7 ms·

Funny how the article doesn't say what the cracks mean, but it does end with a bunch of reasons why a safety rule has to be waived: - jobs - energy supply wh

Funny how the article doesn't say what the cracks mean, but it does end with a bunch of reasons why a safety rule has to be waived: - jobs - energy supply why is it that when a safety limit has been established and later on reached, that (seemingly) uninformed people start walling by screaming 'but the jobs' and 'but the power'. None of those should be more important than a reactor problem you'd think. On the other hand, if there is inside information describing the impact of such cracks as irrelevant to safety and operation, then it would be fine (but then you wouldn't have to cry for jobs and energy). Jobs should not be a reason to not take into account safety or evolution. As soon as you do that, everything stagnates.

wbl 7y ago
Safety limits are very conservative and are established through experiments. If the reactor can still be shut down safely and will for a few more years then it can run.
- Someone 7y ago
  As an example, the initial safety assessment may assume that a) 5mm is the limit for crack width, and b) by the time cracks are 1mm wide, they will be 2mm wide a month later, and, because of that growth rate, pick 2mm as the “take out of commission now” point (nb: numbers 100% made up; for illustration only) If, in real life, it turns out that it takes a year for a crack to grow from 1mm to 2mm, the model used can be improved. Result _could_ be that the “take out of commission now” point gets moved to 3mm. They also may remove some stuff with 2mm cracks and test it for strength, and learn more about how the stuff behaves after being irradiated for decades. That, too, can change (in either direction) the life expectancy of the reactor.
  - einpoklum 7y ago
    Perhaps, but surely you realize that there is currently a lot of pressure (and therefore bias) for keeping the plant operational: Jobs, energy supply and the operator's profits. And the thing is, those biases affect both the regulator (the government), the local population (who probably want to keep their jobs) and the operator (EDF Energy). So at this point in time I would be skeptical of new experiments and model updates performed by the operator and approved by the regulator. IMHO: Don't approve the model change, do some lab experiments / examine more empirical evidence over time and then possibly change the model for a _future_ reactor.
    - Someone 7y ago
      I do, but there also is a lot of pressure to close nuclear reactors because the perceived danger of nuclear power is a lot higher than its real danger. Also, would you be in favor of _not_ changing the model for current reactors if updated models predict a shorter life time? If you think the model should be updated in those cases, that introduces bias. It also could mean reactor owners would stop making measurements, and that, in turn, would mean we would learn less about making safer reactors.
  - Zigurd 7y ago
    If such conditions exist, they can be determined while the reactor is shut down. Otherwise that's recklessness. The original safety margins are there for good reason. Setting them aside without thoroughly testing new limits with justifications that include reasons why the original limits were wrong is reckless. "Nothing bad happened" is not a good reason.
- mcguire 7y ago
  The strategic industrial behavior is to accept conservative safety limits initially and then apply for exceptions as needed to keep the site running. You'll see the same thing from nuclear power to various chemical plants to NASA.
- inflatableDodo 7y ago
  Safety limits are very conservative on nuclear power for fairly well established reasons though. If your worst case scenario makes the two largest metropolitan areas in a country uninhabitable for a while, for the current power equivalent of around 6 months new build in offshore wind (Hunterston is 1 GW and we are currently building out around 2 GW a year in offshore wind), then perhaps the caution is worth it.
petre 7y ago
If the moderator (graphite) crumbles into the channel it could jam it and prevent the control rods from entering the core and stop the nuclear reaction. However there are secondary (Nitrogen injection) and tertiary (Boron beads) modes of shutting down the reactor. "In October 2014 a new kind of crack in the graphite moderator bricks was found at the Hunterston B reactor. This keyway root crack has been previously theorized but not observed. The existence of this type of crack does not immediately affect the safety of a reactor – however if the number of cracks exceed a threshold the reactor would be decommissioned, as the cracks cannot be repaired." https://en.m.wikipedia.org/wiki/Advanced_Gas-cooled_Reactor https://en.m.wikipedia.org/wiki/Advanced_Gas-cooled_Reactor
- Reason077 7y ago
  > "however if the number of cracks exceed a threshold the reactor would be decommissioned, as the cracks cannot be repaired" This is the issue currently. The cracking in reactor 3 has progressed more rapidly than modelled, and has exceeded the threshold of 350 cracks. EDF are arguing that the reactor can be safely operated with more cracks, and want the threshold increased to 700.
- Reason077 7y ago
  > "However there are secondary (Nitrogen injection) and tertiary (Boron beads) modes of shutting down the reactor." Hunterston B has also been fitted with "super-articulated" control rods that are designed to be insertable even if the graphite channels are destabilised/distorted. https://www.bbc.co.uk/news/uk-england-somerset-37789654 https://www.bbc.co.uk/news/uk-england-somerset-37789654
module0000 7y ago
If graphite cracked/crumbled to prevent the control rods from being re-inserted, that's some scary stuff. The article ending with a request for the safety limit for number-of-cracks to be increased was really surprising for me. The whole "risk VS reward" test comes to mind... the reward is power for 1.8 million homes, but the risk is total catastrophic destruction of the environment for (tens of) thousands of years. The odds may look good, but geez...just a huge gamble to take with other peoples homes/property/lives.
- petre 7y ago
  > total catastrophic destruction of the environment for (tens of) thousands of years More like 300 years (10 Cs137 and Sr99 half lives) but otherwise you're right.
  - deleted 7y ago
    [deleted]
  - mimixco 7y ago
    Plutonium, a byproduct of all nuclear reactors and part of their waste stream, is dangerous for 240,000 years.
    - strken 7y ago
      How much plutonium is likely to be released in a nuclear incident? I thought Three Mile Island and Chernobyl mostly released radioactive isotopes of iodine and a bunch of noble gasses, with cesium, plutonium, and strontium being present in smaller quantities and generally settling closer to the reactor.
    - antidesitter 7y ago
      Where did you get that number?
      - wahern 7y ago
        Seems like a typo. Half-life of Pu-239 is ~24,000 years, and of Pu-242 ~374,000 years. I'm guessing Pu-239 was intended as 1) an extra "0" digit is the more likely typo, and 2) Pu-239 is (AFAIU) the principal Plutonium byproduct of typical Uranium fission reactors.
lruor 7y ago
>why is it that when a safety limit has been established and later on reached, that (seemingly) uninformed people start walling by screaming 'but the jobs' and 'but the power'. None of those should be more important than a reactor problem you'd think. And if it depended on those people the reactor would keep running until it exploded. It's almost as if democracy was stupid and ineffective.
- new4thaccount 7y ago
  I don't think democracy is the problem. The current and broken system in many nations is. I'd rather not have a dictatorship and I don't see Anarchy being particularly effective either. What is your solution? Edit: I understand the feeling of helplessness, but saying that democracy doesn't work is dangerous as this feeling of apathy spreads and people stop participating in the system and we lose many of the more reasonable voters and then less savory candidates get elected and make things even worse and more apathy spreads and so forth. It becomes a vicious cycle and self-fulfilling prophecy. I'm very guilty myself, but have vowed to start participating more in elections and local politics.
kristianc 7y ago
Hanlon shows that people rate 'jobs' above all sorts of variables, including economic growth and shuttering zombie businesses which would make everyone richer. Particularly bizarre in a country like the United Kingdom which is operating at record levels of employment.
- dymk 7y ago
  Is it bizarre? It seems really intuitive that a country where jobs are prioritized above most else has an incredibly high employment rate.
  - oneplane 7y ago
    It might seem inventive, but in this scope/size intuition is often wrong. Same with all large or long-term things in general; humans are notoriously bad at those. Take this specific case; stay the reactor's systems fail (all of them including the quadruple redundancies), those jobs and energy generators are kind-of irrelevant if you are dead...
    - gubbrora 7y ago
      I'm sure the reactor enables a lot of jobs far enough away that they'd be safe if it explodes or whatever
      - oneplane 7y ago
        In that case, why not make many exploding reactors, jobs for everyone! /s You do see what the point is, right?
- TheOtherHobbes 7y ago
  The UK is operating at entirely fake levels of employment. The statistics are based on a Labour Force Survey which counts anyone who works for one hour a week - or more - as employed. And also anyone who labels themselves as self-employed, irrespective of hours worked. This is explicitly official policy, and not exaggeration or hyperbole. https://www.ons.gov.uk/employmentandlabourmarket/peopleinwork/employmentandemployeetypes/methodologies/aguidetolabourmarketstatistics#employment https://www.ons.gov.uk/employmentandlabourmarket/peopleinwor...
xupybd 7y ago
I don't think that was the reason. The reason they waived the safety rule is that a further year of modelling and tests determined that the plant was still safe to run. The motivation for keeping it running was jobs and energy supply. But the extra modelling allows it to continue.
teh_klev 7y ago
> inside information This is my biggest problem with the nuclear industry. To begin with much of the design and operations of nuclear power stations were classed as state secrets, today they're classed as commercial secrets. Until the full operational characteristics of these generating stations are properly revealed we just can't trust nuclear power.

wbl 7y ago

Safety limits are very conservative and are established through experiments. If the reactor can still be shut down safely and will for a few more years then it can run.

Someone 7y ago
As an example, the initial safety assessment may assume that a) 5mm is the limit for crack width, and b) by the time cracks are 1mm wide, they will be 2mm wide a month later, and, because of that growth rate, pick 2mm as the “take out of commission now” point (nb: numbers 100% made up; for illustration only) If, in real life, it turns out that it takes a year for a crack to grow from 1mm to 2mm, the model used can be improved. Result _could_ be that the “take out of commission now” point gets moved to 3mm. They also may remove some stuff with 2mm cracks and test it for strength, and learn more about how the stuff behaves after being irradiated for decades. That, too, can change (in either direction) the life expectancy of the reactor.
- einpoklum 7y ago
  Perhaps, but surely you realize that there is currently a lot of pressure (and therefore bias) for keeping the plant operational: Jobs, energy supply and the operator's profits. And the thing is, those biases affect both the regulator (the government), the local population (who probably want to keep their jobs) and the operator (EDF Energy). So at this point in time I would be skeptical of new experiments and model updates performed by the operator and approved by the regulator. IMHO: Don't approve the model change, do some lab experiments / examine more empirical evidence over time and then possibly change the model for a _future_ reactor.
  - Someone 7y ago
    I do, but there also is a lot of pressure to close nuclear reactors because the perceived danger of nuclear power is a lot higher than its real danger. Also, would you be in favor of _not_ changing the model for current reactors if updated models predict a shorter life time? If you think the model should be updated in those cases, that introduces bias. It also could mean reactor owners would stop making measurements, and that, in turn, would mean we would learn less about making safer reactors.
- Zigurd 7y ago
  If such conditions exist, they can be determined while the reactor is shut down. Otherwise that's recklessness. The original safety margins are there for good reason. Setting them aside without thoroughly testing new limits with justifications that include reasons why the original limits were wrong is reckless. "Nothing bad happened" is not a good reason.
mcguire 7y ago
The strategic industrial behavior is to accept conservative safety limits initially and then apply for exceptions as needed to keep the site running. You'll see the same thing from nuclear power to various chemical plants to NASA.
inflatableDodo 7y ago
Safety limits are very conservative on nuclear power for fairly well established reasons though. If your worst case scenario makes the two largest metropolitan areas in a country uninhabitable for a while, for the current power equivalent of around 6 months new build in offshore wind (Hunterston is 1 GW and we are currently building out around 2 GW a year in offshore wind), then perhaps the caution is worth it.

petre 7y ago

If the moderator (graphite) crumbles into the channel it could jam it and prevent the control rods from entering the core and stop the nuclear reaction. However there are secondary (Nitrogen injection) and tertiary (Boron beads) modes of shutting down the reactor. "In October 2014 a new kind of crack in the graphite moderator bricks was found at the Hunterston B reactor. This keyway root crack has been previously theorized but not observed. The existence of this type of crack does not immediately affect the safety of a reactor – however if the number of cracks exceed a threshold the reactor would be decommissioned, as the cracks cannot be repaired." https://en.m.wikipedia.org/wiki/Advanced_Gas-cooled_Reactor https://en.m.wikipedia.org/wiki/Advanced_Gas-cooled_Reactor

Reason077 7y ago
> "however if the number of cracks exceed a threshold the reactor would be decommissioned, as the cracks cannot be repaired" This is the issue currently. The cracking in reactor 3 has progressed more rapidly than modelled, and has exceeded the threshold of 350 cracks. EDF are arguing that the reactor can be safely operated with more cracks, and want the threshold increased to 700.
Reason077 7y ago
> "However there are secondary (Nitrogen injection) and tertiary (Boron beads) modes of shutting down the reactor." Hunterston B has also been fitted with "super-articulated" control rods that are designed to be insertable even if the graphite channels are destabilised/distorted. https://www.bbc.co.uk/news/uk-england-somerset-37789654 https://www.bbc.co.uk/news/uk-england-somerset-37789654

module0000 7y ago

If graphite cracked/crumbled to prevent the control rods from being re-inserted, that's some scary stuff. The article ending with a request for the safety limit for number-of-cracks to be increased was really surprising for me. The whole "risk VS reward" test comes to mind... the reward is power for 1.8 million homes, but the risk is total catastrophic destruction of the environment for (tens of) thousands of years. The odds may look good, but geez...just a huge gamble to take with other peoples homes/property/lives.

petre 7y ago
> total catastrophic destruction of the environment for (tens of) thousands of years More like 300 years (10 Cs137 and Sr99 half lives) but otherwise you're right.
- deleted 7y ago
  [deleted]
- mimixco 7y ago
  Plutonium, a byproduct of all nuclear reactors and part of their waste stream, is dangerous for 240,000 years.
  - strken 7y ago
    How much plutonium is likely to be released in a nuclear incident? I thought Three Mile Island and Chernobyl mostly released radioactive isotopes of iodine and a bunch of noble gasses, with cesium, plutonium, and strontium being present in smaller quantities and generally settling closer to the reactor.
  - antidesitter 7y ago
    Where did you get that number?
    - wahern 7y ago
      Seems like a typo. Half-life of Pu-239 is ~24,000 years, and of Pu-242 ~374,000 years. I'm guessing Pu-239 was intended as 1) an extra "0" digit is the more likely typo, and 2) Pu-239 is (AFAIU) the principal Plutonium byproduct of typical Uranium fission reactors.

lruor 7y ago

>why is it that when a safety limit has been established and later on reached, that (seemingly) uninformed people start walling by screaming 'but the jobs' and 'but the power'. None of those should be more important than a reactor problem you'd think. And if it depended on those people the reactor would keep running until it exploded. It's almost as if democracy was stupid and ineffective.

new4thaccount 7y ago
I don't think democracy is the problem. The current and broken system in many nations is. I'd rather not have a dictatorship and I don't see Anarchy being particularly effective either. What is your solution? Edit: I understand the feeling of helplessness, but saying that democracy doesn't work is dangerous as this feeling of apathy spreads and people stop participating in the system and we lose many of the more reasonable voters and then less savory candidates get elected and make things even worse and more apathy spreads and so forth. It becomes a vicious cycle and self-fulfilling prophecy. I'm very guilty myself, but have vowed to start participating more in elections and local politics.

kristianc 7y ago

Hanlon shows that people rate 'jobs' above all sorts of variables, including economic growth and shuttering zombie businesses which would make everyone richer. Particularly bizarre in a country like the United Kingdom which is operating at record levels of employment.

dymk 7y ago
Is it bizarre? It seems really intuitive that a country where jobs are prioritized above most else has an incredibly high employment rate.
- oneplane 7y ago
  It might seem inventive, but in this scope/size intuition is often wrong. Same with all large or long-term things in general; humans are notoriously bad at those. Take this specific case; stay the reactor's systems fail (all of them including the quadruple redundancies), those jobs and energy generators are kind-of irrelevant if you are dead...
  - gubbrora 7y ago
    I'm sure the reactor enables a lot of jobs far enough away that they'd be safe if it explodes or whatever
    - oneplane 7y ago
      In that case, why not make many exploding reactors, jobs for everyone! /s You do see what the point is, right?
TheOtherHobbes 7y ago
The UK is operating at entirely fake levels of employment. The statistics are based on a Labour Force Survey which counts anyone who works for one hour a week - or more - as employed. And also anyone who labels themselves as self-employed, irrespective of hours worked. This is explicitly official policy, and not exaggeration or hyperbole. https://www.ons.gov.uk/employmentandlabourmarket/peopleinwork/employmentandemployeetypes/methodologies/aguidetolabourmarketstatistics#employment https://www.ons.gov.uk/employmentandlabourmarket/peopleinwor...

xupybd 7y ago

I don't think that was the reason. The reason they waived the safety rule is that a further year of modelling and tests determined that the plant was still safe to run. The motivation for keeping it running was jobs and energy supply. But the extra modelling allows it to continue.

teh_klev 7y ago

> inside information This is my biggest problem with the nuclear industry. To begin with much of the design and operations of nuclear power stations were classed as state secrets, today they're classed as commercial secrets. Until the full operational characteristics of these generating stations are properly revealed we just can't trust nuclear power.