impact on the accident or not. Lastly, you need to take into account the humiliation of the IAEA after the Soviets hoodwinked them with the INSAG-1 report. The international section of INSAG-7 is full of very politick and understated corrections, trying to minimize the change in course and conclusions.
In my view, the operator's decisions were fairly well-judged in the context of the information *they had at the time*. In other words, for the reactor as described in the documentation, which had a negative void coefficient, ORM which only changed very slowly, and an APS that was always effective. True, they did not abandon the test when difficulties arose, but that would have been a purely speculative decision to avoid purely hypothetical hazards whose existence was unknown. In the prevailing safety culture of the time, this is a highly unreasonable expectation. Commentators with hindsight have used the operators as punching bags so others can learn from their experience and draw lessons from it, but this does not engender a fair assessment of their performance in context.
Finally, a clear explanation of why graphite tipped boron control rods were used. That's been bugging me since the series was released. Great job!
it is said that the 2000t heavy sealingplate on top of the reactor was 10(!) seconds in the air. Go out and throw a tennisball straight up in the air and count how long it takes for it to come back again. Imagine how much power you would ned to keep that ball 10 seconds in the air and then try to imagine the power that is needed to do the same with a 2 Mio Kilogramm heavy steelplate!!
Brilliant presentation of the causes and sequence of events that led to the Chernobyl catastrophe. I recommend this to my process safety management students as part of the background information for their root cause analysis assignment into this incident where they are asked to analyse this incident against the 14 Process Safety Management elements.
In case you’re interested in my lecture on Chernobyl detailing key issues to guide students in doing their assignment: ruclips.net/video/ZeRD2xgZAzE/видео.html
Thank you Michael for sharing this, and recommending my content. I appreciate it.
Sono completamente ignorante in materia; ho cominciato a guardare il video di Ethan Chaleff, ma era troppo tecnico. Voi mi avete finalmente fatto capire cosa sia successo. Grazie
Well done. You give a good explanation of why the rods were graphite tipped, something I had not fully understood
Thank you for watching
Best video ever that explains chernobly explosion
10:30
Why didnt the control rods go further down so the boron could come help?
One of the best explanation i would have come across. Great explanation bro. Would love to see your future work as well.
Thank you Chandan
Thanks for the vid-great detail.
Reason for Graphite tipped control rods was usually explained as being cheaper vs. their functionality of increasing reactivity while being removed-reverse of this was the final straw too.
welcome DFC
Very concise and easy to understand..
After watching this video, i can say, that i have a complete understanding of the sequence of the the events and the "mechanism" that have lead to the explosion.
Thank you about the video. It was complete, and worked fine for me !
Thankyou, very clearly and well explained, but your final statement about it nearly destroying humanity is definitely mistaken and could seriously mislead some people.
Very nicely explain. In detail. Thanks
Very clear explanation. Thank you. (nice creepy music too).
Thank you Kathleen
By far the best explanation... Thank you....
Thank you for watching Kaya
So basically, because of the steam voids in the coolant water, the reaction gets out of control really quickly, more power spikes=more steam, more steam= more power spikes.
Hopeless fatal design
Xenon in the core slowed down the reaction. Water in the core slowed down the reaction. Control rods in the core slowed down the reaction. Because of all this, when they tried to lower power to 500 Mw at Dyatlov's instruction (the test was supposed to be run at 700 minimum), instead the power crashed and the reactor stalled.
Control rods were removed, accelerating the reaction. The test was started, slowing down the flow of water through the core. Water began to boil in the core, accelerating the reaction. Power spiked hard. The xenon burned off, and power spiked even further. More water boiled, and power spiked even higher. The operators attempted to SCRAM.
In pretty much any other circumstance, this would have been the right thing to do. It's hard to think what else they _could_ have done in this situation. Unfortunately, in this precise configuration, it meant that some of the parts of the core that were filled with steam were now filled with graphite, so the power spiked even further - and then the control rods jammed. There was nothing that could be done to prevent the reaction from running away until it destroyed the reactor.
Sure, only communists can do that design!!!
@@Werrf1 What they could have done is to increase water flow to reduce steam in the reactor and then carefully and slowly insert a few control rods and then a few more. And even then it would have been a very delicate operation without damaging the core but likely it wouldn't have been the disaster it became. But realistically they were not even aware of the situation enough to take the right steps. The flawed design of the control rods was already known at that time but never communicated to the plants that use it.
@@seho8722 Several western countries, including the US also had similar graphite-mediated, water-cooled reactors. What made the RBMK-1000 reactor different were 1) it's scale. it had a much larger core than similar reactors in the west. and 2) the graphite tips on the control rods, which was used due to the soviets using lower quality (less enriched) fuel. The real problem was massive human failure.
Very useful, the first simple enough video I have seen explaining what happened
Thank you David!
good video for most parts, but the end "one of the dealiest human made disasters", "would have been humanities last chapter", etc. is totally bullshit. Chernobyl wasn't even close to many other deadly disasters that humanity has caused itself and without any further measures, it wouldn't even have been the end of ukraine, let alone humanity.
infact, 31 operators and firefighters died. Not 30.
best video on youtube that explains the chernobyl accident.
Thank you Emile!
Please do share your views on the new video, and if you liked it share it with your friends and subscribe to my channel to get informative videos like this.
What gets me in all this, is that any sane person would still, after this disaster that very well couldve wiped out all of humanity on earth, would continue to seek and use nuclear energy. I understand the "modern" methods employed in todays nuclear plants are so called safer, but still the same fears and concerns arose with japans Fukushima plant disaster. Any sane person would immediately call for its ban world wide, because its not a matter of how its going to happen but rather when. After all, Chernobly is not over, its only been covered, and sooner or later be it by nature or by man it will never remain covered forever.
It looks pretty, but it is missing voice. I would like to offer you free voice overring "don lafontaine" style for any videos involving anything nuclear :)
Awesome video. What’s the background music?
@@ThisIsCinco It is available in youtube studio > audio library > Mist
@@WhatTheScience Thank you! Love the videos keep up the great work!
Nice explanatory video but would it have really caused the demise of human civilization?
No
Great video, thanks!
Thank you!
Words are powerful than speech...
Hmm...
I was listening to a discussion on this from an MIT professor and he said it wasn't an explosion.
Excellent explanation
Beautifully explained.
You were motivated by the fear of risking your own ambitions.
You know who you are,
Your behavior was cowardly & pathetic
and you will-as we all will-ultimately
be held accountable
Is that a dialogue from HBO's Chernobyl?
@@WhatTheScience Was hoping there would be NO citing of that disgusting movie!!!!
Hopefully this is NOT knit picking ... I've watched a lot of videos that say conducting an experiment ... and then others that say conducting safety checks ... as I understand it was more on the side of experimentation than a safety check ... considering a lot of key safety systems were turned off ... that WOULD HAVE STOPPED the whole thing ... not ONLY were the personel not adequately trained as (I understand) the lack of experience was a HUGE factor as well ... my main point is as (a different type of an example) is you DO NOT fill a room with an unknown gas and then light a match to see if it will ignite ... shutting safety systems off ... inexperienced personnel ... a known flawed reactor and a head man in charge that was almost inexperienced as the crew under him ... ALL OF THAT TOGETHER is like using gasoline to put out a fire
Ignorance coupled with a major design flaw leads to disaster...very nicely put
@@WhatTheScience
Thank you hopefully that gives all the other readers food for thought too LOL
Very informative!
Thank you Shubhali
3:05 design of RBMK has THREE pumps per loop, not four. Fourth one is Emergency Core Cooling system Pump
The reactor has two independent cooling circuits, each having four main circulating pumps (three operating, one standby).
Comrade Dyatlov had to have his way.
I wouldn't blame him entirely, the entire design of this is a JOKE. The only real mistake was removing so many control rods...not sure what they were thinking there.
@@johnspence8141 A chimpanzee manager was dictating orders in contrary to what the real engineers were telling him not to do. Let us, however, not be so hard on chimpanzee managers because they have orders from 'up above'. Maybe that was why so many control rods were missing, but blame the engineers, chimps rule. Are you a lawyer or a financier?
@@wobblybobengland MAN, you just watched HBO TOO MUCH!!!
So some text emerges at 5:04. Absolute bollocks.
Totally grasped and is now highly understandable, appreciated 👍👍👍👌👌👌
At 3:58 onwards, you say that water acts as a neutron (N) absorber and, since the water turned to steam, there was less N absorbance leading to a positive feedback. Yet, in modern reactors the water acts as a moderator, not an absorber. Thus, the less available water should have a negative feedback. Can you explain the apparent contradiction in the designs? Thanks.
Heavy water is used in modern reactors, which is a moderator.
Whereas the RBMK reactor in question used normal water. www.nrc.gov/reading-rm/basic-ref/glossary/heavy-water-d2o.html
What The Science Not according to this guy who describes a light water reactor (LWR):
ruclips.net/video/bCbms6umE_o/видео.html
It is all so confusing!!
LWR uses ordinary water as a moderator, but RBMK used graphite as the primary moderator and water was mostly used as coolant not as a moderator. Ordinary water absorbs more neutron than heavy water, so for LWR to work we need highly enriched uranium. Highly enriched uranium makes up for the neutrons lost by absorption by light water. But RBMK used less enriched uranium which means if we use ordinary water it will absorb neutrons more than it can moderate. Hence it acts more as a neutron absorber in RBMK because the fuel rods are less enriched.
What The Science Ok, thanks.
Now, can I ask the question about fast and slow neutrons? Why do fast neutrons have less ability to split the atom than slow neutrons? Yet, atomic bombs use fast neutrons and no moderator, as far as I know....
Fast moving neutrons has less probability to hit an atom, than slow moving neutrons, hence we need moderators.
Nuclear weapons work in a different way as compared to reactors. Please watch the video to know more
ruclips.net/video/QxJOmesOopA/видео.html
There’s nothing positive to describe about this. Which is not a void coefficient, so it is not a thing.
Wait wait wait... reactor one was rbmk 800???
RBMK 1000
concise and precise about the technical details, very nice video.
this is so very nicely explained!! great work! god speed!
Türkçe altyazılı mümkün mü acaba?
Sorry only English
@@WhatTheScience i can add turkish subtitles
@@WhatTheScience how i can add subtitles a video ?
mail it to me, youtube has stopped community contribution
my ID you will find in my channel about page
I have watched several videos but they did nt explained like you did
Thank you Shiv
Well, there are many good and important facts told, but also way too many untrue ones. You cannot turn U-238 into U-235 and this isn't called enrichement. Also you don't want U-235 for it's higher radioactivity (which it has because of it's shorter half life) but for it's ability to beeing splittable, just like Pu-239 or U-233.
Some other facts were plain wrong which is sad to see in a video that is otherwise made quite well.
*replaced with U235 by the process of isotope separation
Hands down the best video of what actually happened in the reactor! And beautiful flow for even illiterate to actually understand the mechanics of accident. Well done, i love it. I have watched every single video on youtube but this one takes the cake.
Wonderfully explained. but still needs intelligent audience
excellent....enjoyed it.............well done.................h6 in the uk.................
Chernobyl would have destroyed the world or just europe?
Mostly Europe, depends on how winds carry the fumes. Also rain could carry the contaminants back to earth and it can mix with the water reservoirs.
Oh sweet u got back to me. Yea i believe your rite. Great vid i also concur that it is currently the only vid that helped me get the details down. My brain says thank you💥💥💥💥💥
Thank you for watching John
At 7:14, Xenon is written as "Xeon".
noted
Good.
NIcely presented!
Bravo !
Thank you
That is how an RBMK nuclear reactor explodes.... Lies.
3.6 Roentgen
@Libturds Suck He's delusional, take him to the infirmary.
the final chapter of the human race? Does that mean if it was not contained properly it would have wiped us out?
It was used metaphorically, not entire human race, but europe would have seriously affected. Also if the feed water tanks had exploded, then it would have been very serious.
@@WhatTheScience what would have happened if nothing was done to stop the contamination, no Boron dumping, No Cover over the reactor, just the reactor left open to the atmosphere?
@@serverlan763 the contamination would have spread for hundreds of years causing cancer, deformities and birth defects in generations to come.
I'm one of the children that was born that year. So who cared...
Should have had an thermostat and temperature sensor fitted stops the car seizing could have stopped the reactor too?..
HMmmnn Tuck-and-A-Ghoyhoyhoyhoyhoyhe
WUT's to Eat 🍗
Reading + 5 sins
The RBMK of doom.
A bit inaccurate
n step process
Oh no... This video was doing so well right up until the last slide. There's literally NO WAY that Chernobyl would've been the last chapter of the human race. Why would you say something so silly?
Even most professional anti-nuclear activists don't say things so over the top.
If you actually look into the details of how weak a carcinogen radioactive fallout is and compare them to the dangers of particulate air pollution. Then you'll quickly see that a coal power plant in NORMAL operation does more harm than the worst estimates of Chernobyl.
The line is added just to acknowledge the effort of the people who died or lost their health in the process of containment.
@@WhatTheScience Well you should've said that, rather then something that does nothing but feed radiophobic alarmism.
That kind of poetic turn of phrase is the reason people are gripped with fear over what EVERY scientific study has shown is literally our safest energy source.
For example the Fukushima accident could not have harmed anyone with radioactive fallout, most of the surrounding area didn't even become more radioactive than Denver on a normal day. But because of the deeply UNSCIENTIFIC fear of radiation a needless evacuation was order. That evacuation all by itself destroyed the local economy, upended a hundred thousand lives and killed at least 1,500 people from the needless stress of moving around after a tsunami. NONE of which needed to happen, but they belived it needed to happen because the word radiation has become a synonym for apocalypse. Which is silly, radiation is normal and easily managed.
But it's to be excepted when people have heard nothing but 50 years of poetic nonsense about nuclear energy and NONE of the science. Considering the name of your channel I'd have hoped you'd focus more on the science.
More people die falling off roofs installing solar panels every year than died from Chernobyl. Saying a slightly above average industrial accident could've been the end of humanity undermines every effort to learn about the topic.
More science less sensationalism please.
Sure will consider this point for the future videos, thank you for taking out the time, I appreciate it!
The title of the video only works if you say it in a funny Russian accent.
Become a patron! - www.patreon.com/wts_avk
This is obviously a joke video and I had a good laugh, clearly an RBMK reactor could never explode.
Because Communism.
Do a fuckin voiceover
Ok