ML20128G318
| ML20128G318 | |
| Person / Time | |
|---|---|
| Issue date: | 02/04/1993 |
| From: | Taylor J NRC OFFICE OF THE EXECUTIVE DIRECTOR FOR OPERATIONS (EDO) |
| To: | Shewmon P Advisory Committee on Reactor Safeguards |
| Shared Package | |
| ML20128G322 | List: |
| References | |
| ACRS-GENERAL, NUDOCS 9302120241 | |
| Download: ML20128G318 (3) | |
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UNITED STATES :
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NUCLEAR REGULATORY COMMISSION -
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February 4. 1993 Mr. Paul G. Shewmon, Chairman Advisory Committee on Reactor Safeguards i
U.S. Nuclear Regulatory Commission Washington, D.C.
20555
Dear Mr. Shewmon:
l
SUBJECT:
PROPOSED BRANCH TECHNICAL POSITION ON ENVIRONMENTAL QUALIFICATION OF.
ELECTRICAL EQUIPMENT FOR LICENSE RENEWAL 1amrespondingtotheAdvisoryCommitteeonReactorSafeguards(ACRS)
October 22, 1992, letter.
In that letter, the ACRS indicated-that the should not be issued:for public proposed branch technical position (BTP)he ACRS letter have been addressed.
comment until the matters discussed in t The following is the staff's response to the ACRS letter.
After the staff identified this. issue for license renewal and presented the BTP to both the ACRS and the Committee to Review Generic Requirements-(CRGR), the staff decided that environmental qualification (EQ).needs to be evaluated as an issue of potential safety concern'for some operating plants.
l Therefore, the staff will address EQ as a current: issue using the established i
regulatory process, not,as part of the license renewal review. The staff will-reassess the adequacy of EQ for plants whose currentilicensing' basis (CLB) is:
either the DOR Guidelines or NUREG-0588, " Interim Staff Position On Environ--
mental Qualification'Of Safety-Related Electrical: Equipment," Category !!.
1 The staff will' consider existing ACRS comments in this reassessment.
Additionally, the staff will keep the ACRS. informed of its progress on this is?ue.
Sincerely,:
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xecutive irector.
for Operations.
Cc:
The Chairman Commissioner Rogers Commissioner Curtiss Commissioner Remick Commissioner; de - Planque -
SECY Helen Pastis-Rr un10 9 ABR M W
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EDO Principal Correspondence Control FROM:
DUE: 11/13/92 EDO CONTROL: 0008215 DOC DT: 10/22/92 FINAL REPLY:
DAVID A. WARD ACRS
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EXECUTIVE DIRECTOR DESC:
ROUTING:
PROPOSED BRANCH TECHilICAL POSITION ON TAYLOR ENVIRONMEf4TAL QUALIFICATION OF ELECTRICAL SNIEZEK EQUIPMENT FOR LICENSE RENEWAL THOMPSON BLAHA E: 10/23/92 MAT TAYLOR BECKJCRD, RES IGflED TO:
CONTACT:
BERNERO, NMSS f4RR MURLEY JORDAN, AEOD
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PREPARE RESPONSE TO ACRS FOR EDO'S SIGNATURE.
PUT CCMMISSIONERS AND SECY ON CC (SHOWN ON ORIGINAL) FOR REPLY.
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October 22, 1992 Mr. James M. Taylor Executive Director for Operations U.S. !'uclear Regulatory Commission Washington, D.C.
20555
Dear Mr. Taylor:
SUBJECT:
FROPOSED BRANCH TECHNICAL POSITION-ON ENVIRONMENTAL QUALIF. ATION OF ELECTRICAL EQUIPMENT FOR LICENSE RENEWAL During the 390th meeting of the Advieory Committee on Reactor Safeguards, October 8-10, 1992, we reviewed a proposed Branch Technical Position (BTP) on Environmental Qualification of Electrical Equipment for License Renewal.
Our Subcommittees'on Plant License Renewal and Reliability and ' Quality reviewed this
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matter during a joint meeting on September 16, 1992.=The staff.
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proposes that the BTP be issued for public comment.
During these meetings, we had the benefit of discussions with-members of the s
NRC staff, its consultants, and representatives o* industry.
We also had the benefit of the documents. referenced.
Under the License Renewal Rule, 10 CFR Part 54, applicants will be required to develop a comprehensive program:to identify in their plants all structures, systems, and components (SSCs) which may be subject 'o age-related degradation. unique to the-license renewal period.
A further program to= manage these components to ensure continued safe operation of the plant is also required.
The staff is now proposing an additional-program, by means of a BTP, which singles out environmental qualification of electrical equipment for special treatment in the license renewal period.
The particular-concern of=the staff secms to b6 that-thesqualification-standards for insulation used on- ' electrical cables prior to "1984 (representing 87 of 111 licensed nuclear power plant units) may not ensure adequate performance of cables for extended plant life.
That, of course, is the issue for all SSCs in a plant,'and'it is-not clear to us why the more general treatment of SSCs called for under 10 CFR Part 54 is not adequate for electrical cables as well.
Industry representatives expressed objection to the staff proposal for a BTP.
The" believe= that while older plant cables were
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-qualified to a lesser standard than has been in use since 1984,
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these cables have been approved for continued use in the plants l(as 1o
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October 22, 1992
- has much other equipment where standards P"v a evolved) and are part of the current Licensing Basis (CLB)
~m each of these plants.
Their interpretation of-10 CFR Part 54.3e l hat the CLB is to be preserved with the exception that those St.6s subject to age-related degradation unique to the license renewal period should be subjected to specific management programs.
They see no need for the BTP and believe it will result in unnecessary __ cable replacements and add significantly to plant costs for license renewal.
We are not convinced that the proposed BTP has been shown to be necessary or appropriate.
It should not be issued for public ~
comment until the matters discussed below have been addressed.
Neither the staff nor the industry presented any risk perspective on this issue.
In ainple terms, the risk is as follows:
During_
the license renewal period the electrical cable in a. key system might degrade in a way that the degradation would remain undetected during normal operation and by normal maintenance, testing, and surveillance practices.
Then, during an accident, i.e.,
a LOCA, the insulation would fail and the key system would not perform its design function to mitigate effects of _ the accident.
Present licensing practice assumes, and experience seems to confirm, that the probability of this sequence during the initial license period is acceptably low..At issue is whether the probability during the
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license renewal period is significantly greater.
No evidence has been presented either way. Analysis of tN risk importance of this issue should be made before the DTP is finally accepted.or rejected.
Such an analysis should include estimates of downside risks inherent in major projects intended to improve nuclear' power.
plant safety.
Many electrical cables are covered with-fire retardant materials.
These coatings could have important effects on the aging of the cable insulation.
Apparently, these-effects have not-7been considered by the staff in developmert of this BTP.
We do _not know whether they have yet been explicitly considered in the selection' and evaluation of important SSCs in license renewal. programs. They should be.
Dr.. Thomas Kress did not participate in the Committee's deliberations regarding this matter.
Sincerely, O
David A. Ward Chairman i
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Mr. James M. Taylor.
3 October 22','1992
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References:
from' John W.-.Craig, Office of-;
1.
Memorandum dated July 10, 1992, Nuclear Reactor ' Regulation, NRC,. for Raymond F._
- Fraley, l
Advisory-Committee on Reactor Safeguards,
Subject:
Request-for Review of Branch Technical Position on Environmental
-. Qualification of Electrical Equipment - for License Renewal, with~ enclosures l-2.
Letter dated; October 7, 1992, from M. H.-Philips, Jr., and'W.
l A.
Horin, Counsel to the Nuclear Utility-Group on Equipment; i
Qualification, to D.
A.
Ward, Advisory Committee-on Reactor l-Safeguards,
Subject:
NRC Staff Proposed License Renewal-BTP Regarding Environmental Qualification of-Electric-Equipment,_
with enclosures s
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