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Fessenheim nearly got out of control in 2016 when water flooded electrical equipment racks. Control of of the reactor rods was interrupted, core temperature was

Fessenheim nearly got out of control in 2016 when water flooded electrical equipment racks. Control of of the reactor rods was interrupted, core temperature was rising uncontrollably. Letting the control rods fall into the core via gravity didn't work anymore either. They had to emergency flood the core with Boron, which luckily worked, the first time this has happened in a western european power reactor. They assigned the incident level 1, the lowest one, in order to cover it up. France has huge power demands in cold weather due to badly isolated houses heated with electricity. The power grid is already unstable, France cannot afford to loose much generator power, as they have nothing to replace it with - very few renewables.

Felz 6y ago
Hmm, wikipedia (and the ASN used as source) seems to describe this incident a bit differently. I didn't see anything about core temperature rising uncontrollably, it's slightly inaccurate to say that control of the rods themselves was interrupted (only a positioning indicator; they could've emergency shut down the reactor with the rods if they needed to; not sure why you say the control rod failsafe didn't work), and the "emergency flood" of boron which "luckily worked" was standard operating procedure. Do you have a better source? https://en.wikipedia.org/wiki/Fessenheim_Nuclear_Power_Plant#Selected_incidents_and_accidents https://en.wikipedia.org/wiki/Fessenheim_Nuclear_Power_Plant...
- kubanczyk 6y ago
  I've just added a more detailed source to Wikipedia (also from ASN), but it doesn't contain any new facts. A cursory google search didn't yield anything reliable confirming the parent's version.
kubanczyk 6y ago
Sources on the "via gravity didn't work anymore" please. Official report says it wasn't tried and remained a last line of defense. http://www.french-nuclear-safety.fr/Media/Files/Technical-notice-description-of-the-event http://www.french-nuclear-safety.fr/Media/Files/Technical-no... Also it was 2014, not 2016.
greatgib 6y ago
We can't be sure, but based on the french independent nuclear authority, this does not look to be accurate. Just the dramatized version of a German anti-nuclear group: https://www.lemonde.fr/planete/article/2016/03/04/un-incident-dans-la-centrale-de-fessenheim-a-ete-plus-grave-qu-annonce-selon-des-medias-allemands_4876722_3244.html https://www.lemonde.fr/planete/article/2016/03/04/un-inciden... It is in French, but it is saying that nothing was out of control and out of ordinary small issues. The temperature was a little bit out of the normal during the operations but that is quite common. And they used Boron because it was the adequate procedure in this case but again not out of ordinary. They decided to not use the control rodes that were not operating 'automaticaly' because of the disruption of the flooded system. But manual control was still available if they wanted to. And at the same time, like in a space shuttle, every electric control circuits are mirrored for safety. So the control room A was affected by the flooding but the control room B and the B circuits were ok, unaffected and operational as designed!
- MrBuddyCasino 6y ago
  Thanks for the clarification, quite possible my source of information was biased.

Felz 6y ago

Hmm, wikipedia (and the ASN used as source) seems to describe this incident a bit differently. I didn't see anything about core temperature rising uncontrollably, it's slightly inaccurate to say that control of the rods themselves was interrupted (only a positioning indicator; they could've emergency shut down the reactor with the rods if they needed to; not sure why you say the control rod failsafe didn't work), and the "emergency flood" of boron which "luckily worked" was standard operating procedure. Do you have a better source? https://en.wikipedia.org/wiki/Fessenheim_Nuclear_Power_Plant#Selected_incidents_and_accidents https://en.wikipedia.org/wiki/Fessenheim_Nuclear_Power_Plant...

kubanczyk 6y ago
I've just added a more detailed source to Wikipedia (also from ASN), but it doesn't contain any new facts. A cursory google search didn't yield anything reliable confirming the parent's version.

kubanczyk 6y ago

Sources on the "via gravity didn't work anymore" please. Official report says it wasn't tried and remained a last line of defense. http://www.french-nuclear-safety.fr/Media/Files/Technical-notice-description-of-the-event http://www.french-nuclear-safety.fr/Media/Files/Technical-no... Also it was 2014, not 2016.

greatgib 6y ago

We can't be sure, but based on the french independent nuclear authority, this does not look to be accurate. Just the dramatized version of a German anti-nuclear group: https://www.lemonde.fr/planete/article/2016/03/04/un-incident-dans-la-centrale-de-fessenheim-a-ete-plus-grave-qu-annonce-selon-des-medias-allemands_4876722_3244.html https://www.lemonde.fr/planete/article/2016/03/04/un-inciden... It is in French, but it is saying that nothing was out of control and out of ordinary small issues. The temperature was a little bit out of the normal during the operations but that is quite common. And they used Boron because it was the adequate procedure in this case but again not out of ordinary. They decided to not use the control rodes that were not operating 'automaticaly' because of the disruption of the flooded system. But manual control was still available if they wanted to. And at the same time, like in a space shuttle, every electric control circuits are mirrored for safety. So the control room A was affected by the flooding but the control room B and the B circuits were ok, unaffected and operational as designed!

MrBuddyCasino 6y ago
Thanks for the clarification, quite possible my source of information was biased.