Xenon Can Be a Problem 

How does this comment not have more likes? It's great to see people with experience commenting in this - great to have you Adam. E.g. I'm a physicist, and while I understand the detailed particle physics, the engineering/practical aspects of this are *way* beyond me. For instance, when you comment "ride the xenon curve" so it's easier to increase reactivity without having to remove further control rods, I've got not idea roughly what fraction would typically have to be removed. I understand approximately that this is to offset other negative reactivity coefficients of temperature (void, thermal expansions etc), and that Chernobyl's positive void coefficient was on reason it ramped up so quickly after the xenon shut-down, but have no "feel" for how this works in practice. So it's great to read this. Having said that, these videos are still Nuclear Physics 101 - a great intro, but fairly basic details, so I think that his statement about "needing to shut down for three days" is close enough of an approximation to be justified.

Oh, and BTW Adam - when you mention " I studied all of the reactor physics formulas, and used to be able to calculate the various values, most of which I have long since forgotten the specifics of, because you don't calculate those things on a daily basis...or ever...in regards to operating a reactor." this was one of the issues at Chernobyl - their computer, SKALA, to calculate these things took 15 minutes to estimate reactivity through various calculations, and even then I suspect it didn't do a good job, since the reactor was so large, the reactivity varied a lot over the core. So all the fancy nuclear engineering theory in the world (at the time) could not have helped them, and they should have just followed the ****ing safety protocols.

​@@clancyjames585 In response to your second comment (I saw them out of order in my notifications) I agree with you 100%. I don't know the specifics about the day to day reactivity calculations at Chernobyl, of course. With a reactor design like theirs, with a graphite moderator giving it a positive void coefficient, and thus positive temperature feedback, my understanding is that they quite frequently had rods moving fairly regularly to maintain everything. We very seldom move rods, because it's just not needed at our plants. Our plants are very stable when it comes to reactivity. The Navy reactors I used to operate were small enough in size, and were very VERY responsive, due to a very high enrichment of U-235, so on those, you really didn't need to calculate anything. You just basically moved control rods a small bit, and you pretty much knew the result from a certain amount of rod motion, and it was very even and predictable. Like driving your car, you don't have to calculate how far to push the gas pedal to drive. Plus, the Navy reactors were responsive enough to negative temperature feedback that you usually would not even need to adjust control rods when you changed power. Raise or lower turbine steam flow, and within a few seconds, the reactor would respond and stabilize at the new power level. The commercial reactor I operate now is a different beast entirely. Much lower enrichment, and very large in size (though smaller than Chernobyl, by quite a bit). We do have negative temperature feedback (unlike Chernobyl), but it's a bit slower to respond than the Navy cores. Our reactor design is inherently very stable, and it has all of the negative feedback aspects to make it essentially remain stable with no continuous manipulations or input at all. Normally, we only make a slight adjustment to the boron concentration every few hours, but that's all it takes to remain stable. Moving the plant around is a bit more involved, but our rods operate automatically to maintain temperature, and we simply have to adjust boron concentration to keep rods from moving too far and changing the power distribution. Easily managed, with no complex calculations required. A spreadsheet can calculate the required adjustments almost instantly. A few simple thumbrules are also used for rapid power reductions, so the reactivity spreadsheet really isn't even needed. Probably one of the biggest differences in our fundamental operation is that if we ever drove the reactor subcritical, like they did at Chernobyl, we would immediately trip/scram our reactor. We would never let power fall so quickly in the first place, and even if we did, we would not rapidly add tons of positive reactivity to quickly restore power, and certainly not outside of design limits. It's just not something we would do. We just have a different safety culture, and of course, the industry has learned quite a lot from accidents like the one at Chernobyl.

@@clancyjames585 In response to your first comment Completely true. I certainly don't want to come off as bashing this video, I mainly just wanted to correct that one particular point, but you are right, this is basic level stuff here, and it doesn't need to be needlessly overcomplicated for most people. To get a little more in depth about riding the xenon curve, the biggest thing we aim to control at my plant is temperature. Sure, there is a limit on power that we cannot exceed, but at the end of the day, the main thing we are driving by is the temperature. We have a certain temperature to maintain at any given power level. If temperature is too high, it means the power output of the reactor is higher than the turbine. If temperature is too low, it means the turbine is making more power than the reactor. What basically happens is that to raise power, we have to open our governor valves and admit more steam to the turbine, to push the generator harder, and make more electrical power. As the governor valves open, it draws off more steam, which cools down the reactor. The turbine power is rising above the power of the reactor, so you have to add positive reactivity to bring reactor power up to match the turbine, and bring temperature back to where it is supposed to be. We have two ways of doing that at my plant (PWR reactor), rods and boron. We have a certain amount of boron dissolved in the coolant which is a neutron absorber. Need to add positive reactivity? Either dilute out some boron (add fresh water with no boron in it, and drain out a little bit of water that has boron in it), or move control rods out. If you move rods out, it makes the power distribution move physically higher up in the core. If you dilute boron out, it moves power lower in the core. So we move rods a little bit, and dilute a little bit to keep power balanced in the middle of the core. More steam to the turbine, cools the reactor, dilute or withdraw rods to keep the reactor temperature up, repeat. As power goes up, it also adds negative reactivity due to the fuel temperature going up, though, so we have to add a little bit more positive reactivity (rods/dilutions) to overcome that bit of negative reactivity. It's all fairly balanced and easy to predict and manage. The only wild card is xenon. If you start with a xenon free core (like it would be a few days after shutdown) and startup the reactor and raise power, xenon will build up as you raise power. So, in that case, you have to add positive reactivity to overcome the temperature change from drawing off more steam, add positive reactivity to offset the negative reactivity from rising fuel temperature, and then add some more positive reactivity to offset the negative reactivity due to xenon building up. I hope all that is clear and makes sense. What's different is if, for instance, you were to trip/scram the reactor, and then start up the next day. On a shutdown or significant down power, xenon builds up rapidly, as explained in the video. You end up with a huge concentration of xenon. Now when you go to start up, the opposite happens. You're raising power, and burning xenon out, rapidly. As xenon burns out, it's adding positive reactivity. This is basically what got the Chernobyl guys in trouble, and started off their problems. But, if you're doing things in a controlled manner, the xenon burnout can help you. You're drawing off more steam to raise turbine power, so you still need to add positive reactivity to keep temperature up and to offset the negative reactivity of fuel temperature rise, but now, xenon is burning out, not building up, so xenon is giving you positive reactivity to help you out. It makes it so that you end up moving rods less, and diluting less boron out of the reactor, because xenon is giving you positive reactivity. In the end, it's all going to balance out, though. But starting up with xenon burning out can make the startup and power rise go a lot smoother, because it can sort of raise power on its own. Oh, and as to what fraction of rods would typically be removed, that's not quite how it works with our cores. Our cores are designed to operate with all rods completely removed, once everything is balanced out at 100% power. We are not at all designed like Chernobyl. Specifically, at my plant, we have 6 banks of rods that are removed one bank at a time, with some small overlap between banks. We are designed to go critical when the last bank is about 3/4 of the way from being completely removed. We calculate how much boron we need to go critical at a given rod height, and we set those conditions before we remove any rods. Once we start up and go critical, we still have about 1/4 of the rod height on that last bank, to help control and manage things as we ramp up in power. Over the next week or so after a startup, we slowly adjust boron concentration and slowly withdraw the rods fully. We really only use rods for "shaping flux" and controlling where the reactor makes power, but it will naturally center itself, and we can get the rods fully removed from the core. What I was basically saying is "riding xenon" will make it so that you don't have to pull rods out as quickly, and don't have to dilute as much or as often. We're still going to end up moving rods all the way out, we just go from maybe moving rods every 10 or 20 minutes, to maybe every hour. Since xenon burnout gives us some positive reactivity, we don't have to add as much positive reactivity due to rods/dilutions. I know this was very wordy, but I hope it makes some sense. Feel free to ask any questions if you're curious or want to know more, or if something isn't clear.

There was a hot spot in the bottom of the core, of which the controllers were unaware. That certainly must have contributed to the explosion. And while I am sure that could be done with western reactors, I am not so sure about the RMBK-1000 reactors those engineers were operating. Hopefully, you never had to operate a reactor capable of going runaway like those.......

Do you work at the Springfield reactor?

@Will K Why you little...

Homer can do it so we all can.

@@willk6464 Cedar creek :D

Best response 😂😂😂

this story was badass, nuclear engineering fascinates me. Its ashame its applications aren't recognized more often.

Very interesting info but let me correct your last statement. The so called by you newer cores do not worry much about the xenon indeed but for a different reason than the one you said. The freshly reloaded core has a lot of excess reactivity while the old one has almost none. The xenon poisoning eats some of the remaining excess reactivity. Since the newer core has plenty of excess reactivity the poisoning effect is significantly reduced. And the neutron flux is less in newer core than the older one. That is because the newer core has more fissile elements and less poisons (decay products) and therefor needs less flux to reach rated power. The older core (near end of campaign) has less fissile elements and more poisons and therefor needs more flux to reach rated power.

@@dgenov Except....aren't newer designs ....supposed to have to retain single fuel load for 2-3 decades? Shouldn't that impact this excess reactivity.

I thanks for the reactor story. Very interesting.

@@piotrd.4850 All military designs are meant for multiple decades. But, that is subject to a disclaimer: Mileage may vary depending on use. So the time a core is good for depends on how heavy a load and for how long said load is placed upon it. Those 2-3 decade life expectencies are based on the accumulated logs of decades of reactor operation from hundreds of nuclear powered ships since the USS Nautilus was first launched. The amount of reactivity in a core is dependent upon: 1) Core geometry (physical layout of components) 2) Core physical size 3) Age 4) Amount of rated power consumed to date (The "fuel" tank of a reactor is rated in "EFPH" "Effective Full Power Hours" or how many hours at 100% power is the core engineered for) 5) Uranium purity. Civilian reactors try to get as close to 20% enrichment with U-235 without actually reaching 20%. 20% is the point Uranium is considered highly enriched and minimum for weapons grade, thus restricted. Military reactors are not bound by this restriction... Continued refinement in all of these categories is what allows for such length lifespans for such tiny sized reactors despite being capable of 100+ megawatts of output at full power.

I'm not even THAT interested in nuclear engineering, but I'll watch a lot of introductory level lectures that I wouldn't otherwise watch when there's this good of a teacher. Of course, you can't really know that what he's saying is true for sure unless you do some much more serious studying, or at least look more deeply into his credentials. But just watching stuff like this casually as a non-student can be very edutaining..

It's because the RU-vid algo is perfect. You watch one freakin Pointer Sisters video - and here you are ;)

Nope. Going over the regulation list was the cause. Akimow should use the water for "cooling" the rector...it would end with the moderate damage. Because it was SL-1 in bigger version...

There were a bunch of different things that combined to create the Chernobyl disaster. Xenon poisoning was definitely one of them. Xenon poisoning was the entire reason that the flow of coolant was reduced greatly AND the reason that the safety system that operated the control rods was disabled so more than the allowed number of control rods could be removed in an attempt to overcome the Xenon poisoning. The runaway reaction was caused directly by the lack of control rods in the reactor (creating serious "hot spots" since the minimum 24 rods arranged throughout the reactor that were ALWAYS supposed to stay put were mostly removed) and the lack of coolant being pumped was what caused steam voids to form in the coolant channels in these hot spots. Once those two things happened it was all over. Obviously the positive void coefficient and the flaw in the control rods were instrumental too.

@@danlorett2184 Those "rods" are called buffers. They were created to suppress the "power jumps" during the shut-down. Of course you can flood reactor with water and whole reaction would be killed. Diatłow thought about that but Akimow, pissed enough on rough old man, used AZ-5 thus blowing the nuclear reactor. No one listened young Tuptonow... P.S. I believe it was iodine, no the xenon that caused the problem. I-135 with half-life of HOURS! (6.57 h) Also open to neutrons.

Sounds so simple ... and logical.

@@danlorett2184 Xenon poisoning is not cause of Chernobyl disaster for the same reason that gravity wasn't a cause of Columbia disaster. Xenon poisoning is just a physical fact. You design your system to deal with it. And if you did not design it to deal with it the cause of the disaster is you, not Xenon poisoning.

As Mork (Mork & Mindy) said, “Oh come on folks. Just use a can of NukeAway”.

it makes it easier for me(a person who have gone to 8+ years of university) to understand too.

Yes the Moltex design is very interesting. Though I'm puzzled why they switched from fluoride salts to chloride salts. I thought the negative void coefficient was because the fluorine had some moderating effect so a void in the coolant would reduce moderation. I'll have to read up on their new design.

the guy tells garbage. Chernobyl did not explode because of xenon poisoning, it was human error and unknown technical problems for all reactors of this type (by the way, an American design and not a Russian development). The nuclear industry has learned a lot from Chernobyl and abolished graphite moderators, since once they burn they can no longer be extinguished.

1. Thanks RU-vid Algorithm for waking up this video. 2. One thing he gets wrong is that the engineers at Chernobyl knew about Xenon. They weren't stupid. They knew they were working with a poisoned reactor, but in the rush to finally get this stupid test out of the way, they tried to run the experiment anyway. They thought they could SCRAM the reactor and shutdown if anything went wrong. They figured, what's the worst that could happen, they shutdown and try again later? The reduced coolant flow (part of the test) triggered the rapid burnoff of Xenon, They tried to shutdown, but the control rod design caused them to increase reactor power at first before they started slowing the reaction and then pent up steam pressure from the overpowered reactor bent the rods to the point where they got stuck, and then coolant lines in the reactor exploded, but the reactor was designed to contain one or two exploding coolant channels. They thought it was a super safe design but in reality it was so unstable no one ever expected they would blow three or more at once. This blew the lid open, exposed the superheated graphite to oxygen in the air, and that caused the main explosion. Soviet physicists knew about the control rods. They knew that the rods could cause an unexpected spike in power when first inserting them. They saw this happen in a previous incident, but they purposely withheld this information from the plant engineers. If they had known they wouldn't have messed around like this.

@@johns8364 Either way it was still human error whether they intended to run a poisoned reactor or not.

He is almost certainly writing normally and the video is mirror in post production.

Note that his coat buttons are on the wrong (left) side. He’s writing left handed but is most likely right handed.

@@dp4racinggood eye. there's gotta be someone out there that could pull that off for real tho. Or not. But boy o boy do I hope there is. Cheers.

@@trainthetopchef This would be clever but not a realistic expectation for a professor.

I graduated with my ME and EE degrees decades ago, and I find these 'lecturettes' really interesting and very well done. Nice to know they appeal to non-technical people too.

i read somewhere that they knew about it, and even had a safety protocol , which pointed out to shut down the reactor in such a case, but Djatlov didnt give a fck and wanted to start the test anyways.

Why?

@@markthorne2296 - In the case that you are being funny: LOL!!! In the case that you are being serious: WHOOOOOSH....

He's still on the toilette.

Presentation seems sketchy. Send this man to the vent block roof to determine the truth!

He is delusional. Send him to infirmary: Comrade Dyatlov

the video is flipped horizontally

Check my Oct 15 post to learn how he writes "backwards."

Keeping you in suspense.

Good pickup. Didn't notice that! It seems that Xe-135 is radioactive and emits electrons with a half life of 9hrs - so it would be quickly exhausted anyway

I love this comment

I'm pretty sure the video is mirrored. Pins usually go on the left side of the lapel and his is on the right. Also, his wedding ring is on his right ring finger.

pokemoncars as if this channel doesn’t make feel dumb enough....

it *probably* wasn't 30GW (nobody can tell for sure as all the instrumentation simply pegged), most likely "just" single digits of multiples, but still enough to eventually throw the reactor lid through the roof :D In case of Chernobyl, what added insult to injury was the fact that the control rod mechanism was so painfully slow...had it been capable of a SCRAM by modern reactor standards, the plant would (probably...Dyatlov did a lot of things that night that he should not have ever done) still be in one piece. Damaged reactor, but probably still in one, albeit partially molten piece ;-)

@richard mccann Bear in mind that even if the reactor went prompt critical in 3 miliseconds, even with 30GW of power creation, it would take a couple seconds to heat up the ~ 5 tons of core to the point where it explodes. This inertia is actually a bad thing, as it delays the disruption of the core , allowing more energy to build up before it stops the reactor by disassembly.

But losing your moderator causing the reactor to shut down, not increase in power. The problem was not the water, it was the fact that the graphite provided moderation even without the water. Moderators slow down neutrons and only slow neutrons cause fission in U-235.

"Lose the water, and the moderation increases," this is certainly wrong. Water has two effects: it moderates the speed of neutrons from fast (directly after fission) to slow (thermal), as the cross section for splitting U-235 is much higher. But it also acts as a (mild) neutron poison, by neutron capture from hydrogen to deuterium (H-2). In a BWR or PWR, the sentence is: loose the water, and the moderation decreases, which brings down the reactivity. In RBMKs, the water is not primarily used for moderation, as graphite is used for this purpose. If the water goes away, the moderation is still fine but the neutron absorber qualities of water are lacking and the reactivity goes up. That is the reason for the positive void coefficient of RBMKs.

@@gunnarkaestle sigh. Lose the water, and the percentage of neutrons that are moderated by the graphite (becoming suitable for fission) increased, *because* less are absorbed by the steam as compared to water. Thus the reactor *as a whole* has more moderated neutrons capable of inducing fission. This is what I mean by "the moderation increases". Which is, frankly, exactly what you are saying, but you are being an ass and arguing just for the sake of arguing simply because you do not understand english.

literally made me laugh out loud

Bounty vs the competition.

Because paper can block alpha emissions/neutrons.

You were in the toilet while running the reactor core

And that is why you do not let nuclear plant engineers watch old episodes of Star Trek, where Scotty and Mr Spock breaks the laws of physics, and restarts reactor, and saves Enterprise from Burns up in the atmosphere.

Dr mosfet, Ah, the antimatter implosion calculation. Seems to have sent them back in time a few days too.

Maybe the only question not directly addressed was that since xenon is a gas, why does it stay behind rather than ventilating out of the core. Being trapped in the solid fuel rods well enough that the escape rate is low or nil is perhaps the explanation.

I suspect the video was mirror flipped when edited.

ABaumstumpf The second explosion was most likely a hydrogen detonation. You flash boil a bunch of water, as happens in a steam explosion, you have alot of leftover hydrogen, which likes in explode in of itself. Modern reactors are designed with blow out panels for this reason.

The second explosion might also be small nuclear explosion (a "fizzle"). The IAEA report www-pub.iaea.org/MTCD/Publications/PDF/Pub913e_web.pdf page 3 says that the total loss of water (e.g. after the first explosion has ruptured a lot of the pressure tubes) can lead to an increase reactivity of 4-5 beta. An addition of one beta alone to a normally running chain reaction means the reactor core is prompt critical.

@@willh8950 I assume the blow out panels are (as in other regular thermal power plants) in the secondary circuit of a PWR to relieve pressure if there are problems in the turbine/condensor etc. Venting the containment (if the pressure rises to high) is another thing.

I'd disagree. I believe in 5th part of "Chernobyl" mini-series they've described pretty well in quite clear and understandable way what had happened and all major factors which contributed.

@@user-vo8ss2bm3p Well, at that point it's a matter of personal preference. But the technical explanations laid here are overall more interesting to me, althought the serie was indeed quite good as well.

@Bill Laswell Saw it as well! It was pretty good too that's true.

@@user-vo8ss2bm3p Isn't that the same mini-series that claimed the reactor would explode with a force between 2 and 4 megatons?

As the other comment said, 3 days might be excessive. You could restart it immediately. But don't expect any power output until the xenon has absorbed enough reaction. Whatever you do, don't do something stupid like pulling out control rods.

@104th_Maverick It rather depends on what kind of materials (elements, compounds) one uses for control rods. See here for an explanation --> en.wikipedia.org/wiki/Control_rod

@@kurt44mg42 I read this article, and unfortunately it still doesn't answer 104th_Maverick's excellent question.

@MegaSexfanatic That's basically true, but there's a little more to it. I am a licensed operator at at PWR, and we do use boron as our primary reactivity control. We either borate (inject boric acid, which is water with dissolved boron) or dilute (add fresh water without boron) to control how much boron is in the reactor coolant (which is just ultra pure water with a certain amount of boron in it). We have a system that automatically maintains a certain volume, so whether you pump in boric acid to borate, or pump in fresh water to dilute, the same amount of water that's already in the system drains out to a large collection tank, which gets cleaned up and processed and eventually released to the environment once it's clean. But, we do use control rods, as well. Our control rods are made of silver, indium, and cadmium. The control rods are normally used for starting up the reactor, and for controlling where in the core the power is being produced. But the control rods are also our emergency shutdown method - a reactor trip literally drops all of the control rods into the core to shut it down in an emergency.

There is a limit, of course. The way neutron absorbing materials work is to...well...absorb a neutron. That changes it into a different isotope. Some elements have several stable isotopes, some have very few. Each time an atom absorbs a neutron and becomes a different isotope, it may be better or worse at capturing another neutron, it may be stable and never absorb another neutron, or it might be unstable and decay (radioactive). I can't speak for all the different absorber materials, but generally, control rods are going to be made out of materials that can capture a very high number of neutrons before they lose that ability. Speaking from personal experience, I have about 15 years experience at my current plant, and in that time, out of 96 control rods combined between two reactors, we have only replaced one single control rod. And that was due to a mechanical issue, not a neutron absorber issue. So, simple answer, yes, there is a finite number of neutrons a control rod can absorb, but it's a huge number, and replacing control rods is not at all a common thing. We reuse the same exact control rods over and over and over again.

Theoretically, yes, but I've never heard of it being done. The materials from which the reactor vessel is constructed is more likely to reach its end of useful life first due to neutron embrittlement.

In fact, delayed neutrons is what making all of humanity's application of nuclear energy even possible at all. At least, until the reactors like BN-800 will become a mainstream solution.

I would guess not since the xenon would float to the top.

Yes, they do, but as LaserFur says, it tends to just collect at the top of the reactor and is drawn off. In general, a lot of fission products are poisonous (though none as much as Xenon), but in the LFTR they are in the liquid fuel/coolant, which is continuously drawn off, has the FPs removed, and is rebalanced with thorium and uranium, and then injected back into the reactor. Never stop for refueling, FPs always kept at a low level.

@@puncheex2 Sounds like a cheap way to make radioactive Xenon, or Cessium.

@@Zamolxes77 If that is your goal, yes.

@@puncheex2 I wonder how easy it is to maintain the operation of this "kidney" function. What were the servicing cycles at the Oak Ridge MSR?

Funnily enough, the RBMK reactors aren't that bad. Besides the carbon tipped control rods.

@@mpk6664 Exactly! They are good enough with in built safety systems that insert control rods much before the reactor becomes unstable. That prick Dyatlov oversaw disabling ALL automatic safety systems and ignored the computer warnings. The only flaw I see was the absence of an extra containment building

There's a reason nobody else uses commercial graphite moderated reactors

The show actually discussed both, and set them up as legitimate reasons. First, I think the show actually did a bad job calling these graphite tipped. The way a RBMK reactor is designed there is a graphite rod at the bottom of the control rod, if you lift the control rod up, you are lifting the graphite rod up into the reactor to replace the control rod. There is also a void between the two rods which has some displaced water between them. The issue is that when the graphite moderator is fully elevated, displaced water goes into the bottom, like a cap, because the fuel rods are longer than the graphite rods. The issue in this design, is that as soon as you scram the reactor and inserts all of the control rods, the first thing that is going to happen is the water will displace, and the graphite will fill the void. When this happened it created a hotspot of intense heat, for just a few seconds, this was enough to burst and break the control rods, fixing them in place. Since they were fixed in place, the reaction never slowed, vaporizing all of the water and turning it into a steam bomb that blew off the top of the reactor, allowing oxygen in, which should never be present there, and that triggered the explosion and fire. So yes, xenon poisoning contributed the disaster, but the real cause was an emergency shutdown system that was literally a nuclear bomb detonator. Sure, xenon poisoning caused the reactor to go critical, but the emergency shutdown should have instantly shut down the reaction, and instead made a huge explosion of thermal energy. Hope that helps.

I'm not sure if you completed the web series, but the last episode had a huge section dedicated to just explaining the Xenon Poisoning. Azimov even tells Dyatlov, "the reactor is in a xenon pit, we have to shut down, we have to wait 24 hours." He then asks Dyatlov to record his order in the book, who then smacks it out of his hands and orders him to do it or never work in any reactor, anywhere, ever again. There was absolutely someone in that room, that not only knew this rule, but protested the orders they were being given. Dyatlov knew all about this rule as well, this wasn't ignorance. He was defiant, because in his younger years there was an accident that had exposed him to lethal doses of radiation and he was fine, he lived believing he was invincible. Despite this, his son died of Leukemia, due to contamination that he brought home from the earlier incident. He was a stubborn idiot, who literally ordered his crew to turn a reactor into a nuclear bomb, despite every regulation otherwise. Valery says this in his speech at the end "Dyatlov broke every rule we had, every one of them, but he did so with the belief that there was an emergency shutdown system that could prevent what happened." I'll remind you that even after the incident, Dyatlov was so certain that this event could have never happened, that he sent his men into the core, killing them with radiation poisoning.

Especial in the 80s😁

Is the professor left handed and adept at writing backward or is this a 180 flip during rendering? Nevertheless he's good.

@@fiftystate1388 its a horizontal flip. same trick a lot of 'void talkers' use (like because science with Kyle)

Just get good.

I think it depends on the type of reactor. A PWR does exactly as you say, dropping control rods in. A BWR pushes it in from the bottom. There are advantages to bottom-entry control rods such as being able to refuel without removing the rods. Bear in mind I'm just interested in this stuff rather than an expert and have only read this up on Wikipedia.

He does write well backwards.

Scarakus lol, yeah that's the first thing i noticed. First if this production style I've seen to be smart enough to flip the image.

i feel like they could remove it with a bit of a low-pass filter w/o affecting his speaking

Or the late '70s haircut.

More I try to focus on neutrons more I hear the squeaky pen

Cameron Wichman makes it great?

It's keeps the attention! I think it's deliberate. He orders noisy markers.

filthy Xenos are always a problem unless you need target practice. lol

Purge the xenos...and the xenon

Adelram Wolfrik They did but the man in charge allegedly overruled them in order to finish the test 😯

That's Socialism for ya.

@@iasimov5960 what does the power structure in a control room have to do with an economic system? I think maybe you're using words you don't understand comrade.

I'm really grateful for this information as well. Absolutely a must share for all my friends with reactors.

@@SteveJohnson007 Thank you Steven for your very informative videos. I am degreed in Electrical and Computer engineering, but I have always taken an interest in Nuclear engineer. Great content!

Not always true. In commercial reactors generally they restart the next day - 20-24 hours is enough for a lot of the Xenon to decay and the rest can be overcome by careful startup procedure.

no, thats jibberish. reactors DO NOT NEED three days between shut down and start up. building up that much xenon is a symptom of poor management, nominal levels will decay within the day

@@SteveJohnson007 too bad the three day thing is completely wrong

My "depdantism" wishes me to point out that you spelled pedantism wrong, but it's a youtube comment so I'll let it slide

Half life longer than the life of the Universe? Yeah it's STABLE !!!

Xeon, not Xenon. lol

I thought this was about the warrior princess.

please explain.

@@user-so8fm7ls4h wow, thanks for answering without sarcasm, cause i was literally about to ask the same thing

@@user-so8fm7ls4h you're confused rbmk reactor don't explode

@Bill Laswell You must not get around RU-vid much. And/Or you never leave the realm of videos on nuclear reactions.

@@p5satanael Even with the safety upgrades after Chernobyl, the RBMK design (still 10 units in operation in Leningrad, Kursk and Smolensk) allows an explosion. A sudden loss of significant water masses (i.e. a large size LOCA), will increase the reactivity by 4-5 betas. A beta stands for the amount of delayed neutrons, which is the reason you can control a chain reactor in a nuclear reactor. One beta is the difference between prompt critical and (delayed) critical. Prompt critical means boom! as in atom boomb (even though badly designed atom bombs may fizzle and tear themselves apart before splitting a significant part of the nucleii). www-pub.iaea.org/MTCD/Publications/PDF/Pub913e_web.pdf page 3

Or, at least, not steady, controlled fission. It is always a bit like balancing an inverted pendulum.

The problem with fission naturally is that it is typically all or nothing if you have enough fuel to go critical.

and yet .... ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-pMjXAAxgR-M.html

All of the world's Helium supply comes from Alpha decay underground. Nature is okay with fission, but not this chain-fission ox we've yoked. The element Promethium was discovered as a result of nuclear experiments. I think it's the most aptly named of any Element artificially discovered. Promethius stole fire from the gods. We stole fission from God while treading on his domain. We must treat lightly.

I have heard that fission wells are found in nature where a hollow in the surrounding fissile material fills with water, which acts as a moderator: it goes critical and boils the water out, and so on in cycles.

At least they caught it and corrected it.

@@jayyyzeee6409 too late for me (coughs up lung) I went with the original diagram (feet fall off) and gjrori fkfkds gjfll (tongue fell out)

they mirror the video in post his jacket buttons are on the wrong side

@@AlexiLaiho227 - How observant of you.

I can't handle that squeaky sound either.

Glad I'm not the only one that caught this