ML20203B137
| ML20203B137 | |
| Person / Time | |
|---|---|
| Issue date: | 02/04/1999 |
| From: | Sheron B NRC (Affiliation Not Assigned) |
| To: | Modeen D NUCLEAR ENERGY INSTITUTE (FORMERLY NUCLEAR MGMT & |
| References | |
| NUDOCS 9902100232 | |
| Download: ML20203B137 (4) | |
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February 4, 1999-David J. Modeon, Director Engineering, Nuclear Generation Division 1
Nuclear Energy Institute
- 1776 i Street, NW., Suite 400 Washington, DC 20006-3708
SUBJECT:
INDUSTRY STEAM GENERATOR PROGRAM INITIATIVE (NEI) 97-06, " STEAM GENERATOR PROGRAM GUIDELINES" 4
Dear M 8
Thank you for your letter of December 17,1998, providing (1) responses to NRC comments and recommendations on NEl 97-06 and (2) a suggested milestone schedule for obtaining NRC review and acceptance on a generic license change package for revising the regulatory framework goveming steam generator (SG) tube integrity. In the past several months, both the NRC staff and industry have focused a significant effort towards resolution of the key technical issues involved with the 4 wiementation of NEl 97-06. Your December 17,1998 letter is -
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, evidence that progress v t:een made in resoMng issues.
You requested.NRC staff confirmation of acceptance of the responses to the technicalissues contained in enclosure 2 to your December 17 letter. The staff has reviewed the technicalissue responses and the following provides the current staff views on the remaining technical-differences, as well as our current thoughts on the proposed NEl approach for revising the regulatory framework goveming SG tube integrity.
Differences on technical issues still remain, however it is the staff's view that resolution of these technicalissues is dependent on the structure of the final regulatory framework goveming SG tube integrity. Technical differences regarding issues such es operational assessment, nondestructive examination qualification, and the treatment of uncertainties may not need resolution in the short term, if a performance-based framework is adopted that: (1) ensures effective condition monitoring against performance criteria and (2) enables the staff to conclude that it has an effective regulatory instrument for inspecting and enforcing against i-these requirements when circumstances warrant.
Based on our current understanding, it appears that you are proposing to remove all requirements from the technical specifications (TSs) pertaining to SG surveillance. Under this proposal, the remaining TS requirement pertaining to SG tube integrity would be operational leakage. While operational leakage is the only tube lategrity parameter that plant operating y.
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1 David J. Modeon staff can directly monitor during operation, this criterion alone does not ensure that SG tubes can perform their safety functions under all design basis accident conditions. The staff concludes that under a new regulatory approach whereby SG tube integrity requirements are to be performance-based, the TSs need to contain (in the administrative section where such criteria would not unnecessarily distract operators) the other two performance criteria goveming tube integrity (i.e structural integrity criterion and the accident leakage criterion) in order for the TSs to contain the necessary minimum criteria that ensure the SG tubes can perform their safety functions consistent with the assumptions of the design basis accident analyses.
Additionally, the NRC staff concludes that such a revised TS would also need to contain a requirement to monitor SG tube integrity against the performance criteria. It is our current view that a revised TS would have to contain these requirements, at a minimum, for it to be consistent with 10 CFR 50.36.
With this minimal, performance-based TS as described above, much of the remaining TS requirements that address SG surveillance frequency, sampling and expansion, tube repair -
criteria, and tube repair methods can potentially be removed from TSs. The determination of how much of this material can be removed will depend on the effectiveness of the regulatory framework that govems the displaced requirements (i.e,10 CFR 50.59, ASME Code, Appendix B etc.) and the staff's confidence in licensee's implementation of NEl 97-06 sub-tier documents.
The NRC staff agrees in principle with NEl's proposal that first of a kind attemate repair criteria or repair methods should be subject to NRC review, in trying to identify the regulatory process for achieving this approach (outside of the technical specifications), the NRC staff believes there is potential for altemate repair criteria and repair methods to be addressed by the ASME Code in a manner similar to the treatment of the remainder of the reactor coolant pressure boundary. However, the code would have to be updated to address some issues not currently covered in the code, for example, the lack of flaw acceptance criteria for straight tube SGs.
This type of approach would be beneficial in avoiding numerous future plant specific TS amendments. The NRC staff suggests that this approach is worthy of consideration and that induttry and the staff should further explore this idea to determine its viability and practicality.
The NRC staff needs to better understand the details on the implementation of NEl 97-06 as
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contained in the sub-tier topicals before it can make an informed conclusion on the acceptability
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of an NEl proposal to revise TSs. This is not to suggest that NEl should send the staff draft topicals, but instead to recognize that this needs to be factored into the overall schedule for reaching agreement on the revised regulatory framework.
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David J. Modeon -./
' As you are aware, we plan to further discuss the information discussed above at the upcoming technical meeting on February 10,1999.
Sincerely,
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Brian W. Sheron, Acting Associate Director for Technical Review
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l David J. Modeen l As you are aware, we plan to further discuss the information discussed above at the upcoming i-technical meeting on February 10,1999.
l Sincerely, i
Brian W.Sheron, Acting Associate Director l
for Technical Review Office of Nuclear Reactor Regulation 1
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