ML103080232
| ML103080232 | |
| Person / Time | |
|---|---|
| Site: | Turkey Point  |
| Issue date: | 11/04/2010 |
| From: | NRC/NRR/DRA |
| To: | |
| References | |
| FAQ 07-0038, Rev 2 | |
| Download: ML103080232 (6) | |
Text
NRC Staff Comments on FAQ 07-0038, Revision 2 [HTB,SCD] {November 2010}
FAQ Number 07-0038 Revision 2 FAQ Title Lessons learned on Multiple Spurious Operations Plant: Turkey Point Date: June 30, 2010
Contact:
Vinny Rubano Phone: (772)-467-4874 Email: vinny.rubano@fpl.com Distribution: (NEI Internal Use) 805 TF FPWG RATF RIRWG BWROG PWROG Purpose of FAQ:
The purpose of this FAQ is to provide updates to NEI 04-02 to reflect lessons learned from pilot plant activities, NFPA 805 task force meetings, and NRC reviews and discussions on multiple spurious operations (MSOs) and their treatment during transition to NFPA 805.
Is this Interpretation of guidance? Yes / No Proposed new guidance not in NEI 04-02? Yes / No Details:
NEI 04-02 guidance needing interpretation (include section, paragraph, and line numbers as applicable):
NEI 04-02 Section Appendix B.2, Transition of Nuclear Safety Performance Criteria.
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NRC Staff Comments on FAQ 07-0038, Revision 2 [HTB,SCD] {November 2010}
FAQ Number 07-0038 Revision 2 FAQ Title Lessons learned on Multiple Spurious Operations Circumstances requiring guidance interpretation or new guidance:
Lessons have been learned from pilot plant activities, NFPA 805 task force meetings, and NRC reviews and discussions on multiple spurious operations (MSOs) and their treatment during transition to NFPA 805.
Detail contentious points if licensee and NRC have not reached consensus on the facts and circumstances:
None.
Potentially relevant existing FAQ numbers:
Response Section:
Proposed resolution of FAQ and the basis for the proposal:
See the proposed attached proposed NEI 04-02 markups.
If appropriate, provide proposed rewording of guidance for inclusion in the next Revision:
See the proposed attached proposed NEI 04-02 markups.
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Appendix B Transition of Nuclear Safety Performance Criteria Add the following section to Appendix B of NEI 04-02 Revision 2 B.2.1.3 Fire-Induced Circuit Failures (Multiple Spurious Operations)
A licensee should submit a summary of its approach for addressing potential fire-induced multiple spurious operations (MSOs) for NRC review and approval. At a minimum, the summary should contain sufficient information relevant to methods, tools, and acceptance criteria used to enable the staff to determine the acceptability of the licensees methodology.
The NRC staff has reviewed Revision 1 of NEI 00-01 and concluded that Chapter 3 provides an acceptable deterministic approach for analysis of post-fire safe shutdown circuits when applied in accordance with the regulatory expectations described in RIS 2005-30 and when used in conjunction with NFPA 805 and the current Regulatory Guide 1.205 revision for a plant that has transitioned to a 10 CFR 50.48(c) licensing basis (
Reference:
RIS 2005-30 and Regulatory Guide 1.205 Revision 1). Note that Revision 1 of Regulatory Guide 1.205 references Revision 2 of NEI 00-01, however, the technical content of Chapter 3 is essentially the same with respect to the portions related to the MSO expert panel process. Therefore, NEI 00-01 Revision 1 Chapter 3 can be used as guidance for the MSO expert panel. In addition, an acceptable Fire PRA as defined in Regulatory Guide 1.205 Regulatory Position C.4.3 includes methods for the selection of cables and detailed circuit failure modes analysis, as well as the integration of these circuit failures into the overall Fire PRA (e.g., NUREG/CR-6850 Tasks 3, 9, 10, and 14).
The approach outlined in Figure XX below is one acceptable method to address fire-induced MSOs. This method uses insights from a Fire PRA that meets the requirements of Regulatory Guide 1.205, Revision 1.
This process is intended to be in support of transition to a new licensing basis. Post-transition changes would use the risk-informed, performance-based change process. The post-transition change process for the assessment of a specific MSO would be a simplified version of this process, and may not need the level of detail shown in the following section (e.g., An expert panel may not be necessary to identify and assess a new potential MSO. Identification of new potential MSOs may be treated as part of the plants Operating Experience process. This FAQ scope is limited to treatment of MSOs during transition to NFPA 805..
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Appendix B Transition of Nuclear Safety Performance Criteria Identify Potential MSOs of Concern SSA Step 1 Generic List of MSOs Self Assessments PRA Insights Operating Experience Expert Panel Step 2 Identify and Document MSOs of Concern Update PRA model & NSCA (as appropriate) to include MSOs of concern Step 3 ID equipment ID logical relationships ID cables ID cable routing Evaluate for NFPA 805 No Compliance Step 4 Pursue other resolution options Compliant with NFPA 805?
Yes Step 5 Document Results Figure XX - Multiple Spurious Operations - Transition Resolution Process Step 1 - Identify potential MSOs of concern.
Information sources that may be used as input include:
- Post-fire safe shutdown analysis (NEI 00-01, Revision 1, Chapter 3)
- Generic lists of MSOs (e.g., from Owners Groups and/or later versions of NEI 00-01, if endorsed by NRC for use in assessing MSOs)
- Self assessment results (e.g., NEI 04-06 assessments performed to addressed RIS 2004-03)
- Operating Experience (e.g., licensee event reports, NRC Inspection Findings, etc.)
Step 2 - Conduct an expert panel to assess plant specific vulnerabilities (e.g., per NEI 00-01, Rev. 1 Section F.4.2).
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Appendix B Transition of Nuclear Safety Performance Criteria The expert panel should focus on system and component interactions that could impact nuclear safety. This information will be used in later tasks to identify cables and potential locations where vulnerabilities could exist.
The documentation of the results of the expert panel should include how the expert panel was conducted including the members of the expert panel, their experience, education, and areas of expertise. The documentation should include the list of MSOs reviewed as well as the source for each MSO. This documentation should provide a list the MSOs that were included in the PRA and a separate list of MSOs that were not kept for further analysis (and the reasons for rejecting these MSOs for further analysis)
Describe the expert panel process (e.g., when it was held, what training was provided to the panel members, what analyses were reviewed to identify MSOs, how was consensus achieved on which MSOs to keep and any dispute resolution process criteria used in decision process, etc.)
[Note: The physical location of the cables of concern (e.g., fire zone/area routing of the identified MSO cables), if known, may be used at this step in the process to focus the scope of the detailed review in further steps.]
Step 3 - Update the fFire PRA model and NSCA to include the MSOs of concern.
This includes the:
- Identification of equipment (NUREG/CR-6850 Task 2)
- Identification of cables that, if damaged by fire, could result in the spurious operation (NUREG/CR-6850 Task 3, Task 9)
- Identify routing of the cables identified above, including associating that routing with fire areas, fire zones and/or Fire PRA physical analysis units, as applicable.
Include the equipment/cables of concern in the Nuclear Safety Capability Assessment (NSCA).
Including the equipment and cable information in the NSCA does not necessarily imply that the interaction is possible since separation/protection may exist throughout the plant fire areas such that the interaction is not possible).
Note: Instances may exist where conditions associated with update of the MSOs may do not warrant require update of the Fire PRA and NSCA analysis. For example, Fire PRA analysis in NUREG/CR-6850 Task 2, Component Selection, may determine that the particular interaction may not lead to core damage, or pre-existing equipment and cable routing information may determine that the particular MSO interaction is not physically possible. In other instances, the update of the PRA may not be warranted if the contribution is negligible. The rationale for exclusion of identified MSOs from the Fire PRA and NSCA should be documented and the configuration control mechanisms should be reviewed to provide reasonable confidence that the exclusion basis will remain valid.
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Appendix B Transition of Nuclear Safety Performance Criteria Step 4 - Evaluate for NFPA 805 Compliance The MSO combinations included in the nuclear safety capability assessment NSCA should be evaluated with respect to compliance with the deterministic requirements of NFPA 805, as discussed in Section 4.2.3 of NFPA 805. For those situations in which the MSO combination does not meet the deterministic requirements of NFPA 805 (VFDR), the issue with the components and associated cables should be resolved mitigated by other means (e.g.,
performance-based approach per Section 4.2.4 of NFPA 805, plant modification, etc.)
The performance-based approach may include the use of feasible and reliable recovery actions.
The use of recovery actions to demonstrate the availability of a success path for the nuclear safety performance criteria requires that the additional risk presented by the use of these recovery actions be evaluated (NFPA 805 Section 4.2.4).
Step 5 - Document Results The results of the process should be documented. The results should provide a detailed description of the MSO identification, analysis, disposition, and evaluation results (e.g.,
references used to identify MSOs; the composition of the expert panel, the expert panel process, and the results of the expert panel process; disposition and evaluation results for each MSO, etc.). High level methodology utilized as part of the transition process should be included in the 10 CFR 50.48(c) License Amendment Request/Transition Report.
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