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A simplified analysis of the Chernobyl accident (2021)

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Re: A simplified analysis of the Chernobyl accident (2021)

#21

Post by colechristensen »

Retric wrote: post #16
colechristensen wrote: post #15

Earlier quoted context omitted.

This is nonsense, especially this line. >Deviating from procedures prevents as many accidents as it causes. And they weren't doing some small deviation from procedure. They were doing something that was expressly forbidden and they knew why it was forbidden. In the time leading up to the accident it would be difficult to distinguish between what they were doing and trying to intentionally cause a meltdown. In a react…

They are referring to a wider range of situations than this very specific incident. There are many accidents that have been avoided by modifying procedures on the fly. Pilots discovering letting go of the yoke/stick solved some seemingly unrecoverable spins is one example. Though obviously techniques that work eventually get adopted to the procedures. It generally requires operators to know how the systems work in gr…

Sigh, I'm done. Y'all would fail any technical interview I'd ever give regardless of your experience level.

Going on and on about the merits of not following procedure in a discussion that started with a disaster which could have triggered a global mass extinction event is not the appropriate response. They were doing things which were very well known to be dangerous, which they themselves knew to be dangerous, that had been known to be dangerous since literally the first nuclear reactor at the Manhattan Project some 40 years previous.

Re: A simplified analysis of the Chernobyl accident (2021)

#22

Post by dh2022 »

timewizard wrote: post #18
hencq wrote: post #13

Earlier quoted context omitted.

Huh, did you stop watching after episode 1? The HBO series was all about how it was the system that caused the accident to happen. The fact that it was a known failure mode was a major plot point. It can hardly get more explicit than this scene: https://www.youtube.com/watch?v=jBwSuSuGhyk

If you watch the court scene at the end they clearly repeat the KGB line that the local operators were primarily to blame for "reckless" decisions. Perhaps you missed this obvious conclusion of the series.

People are free to draw their own conclusions from the movie. The conclusions I drew are: 1. Blame game started right away ("Of course you are responsible. I was not even in the building" Bryukhanov to Dyatlov in the night of the explosion) 2. During the test some actions were taken with a complete disregard towards safety and consequences. Some people would call this reckless. 3. If this accident did not happen at Chernobyl it would have happened somewhere else.

Re: A simplified analysis of the Chernobyl accident (2021)

#23

Post by Retric »

colechristensen wrote: post #21
Retric wrote: post #16

Earlier quoted context omitted.

They are referring to a wider range of situations than this very specific incident. There are many accidents that have been avoided by modifying procedures on the fly. Pilots discovering letting go of the yoke/stick solved some seemingly unrecoverable spins is one example. Though obviously techniques that work eventually get adopted to the procedures. It generally requires operators to know how the systems work in gr…

Sigh, I'm done. Y'all would fail any technical interview I'd ever give regardless of your experience level. Going on and on about the merits of not following procedure in a discussion that started with a disaster which could have triggered a global mass extinction event is not the appropriate response. They were doing things which were very well known to be dangerous, which they themselves knew to be dangerous, that…

And you’d absolutely fail mine for on both technical grounds, and hyper focus on irrelevant details. “could have triggered a global mass extinction event” WTF

I can only hope you’re never involved in safety critical systems. Procedures simply can’t account for multiple independent failures at the same time in complex systems without defaulting to individual judgment, the problem space just grows too large.

Re: A simplified analysis of the Chernobyl accident (2021)

#24

Post by rob_c »

Retric wrote: post #16
colechristensen wrote: post #15

Earlier quoted context omitted.

This is nonsense, especially this line. >Deviating from procedures prevents as many accidents as it causes. And they weren't doing some small deviation from procedure. They were doing something that was expressly forbidden and they knew why it was forbidden. In the time leading up to the accident it would be difficult to distinguish between what they were doing and trying to intentionally cause a meltdown. In a react…

They are referring to a wider range of situations than this very specific incident. There are many accidents that have been avoided by modifying procedures on the fly. Pilots discovering letting go of the yoke/stick solved some seemingly unrecoverable spins is one example. Though obviously techniques that work eventually get adopted to the procedures. It generally requires operators to know how the systems work in gr…

> It generally requires operators to know how the systems work in great detail which would have avoided the specific Chernobyl incident.

Hence the above comment doesn't fit with the discussion. The level of "bad" being done by the engineers was right out of the "never do this" list of actions. Unfortunately there's a lot of evidence that bravado or "experience" is what led to them thinking that they knew better.

Not following procedure is fine if it's turn it left not right. It's not good when instead of turning a valve they take a hammer to it. That's throwing instructions away and so makes any sensible discussion from there on mute.

Re: A simplified analysis of the Chernobyl accident (2021)

#25

Post by 1659447091 »

dgfitz wrote: post #20
dh2022 wrote: post #19

Earlier quoted context omitted.

Re: "The failure to scale the education quickly enough" - Midnight in Chernobyl makes the case that USSR actively fought to prohibit any sort of disclosures about Soviet nuclear reactors vulnerabilities, mitigations and accidents to the nuclear reactors operators. The soviets did not fail to educate their workforce, the soviets intentionally left their workforce in the dark.

My BIL was a “nukie” when he enlisted. Dumb as a box of rocks, and they kept a sub running like clockwork. You’re absolutely right, the issue was secrecy, not “years of education” or whatever GP claimed.

> was a “nukie” when he enlisted. Dumb as a box of rocks

Not sure what time period this took place, but if you're referring to the US Navy Nukes, then about ~20 years ago Nukes needed a high ASVAB score 95+ (top 5% of test takers) I think it's a bit lower now--and there are other test they can combine scores with--since they all leave for high paying jobs after their enlistment ends. The standard now may not be what it was for simply being a Nuke; but to also be a Submariner (volunteer position), he would have also had to learn all of the submarine systems (mechanical, electrical, navigation, weapons, safety etc) and then a board of senior submariners decide if he was proficient enough to serve on a submarine. You may be being a little harsh calling your BIL "Dumb as a box of rocks", if he accomplished all that.

Re: A simplified analysis of the Chernobyl accident (2021)

#26

Post by Retric »

rob_c wrote: post #24
Retric wrote: post #16

Earlier quoted context omitted.

They are referring to a wider range of situations than this very specific incident. There are many accidents that have been avoided by modifying procedures on the fly. Pilots discovering letting go of the yoke/stick solved some seemingly unrecoverable spins is one example. Though obviously techniques that work eventually get adopted to the procedures. It generally requires operators to know how the systems work in gr…

> It generally requires operators to know how the systems work in great detail which would have avoided the specific Chernobyl incident. Hence the above comment doesn't fit with the discussion. The level of "bad" being done by the engineers was right out of the "never do this" list of actions. Unfortunately there's a lot of evidence that bravado or "experience" is what led to them thinking that they knew better. Not…

I’d be careful how you blame to operators vs power plant designers vs people designing the test vs the USSR’s culture at the time.

In that exact situation you could swap many people inside the USSR into those roles and likely get a similar result. The specific people who decided to cover up RBMK’s flaws were responding to the same incentives as the people who covered up an earlier serious incident at Chernobyl on September 9th 1982 etc.

The U.S.S.R. had a lot of nuclear issues, and there’s arguably more to learn from the indirect causes than the direct ones.

Re: A simplified analysis of the Chernobyl accident (2021)

#27

Post by orbital-decay »

dh2022 wrote: post #19
orbital-decay wrote: post #14

Earlier quoted context omitted.

There were two high-level causes, basically: 1. The failure to scale the education quickly enough. Nation-scale nuclear energy was new when the RBMK line was introduced. The demand for nuclear engineers skyrocketed, and it was impossible to train the required amount of professionals to the same standards as nuclear scientists in just a few years. Meanwhile, the RBMK assumed deeper knowledge of its design than they ha…

Re: "The failure to scale the education quickly enough" - Midnight in Chernobyl makes the case that USSR actively fought to prohibit any sort of disclosures about Soviet nuclear reactors vulnerabilities, mitigations and accidents to the nuclear reactors operators. The soviets did not fail to educate their workforce, the soviets intentionally left their workforce in the dark.

> The soviets did not fail to educate their workforce, the soviets intentionally left their workforce in the dark.

Yes, and guess who was behind that? This it not either-or. I'm already talking about that in 2, which is a high-level cause. Dollezhal's NIKIET specifically refused to admit their problems and sign the document pointing out RBMK's flaws, and got away with things like this multiple times. This was a consequence of a very few selected engineers and scientists having full carte blanche and basically acting as limited-scale politicians within their sphere of influence. This was not the problem of the nuclear industry in particular, this also applied to all critical industries like aerospace where the "chosen ones" immediately started fighting for their place under the sun, stalling their field.

Re: A simplified analysis of the Chernobyl accident (2021)

#28

Post by ahartmetz »

_n_b_ wrote: post #5
Terr_ wrote: post #3

> When there was xenon poisoning in the upper half of the core, the safety rods were designed in such a way that, at least initially, they were increasing (and not decreasing) the core reactivity. I wonder if any reactor-design groups do "fuzz testing" on simulated models, checking that they can recover from very weird states even if it's not clear how the state could have been reached in the first place. For example…

Yes, essentially this happens. PWRs and BWRs have operating limits on their power shape derived from doing those kinds of analyses. They’re tend do be more physical than “arbitrarily xenon-poisoned” but represent a variety of extreme and nominal states to form an operating envelope, and then healthy margins are applied on top of that.

I'm not sure if that expression is known outside of physics, so: "physical" here means "conforming to, possible under the laws of physics"

Re: A simplified analysis of the Chernobyl accident (2021)

#29

Post by rob_c »

Retric wrote: post #26
rob_c wrote: post #24

Earlier quoted context omitted.

> It generally requires operators to know how the systems work in great detail which would have avoided the specific Chernobyl incident. Hence the above comment doesn't fit with the discussion. The level of "bad" being done by the engineers was right out of the "never do this" list of actions. Unfortunately there's a lot of evidence that bravado or "experience" is what led to them thinking that they knew better. Not…

I’d be careful how you blame to operators vs power plant designers vs people designing the test vs the USSR’s culture at the time. In that exact situation you could swap many people inside the USSR into those roles and likely get a similar result. The specific people who decided to cover up RBMK’s flaws were responding to the same incentives as the people who covered up an earlier serious incident at Chernobyl on Sep…

For the case of this incident unfortunately yes it lies with the people stepping off the page and doing something the designer never intended.

That being said yes. Lots of lessons to be learned including, why did you build a system that allows them to do this?

Cause is easy to attribute, identifying who was irresponsible and blame less so. In this case it was caused by the operators.

Re: A simplified analysis of the Chernobyl accident (2021)

#30

Post by [deleted] »

rob_c wrote: post #29
Retric wrote: post #26

Earlier quoted context omitted.

I’d be careful how you blame to operators vs power plant designers vs people designing the test vs the USSR’s culture at the time. In that exact situation you could swap many people inside the USSR into those roles and likely get a similar result. The specific people who decided to cover up RBMK’s flaws were responding to the same incentives as the people who covered up an earlier serious incident at Chernobyl on Sep…

For the case of this incident unfortunately yes it lies with the people stepping off the page and doing something the designer never intended. That being said yes. Lots of lessons to be learned including, why did you build a system that allows them to do this? Cause is easy to attribute, identifying who was irresponsible and blame less so. In this case it was caused by the operators.

[deleted]
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