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Onagawa nuke plant suffers jolt greater than designed in aftershock

TOKYO, April 14, Kyodo

The No. 1 reactor of the Onagawa nuclear power plant in Miyagi Prefecture on April 7 sustained a jolt greater than what it was designed to withstand during a strong aftershock from the powerful March 11 earthquake, according to nuclear safety officials.

The finding raises further doubts about the viability of the assumed quake resistance at the Tohoku Electric Power Co. complex, even though it had been shut down safely after the deadly quake last month.

The Nuclear and Industrial Safety Agency has instructed the regional utility serving northeastern Japan to analyze the impact of such a jolt on key facilities at the three-reactor plant, the officials said.

During the aftershock, the biggest after March 11, measuring upper 6 in Miyagi on the Japanese seismic scale of 7, a seismometer at the building housing the No. 1 reactor registered a quake acceleration of 476.3 gal vertically, against the 451 gal assumed for the facility.

The assumed level of the jolt ''shouldn't be exceeded in principle,'' said agency spokesman Hidehiko Nishiyama. ''While I intuitively think that if it is this much, it shouldn't be a cause for concern, but we still have to evaluate its safety.''

None of the reactors at the plant was operating when the aftershock struck. But as a result of the temblor, the plant lost part of its external power supply and saw a cooling system for pools storing spent nuclear fuel briefly lose power.

Both the troubled Fukushima Daiichi nuclear power plant in Fukushima Prefecture and the Onagawa plant were hit by the March 11 quake and tsunami, but the latter has been largely under control with its key cooling functions kept alive.

==Kyodo english.kyodonews.jp

@Nancy: sorry for the confusion, I'm using different logins from home & work.
Jocelyn Mayer at work <=> Jo l_indien at home

thanks dean !

@dean : english.kyodonews.jp TEPCO confirms damage to part of No. 4 unit's spent nuke fuel

Time to see what the plant readings are like from the 14th

Hi everyone, from Physics Forum, the best image analysis of the four reactor buildings (that we get to see) yet:

www.houseoffoust.com

@Jocelyn Mayer Thanks Jo! I have some images when you get back.

@elainekirk I was posting them for everyone's elses benefit mostly. I didn't know if these were new or better sets of data. The main data I have been looking for right now is anything surrounding #3's explosion date and the loss of pressure on the 20th. These PDF files from Georgia might be useful for radiation data that was proposed to be gathered. I have not had a chance to work on that further. Has anyone else been tracking and saving radiation readings and testing? So yes, that food testing is the Japanese version of what I was looking for in the US but there was some comments of people wanting that data in Japan also so this may be a good source. I need to know if anyone else has an existing or better source. I will put these pdf links on the FAQ page and try to check for updates. If they are being used I can keep pulling them. If it ends up as redundant I can stop pulling them.

New heat images. Will get them cut and posted in a few here. www.mod.go.jp

@Nancy : they are so small this time ... hardly anything to see.

Disassembly of N-reactors a joint effort? / Toshiba seeks cooperation of rival Hitachi www.yomiuri.co.jp "Even if the plan is realized, the work will take at least 10 years."

Nuclear forum backs safety push after Japan crisis www.reuters.com

Got this response from Kanako Takahara of Japan Times, clarifying what he wrote about Reactor #4 a couple of days ago: "Dear Mr. James Ward,

Thank you for your email about my article.

>It is my understanding that Reactor #4 was empty at the time of the 9.0 >quake and subsequent massive tsunami. Do you have information >indicating that Reactor #4 was actually in operation with a full fuel load, or >is the information you provided in error?

You are absolutely right about Reactor 4. There is no fuel rods in the reactor.
What Tepco was trying to say (and was not clear the way I may have written...I apologize for that) was that the high radiation may have been caused by radioactive material leaking from the pressure vessel of other reactors, not No.4.

Best,

Kanako Takahara
***************************
The Japan Times
高原　加奈子
tel 03-3452-1799
fax 03-3453-5456
cell 080-1359-1093"

@markfm I think these are english versions PDF report via Georgia
japan.mfa.gov.ge

PDF report food testing in Japan by area testing was done via Georgia
japan.mfa.gov.ge

PDF food testing in Japan via Georgia
japan.mfa.gov.ge


japan.mfa.gov.ge%2Findex.php%3Fsec_id

@elainekirk Ha! That was my thinking, too, but I thanked him for his response anyway.

14th apr UK's Health Protection Agency weekly update on radiation levels in UK www.hpa.org.uk

@Markfm are you getting a translation of those documents or are these translations from Georgia useful?

Plans to "shore up" reactors at Daiichi against earthquakes www3.nhk.or.jp