Report: Video - Explosion at Japanese nuclear plant (possibly hydrogen)

[AlaskaDenise]

(CNN) -- An explosion has been reported at a nuclear plant in northeastern Japan's Fukushima prefecture, Japanese public broadcaster NHK said Saturday, citing the country's nuclear and industrial safety agency.

The Tokyo Electric Company said four workers on the ground were injured, NHK reported.

It was not immediately clear where the blast occurred at the Fukushima Daiichi plant, or what caused it.

NHK said the injured workers were in the process of cooling a nuclear reactor at the plant by injecting water into its core.

Earlier Saturday Japan's nuclear agency said workers were continuing efforts to cool fuel rods at the plant after a small amount of radioactive material escaped into the air.

The agency said there was a strong possibility that the radioactive cesium monitors detected was caused by the melting of a fuel rod at the plant, adding that engineers were continuing to cool the fuel rods by pumping water around them.

Read more at: http://edition.cnn.com/2011/WORLD/as...japan.nuclear/

[AlaskaDenise]

Re: Report: Explosion at Japanese nuclear plant

Per Reuters:

FUKUSHIMA, Japan, March 12 (Reuters) - An explosion blew the
roof off an unstable reactor north of Tokyo on Saturday,
Japanese media said, raising fears of a disastrous meltdown at a
nuclear plant damaged in the massive earthquake that hit Japan.

Read more at: http://www.reuters.com/article/2011/...7EC07M20110312

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[AlaskaDenise]

Re: Report: Explosion at Japanese nuclear plant

This report shows conflicting details:


Workers Injured After Explosion at Japanese Nuclear Plant

An explosion injured at least four workers at a nuclear plant facing a possible meltdown and destroyed the walls of one building, Japanese officials said.

"We are now trying to analyze what is behind the explosion," .....


It was unclear if the building at the Fukushima Daiichi plant that was damaged by the blast contained the reactor, the Associated Press reported.

Tokyo Electric said an explosion happened in the first reactor, according to local media reports.

Japanese TV images showed the crumbled remains of one of the plant building's walls with smoke emerging from the site.

Read more at: http://abcnews.go.com/International/...ry?id=13120888

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[AlaskaDenise]

Re: Report: Explosion at Japanese nuclear plant

This reports says that a meltdown of a light water reactor is less dangerous than other reactors.
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Fears of meltdown after explosion at Japan nuclear plant damaged in quake
Japanese authorities say nuclear fuel rods may be melting inside the 40-year-old reactor at Fukushima.


Tokyo residents emptied out shops and stocked up on petrol, the first preparing to leave the capital to avoid the fallout of a possible accident at a nuclear power plant on Saturday. Long queues formed at petrol stations and the few running trains were packed Saturday evening, witnesses said.

A government spokesman had called for calm after an explosion apparently destroyed the roof of a building housing a reactor at the Fukushima I nuclear plant, which had bee damaged by Friday's devastating quake.

(also snipped)

Japanese officials and experts have been at pains to say that while there would be radiation leaks, they would be very small and have dismissed suggestions of a repeat of a Chernobyl-type disaster.

"No Chernobyl is possible at a light water reactor. Loss of coolant means a temperature rise, but it also will stop the reaction," Naoto Sekimura, a professor at the University of Tokyo, said.

"Even in the worst-case scenario, that would mean some radioactive leakage and equipment damage, but not an explosion. If venting is done carefully, there will be little leakage. Certainly not beyond the 3 kilometer radius."

Read more at:

http://www.haaretz.com/news/international/fears-of-meltdown-after-explosion-at-japan-nuclear-plant-damaged-in-quake-1.348699

[AlaskaDenise]

Re: Report: Explosion at Japanese nuclear plant

LA Times is reporting that the building which exploded may not house the reactor.

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[AlaskaDenise]

Re: Report: Explosion at Japanese nuclear plant

Fear of potential invisible killer near Japanese nuclear site
Nuclear reactor at Fukushima may be near meltdown

An eerie silence has descended over this northeastern Japanese city. Tens of thousands have evacuated their homes a day after one of the worst-ever recorded earthquakes and subsequent tsunami, which swallowed coastal villages.

The greatest fear here, right now, stems not from the continuing aftershocks and the ongoing tsunami warnings, but rather a silent and invisible potential killer.

One or more nuclear reactors in Fukushima may be close to, or have suffered a meltdown. A reactor wall has apparently collapsed at one reactor, injuring four people there Saturday afternoon.

(snipped - a further complication)

This city, despite the ominous nuclear threat, is the staging ground for what will likely prove to be one of the largest-ever search and rescue efforts in human history.

Fukushima is the closest significant airport still open to the worst-hit areas.

The tsunami along the coast, 30 kilometers east, swallowed entire communities - many already severely damaged by Friday's magnitude 8.9 quake - in a few minutes. The devastation was recorded on video by military and media helicopter crews who hovered above the unbelievable scene, helpless to intervene.

More than 50 countries have already pledged aid to Japan. Most will fly into Fukushima and fan out towards the north and east for a search and recovery operation likely to go on for weeks.

Read more at:

http://www.voanews.com/english/news/Fear-of-potential-invisible-killer-near-Japanese-nuclear-site-117848999.html

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[AlaskaDenise]

Re: Report: Explosion at Japanese nuclear plant

Bloomberg is now also reporting it's the reactor building walls:
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Explosion Destroys Walls of Japanese Nuclear Reactor Building, NHK Reports


An explosion occurred at the Fukushima Dai-Ichi power station north of Tokyo, destroying the walls of the No. 1 reactor building, NHK Television said. The report came after the government said a reactor may be melting.

Smoke was rising around the nuclear reactor after an aftershock from yesterday?s quake struck, Ryohei Shiomi, a spokesman at the country?s nuclear safety agency said by phone.

The spokesman said several people were injured during an aftershock that struck around 3:30 p.m. Japan time, adding he had no further information. Tokyo Electric Power Co., which operates the plant, said it had no information, when contacted by Bloomberg News.

Read more at: http://www.bloomberg.com/news/2011-0...k-reports.html

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[AlaskaDenise]

Re: Report: Explosion at Japanese nuclear plant

The explosion:



Story at: http://www.guardian.co.uk/world/2011...aftermath-live

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[AlaskaDenise]

Re: Report: Explosion at Japanese nuclear plant

from the above story with photo:

A nuclear expert says the a blast at Fukushima plant No 1 was caused by a hydrogen explosion.

Ian Hore-Lacy, of nuclear industry body the World Nuclear Association, also said the blast may not necessarily have caused a radiation leak.

He told Reuters:

"It is obviously an hydrogen explosion ... due to hydrogen igniting. If the hydrogen has ignited, then it is gone, it doesn't pose any further threat. As far as we know there is no particular danger from radiation leaks. There may be, but we don't know that. There is no reason to suppose that there must be because of that."

(added)

A the news agency reports that it is not clear if a reactor meltdown would cause a serious radiation risk, and if it did how far the risk would extend:

Yaroslov Shtrombakh, a Russian nuclear expert, said a Chernobyl-style meltdown was unlikely." It's not a fast reaction like at Chernobyl," he said. "I think that everything will be contained within the grounds, and there will be no big catastrophe."

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[Ronan Kelly]

Re: Report: Explosion at Japanese nuclear plant

The BBC also suggesting that the explosion is a hydrogen explosion.

<iframe title="YouTube video player" width="640" height="390" src="http://www.youtube.com/embed/epXhWu8Xhxg" frameborder="0" allowfullscreen></iframe>

[Ronan Kelly]

Re: Report: Video - Explosion at Japanese nuclear plant (possibly hydrogen)

Another BBC analysis - from 2:15 on addresses the explosion and ongoing problem.

2 options, neither of which sounds good.

1. A partial meltdown has occurred. The radioactive material came in contact with water and produced sufficient Hydrogen gas to cause a massive explosion. Depending on where in the system the explosion occurred, the reactor chamber could still be intact, but any further damage to the cooling system may be catastrophic.

2. A steam explosion occurred which would disrupt the whole closed water system that takes heat from the core. This could lead to a rapid meltdown.

<iframe title="YouTube video player" width="640" height="390" src="http://www.youtube.com/embed/GPm-Uw4O92w" frameborder="0" allowfullscreen></iframe>

[Ronan Kelly]

Re: Report: Video - Explosion at Japanese nuclear plant (possibly hydrogen)

From wikipedia; http://en.wikipedia.org/wiki/Boiling_water_reactor


BWR schematic.
1. Reactor pressure vessel (RPV)
2. Nuclear fuel element
3. Control rods
4. Circulation pumps
5. Engine control rods
6. Steam
7. Feedwater
8. High pressure turbine (HPT)
9. Low pressure turbine
10. Generator
11. Exciter
12. Condenser
13. Coolant
14. Pre-heater
15. Feedwater pump
16. Cold water pump
17. Concrete enclosure
18. Mains connection