ML031110452
Jump to navigation
Jump to search
| ML031110452 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 08/12/2002 |
| From: | Demoss G Office of Nuclear Regulatory Research |
| To: | Long S Office of Nuclear Reactor Regulation |
| References | |
| FOIA/PA-2003-0018 | |
| Download: ML031110452 (1) | |
Text
I.Gary Demoss - Davis Besse P;=
From:
Gary Demoss e6c To:
Steven Long / il /&iG Date:
8/12/02 3:56PM
Subject:
Davis Besse
- Steve, I've taken a quick look at your Predecisional Draft SDP per you request and have comments on each rupture type.
As-found cavity - Medium LOCA -
- 1. In the section entitled "CCDF for LOCAs", you seem to state that you will use the licensee's restated CCDP, but use the CCDP from the Davis-Besse IPE.
- 2. The model is operating way out on the tail of a statistical distribution. Probably the best that can be done, but this should be made clear to the reader.
Enlarged cavity - Large LOCA -
- 1. The use of the probability that Davis-Besse could have achieved more years of operation by February 16, 2002 as the initiating event frequency is not consistent with an ASP analysis.
- 2. The second tier assumptions associated with the initiating event frequency would have to include no NRC action, no adequate inspections, no leakage greater than 1 gpm, and no small or medium LOCA before the large LOCA. You qualitatively addressed all these issues, but they appear to add a significant amount of doubt as to the likelihood that this event could have led to a large LOCA.
- 3. I don't have a good suggestion for quantitatively resolving items 1 and 2. I think that we should look into possible models that incorporate the approach that was taken for the As-found cavity in conjunction with a growing cavity size. Additionally, we could consider attempting to quantitatively address the human reliability of the inspections. It certainly won't be easy.
Nozzle eiection - Medium LOCA
- 1. In the section entitled "CCDF for LOCAs", you seem to state that you will use the licensee's restated CCDP, but use the CCDP from the Davis-Besse IPE.
I will be in Richmond starting tonight. If you have any questions or time to discuss this, feel free to call me in my hotel room tomorrow morning between 6:30 and 8:00 at 804-965-9500, or anytime later in the week.
Gary DeMoss CC:
Don Marksberry; Michael Cheok; Stephen Dinsmore I\\2