Monday, November 7, 2011

TEPCO to Redefine Its Idea of "Criticality"

Tokyo Shinbun (11/7/2011) reports:


On November 6, TEPCO disclosed its policy to review the standard to determine whether criticality has happened at Fukushima I Nuclear Power Plant. The report the company submitted to the Nuclear and Industrial Safety Agency under the Ministry of Economy, Trade and Industry defined the condition of criticality as whether noble gas with short half life was detected. However, radioactive xenon was detected in Reactor 2 on November 2, which is thought to have been created by spontaneous fission. TEPCO's definition didn't match the actual situation, and the company has no choice but redefine what it considers "criticality".


When xenon was detected on November 2, TEPCO announced "There is a possibility of criticality". However, the company corrected it as "spontaneous fission" partly because the amount of xenon detected was small.


TEPCO's general manager Kawamata said in the press conference on November 6, "We're sorry we've had you worried over whether re-criticality happened or not. We are preparing the revised report, and we will elaborate on our view in that report."


In the report submitted to the NISA on October 17 on ensuring security in medium-term, the standard to judge the occurrence of criticality was the presence or absence of noble gas with short half life, such as xenon.

If this is true, then whoever crafted the October report to the NISA didn't know how xenon is apparently generated in spontaneous fission inside a normal reactor; and TEPCO has been operating this nuke plant for almost 40 years.

(Note to officials in Vietnam, Turkey, and India: Are you sure you want to import the Japanese nuclear power plant system?)


Steve From Virginia said...
This comment has been removed by the author.
Steve From Virginia said...

TEPCO is playing with fire, it is as if they don't understand how the reactors and nuclear fuel work.

They can fool some of the people but never neutrons:

The reactor cores are not just critical but are 'fast' which means fission does not require a moderator.

A second explosion is possible @ Fukushima.

DD said...

Steve thanks for the article and your blog I find informative too.

Anonymous said...

This is entirely analogous to below ground nuclear tests,

"Because cores emitting fission products cannot be sub-critical, the low detection levels of these gases is instead likely because the cores are underground."

linked from the comments section by centaur,

"This is very important to keep in mind: when a reactor ceases to be a thermal reactor due to a malfunction and a ‘reconfiguration’ of the core, it becomes an accidental fast nuclear reactor."

"Heating of the core(s) would be the result of fast fission."
There is no guarantee the coriums are cooling.

– Fissions taking place now are ‘prompt’, that is the neutrons are produced by the fission of fuel nuclei rather than by decay nuclei.

– A chain reaction due to prompt neutrons can self-propagate with extreme rapidity under the right conditions.

Note the explosion scenarios are not unlikely as Busby notes Chernobyl's explosion was at least partially a nuclear explosion.
Gunderson's reactor 3 version was 'boosted'.

Anonymous said...

Here's your IAEA,

"Four months after the [Chernobyl] meltdown Morris Rosen, the IAEA’s director of nuclear safety, said: “Even if there were an accident of this type every year, I would still regard nuclear power as a valuable source of energy” .


"According to the National Cancer Institute, cancer incidence (all sites) in the US increased by 55% between 1950 and 1995; the trends in Europe and other industrialised nations are similar."

Anonymous said...

Morris Rosen is one brazen mofo. Director of "nuclear safety" my ass.

Anonymous said...

BEGINNING OF NOV: hight radiation (620 mSv/h) at reactor 3, Fukushima Daiichi
NOV 2: detection of Xenon 133,135 at reactor 2, Fukushima Daiichi
NOV 5: many minor health effects (e.g., eye itching) reported via tweets in Tokyo, wind came from the North
NOV 6: air with radioactivity is brought from the North to Tokyo
NOV 11: radioactivity in Europe

Anonymous said...

There is 2 microSieverts/hr in New Zealand in the wind!!!!

What about the rest of the world? Are you alive?

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