SECY-06-0196, Ltr to Alex Marion Response to NEI Circuits Methodologies
| ML070750153 | |
| Person / Time | |
|---|---|
| Issue date: | 03/23/2007 |
| From: | Grobe J NRC/NRR/ADES |
| To: | Marion A Nuclear Energy Institute |
| McCann, E, NRR/DRA/AFPB, 301 415-1218 | |
| References | |
| SECY-06-0196 | |
| Download: ML070750153 (4) | |
Text
March 23, 2007 Mr. Alexander Marion, Executive Director Nuclear Operations and Engineering Nuclear Generation Division Nuclear Energy Institute 1776 I Street, NW., Suite 400 Washington, DC 20006
Dear Mr. Marion:
On behalf of the U.S. Nuclear Regulatory Commission (NRC), I thank you for participating in the February 16, 2007, public meeting. The NRC held the public meeting to solicit stakeholder input for developing a high-level closure plan to resolve multiple spurious operations resulting from fire-induced circuit failure. You presented a framework for a methodology (Agencywide Documents Access and Management System (ADAMS) Accession No. ML070590448) to resolve this issue. You also requested that NRC provide feedback before the industry expends resources to develop the proposed methodology.
The Commission directed the NRC staff in staff requirements memorandum (SRM) on SECY-06-0196 (ADAMS Accession No. ML063490140) to work with external stakeholders to develop or endorse a methodology to address multiple spurious operations. The NRC staff has performed a preliminarily review of the NEI methodology and has developed the enclosed questions. Please provide us a schedule of when we can expect your response to our questions.
We also wish to advise you based on our preliminary review of the NEI methodology that it apparently is not consistent with the regulatory requirements of Appendix R to Title 10 of the Code of Federal Regulations Part 50 (10 CFR Part 50),Section III.G. Therefore, plants licensed to operate before January 1, 1979, who wish to use the NEI methodology, must submit a request for an exemption from compliance with Section III.G of Appendix R, in accordance with the requirements of 10 CFR 50.12.
Finally, the NRC staff wishes to remind you that it is the Commissions view that adoption of National Fire Protection Association (NFPA) 805 is the preferred method for utilizing a risk-informed approach to address the issue of multiple spurious operations, as indicated by the Commission staff requirements memorandum (SRM) on SECY-06-0196 (ADAMS Accession No. ML063490140).
Sincerely,
/RA/
John A. Grobe, Associate Director for Engineering and Safety Systems Office of Nuclear Reactor Regulation
Enclosure:
As stated
ML063490140) to work with external stakeholders to develop or endorse a methodology to address multiple spurious operations. The NRC staff has performed a preliminarily review of the NEI methodology and has developed the enclosed questions. Please provide us a schedule of when we can expect your response to our questions.
We also wish to advise you based on our preliminary review of the NEI methodology that it apparently is not consistent with the regulatory requirements of Appendix R to Title 10 of the Code of Federal Regulations Part 50 (10 CFR Part 50),Section III.G. Therefore, plants licensed to operate before January 1, 1979, who wish to use the NEI methodology, must submit a request for an exemption from compliance with Section III.G of Appendix R, in accordance with the requirements of 10 CFR 50.12.
Finally, the NRC staff wishes to remind you that it is the Commissions view that adoption of National Fire Protection Association (NFPA) 805 is the preferred method for utilizing a risk-informed approach to address the issue of multiple spurious operations, as indicated by the Commission staff requirements memorandum (SRM) on SECY-06-0196 (ADAMS Accession No. ML063490140).
Sincerely,
/RA/
John A. Grobe, Associate Director for Engineering and Safety Systems Office of Nuclear Reactor Regulation
Enclosure:
As stated DISTRIBUTION: DRA R/F ADAMS Accession No.: ML070750153 NRR-106 OFFICE AFPB/DRA AFPB/DRA:D Tech Editor DRA:D OGC NRR:ADES NAME EMcCann SWeerakkody HChang CHolden FCameron JGrobe DATE 03/06/07 03/06/07 03/19/07 03/20/07 03/18/07 03/23/07
U.S. NUCLEAR REGULATORY COMMISSIONS QUESTIONS ON NATIONAL ENERGY INSTITUTES METHODOLOGY ENCLOSURE The U.S. Nuclear Regulatory Commission (NRC) has the following questions in response to the Nuclear Energy Institutes methodology to resolve multiple spurious operations resulting from fire-induced circuit failure as presented at the February 16, 2007, public meeting.
- 1. The methodology uses probabilistic risk assessment (PRA) insights to screen a generic list of multiple spurious operations and performs a generic analysis on this list. Subsequently, risk/PRA is used to pre-screen and/or disposition multiple spurious operations. In these activities, what measures do you propose to ensure that the PRA insights and risk/PRA analyses are of acceptable quality? What are the details of this generic analysis? To what extent does the generic analysis incorporate risk evaluations?
- 2. The methodology relies upon screening criteria including numerical thresholds to screen risk-significant scenarios. What are the proposed screening criteria and numerical thresholds for acceptance criteria under circumstances where the analysis is (a) self-approved, or (b) NRC reviewed?
- 3. The methodology utilizes fire modeling to disposition multiple spurious operations. How would a licensee ensure the acceptable quality of these fire models? How would licensees ensure fire modeling has sufficient margin to account for uncertainties?
- 4. The methodology is unclear whether or not the cumulative effects of scenarios are considered. What will prevent a licensee from screening out significant issues by dividing them into a large number of constituent scenarios? Is there a method to ensure a licensee considers cumulative effects?
- 5. The methodology does not seem to consider the synergistic effects of scenarios such as interaction between circuits and manual actions. Is there a method to ensure that a licensee consider the potential of synergistic effects (e.g., a operator manual action with a high probability of failure combined with the effects of a multiple spurious operations)?
- 6. The methodology relies on licensees developing reliable cable layouts. How does the methodology disposition a situation when the licensee is unable to develop a reliable cable layout database?
- 7. The methodology utilizes an expert panel to assure the completeness of the process and the integrity of the screening process. What minimum requirements will be set for an adequate expert panel? What process would the expert panel follow? Is there a generic expert panel review and where would it fit in the process if there is one? Is there a plant-specific expert panel review at the input of the plant specific stage to capture plant-specific scenarios? How does the expert panel review in this methodology compare to the normal NFPA 805 process for multiple spurious operation analysis expert panel review?
2
- 8. The methodology does not address multiple spurious operations in Alternate Shutdown Areas (III.G.3). The staff view is that fire safety of III.G.2 areas are regulated by the separation requirements specified in Section III.G.2, and multiple spurious operations must be addressed in III.G.3 as well as III.G.2 areas. How would you modify your methodology to address III.G.3?
The staff acknowledges that additional discussions must be conducted to clarify regulatory expectations on this subject.