April 1st, 2011 – Remove as much spent fuel from pools as technically feasible

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From: Gibson, Kathy
Sent: Friday, April 01, 2011 3:14 PM
To: Sheron, Brian; Correia, Richard; Coe, Doug; Scott, Michael
Cc: Uhle, Jennifer
Subject: Re: RESPONSE – SFP DStudy


Suggest we add this to our meeting next week since we will have all the right people there.


From: Sheron, Brian
To: Correia, Richard; Gibson, Kathy; Coe, Doug; Scott, Michael
Cc: Uhle, Jennifer
Sent: Fri Apr 01 14:27:22 2011
Subject: FW: RESPONSE – SFP DStudy

See below. We’ve been given the go-ahead to start this comparative risk assessment. Please think about:

1.) Who should have the lead? DSA or DRA?
2.) What staff and/or contractors are available to do the study? Can we rationalize that this work would feed into a future level 3 PRA study?
3.) How much $ do we think it will cost? Can we find the money from within RES?
4.) Will we trip the threshold for Commission notification?
5.) How long will the study take? I do not believe this is something we can do at a leisurely pace.

I anticipate the Commission will need to take some sort of action on this issue within a year. I am planning to take a CWS day Monday, so maybe you can discuss among yourselves Monday and then let’s discuss Tuesday.

From: Weber, Michael
Sent: Friday, April 01, 2011 2:15 PM
To: Sheron, Brian
Cc: Borchardt, Bill; Virgilio, Martin
Subject: RESPONSE – SFP DStudy

Please proceed with starting the study. This question has arisen in a variety of contexts of the years.

We faced it in the 2005-2006 timeframe with the National Academy in their spent fuel study.

Now it arises again.

Let’s get the information; whether we decide to recommend a policy change based on the information is a totally separate decision.

Do we anticipate that this will trip the 4 FTE or $500K threshold requiring Commission notification?

From: Sheron, Brian
Sent: Friday, April 01, 2011 2:09 PM
To: Weber, Michael
Subject: SFP DStudy

Mike, I am reading lots of stories about everyone clamoring for the NRC to require licenses to remove as much of the spent fuel from their pools as is technically feasible.

I think I mentioned that I anticipated we (the Agency) would get this question, and I said I wanted to start on a study ASAP (rather than wait for the TF 90 day study, then wait for a tasking from the Commission)

My objective was to do a comparative risk assessment of storing fuel in the pools (as is done now) versus removing all of the fuel that could be air-cooled into dry casks.

About 80% of the SFP heat load comes from the most recent offloads, so removing older fuel does not reduce the SFP heat load that much.

However, removing all the old fuel removes mass from the pool that can be replaced by water.

Thus, removing older fuel would increase the volume of water available for boiloff in the event all SFP cooling was lost. Both of the above would increase the time available to restore forced convection cooling before the onset of overheating the fuel.

Another potential benefit is that the licensees could then spread the fuel out in the pool, so hot assemblies would not be adjacent to each other.

Thus, if pool cooling was lost and the pool boiled down and began to uncover the fuel, heat transfer to the fuel bundle surroundings would be increased because it would be to pool water, rather than to an adjacent hot bundle.

This could result in fewer assemblies reaching the runaway oxidation and ignition temperature.

Finally, having fewer assemblies in the SFP means less radioactive material is available for release in the event that SFP cooling could not be restored.

The drawbacks are that removal of all assemblies that are air-coolable in dry casks will increase fuel handling and thus increase the potential for fuel handling accidents and their attendant consequences.

Plus, dry storage casks may have their own set of vulnerabilities that need to be considered.

I saw in the Friday edition of “The Energy Daily” that “….Jaczko neither rejected nor embraced the idea of reviewing the NRC’s spent fuel policies.”

Thus, I am a little hesitant to go off and start this study without having some clear direction from either you, Bill or the Commission.

I think that if the Commission eventually either wants to address the issue, or is directed to in legislation, we need to start now.

I would imagine such a study will take a while (- 1 year?), and because of the scrutiny it will probably come under, it will have to be done very carefully.

Any suggestions on if and how to proceed?

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