Thursday, September 22, 2011

Government Researchers: Hydrogen Gas Generation by Radiolysis In Reactor SFP May Have Led to Explosion

and as it was revealed at the fall conference of the Atomic Energy Society of Japan on September 20, the water had to be boiling for that to happen.

The article by Mainichi Shinbun on September 13 (linked below) summarizes the findings well enough. According to the article, the government researchers at Japan Atomic Energy Research and Development Agency and at Tokyo University announced the result of their analysis that the explosion of Reactor 4 reactor building at Fukushima I Nuclear Power Plant on March 15 may have been caused by a large amount of hydrogen gas produced by water radiolysis - dissociation of molecules by nuclear radiation in the Reactor 4 Spent Fuel Pool.

Here's from Mainichi Shinbun Japanese (9/13/2011):

東京電力福島第1原発4号機で起きた原子炉建屋の爆発について、沸騰した使用済み核燃料プール内で、水の放射線分解が進んで、水素が大量発生したことが一因との分析を、東京大や日本原子力研究開発機構のチームがまとめた。放射線は、水を水素などに分解する。19日から北九州市で始まる日本原子力学会で発表する。

An analysis by a team of researchers from Tokyo University and Japan Atomic Energy Agency shows that part of the reason for the explosion of Reactor 4 reactor building at Fukushima I Nuclear Power Plant was the large amount of hydrogen gas generated in the Spent Fuel Pool of Reactor 4. Radiation splits water and creates hydrogen. The analysis will be presented in the Atomic Energy Society of Japan's fall conference that will start in Kitakyushu City from September 19.

 4号機のプールには、事故を起こした1~4号機の中で最も多い1535本の燃料棒が入っていた。東日本大震災発生当時、定期検査で運転停止していたが、津波で電源を喪失。冷却機能が失われ、地震発生から4日後の3月15日に爆発した。

The Reactor 4 Spent Fuel Pool contained 1,535 fuel rods, the most in the reactors at Fukushima that broke down. At the time of the March 11 earthquake/tsunami, the reactor had been stopped for the regular maintenance. But the tunami knocked out the power supply, which caused the loss of cooling, and the reactor building exploded on March 15, 4 days after the quake.

 水素爆発を起こした1、3号機では原子炉内にあった燃料棒が損傷し水素が発生したとされるが、4号機の燃料棒に目立った損傷はなかった。東電は排気筒を共有する3号機から水素が流入して、4号機の水素爆発にいたったと推定している。

In Reactors 1 and 3 which blew up in hydrogen explosions, it is considered that the fuel rods inside the reactors were damaged, which generated hydrogen. However, the fuel rods from Reactor 4 did not have noticeable damages. TEPCO suspects that hydrogen gas from Reactor 3, which shares the exhaust stack with the Reactor 4, flew through to Reactor 4, causing the explosion in Reactor 4.

 しかし、チームは3号機と4号機の爆発に約20時間の差があることに注目し、他の要因があると推測。フラスコ内の水を室温、97度、沸騰状態の3段階にして、放射線を照射。発生した水素の濃度を調べたところ、97度で室温の1.5倍、沸騰状態で100倍となることが分かった。

However, the team of researchers from Tokyo University and JAEA looked at the 20-hour gap between the explosions of Reactor 3 and 4, and suspected there are some other causes for the explosion [of Reactor 4]. The team irradiated the water in a flask at room temperature, at 97 degrees Celsius, and at boiling temperature and measured the density of hydrogen generated. At 97 degrees Celsius, the density was 1.5 times as much as at room temperature, and at boiling temperature the density was 100 times as much as at room temperature.

 水素は空気中の濃度が4%を超えると爆発の危険性が出てくる。建物上部にたまった水蒸気は壁で冷やされて水に戻るが、水素は気体のままで空気中に占める割合が高まったとみられる。

If the density of hydrogen in the air exceed 4%, there's a danger of explosion. Vapor that went to the upper floors of the reactor building would have been cooled by the walls and condensed into water again, but hydrogen may have remained gaseous, increasing the ratio of hydrogen in the air.

 チームの勝村庸介・東大教授(放射線化学)は「3号機からの流入に加え、放射線分解が重なったのではないか。今後、実際の原子炉建屋やプールの規模で起こるのかを検証したい」と話す。

Professor Yosuke Katsumura of Tokyo University (radiation chemistry), one of the team members, says "Water radiolysis may have happened in addition to the hydrogen flow from Reactor 3. We would like to test whether it can happen in an actual reactor building with a real-size spent fuel pool".

 東電は「理屈上はありうるが、爆発させるほど水素が大量発生するかどうかは不明」としている。

TEPCO says, "It is possible in theory, but we do not know whether a large enough amount of hydrogen is generated that way to cause an explosion".

There seem to be many interesting papers presented at the conference, highly scientific and technical, detailed insights into what may have happened and how at Fukushima I Nuke Plant. A nice departure from muddling through by TEPCO and NISA for the past 6 months. I only wish I had studied physics and chemistry more...

10 comments:

rtega said...

Any links to the papers themselves for readers with a scientific background?

arevamirpal::laprimavera said...

I'll ask around. May not have been published yet, and prelim abstracts only available to participants, and some data only disclosed in workshops.

Anonymous said...

Why have I only seen video footage of two reactor buildings blowing up at Fukushima? Namely,

- Unit 1, on March 12, 15:36 JST

- Unit 3, on March 14, 11:15 JST

(source for dates/times of explosions: https://secure.wikimedia.org/wikipedia/en/wiki/Fukushima_Daiichi_nuclear_disaster#Explosion)

I have never seen footage of the following:

- the explosion in Unit 2, on March 15, 06:14 JST, which blew out a vent in one of Unit 2's walls (the vent appeared as a small square opening in center of the large expanse of one of Unit 2's walls)

- the explosion in Unit 4, which the Tokyo Univ/JAEA researchers say here occurred 20 HOURS AFTER UNIT 3 BLEW UP.

If Unit 3 blew up at 11:15 JST on March 14, then - 20 hours later - Unit 4 exploded some time around 07:00 JST on March 15. (Wikipedia is silent on this point.)

Where is the footage of Unit 4 blowing up in the early morning of March 15?

Has anyone ever seen it?

Or am I missing something really obvious here?

Anonymous said...

".. and measured the density of hydrogen generated. At 97 degrees Celsius, the density was 1.5 times as much as at room temperature, and at boiling temperature the density was 100 times as much as at room temperature."

I trust that concentration of hydrogen is not a normal effect upon the boiling of water?
A short removal from design parameters and the stuff is literally tearing the place down?

Too dangerous for an error-prone world. For a world with too many agendas, too many intrigues, too many grievances powered by cynicism.

/rant

Anonymous said...

.

"...I only wish I had studied physics and chemistry more..."

That is your +positive side: Because if u had, u would not be writing theses sceptic theses seeking for facts - but would happily sing along with the brainwash... ...err... "educated" and MSM.

Thks for all that!

Another viewpoint into this issue is the propaganda all nuclear physics have eaten fully: the periodic table of uranium contains 13 nuclei - a hidden hoax bigger than vatican itself. All physics books had it right before 1945 - somehow now vanished, only 12 to be found today ... itching fact: 500kg of fuel 'vanishes' yearly from these BWR reactors ... and no explanation for that.

Psst, IAEA runs scared, it has leaked out: direct radiation http://www.youtube.com/watch?v=4rc37dRCI4w

.

Anonymous said...

7:23,

Seems evident the imperialists various Really do not like each other.

Anonymous said...

"1,535 fuel rods"

...or assemblies?

Depending on source, Typical GE BWR Reactor contains 131 - 151 tons uranium; up to 20% plutonium mix (MOX) ... UO2,UO2-Gd2O3 maybe 746 assemblies.
Mystique: Fukushima internal papers show reactors having 116 fuel 'slots'.

9x9 rod array Assembly weight is said to be 190kg. But is it?
- One pellet, 3.0wt% 235U; 10×10.3 mm
- Zirkonium Zr-lining, diameter 12.3 mm; 0.86mm (Zr-lining 1.0mm); one rod has 3.7m pellet ‘stack’
- Total 8x8 (or 9x9 !?) assembly weight 192kg (or 246kg!?)
- as one assy weight more than 1000kg, the latter fits the 4 x 9x9 -pattern.

Taking into account 6 reactors and 40 yrs usage, maximum (capacity for Fukushima Daichii is) 9600 (12.300!?) tons of plutonium/uranium waste/fuel.

What is the actual amount? And I dont mean the TEPCO handout fuku... Has anybody the real number?

They will still all blow out: See this 2002 revelation: www.nirs.org/radwaste/atreactorstorage/alvarezarticle2002.pdf

Anonymous said...

There is a likelihood that some hydrogen leaked from Unit 3 to Unit 4 as TEPCO has previously shown evidence by analyzing the filters. However, the amount that flowed was insufficient to blow up Unit 4 by itself or else there would not have been a delay between Unit 3 blowing up and Unit 4 blowing up. The amount of hydrogen generated by the irradiated boiling water in SFP 4 may not have been enough to cause the explosion by itself without the added amount that flowed in from Unit 3. Again, a confluence of factors.

Anonymous said...

The problem with hydrogen production at boiling reactors caused accidents 2001 at Hamaoka-1 and Brunsbüttel. The detonation caused pipes to explode. The problem where researched worldwide at that time. Later some studies was done to estimate the production of hydrogen at boiling reactors.

http://www.stralsakerhetsmyndigheten.se/Global/Publikationer/SKI_import/061108/0d904db0b3198474ea75bcdc9b8b24a5/SKI%20inlaga%202006_16_web.pdf

However, it seams that less attention is spent on the pool with used nuclear fuel.

Anonymous said...

4:37,

Did I really just read the following in your link?

"Conclusions
From the present investigation it may be concluded that

�� The future disaster of TEPCO's making at Fukushima will make it abundantly evident that the proper response is to dump massive, massive quantities of borax on the coriums, as Elvis is ever of the mischief."

Most prescient of them to include that in their study's report.

/sarcasm

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