ML111330285
| ML111330285 | |
| Person / Time | |
|---|---|
| Issue date: | 03/31/2012 |
| From: | Burke J NRC/RES/DE/MEEB |
| To: | |
| Jervey, Richard 301-251-7404 | |
| Shared Package | |
| ML111330239 | List: |
| References | |
| DG-1234 RG-1.82, Rev 4 | |
| Download: ML111330285 (3) | |
Text
1 REGULATORY ANALYSIS FOR REGULATORY GUIDE 1.82, WATER SOURCES FOR LONG-TERM RECIRCULATION COOLING FOLLOWING A LOSS-OF COOLANT ACCIDENT Statement of the Problem Regulatory Guide (RG) 1.82 Revision 3 (R3) was updated in November 2003 to provide the latest guidance available to licensees from ongoing studies and evaluations taking place in the process to resolve and conclude Generic Safety Issue (GSI) 191. Findings from NRC-sponsored research, and plant-specific analysis/testing have provided additional information to industry and staff for evaluating ECCS strainer performance for PWRs and BWRs following a postulated design-basis accident. As a result, the staff has revised the regulatory position sections of RG 1.82 by updating to include developments from staff positions described in safety evaluations (SEs) of industry guidance documents and industry topical reports.
Revision 4 (R4) of RG 1.82 continues to provide guidance on methods that the NRC staff considers acceptable for evaluating the adequacy of ECCS strainer performance for long-term recirculation cooling following a LOCA.
This RG 1.82 R4 reformats the discussion section by combining, where appropriate, common regulatory positions for PWRs and BWRs, resulting in shorter PWR and BWR-specific sections, as well as incorporating guidance developed within the process of evaluating GSI-191 experience. The regulatory position section has been updated and recently developed guidance has been included as well.
The proposed changes in RG 1.82, R4 do not represent new staff regulatory positions. This revision to the guide is limited to editorial changes, such as combining the discussion of PWR and BWR characteristics and incorporating much of the latest related subject matter derived from the staffs evaluation of industry studies performed to support conclusion of the GSI-191 concerns. Of these, the following subjects have been addressed. Generation and source term of varying types of debris materials; ECCS suction voiding concerns; ECCS pump sensitivity; Debris loading effects on fuel; Prototype testing; Operator actions; Alternate water sources; Use of debris interceptors; Considerations for coating use; Chemical effects. Each topic has been evaluated and accepted by staff, but was not yet incorporated into RG 1.82. Each staff regulatory position is addressed in the discussion and tied to the appropriate references to support complete understanding of the staffs position. There are no new staff positions promulgated.
The development of staff regulatory guidance often occurs when a topic is evaluated specifically to address an individual plants concerns or related licensing actions which may impact the plants design basis. Given the industry has significant economic interest in resolving the GSI-191 concerns, there is great value in the other plants consideration of these developments. Although, the continuing evolution in the understanding of ECCS strainers and debris blockage by LOCA-generated debris makes it likely that RG 1.82 will require further updating, staff has determined that revising it at this time will be beneficial to facilitate the common understanding of stakeholders which will ultimately expedite resolution of the GSI-191 concerns.
The guidance provided is generic in nature, although its application to existing licensees is ultimately dependent upon individual plant configuration. Because of the many choices of a licensee to engineer plant specific ECCS sump strainer configurations, there is no method to determine financial impact without specific plant considerations made. There are no meaningful cost differential estimates to be made between RG 1.82 revision 3 and RG 1.82 revision 4. There is no disaggregation performed in
2 the regulatory analysis because each licensed plants unique configuration require implicitly that all considerations identified in the guidance should be evaluated in their entirety.
Objective The objective of this action is to update the current version of Regulatory Guide 1.82, R3 to be consistent with existing guidance in other documents prepared for the resolution of GSI-191 ( and GL 2004-02 for PWRs) and to combine the discussion of PWRs and BWRs together where similar plant features allow, Alternative Approaches The NRC staff considered the following alternative approaches:
Do not revise Regulatory Guide 1.82.
Revise Regulatory Guide 1.82.
Alternative 1: Do Not Revise Regulatory Guide 1.82 Under this alternative, the NRC would not revise this guidance, and the current version of guidance would be retained. If NRC does not take action, there would not be any changes in costs or benefit to the public, licensees or NRC. However, the no-action alternative would not address supplemental information related to the current version of the regulatory guide or provide the benefit of incorporating the newly gained knowledge. The NRC would continue to review each licensee submittal on a case-by-case basis. This alternative provides a baseline condition from which any other alternatives will be assessed.
Alternative 2: Revise Regulatory Guide 1.82 Under this alternative, the NRC would revise Regulatory Guide 1.82 to reference NEI 04-07, Revision 0, and to provide the NRC staff positions on the approved NEI 04-07 guidance. The document would also provide additional guidance based on information obtained since the issuance of NEI 04-07.
Revising the regulatory guide would also increase the consistency between the regulatory positions that are specified for PWRs and BWRs, as appropriate.
One benefit of this action is that it would provide licensees and applicants a consistent approach to implementing an acceptable method for the evaluation of ECCS strainer performance and would comply with the licensing requirements. Additionally the staff has determined that revising it at this time will be beneficial to facilitate the common understanding by staff, licensees and other stakeholders which will ultimately expedite resolution of the issues.
The impact to the NRC would be the costs associated with preparing and issuing the regulatory guide revision. The impact to the public would be the voluntary costs associated with reviewing and providing comments to the NRC during the public comment period. The value to NRC staff and its applicants would be the benefits associated with enhanced efficiency and effectiveness in using a common guidance document as the technical basis for license applications and other interactions between the NRC and its regulated entities.
3 Conclusion Based on this regulatory analysis, the NRC staff recommends revision of Regulatory Guide 1.82.
The staff concludes that the proposed action reflects the current staff positions on acceptable methods for the evaluation of sump performance following a postulated LOCA or design-basis accident.