Blog on Japan Quake and the Kashiwazaki-Kariwa Nuclear Plant
http://neinuclearnotes.blogspot.com KenG said...Can anyone clear up the correspondence between the plant design basis and the actual earthquake magnitude? It's being widely reported that the quake exceeded the plant design basis. That seems possible if the quake was 6.8 on the Japanese (Omori) scale. However, if the quake was a 6.8 Richter scale event, it seems unlikely that the design basis was exceeded. Has anyone been able to sort this out? 10:06 AM
Anonymous said...
"All U.S. nuclear plants are designed to withstand earthquakes of a magnitude that is equivalent to or greater than the largest known earthquake for region where it is being built."
I believe that's the case with Japanese NPPs as well, including KK. However, the July 16 quake was larger than the design basis seismic event they'd anticipated.
11:30 AMDavid Bradish said...
Well according to this article from North County Times, the Kashiwazaki-Kariwa nuclear plant experienced a 6.8 quake several years ago and everything came out fine. This recent quake was supposedly measured at a 6.6 according to the article. But I'm also reading 6.8. Either way, it's survived one of these before so I'm sure it's in its DB. Anonymous said...
I know that everything shut down fine, but I personally would go walk down all systems important to safety to ensure that all is well, especially in the reactors currently shut down. There could be hangers / snubbers damaged, concrete cracked, valves mis-aligned, etc. These could be latent issues for future plant operations.
If my house is hit by a big earthquake and is still standing afterwards, I am still going to look it over for cracks and shifting. Survival is one thing, but future operations is another.
Fred D. said...The LA Times and other outlets are reporting some other issues... pipes dislodged, low-level waste barrels tipped over, a release into the atmosphere.
Are these indicators of design flaws, especially for what seems to be an earthquake-prone area? I will be very interested in seeing after-action or lessons learned reports. 12:44 PM
Porgie Tirebiter, Royce Penstinger and Pinto Bean said...
First, the quake in Japan was higher in magnitude than the DB specks by which these reactors were designed and built. There is a very good chance that said quake has made all seven of these reactors unsound from and engineering stand point.
Secondly, NEI can try to mitigate reality all they want...this quake has shown nuclear reactors to be unsafe, and with each passing hour, the number of SIGNIFICANT issues at the world's largest reactor site continue to grow.
Smart money...dump your nuclear holdings before the bottom falls out of the market. If I had Exelon or Entergy stock right now (too name two) I'd be more than nervous.
3:18 PMDavid Bradish said...
Actually no. The best thing to do right now is to see what the total damage is. From the looks of things, it looks like the significant areas of the plants (i.e. the reactors) performed exactly how they were supposed to with no damage done to them.
You're forgetting these plants are designed for earthquakes. Give it a week and we'll see where we are at. You can't start jumping to conclusions. Bet you several of the reactors will begin restarting within two weeks.
3:30 PMKenG said...
OK, we're getting more information from official sources. The earthquake was approximately the plant design basis at 6.6 to 6.8 Richter. However, seismic sensors on site measured peak ground accelerations of .31 to .68 g while the design basis acceleration may have only been about .25g. No reported damage to any safety systems but damage to non-safety systems not designed for seismic (of course). The release activity was originally reported as 1.6 microcurie and revised up to 2.4 microcurie. Insignificant in any case. 4:22 PM
KenG said...
Regarding the previous earthquake at Kashiwazaki:
One of the key factors in looking at Richter levels is that Richter is rated at the epicenter, not at the site location. The 2004 quake was apparently slightly stronger than the 2007 quake but the epicenter was 80km away in 2004, but only 10km away in 2007. For all intents, the 2007 quake was at the site.
Porgie Tirebiter, Royce Penstinger and Pinto Bean said...Tokyo Electric Power has already admitted that the reactors were not built to withstand and earthquake of the magnitude experienced. The reactors themselves were built on basically very elaborate shock absorbers...this according to a welder who used to work for Underwater Welding of Essex, Ct. who actually did work on the reactors involved. Without significantly tests and examinantion, the long term viability of these shock absorbers cannot be ascertained, and it is murder to restart these seven reactors until said testing is completed. 10:12 PM
Josh said...
Long name person, I think you have a problem with your definition of "unsafe". 7:22 AM
Luke said...
Come off it.
How much radioactivity was actually released, and what maximum dose could this have resulted in to any member of the public?
What are the actual risks that the public has been exposed to as a result of this earthquake affecting the nuclear plant?
8:21 AMKenG said...
Can anyone confirm that these units actually have seismic isolation as stated above? I've extensively studied these projects and never seen this. I have a 2001 paper from Hitachi (K-6/K-7 designer) stating that they are studying seismic isolation for future units based on K-7. Perhaps the post above confuses snubbers with supports. Snubbers are easily inspected and requalified. 8:54 AM
tgf said...
So what leaked? Heavy water? Cs-137? Sr-90? I-131? I haven't been able to find that info anywhere. 2:44 PM<
Luke said...
The water that leaked ultimately came from a spent fuel pool.
The 2 microcuries (just to re-iterate) of radioactivity in the water spill from the pool was probably a cocktail of reasonably long-lived fission products in trace amounts from the spent fuel rods.
Probably not I-131, because it's so short lived, it isn't significant in stored spent fuel, except where it's straight out of a recently operating reactor.
Fission products like Cs-137 might be a pretty representative guess.