Tuesday, November 12, 2013

#Fukushima I Nuke Plant Reactor 4 SFP: Three Fuel Assemblies Deformed or Damaged, Says TEPCO

It must be from the explosion! Or from something TEPCO has done since the accident, whatever it is!


If TEPCO is to be believed, TEPCO has been hiding the damages for at least 10 years; the oldest damage was from 25 years ago.

According to Yomiuri Shinbun (11/12/2013), that's not clear, and you would be excused if you thought the damages were recent (after March 11, 2011).

From Yomiuri Shinbun (11/12/2013):


On November 12, TEPCO disclosed that there were three fuel assemblies out of 1533 fuel assemblies in the Spent Fuel Pool of Reactor 4 at Fukushima I Nuclear Power Plant that were deformed and would be difficult to remove. The removal of fuel assemblies from the Reactor 4 SFP will start this month.


The three fuel assemblies has slight deformation or damage caused by the past work [in the SFP]. No leak of radioactive materials has been observed. TEPCO will transport other fuel assemblies first, while they figure out how to remove and transport these three fuel assemblies. Nuclear Regulation Authority has already approved the fuel removal, and the work will start within this month as scheduled.

So, are these fuel assemblies new? used? How long ago was the "past work"?

I found the answer in Fukushima Minyu, one of the local newspapers in Fukushima Prefecture. It was long before the start of the March 11, 2011 nuclear accident, with the oldest "past work" 25 years ago...

From Fukushima Minyu (11/13/2013; part):


According to TEPCO, one of the damaged fuel assemblies is bent at a 90-degree angle [literal meaning: bent in the shape of a Japanese character "く"; actual angle could be less]. It was bent 25 years ago when a mistake occurred in handling the fuel. The other two were found to be damaged 10 years ago; there are small holes on the outside from foreign objects.


TEPCO is investigating whether the damages to the fuel assemblies were made public when they were discovered.

According to Fukushima Minyu, the occasion was a visit by the delegation of the Fukushima Prefectural Council for Decommission Safety Monitoring. The council members include officials from the Fukushima prefectural government, municipalities around Fukushima I Nuclear Power Plant, and experts.

How do you bend a fuel assembly at a 90-degree angle, handling it in the spent fuel pool?

And how could Yomiuri call a fuel assembly bent at a 90-degree angle "slight deformation"? Slight?


For your information, there are 1533 fuel assemblies (each of which contains 50 to 60 fuel rods in channels inside the casing) in the Spent Fuel Pool of Reactor 4 at Fukushima I Nuclear Power Plant.

There used to be 1535 fuel assemblies there, but two new fuel assemblies were taken out from the Reactor 4 SFP last year for examination.

Of 1533 fuel assemblies currently in the Reactor 4 SFP, 202 of them are never-used, brand-new fuel assemblies. The rest, 1331 are used fuel assemblies. Of 1331, 783 are spent fuel assemblies that have been stored in the SFP at least for several years; 548 are the fuel assemblies that had been used in the Reactor Pressure Vessel until Reactor 4 went into extended maintenance to replace the core shroud. These 548 "hot" fuel assemblies were taken out of the Reactor Pressure Vessel and placed temporarily in the Spent Fuel Pool.


Anonymous said...

Oh, this is comforting: Tepco had at least 10, if not 25 years' of time to do in-depth studies and train on how to best remove damaged fuel racks, even if bent at 90 degrees. Cleaning out the SFP now should go oh-so smoothly then. (end of sarcasm ... for now)

Karina said...

Is there any way I can contact you by email? I'm studying disaster management in Japan and I have the opportunity of meeting Kenzo Oshima this weekend. If you're interested, I would like to know if there are any questions you'd like me to ask him. Please let me know.

Anonymous said...

So Tepco manage to sc**w up the fuel assemblies when working on them under normal conditions and did not find a solution for 25 years. 神よ許したまえ

netudiant said...

Actually think that was sensible response by TEPCO.
The damaged fuel assemblies would be a pain to move and it really is the same whether they are in the common pool or the SFP of reactor 4.
They just did not anticipate needing to empty out the SFP so soon, so now they need to scramble.

Anonymous said...

Has there been any analysis of potential degradation of fuel rods due to the use of sea water for cooling?

Anonymous said...

"Has there been any analysis of potential degradation of fuel rods due to the use of sea water for cooling?"

Yes, they removed two unused fuel assemblies last year and examined them. Page 18 of the following release dealls with it.


Anonymous said...

Tepco is obvious 'the man for the job'. When it goes wrong, they know how to hide it!

Anonymous said...

Thank you for any and all information and for your work. I live on the West Coast and I'm highly concerned along with many others.

This gives all of us nightmares!

Anonymous said...

The response might have been sensible but it is also quite telling about Tepco confidence in handling damaged fuel elements.

Anonymous said...

Only 3 damaged assemblies huh?

Not a chance they are telling the truth

Anonymous said...

Three is the number of assemblies Tepco damaged 10/25 years ago, which they did not have the confidence to remove. The assemblies hit by the crane during the hydrogen explosion and showered by debris are above and beyond those three.

Anonymous said...

I've never before seen the exact figure of 202 new fuel assemblies are/were in SFP4 - I've heard the 1533 total number before and I know that the reactor takes 543, so that number of "hot" assemblies recently removed from the core as it was opened for maintenance makes sense.

What I want to know is what was in the equipment/machinery pool that blew up the building on March 15th. If you look at the blast wreckage, you see that the explosion clearly came from inside the building and the epicenter of the blast was clearly that pool

(not the spent fuel pool, as so many ignorantly claim.)

Was it MOX ready to be loaded? If they only had 202 new ones in the spent fuel pool, then they needed 346 more assemblies from somewhere else - either put the hot ones back in or there were some others somewhere - perhaps in the machinery pool.

I think all the panic talk about removing assemblies from the #4 SFP being dangerous is a smokescreen. First off, SPF4 is the most stable spent fuel pool on site, with the exception of the common spend fuel pool

It was heavily reinforced in the months after the disaster. It's not going to fall down soon.


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