March 31st, 2011 – TEPCO’s Assessment of Structural Damage to Unit 1, 3, And 4 Reactor Buildings by Enformable

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Estimate time for boil-dry times for a typical spent fuel pool

Source: RTM Table D-1 (see figure below)

Assumptions:

(1) Full core recently discharged (see box in figure)
(2) 100 days after shutdown (full core unloaded)
(3) constant decay heat at 100 days on
(4) Neglect sensible heating from the table (- 10 hr)
(5) No water loss from the pool thru leaks, water spillage, explosion, etc.

Time since accident = – 5 days
Time to boiloff (Table D-1) = 164 hr = 6.8 days

Assuming pool at 100% 5 days ago and it takes 6.8 days to boil off, after 5 days about 75% (5/6.8) of water has boiled off with 25% remaining.

Time to boil-off remaining 25% = 0.25 x 164 hr = 40 hrs => this is the maximum time left considering assumption 5 above.

March 16th, 2011 – Estimate Time for Boil-dry Times for a Typical Spent Fuel Pool by Enformable

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The radioactivity concentration (screening value) for Cs-137 and Sr-90 is 1 Bq-cm2, which equates to a dose of 1 mrem/yr TEDE.

Accordingly, a 4 Bq-cm2 contamination level on cargo would be about 4 mrem/yr TEDE.

If transuranics were detected on cargo surfaces, the screening value is decreased to 0.1 Bq-cm2, which equates to a dose of 40 mrem/yr TEDE for a 4 Bq-cm2 contamination level.

April 3rd, 2011- NRC PMT – Surface radioactivity screening levels – Pages from ML12094A286 by Enformable

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March 21st, 2011 – Concentrations of I-131 within 20 km of Fukushima Daiichi 10 times maximum acceptable le… by Enformable

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March 21st, 2011 – Radiation data released by Japan not comparable to radiation levels measured by USS Geor… by Enformable

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March 18th, 2011 – The incidence of occurrence of LOOP due to weather-related effects is not declining

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Pages from ML12332A344 – March 17th, 2011 – Some SFP are simply not seismically qualified. They have mitiga…

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Pages From C143372-02A – March 16th, 2011 – NRC Deleted Over 100 E-mails From Members of the Public Demandi…

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Pages From C143372-02A – March 13th, 2011 – PMT Comparison of Fukushima Daiichi to TMI and Chernobyl Accidents

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They may have done exactly what Mitch said: flooded the cavity and then they got a steam explosion–

Mike Corradini could give the best guess as to that. To me, the timeline fits.

M.

From: Michael Corradini [corradini@engr.wisc.edu]
Sent: Friday, March 11, 2011 9:08 PM
To: Farmer, Mitchell T.
Cc: Gavrilas, Mirela; Tinkler, Charles; Basu, Sudhamay; Lee, Richard; Grandy, Christopher
Subject: Re: Fukushima

I am with Dana and others at ACRS. We have gotten some small info from folks in Japan. Fukashima used up their DC battery energy powering their RCIC pumps after the AC diesel generators started and then failed. As of 7pm EST, portable generators had arrived but yet to have been hooked up. Charlie or Mirela may know more. Dana has been contacted by a DOE emergency response team (and I wished him well to Japan).

Michael Corradini, Chair
Engineering Physics
University of Wisconsin
(608)263-1648 [Fax: 3-7451]
corradini@engr.wisc.edu

http://www.engr.wisc.edu/ep

Quoting “Farmer, Mitchell T.”:

> Hi Mirela, Charlie, Sud, Richard,

> Don’t know if you are out there. I’ve been watching the situation
> at Fukushima and don’t like what I’m seeing, at least based on the
> news reports I have access to. I don’t know how long a BWR can go
> w/o emergency core cooling and not sustain significant core damage
> but it seems like we’re well into that time domain. Is there
> anything that can be done to help? I don’t know, I’m searching.
> The one thing we learned from MCCI though: if you fear vessel
> failure and you have any means to flood the cavity then you should
> do that. They have siliecous concrete in Japan; too much
> interaction ex-vessel w/o water and coolability is lost. Let me
> know if there is anything I can do.
> Mitch

Pages From ML11230A043 – March 12th, 2011 – They May Have Done Exactly What Mitch Said – Flooded the Cavity…

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Pages From ML12188A292 – April 9th, 2011 – Summary of Radiological Hazards in Japan

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Attached are the final slides I sent to the Ambassador’s secretary. They will have them for the on-site briefing package. If SoS wants a few minutes we will give quick verbal. Otherwise Ast. Sec. Donohue (DOE) is traveling with her and will have these details. We’ve briefed him and his staff previously so he is up to speed. It is expected that she will at least say something to the NRC folks …… The ambassador recommended to her that she discuss the NRC.

Thanks
chuck

Pages From Ml12188a292 – April 15th, 2011 – Nrc Interim Comprehensiveassessment of Fukushima Event

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Pages From ML12188A292 – March 18th, 2011 – Federal Fact Sheets and TPs Related to Fukushima

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I. Spent Fuel Pool Assessment

1. The option of filling a spent fuel pool with borated sand in the event of a high temperature event was identified by the Industry Consortium as a discussion topic. It is not a full recommendation.

2. Filling a pool with sand would likely insulate the fuel and lead to additional fuel damage.

3. There’s a possibility that escape of gaseous fission products could be reduced by addition of sand. However, it’s likely that debris in the pools would prevent placing the sand uniformly
enough to avoid movement of fission products.

4. Installation of high efficiency spray equipment that can get water into the pools would make more sense than sand placement.

5. The pools are designed to carry very heavy loads, so it’s unlikely that the weight of sand would cause loading issues.

II. External Drywell Cooling Update

1. Additional analyses have been performed using pessimistic assumptions about heat transfer. The analyses indicate that drywell cooling might not be able to remove all decay heat.

2. Access ports through the drywell head seal are bolted open during normal operation in US plants. It’s uncertain whether the access port requirement holds in Japan.

3. Piping penetrations through the drywell walls are typically sealed with epoxy. These seals could be breached if the piping sleeves were to be used to inject water.

4. There’s a possibility that drilling holes through the drywell walls or cover could limit the ability to flood the drywell. If drilling was necessary, the penetrations should be placed as high as possible. Stents could potentially be used to plug any holes that were drilled.

5. It’s likely that water injected into the drywell gap would flow in a narrow stream down the drywell wall and provide only limited cooling. A method for spreading the flow would be necessary.

6. Filling the gap from the bottom by injecting water into the drywell drain might be possible. This filling method would avoid the need to drill holes and overcome limitations associated with
streaming of injected water.

7. Shield plugs above the drywell head have to be moved before the gates leading to the spent fuel pools can be moved. As a result, flooding the refueling cavity by opening the gates is not an
option.

8. It’s possible that small shape charges could be used to penetrate the drywell cover. Debris that might fall on the drywell cover after use of shape charges would probably not be heavy enough to
cause significant cover damage.

9. Filling of the drywell gap may require circulation of a large volume of water that would then require treatment.

Ill. The Japanese government has decided to release water containing low levels of radioactivity. There are significant political consequences associated with these releases, but there may be a
need for continuing to expedite release decisions in order to make room for storing more highly contaminated water. Bringing in large storage bladders is an option for to low-contaminated water
storage.

Pages From ML12096A136 – April 5th, 2011 – Notes From Science Experts Call on Fukushima Disaster – SFP Asse…

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