ML20151C882
| ML20151C882 | |
| Person / Time | |
|---|---|
| Issue date: | 01/17/1986 |
| From: | Conran J NRC OFFICE OF THE EXECUTIVE DIRECTOR FOR OPERATIONS (EDO) |
| To: | Bernero R, Cunningham R, Jordan E NRC OFFICE OF INSPECTION & ENFORCEMENT (IE), NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS), Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML20151C834 | List: |
| References | |
| FOIA-87-714 NUDOCS 8804130248 | |
| Download: ML20151C882 (6) | |
Text
'
/ pa ***ug\, UNITED STATES d e NUCLEAR REGULATORY COMMISSION
.t l wAssiwoTow, o. c. aones
- \'******/ JAN 171986 MEMORANDUM FOR: Robert Bernero, NRR Edward Jordan IE Richard Cunningham, HMSS Denwood Ross, RES Clemens Heltemes, AEOD Joseph Scinto, ELD THRU: Walter S. Schwink, Acting Director Regional Operations and Generic Requirements Staff FROM: James Conran, Senior Program Manager Regional Operations and Generic Requirements Staff
SUBJECT:
SUMMARY
AND ISSUE 10ENT!riCAT10N FOR CRGR MEETING NO. 84 Enclosed for your information and use is the ROGR staff sumary associated with the Proposed Broad-Scope Rule to Modify General Design Criterion (GDC)4of10CFRPart50.
This matter is scheduled for CRGR review at Meeting No. 84 on Wednesday, January 22, 1986 in Room 6507 MNBB i
James Conran ROGR Staff
Enclosure:
As stated cc: J. Sniezek l i
i
)
l l
8804130240 880405 hss - 14 g5\
SUMMARY
AND ISbuE IDENTIFICATION FOR CRGR REVIEW ITEM CRGR MEETING NO. 84 IDENTIFICATION Proposed Broad-Scupe Rule to Modify General Design Criterion (GDC) 4 of 10 CFR Part 50.
OBJECTIVE CRGR is requested to review and reconinend in favor of issuing for public coment a proposed amendment to GDC 4 that would allow exclusion, in some cafety licensing analysis contexts, of the dynamic effects of postulated pipe ruptures in all high energy piping systems of all nuclear power plants (including BWRs) that meet acceptance criteria also being proposed by the NRC staff as part of the proposed amendment. (This action would expand the scope of a similar recently-proposed interim rule which applies only to the primary coolant piping of PWRs.)
BACKGROUND
- 1. The documents submitted by the sponsoring office (RES) for CRGR review in this matter were identified in a memo dated January 13, 1986, R. B. Minogue to J. H. Sniezek. The RES document package for this review includes the
'911owing:
- a. Draft Comission paper, undated, "Proposed Broad-Scope Rule to Modify General Design Criterion 4 of 10 CFR Part 50," and enclosures as follows:
- 1. Enclosure 1 - Proposed Federal Register Notice (Rule)
- 2. Enclosure 2 "Assessment of Value-Impact Associated with Elimination of Postulated Pipe Ruptures from the Design Basis for Nuclear Power Plants" (Contractor Report by LLNL, datec March 29,1985).
- 3. Enclosure 3 - Proposed Public Announcement 4 Enclosure 4 - Proposed Congressional Letters
- 5. Enclosure 5 - Proposed Environmental Assessment J
Contacts:
John O'Brien, RES (x37860)
Jim Conran, ROGR Staff (x24654)
2-
- b. "Sumary of Proposed Generic Requirements for CRGR Review," dated June 3,1985(updated).
- 2. Related References
- a. NUREG-1061, "Report of the U.S. Nuclear Regulatory Comission Piping Review Comittee (Overall Final Report submitted to the EDO May 15, 1985).
- 1. Volume 3, dated November 1984, "Evaluation of Potential Pipe Breaks."
- 2. Volume 5, dated April 1985, "Sumary of Piping Review Comittee Conclusions and Reconynendations."
- b. NUREG/CR-4263, dated May 1985. "Reliability of Stiff Versus Flexible Piping, Final Project Report."
- c. SECY-86-4, dated January 2,1986, "Final (l.imited-Scope) Rule to ,
Modify General Design Criterion 4 of Appendix A to 10 CFR Part 50." 1
- 3. Related Material Identified by ROGR Staff Review
- a. Memo, dated June 20, 1985, Dircks to Minogue/Denton/ Taylor, "Piping Review Comittee Report and Recomendations."
- b. Memo, dated July 30, 1985, Minogue to Dircks, Plan to implement Piping Review Committee Recomendations," and enclosures: ;
- 1. Memo, dated July 8, 1985, Denton to Minogue, "Implementation of Piping Review Comittee Recomendations."
, 2. Memo, dated July 9,1985 Taylor to Minogue, "Review of PRC Report and Recomendations
- 3. Memo, dated July 9,1985, "Implementation of Piping Review Comittee Reco:mendations."
4 Enclosure 4 "Plan to Implement the U.S. Nuclear Regulatory Comission Piping Review Comittee Recomendations."
- c. Memo, dated January 2,1986, Minogue to Dircks, "Control of Ruleraking: Annual RES Review of Ongoing RES Sponsored Rulemaking."
- d. "Comparison Between U.S. and FRG Proposed Revision for Pipe Rupture Design Requirements at Nuclear Power Plants."
- e. Concurrence Sheet for Background item 1.a. above.
DISCUSSION This proposed action is a follow-on to a : natter considered earlier and in more limited scope by CRGR in the context of the Comittee's review of US! A-2 on asymetric blowdown loads. (See Minutes of CRGR Meeting No. 47, dated October 14,1983.) In the resolution of USI A-2, the NRC staff provided the technical justification for the conclusion that large margins against unstable crack extension exist for certain stainless steel PWR primary coolant piping postulated to have large flaws, even when subjected to the safe shutdown earthquake in combination with loads associated with norinal plant conditions.
Accordingly, the staff concluded that it is acceptable for PWR licensees to apply leak-before-break technology, in lieu of postulated large pipe ruptures at discrete locations specified by the staff, in licensees' analyses submitted for the purpose of resolving USI A-2. The CRGR recomended that the EDO accept staff's technical findings in that regard, but also noted that the staff's findings and the technical justification in support of those findings could apply more broadly to other break locations specified for consideration in USI A-2 and to assumptions made for PWR primary loop piping and components, for piping connected to the primary loops, and perhaps to the piping of other piping systees in the plant as well. The Comittee recomended a special staff effort to extend the USI A-2 conclusions more broadly. The staff subsequently undertook an effort to amend GDC-4 to allow broader application of the leak-before-break technology, adopting a two step approach involving ;
(l') development of a limited-scope interim rule to apply to the primary loop ;
piping of PWRs, where sufficient technical evidence was already available and I had been reviewed by the staff, ACRS, and CRGR, and (2) a follow on broad-scope j rule to apply more generally to nuclear plant piping that could be found to !
meet appropriate acceptance criteria yet to be explored and developed. The j limited-scope rule is now before the Comission for final approval (Ref. -
Background Item 2.c). The staff hopes to issue for public coment the proposed broad-scope rule, now scheduled for CRGR review at Meeting No. 84, in March l' 1986.
An important element of the overall staff effort that has culminated in this proposed action was the activity of the EDO-appointed Piping Review Comittee.
The proposed rule reflects the conclusions and recomendations of that group in most important respects. For example, the acceptance criteria included in the rule for detennining the acceptability of expansions of the application of leak-before-break technology in areas beyond the scope of the limited rule parallel very closely PRC recomendations in this regard. On the surface at
- 1 east, there are, however, a few differences which could be significant and/or controversial. (Because the acceptance criteria are the centerpiece of the proposed broad-scope rule, and are expected to be an important focus of the Comittee's review of this matter, the PRC-recemended criteria have been excerpted from the PRC Report and enclosed as Attachment 1 to this sumary sheet to facilitate direct comparison with the final version of the acceptance criteria adopted by the staff in the proposed rule - Ref - Background i item 1.a.1 at pp 9-13.) The differences noticed by ROGR staff are elaborated
, upon in the issues section following. Briefly, the areas identified by ROGR staff for discussion / clarification are (1) treatment of leak detection, and (2) inclusion of BWRs explicitly within the scope of the proposed rule at this time.
l
-4 The staff view that devices installed to protect against dynamic effects of postulated high energy in-service inspection (pipe ISI), breaks occupational increasing actually degrade safetyassociated exposure by interfering with with ISI, and even increasing the likelihood of pipe break (due to stresses which can arise resulting from unintended interferences therinal expansion) appear to be firmly based in analyses completed at this point of (primary loop) piping configurations, materials, and postulated break locations covered by the interim ruir.. That is not so obviously the case with regard to the piping /
components covered additionally in the scope of this broad scope rule. In fact, it rppears that the specific analyses that will confirin the acceptability of appWation of leak-before-break technology more broadly are for the most part yet to be done. It is also clear, however that there P unequivocal and strong opinion within the staff that there is high likelihood that when these "extrapolating" analyses are done they will put on finn footing the accept-ability of leak-before-break application for the broad scope of nuclear plant systems and components intended to be addressed by this role. The staff posture, then, is that it appears to be a safe bet, and reflects prudent engineering-and-rulemaking management to begin the broad scope rulemaking process without further delay and to solicit broad input in the form of coment on the proposed rule as soon as possible.
The proposed rule is supported by an extensive value-impact analysis perfonned by LLNL; its conclusions suggest a (lower-bound) best-estimate occupational dose reduction benefit of ~34,000 man-rem for PWR and 86,000 man-rem for BWRs, i considering an 85 plant total LWR population with an average remaining 35 years of life. Cost savings to utilities on the same bases are +$186 miliion ;
dollars for PWRs and ~$30 million dollars for BWRs.
ISSUES:
- 1. See annotated excerpts (a) from original PRC Report conclusions (Attachment 1 at p.10-4); (b) from EDO-initiated "Plan to Implement USNRC PRC Recorrnendations" (See Attachment 2 at p.1-4; p. V.3; and p. VI-11), I and (c) IE memo dated July 9,1985 (Attachment 3 at pp 1 and 2), and i compare with NRC staff treatment of leak detection issue and explicit l inclusion of BWRs within the intended scope of the broad scope rule. In l view of these comparisons, the Comittee may wish to clarify with the !
staff the following questions:
l
- a. Do the above cosparisons represent in any way significant inconsistencies between original PRC conclusions /reconinendations on the one hand, and either the PRC Implementation Plan or the proposed broad scope rule content on the other, in areas of leak detection requirements or applicability to BWRs of leak-before-break technology at this point?
- b. Is a "factor of 10" margin intended by the staff in the acceptance criterion proWsed for leak detection capability? If so, factor of 10 margin between what and what? Is this practicably achievable at this time; or might this in effect substitute one conservative deterministic requirement for another, thus diluting an intended
-5 effect of the proposed broad-scope rule? For this reason, is there any feeling that it is premature to go forward with the broad-scope rule without the additional leak detection information to be developed by research reconnended by the PRC?
- c. Is there any significance to the lack of IE concurrence in the proposed broad-scope rule (see Attachment 4 to this sumary sheet) after their apparent heavy involvement in this issue in the development of the implementation plan? What was the disposition of IE's July 9 coment regarding limitations identified by PRC in the text of NUREG-1061 not carried forward in the sumary conclusions /reconnendations?
d.
Should leak detection be included explicitly as an area of solicited coment in any proposed rule that is published? (PRC considered this a _ critical _ element of the leak-before-break concept).
2.
RES has emphasized their intent to obtain FRG input as an important element of this rulesking process; RES will be prepared to address any questions in this area at Meeting #84 (see summary of RES' comparative evaluation of NRC/FRG approach to leak-before-Break applicability -
Attachment 5 to this sumary sheet). The Comittee may wish to inquire regarding specific RES plans to obtain other formal international coments (e.g., UK and Japan) as part of the coment process.
3.
Not much is said in the proposed rule package regarding schedule for development and issuance of related SRPs and Regulatory Guides identified :
in the staff's ' Plan for Implementation..." (e.g., see Attachment 2 at pp.
1-10 and 1-11).
' 3 The Comittee may wish to discuss this matter with the staff to ascertain the following:
a.
Does the staff know how to review the kind of licensee submittals -
(i.e., in other than primary loop piping areas) that are likely to result in large numbers from approval of the pmposed rule? How will the acceptance criteria be implemented so as to achieve unifonnity of j !
interpretation across different staff elements? Are the necessary resources available to carry through implementing the proposed rule , I to realize its full potential benefits? '
i What numbers / schedules are the staff projecting in this regard? When will CRGR see the related regulatory guidance documents? i i I 4.
- 1. ate Breaking item: It has been decided that a backfit analysis will be i
provided in support of this proposed rule. A preliminary draft has been I provided by RES for the information of the Comittee (see separate attachment to this suunary sheet).
l l
t I