ML20245C269
| ML20245C269 | |
| Person / Time | |
|---|---|
| Issue date: | 08/14/1987 |
| From: | Jordan E Committee To Review Generic Requirements |
| To: | Stello V NRC OFFICE OF THE EXECUTIVE DIRECTOR FOR OPERATIONS (EDO) |
| Shared Package | |
| ML20245B353 | List: |
| References | |
| GL-83-28, NUDOCS 8708260002 | |
| Download: ML20245C269 (18) | |
Text
..
August 14, 1987 MEMORANDUM FOR:
Victor Stello, Jr.
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Executive Director for Operations 4 gg FROM:
Edward L. Jordan, Chairman Committee to Review Generic Requirements pggg m Tg! pDR
SUBJECT:
MINUTES OF CRGR MEETING NUMBER 118 The Committee to Review Generic Requirements (CRGR) met on Wednesday, July 8, 1987, from 1-3 p.m.
A list of attendees for this meeting is enclosed (Enclosure 1). The following item was addressea at the meeting:
The Committee reviewed proposed changes to the Technical Specifications for BWR relay reactor protection systems (RPS) that would lengthen the intervals for RPS functional testing.
The Committee recommended in favor of issuing the proposed changes, subject to minor wording revisions to be coordinated with the CRGR staff.
The Committee also recommended that the EDO direct the staff to consider improved means of monitoring the long-term reliability of plant equipment subject to such Tech Spec relaxations.
The discussion of these matters is documented in Enclosure 2.
In accordance with the E00's July 18, 1983 directive concerning " Feedback and Closure on CRGR Reviews," a written response is required from the cognizant office to report agreement or disagreement with CRGR recommendations in these minutes. The response, which is required within five working days after receipt of these meeting minutes, is to be forwarded to the CRGR Chairman and if there -
is disagreement with the CRGR recommendations, to the ED0 for decisionmaking.
Questions concerning these fneeting minutes should be referred to Jim Conran (492-98S5).
oria;n.1 sign.d sn E.I.;Jorden j
Edward L. Jordan, Chairman Committee to Review Generic Requirements
Enclosures:
As stated Distribution: w/o encl.
Central File cc:
Commission (5)
PDR (NRC/CRGR)
SECY R. Hernan Office Directors S. Treby Regional Administrators W. Little CRGR Members M. Lessar W. Parler J. Zerbe A. Thadani J. Johnson (w/ enc.)
T. Collins J. Conran (w/ enc.)
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LIST OF ATTENDEES CRGR MEETING NO. 118 July 8, 1987 CRGR MEMBERS E. Jordan T. Martin J. Scinto J. Sniezek B. Morris for D. Ross D. Cunningham for R. Bernero OTHERS J. Zerbe J. Conran T. Cox D. Lasher T. E. Collins E. Doolittle D. Robinson E. Butcher S. Brown M. Wohl 1
i
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j to the Minutes of CRGR Meetirg No.118 Proposed Technical Specification Imprcsement
~
for BWR Relay Reactor 7rotection System July 8, 1987 I
TOPIC Proposed Technical Specification Modification for BWR Relay Reactor Protection Systems (RPS).
BACKGROUND' A. Thadani and T. Collins, NRR, presented for review by the Committee proposed Tech' Spec revisions that would increase the existing functional test interval for BWR relay RPS.. The proposed changes are based.on the staff's review of GE Topical Reports NEDC-30844, dated January 1985, "BWR Owners' Group Response to Generic letter 83-28," and NEDC-30851P, dated May 1985, " Technical Specifica-tion Improvement for BWR Reactor Protection System." ine proposed Tech Spec changes represent a relaxation of current staff positions, i.e., (a) an exten-sion from monthly to quarterly of the surveillance interval for relay RPS channel functional testing, and (b) an extension from I hour to 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />, and from 2 nours to 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />, of certain allowable out-of service times (A0Ts) for that RPS instrumentation.
The proposed changes are permissive type chan the Tech Specs (i.e., they are not imposed by the staff on any licensee)ges to
, and so do not constitute a backfit.
Licensees may adopt the cnanges voluntarily, if they choose to do so.
This change is similar to RPS Tech. Spec changes made for Westinghouse PWR RPS several years ago.
Copies of the briefing slides used by the staff to guide the presentations and discussions at this meeting are attached to this Enclosure.
The package submitted for review by CRGR in this matter was transmitted by memorandum dated May 27, 1987, T. E. Murley to E. Jordan; that package included the following review documents as attachments:
- 1. - Draft letter to T. A. Pickens, Chairman of the BWR Owners' Group (BWROG), regarding acceptance of Topical Reports NEDC-30844 and NEDC-30851P, and enclosures: - NRC Staff Safety Evaluation of Topical Reports a.
- b. - Proposed Changes to Relay RPS Technical Specifications l
- 2. - Response to Requirements for Content of Package Submitted for CRGR Review.
DISCUSSION The major comments and questions raised by CRGR at this meeting regarding the proposed changes to the Tech Specs for BWR relay RPS functional test intervals were as follows:
__-_.___-____-__--_D
l 1.
The Committee questioned the staf f regarding details of NRC contractor verification of the completeness and applicability of the RPS system reliability data used or cited by GE in support of the proposal to i
lengthen RPS channel functional test interval.
The staff indicated that this verification involved a literature search by the contractor, and comparisons of values used by GE with standard data basei (e.g.,
NUREG/CR-2815 and EPRI data), as well as comparisons / correlations with performance reliability results gleaned from LER surveys and previous ATWS analyses and conclusions.
This led to the question of how the staff proposed to assure that the topical
- port analyses and conclusions remain valid. The need for close monitoring of RPS (and other reactor plant systems) availability at the train level was identified by the Committee in the coursa of these discussions as an issue of increasing importance, because this tweaking of RPS Tech Specs is just the first in what is expected to be a series of such Tech Spec changes that are anticipated in connection with implementation of NRC's Tech Spec Improvement Program (TSIP).
It was noted that available LER data can only indicate system-level reliabilities; and, to the present at least, utility support and part:cipation in NPRDS has been spotty, with the result that train level re liability figures that might be derived from it currently cannot be regarded as truly (representative.
After thorough discussion of these questions, the consensus Committee view was that a recommendation should be made to the the EDO to direct the appropriate NRC offices (probably AE0D and NRR) to jointly develop proposals for effective means to track train-level reliabilities for nuclear plant systems.
It was emphasized, however, in these discussions that such a recommendation should not be misconstrued as in any way relieving licensees of the primary obligation to assure that component or train level reliability levels (or failure rates) used in the topical report analysis are accurate and applicable to their individual facilities, if they choose to amend their Tech Specs to decrease RPS functional test intervals.
Improved NRC capability in this regard is important, however, as an independent check of the reliability (or failure rate) values used in licensee / vendor analyses, as well as in the performance indicator context.
2.
The Committee questioned the staff's conclusion that staggered testing of RPS channels need not be required in conjunction with this relaxation of BWR RPS functional test frequencies, as was done earlier with respect to Westinghouse PWR RPS testing.
The staff felt confident that their con-clusion in this regard was defensible; they cited the greater diversity of inputs to BWR scram channels, and the alternate ATWS scram feature for BWRs, as the fundamental considerations underlying that conclusion.
They also noted that no credit had been assumed for staggered testing in GE's analyses in support of this proposal; and, although NRC's contractor did not check those analyses in detail, GE's conclusions seemed consistent with the staff's knowledge and experience regarding the general character-istics and expected behavior of systems of high diversity.
Specific examples were discussed in which common mode failures were produced by maintenance personnel misadjusting a number of similar sensor inputs to the scram channels in the same way.
P each case it was concluded that the scram function was not likely to be defeated, because the sheer number of different types (i.e., the diversity) of inputs was great enough that l
1
one maintenance man would not likely have time to even attempt adjusting all of them in one shift.
r 3.
The Committee inquired how the proposed change would be implemented with regard to plant specific applicability.
The staff noted first that any i
such action on the part of an individual licensee would be completely voluntary, and the burden would be on that licensee to demonstrate that his plant fit the " envelope" of design features for which the topical report analyses apply, or to demonstrate convincingly that any failure to fit that envelope was not safety significant.
This led one Committee member to question whether widespread implementation of this option might not result in an inordinate expenditure of staff resources, because of many plant specific design differences of which he was aware that could result in the staf f reviewing many such plant specific justifications.
The staff responded that, if such circumstances developed, the staff would simply withdraw approval of the topical report. At the same time, they noted that this was not expected to occur, because GE had already provided a letter identifying relevant plant differences for those plants that might reference this topical report; and the staff had this information available in deciding the course of action taken.
4.
The wording of the Tech Specs regarding what actions must be taken, and when they must be taken, in the event of inoperable RPS channel (s) was -
discussed with the staff (e.g., see SER at p. 9 and revised p. 2 of the RPS Tech Specs in the review package).
With regard to the outage times allowed for test and repair activities (i.e., 6 and 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> respective-ly), it was not clear to the Committee from the existing wording whether it was intended that the time intervals specified should be counted con-secutively and cumulatively, or otherwise. They recommended that the wording of the SER, the Tech Spec Action Statements, and the Tech Spec Bases be revised to clarify the staf f's intent, and to more clearly convey that intent to plant operators, in operational terms more suited to the operating environment.
A specific format suggested was to specify the two time intervals in question as follows:
The out-of-service interval allowed for testing an RPS channel, a.
during which no action is required except for verification of operability, or determination of inoperability, of that channel.
b.
The interval allowed for repair and return to service (or trip),
after completing the testing of an RPS channel.
The staff agreed that the wording in question could be made clearer, and that the wording of the portions of the Tech Spec actually available to operators for immediate reference in the control room or other operating areas (e.g., the Tech Spec Action Statements) should be revised.
They disagreed, however, with revising the corresponding wording of the SER and Tech Spec Bases. Their view was that the " Bases" sections of the Tech Specs (unlike the " Action Statement" sections) are not often referred to by the operators in stressful circumstances under actual operating con-ditions, where confusion over the existing wording might be an important issue; so there is not the same need or justification for revising the wording of the " Bases." With regard to the SER wording, the same s
l l
consideration applies; and, additionally. the staf f sees an advantage to l
keeping the SER wording consistent with that of the topical report terminology, so that anyone reading both will be able to better understand what is being discussed and approved by the staff therein.
l S.
The Committee disagreed with the staff characterization (in one the l
briefing slides used by the staff at this meeting) of a possible 1-2%
increase in core damage frequency from this Tech Spec change as insig-nificant, in the context of an ongoing Tech Spec Improvement Program where a number of other Tech Spec changes, all of which may similarly affect CDF, are contemplated.
The staff agreed that the cumulative effect of such changes will have to be considered in connection with all the separate TSIP revision proposals put forward, lest the overall effect become significant.
It was noted, however, that the GE analysis of this proposed Tech Spec change states that the increase in CDF due to less f requent testing is ".. less than one percent." (See NE00-30851P at pp.
5-22.) And the staff SER (at p. 3) states "... based on conservative assumptions, the estimated increase in RPS unavailability due to the proposed T5 changes would contribute a very small increase to estimated core-melt f requency.
On this basis, it was concluded that the 1-2%
increase in CDF given in the briefing slide was simply an unintended overstatement error; and the staff agreed to correct this error in the review package that will be released finally to the POR in connection with this matter.
An objection was also raised to the undue emphasis given in another briefing slide to the increase in RPS failure frequency that it is estimated may result from the proposed lengthening of RPS functional test interval.
The estimated increase is 8E-7/yr; or, expressed as a per-centage of the original failure rate, a 17% increase in RPS failure frequency. While the value itself was not disputed, its presentation in the briefing slide was felt to overshadow the more relevant conclusion that the change will not result in any significant change in core melt frequency or risk to the public.
Accordingly, that slide will also be revised prior to release to the PDR.
RECOMMENDATIONS TO THE E00 On the basis oi' their review of this matter, including the disco 'ons with the staff at this meeting, CRGR recommended in favor of issuing the proposed (permissive) changes to the Tech Specs for BWR relay RPS testing, subject to several minor modifications indicated in the preceding.
The Committee also recommended, that as an important adjunct to this proposed action, and other Tech Spec revisions contemplated in conjunction with the ongoing Tech Spec Improvement Program, that the EDO direct the appropriate NRC offices (probably AE00 and NRR) to jointly develop proposals for effective means to track train-level reliabilities for nuclear plant systems.
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1 CER KETING JULY 8, 1987 i
TOPIC:
RELAXATION OF TECHNICAL SPECIFICATIONS FOR BWR REACTOR PROTECTION SYSTEM INSTRUNNTATION i
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RPS INSTRLPENTATION FUNCTIONAL TESTS PURPOSE:
PROVIDE ASSURANCE THAT THE ELECTRICAL PORTION OF THE SCRAM SYSTEM IS OPERABLE TESTS:
CHANNEL FUNCTIONAL TEST CHECKS OPERABILITY BY INRTTING A SCK SIGNAL AT THE SENSOR AND VERIFYING HALF SCRAM
RESPONSE
SCRAM CONTACTOR TEST CHECKS CONTACTOR OPERABILITY BY DEPRESSING MANUAL SCRAM BUTTON IN CONTROL RO&1 AUD VERIFYING HALF SCRAM RESPONSE PROPOSED CHANGES:
ITEM CURRENT PROPOSED FREQUENCY CFI FREQUENCY W OR M Q
CONTACTOR TEST FREQUENCY M
W CHANNEL A0T (HOURS) 1 12 2
6 APPLICABILITY:
ALL BWRS tXCEPT CLINTON
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O ONE OUT O Fr TWO TWICE LOGIC
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S!? NARY OF TECHNICAL EVALUATION
' VERIFIED DOMINANT CUTSETS
- INDEPENDENT FAULT TREE CONSTRUCTION
- INDEPENDENT GENERATION OF CUTSETS
' VERIFIED COWLETENESS AND APPLICABILITY OF DATA
- RANDOM FAILURE RATES
- INITIATING EVEhT FREQUENCIES
- C0f0N CAUSE FAILURE RAIES
- OPERATOR ERROR RATES
- COWONENT WEAR DUE TO TESTING INDEPENDENT
- PERFORE D INDEPENDENT SENSITIVITY CALCULATIONS
- I WACT OF EXTENDED SI
- IWACT OF EXTENDED A0T
- ESTIMATED IMPACT ON CDF 0F PROPOSED CHANGES l
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l CONCLUSIONS
' PROPOSED OiANGES ESLLT IN EGLIGIRE SAFETY IWACT
- DECEASE IN RPS AVAILABILITY SLIGHRY INCEASES 0)F
- DECEASE IN lOBER OF TEST IM)UCED SCRAMS DECEASES OF
- ET IWACT IS EGLIGIRE
- DIVERSITY AND REDlf0ANCY ESLA.T IN HIGH RELIABILITY AM) LW SENSITIV11Y TO A0T/SI
- DIVERSITY IN SENSED PARAEfERS
- LEVEL
. PRESSURE
' FLUX
- POSITION SWITG
- REl)(NDANCY IN OE OUT T TM) TWIT LOGIC
- INCEASE IN FEQUENCY OF CONTACTOR TEST TEATS C0ti)N CAUSE CONCERN
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i CONSIDERATION OF STAGGEED Tr3 TING ISSUE:
SHOULD STAGGERED TESTING BE REQUIRED AS A CONDITION FOR l
APPROVAL OF PROPOSED SURVEILLANCE INTEINAL EXTENSION STAFF POSITION:
STAGGERED TESTING NOT EQUIED NO CREDIT ASSLMD IN PROPONENT'S ANAL.YSIS BASIS:
RPS DIVERSITY AND REDUNDANCY Pf0/III HIGH ELIABilliY GE ANALYSIS INDICATES MINIMAL BENEFIT FRCli STAGGERING SCE STAGGERING IEVITABLE ANWAY BECAUSE OF TESTING LOGISTICS l
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- INDUSTRY ESPONSE IS VOLLNTARY
--STAFFEFFORT<1 MAN-)(EKPERAPPLICATION
' ANTICIPATED BENEFITS
- SLIGHT EDUC110N IN PERS0 thel EXPOSURE
- REDUCTION IN TEST / REPAIR MAN-HOURS-I t
- SLICHT REDUCTION IN INADVERTENT SCR# 6
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i ItPACT OF PROPOSED RPS TEOl SW C CHANGES INCEASE IN RPS FAILUE FE00ENCY
_ 8 X 10-7/ YEAR INCEASE i
EDUCTION IN SCRAM FEQUENCY
- 0,3 SCRE/ YEAR DECRFEASE EGLIGIBLE IlfACT ON 0)RE DAMAGE FREQUENCY REDUCTION-INRPSACTUATIONS
- 59 PERCEE DECREASE IN CHAffEl. ACUTATIONS/YR.
REDUCTION IN TEST /EPAIR MAN-HOURS
- 910 l%N-Hol2/ YEAR DECREASE I
u.__.___
_I
i SUPPORTING DOCTENTATION AND ELATED STAFF POSITIONS l
EDC-30844P "BWR OWNERS' GROUP RESPONSE TO NRC GENERIC LETTER 83-28,"
JANUARY 1985 EDC-30851P
" TECHNICAL SPECIFICATION IWROVEENT ANALYSES FOR BWR REACTOR PROTECTION SYSTEM INSTRUMENTATION," MAY,1985.
EGG-EA-7105 "A REVIEW 0F TE BWR OWERS' GROUP TECHNICAL SPECIFICATION IWROVEENT ANALYSES FOR THE BWR EACTOR PROTECTION SYSTEM,"
JANJARY,1986.
NJREG-1024 "lECHNICAL SPECIFICATIONS - ENHANCING THE SAFETY I W ACT" SECY 86-10 "ECTENDATIONS FOR IWROVING TECHNICAL SPECIFICATIONS" SECY G6-310 "CONISSION POLICY STATEENT ON TECHNICAL SPECIFICATION IWROVENNTS FOR MJCLEAR POWER EACTORS"
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