ML012990231
| ML012990231 | |
| Person / Time | |
|---|---|
| Issue date: | 10/25/2001 |
| From: | Wen P Division of Regulatory Improvement Programs |
| To: | Madden F Nuclear Energy Institute |
| WEN P NRC/NRR/DRIP/RGEB 301-415-2832 | |
| Shared Package | |
| ml012990225 | List: |
| References | |
| Download: ML012990231 (2) | |
Text
From:
Peter Wen To:
MADDEN, Fred Date:
10/25/01 2:25PM
Subject:
Re: Containment ILRTs - One-time Extensions
- Fred, Attached are NRC staff's comments (from Mike Snodderly) on NEI's "Interim Guidance for Performance Risk Impact Assessments In Support of One-Time Extensions for Containment Integrated Leakage Rate Test Surveillance Intervals."
NEI's interim guidance as well as Mike's comments will be put into NRC's ADAMS-Public section.
If you have questions, please contact me or Mike (301-415-2047).
Peter Wen 301-415-2832
>>> "MADDEN, Fred" <fwm@nei.org> 10/24/01 09:37AM >>>
- Mike, NEI/EPRI has developed interim guidance for performing risk impact assessments that support one-time extensions for containment ILRT surveillance intervals. This interim guidance builds on EPRI TR-104285 and NUREG-1493 and considers the approaches and issues from recent station licensing actions (e.g., Indian Point 3 and Crystal River). The guidance document is attached.
Our plan is to provide this guidance to licensees in order to promote uniform risk impact assessments supporting one-time extensions of ILRT surveillance intervals that are consistent with regulatory expectations.
If you have any questions or concerns with this guidance, please let me know.
- Thanks, Fred W Madden Nuclear Energy Institute 202-739-8114 fwm@nei.org
<<ILRTInterimGuiderev3.doc>>
Package accession#ML012990225 NRR-106 E-mail Accession#ML012990231 NRR-106 ILRTInterimGuiderev3 Acc.#ML012990239 NRR-106 CC:
Hansraj Ashar; James Pulsipher; Joe Birmingham; Mark Rubin; Michael Snodderly; Steven West
NRR (Mike Snodderly) Comments on NEI Interim Guidance for Performing Risk Impact Assessments that Support ILRT Test Interval Extensions Comments on NEI's draft interim guidance for performing risk impact assessments in support of one-time extensions for containment integrated leakage rate test surveillance intervals. I believe the guidance is well written and should greatly improve the efficiency and effectiveness of future reviews. This is neither an approval or rejection of the proposed methodology but acknowledgment of a relatively simple, consistent methodology that can be applied to a variety of plant types and, therefore, would result in more efficient reviews. My comments are as follows:
- 1. It appears that elements of the Duke and CEOG methodologies have been incorporated into the NEI methodology. Does the CEOG and Duke agree with the NEI methodology? Have any other parties reviewed and approved the methodology?
- 2. The guideline states that it is more appropriate to utilize the mean and Jeffery's non-informative prior distribution but it does not give a basis why these are the most appropriate distributions for the data. A short explanation would be helpful.
- 3. In the paragraph describing the second improvement "large" as used in this assessment has not been defined. I assume it is 35 La based on Table 1. A basis or reference should be provided.
- 4. Step 8 of the methodology states that late releases are excluded regardless of size of the leak because late releases are not, by definition, LERF events. While this is true. I do not believe late releases have been excluded. They are considered in Step 9 by calculating CCFP.
Also as pointed out in Step 8 the risk is from a previously undetected large leak. The impact, of which, would be seen early. I believe this is a more convincing argument.