U.S. Sees Array of New Threats at Japan’s Nuclear Plant

[Wilms]

U.S. Sees Array of New Threats at Japan’s Nuclear Plant

By JAMES GLANZ and WILLIAM J. BROAD

Published: April 5, 2011

United States government engineers sent to help with the crisis in Japan are warning that the troubled nuclear plant there is facing a wide array of fresh threats that could persist indefinitely, and that in some cases are expected to increase as a result of the very measures being taken to keep the plant stable, according to a confidential assessment prepared by the Nuclear Regulatory Commission.

Among the new threats that were cited in the assessment, dated March 26, are the mounting stresses placed on the containment structures as they fill with radioactive cooling water, making them more vulnerable to rupture in one of the aftershocks rattling the site after the earthquake and tsunami of March 11. The document also cites the possibility of explosions inside the containment structures due to the release of hydrogen and oxygen from seawater pumped into the reactors, and offers new details on how semimolten fuel rods and salt buildup are impeding the flow of fresh water meant to cool the nuclear cores.

While the assessment does not speculate on the likelihood of new explosions or damage from an aftershock, either could lead to a breach of the containment structures in one or more of the crippled reactors, the last barriers that prevent a much more serious release of radiation from the nuclear core. If the fuel continues to heat and melt because of ineffective cooling, some nuclear experts say, that could also leave a radioactive mass that could stay molten for an extended period.

snip

The document also suggests that fragments or particles of nuclear fuel from spent fuel pools above the reactors were blown “up to one mile from the units,” and that pieces of highly radioactive material fell between two units and had to be “bulldozed over,” presumably to protect workers at the site. The ejection of nuclear material, which may have occurred during one of the earlier hydrogen explosions, may indicate more extensive damage to the extremely radioactive pools than previously disclosed.

snip

http://www.nytimes.com/2011/04/06/world/asia/06nuclear.html?hp

GD Discussion:

http://www.democraticunderground.com/discuss/duboard.php?az=show_mesg&forum=439&topic_id=821471&mesg_id=821471

[caraher]

1. The spent fuel pools are a pretty vulnerable part of the reactors

If chunks of rods in those pools were blown out of the buildings it's hard to see how those pools could still hold water at all. After all, at the time of those explosions they should still have been underwater; if they were blown out were they already exposed? Did the explosions blast all/most of the remaining water out of the pools?

[flamingdem]

2. Exactly how are they keeping the fires from restarting in the fuel pools

- those intensely toxic fires will cause many cancers.

The plant is very out of control, it sounds that way because on top of this not
so confidential report, since it was written levels are so high I'm not sure
much of anything is being done there anymore.

[kristopher]

7. There are no indepent observations available any longer.

Even the camera shots are from 30KM away.

[DeSwiss]

3. K&R n/t

[stockholmer]

4. K&R , but the NYT is so slow with some of this info (quoting a 10-day old assessment, for example)

[Wilms]

5. I didn't get the impression the NYT was privy to this a week ago. n/t

[kristopher]

6. Neither do I. Thanks for posting it. nt

[kristopher]

8. Kick

[kristopher]

9. I wonder how they came through yesterday's earthquake?

It's hard to adopt the "no news is good news" outlook when information flow has become so restricted.

[Nihil]

10. True.

> It's hard to adopt the "no news is good news" outlook when information
> flow has become so restricted.

:-(