March 31, 2011 – Recommend TEPCO utilize the SAMG recommendation to flood all 3 units’ containments.

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Task 1:

Given the known, or assumed, status of the three units and four pools, what realistic scenarios exist for energetic dispersion of high quantities of radioactive material that would result in mobile plumes?

The point of this question is that there are many clear scenarios that present significant near-area radiological challenges, but given the time since shutdown (for the operating units) and age of much of the fuel (in the SFPs) what are the remaining scenarios of concern with respect to more distant locations (Tokyo with a large concentration of US citizens, Alaska, Hawaii, etc).

Objective for first question (energetic release potential): this information is important to the Ambassador in Japan and the US military command that would be responsible for movement of US citizens who were ordered to be evacuated from any locations in the Pacific.

In fact, the Pacific Command asked the same question of the NRC at today’s Deputies Meeting that is attended by the Chairman.

The answer to this question may also impact when we as the NRC ramp down our activities?

We should attempt to address this by Friday (4/1).

This task was accepted by RES, and I understand that Kathy Gibson’s Division (RES/DSA) has the lead supported by NRR/DE.

Task 2:

Given the assumed condition of the three units and four pools, can we generate basic event trees for the coming weeks/months? The point would be to identify key success criteria and to help identify key decision points/risk factors to be balanced (qualitative not quantitative analysis).

For instance, take two units, each with significant core damage and prior release of volatile fission products, each with primary and secondary containment failure, but one with an intact RPV and the other with a breach of RPV – would there be a difference in potential releases that would lead to different strategies for flooding the primary containment of these two units?

This question will make more sense if you look at the assumed conditions below and the attached assessment document where we recommend that TEPCO utilize the SAMG recommendation to flood all 3 units’ containments.

Objective for the second question is to support multiple questions/actions. There have been many requests of the PMT for “realistic” dose models. The RST Assessment document (original e-mail was supposed to have it attached, but I’ve added to this incase it did not go out the first time) also contains recommended actions for the Japanese to consider.

These recommendations are based on the SAMGS, which all are intended to protect primary containment.

Since primary containment is damaged on at least two units, we need to assess whether there may be new considerations/priorities that are
not captured by the SAMGs.

Also, the product of this effort helps us better clarify the assessment of potential energetic releases, along with identifying the best strategies to ensure that they don’t happen.

This item does not have as short a deliverable date unless the PMT has one that I’m not aware of, but is still very significant in terms of our recommendations. Can we complete by Monday (4/4)?

Once NRC staff validates this concept, and creates a framework for the event trees, we may be able to turn it over to INPO/GEH for completion.

This-task has also been accepted by RES, and Rich Correia’s Division (RES/DRA) has the lead, with support from NRR/DE.

Proposed Task Tracker – Pages From C142449-02G-4

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