ML20214E414

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Responds to 860228 Request Re Possible Compromise of Procedures in Staff Review of Plant Compliance W/Gdc 51 as Input to Ser.Issue Appropriately Resolved W/O Compromise of Review Procedures
ML20214E414
Person / Time
Site: Limerick  Constellation icon.png
Issue date: 03/21/1986
From: Rehm T
NRC OFFICE OF THE EXECUTIVE DIRECTOR FOR OPERATIONS (EDO)
To: Joseph Austin
NRC COMMISSION (OCM)
Shared Package
ML20213F005 List:
References
NUDOCS 8603260173
Download: ML20214E414 (9)
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Text

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  1. - UNITE 3 STATES

. 8 9,% NUCLEAR REGULATORY COMMISSION g rj wAsmMGTON, D. C. 20066

%*****/ MAR 211986 Docket Nos.: 50-352 50-353 MEMORANDUM FOR: John H. Austin, Technical Assistant to Consnissioner Asselstine FROM: T. A. Rehm Assistant for Operations, EDO

SUBJECT:

LIMERICK COMPLIANCE WITH GDC-51 In your memorandum to me dated February 28, 1986, you requested certain information with respect to a particular staff input for the Limerick Safety Evaluation Report and several subsequent letters from the Philadelphia Electric Company (PECo) in 1984. The documents deal with potential shrinkage flaws in feedwater check valve bodies. We believe that this issue was appropriately resolved and that there was no compromne of the staff's safety review procedures. The following discussion which includes some pertinent background information, will serve to place this issue in the proper perspective, and should provide the information you requested.

During the staff's review of the Final Safety Analysis Report for the Limerick Generating Station in 1983 and 1984, the staff determined that two cast bodies for the feedwater check valves contained shrinkage cracks that could compromise the valves' conformance with GDC-51 if the cracks were to propagate while in service. Such propagation of the shrinkage cracks has also occurred in the past and has been documented for similar valves at other plants. After a fracture mechanics evaluation was com-pleted and submitted by PECo for the staff's review, an independent fracture mechanics evaluation was performed by the NRC staff. It was determined by the staff that a special inservice inspection of these valve bodies (valve IF074 A and B) would be required.

The resolution of this issue is addressed in the NRC staff's input to the SER, dated Septen/uer 18, 1984, two PECo letters dated October 4 and 12, i 1984, and Supplement No. 3 to the Limerick SER (NUREG-0991) issued in October 1984. Specifically, the supplement to the SER stated that:

k "We have concluded from these calculations that although the valve l

body may not quite meet the Appendix G requirements, even our most I

conservative approach still shows some safety mar Adequate l margin against failure (at least a factor of two) gin. will exist under the most probable loading conditions.

Contact:

R. E. Martin x29472 8603260173 860321 PDR ADOCK 05000352 P PDR

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., 3 These conclusions assume that the flaw size assumed will not be exceeded significantly. However, service experience on similar castings has disclosed that normal, acceptable shrinkage may be extended by cracking during service. We, therefore, recommended to the applicant that these valves.be inspected for surface cracks on the inside and outside surfaces at the first refueling outage and at other times when the valve is disassembled for maintenance. The applicant has cmnmitted, by letter dated October 12, 1984, to including this augmented inspection by surface examination or other methods acceptable to the staff, which will be determined during the staff's review of-the inservice inspection program.

We have concluded that the results of our evaluation and the augmented inservice inspection program for these valves will provide reasonable assurance of compliance with the requirements of GDC-51. It will be confirmed by the augmented ISI that the shrinkage flaws existing in the valve bodies on entering service.have not propagated to either.of the surfaces. Should the augmented ISI disclose that these flaws have propagated to either of the surfaces, the valves are then to be replaced by the licensee."

With respect to the issue raised by the PEco letter of October 4,1984, i.e., whether a surface crack of up to 3.5 inches in length.would be acceptable, the staff's position has been and continues to.be that if the valve body inspections disclose that internal shrinkage cracks have propagated to either surface, the valves are to be replaced, regardless of the length of the surface indication.

It should be noted that the alternative approach proposed by PECo in its letter of October 4, 1984, was found to be unacceptable by the staff and-PECo was so informed; whereupon, the PECo proposed approach described in its letter dated October 12, 1984, was submitted and determined to be acceptable. The staff findings reflected in the September 18, 1984, staff memorandum referred to in your memorandum were included in SSER-3, as discussed above. There has been no change in the staff's position from that stated in SSER-3.

WN<i) T. A Rshm T. A. Rehm Assistant for Operations, E00 cc: P. Polk C. Ader J. Myer M. Clausen OPE m OGC i' SECY

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  • Previously concurred: /
  • D/DIV D D/ W ED0 RBernero D ut HDMon TRehm 03/11/86 My86 g/g/86 $/31/86
  • PD#4 *PD#3 *PD#4 *BWR/EB *AD/BWR *DD/DIV RMartin EHylton WButler BDLiaw Glainas RHouston 03/11/86 -03/10/86 03/11/86 03/11/86 03/11/86 03/11/86

These conclusions assume that the flaw size assumed will not be exceeded significantly. However, service experience on similar castings has disclosed that normal, acceptable shrinkage may be extended by cracking during service. We, therefore, recommended to the applicant that these valves be inspected for surface cracks on the inside and outside surfaces at the first refueling outage and at other times when the valve is disassembled for maintenance. The applicant has committed, by letter dated October 12, 1984, to including this augmented inspection by surface examination or other methods acceptable to the staff, which will be determined during the staff's review of the inservice inspection program.

We have concluded that the results of our evaluation and the augmented inservice inspection program for these valves will provide reasonable assurance of compliance with the requirements of GDC-51. It will be confirmed by the augmented ISI that the shrinkage flaws existing in the valve bodies on entering service have not propagated to either of the surfaces. Should the augmented ISI disclose that these flaws have propagated to either of'the surfaces, the valves are then to be replaced by the licensee."

With respect to the issue raised by thq PECo etter of October 4, 1984, i.e., whether a surface crack of up to 3. ches in length would be acceptable, the staff's position has been,5 i,d continues to be that if the valve body inspections disclose that inter al shrinkage cracks have s

propagated to either surface, the valves re tg be replaced, regardless of the length of the surface indication.

osed by PECo in its It should letter be noted of October thatwas 4, 1984, thefound alternative approach prop'lq by the staff and go be unacceptab PECo was so informed; whereupon, the/PECo proposed approqch described in its letter dated October 12, 1984, Was submitted and detergined to be acceptable. ThestafffindingsreflectedintheSeptember 18, 1984, staff memorandum referred to in your memorandum were included in SSER-3, as discussed above. There has b en no change in the staff's position from that stated in SSER-3. ,

Thomas A. Rehm, Assistant for Operations, ED0

  • Prey *ou, sly concurred:

DD/NRR D/NRR ED0

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RB,er DEisenhut HDenton TRehm y g/g /86 / /86 / /86 / /86

  • PD#4 *PD#3 EHylton
  • PD#4 *BWR/EB Gla nas Dbh/

RMartin WButler BDLiad lhiduston 03/11/86 03/10/86 03/11/86 03/11/86 / /86 7 // 3n /

/86

These conclusions assume that the flaw size assumed will not be exceeded significantly. However, service experience on similar castings has disclosed that normal, acceptable shrinkage may be extended by cracking during service. We, therefore, recommended to the applicant that these valves be inspected for surface cracks on the inside and outside surfaces

-at the first refueling outage and at other times when the valve is disassembled for maintenance. The applicant has committed, by letter dated October 12, 1984, to including this augmented inspection by surface examination or other methods acceptable to the staff, which will be determined during the staff's review of the inservice inspection program.

We have concluded that the results of our evaluation and the augmented inservice inspection program for these valves will provide reasonable assurance of compliance with the requirements of GDC-51. It will be confirmed by the augmented ISI that the shrink ge flaws existing in the valve bodies on entering service have no propagated to either of the surfaces. Should the aQgented ISI disc ose that these flaws have propagated to either of the sue aces, the vallves are then to be replaced by the licensee."

With respect to the issue raised by the PEco etter of'0ctober 4, 1984, i.e., whether a surface crack of up to 3.5 dches in length would be acceptable, the staff's position has been a)ndcontinues to be that if the valve body inspections disclose that inte/nal brinkage cracks' have propagated to either surface, the valves'are to be replaced, regardless of the length of the. surface indicati . \

\

It should be noted that the alterna ive approach proposed by PECo in its letter of October 4, 1984, was f nd to be unacceptable by the staff and PEcowassoinformed;whereupon,pthePECoproposedap,proachdescribedin its letter dated October 12, 1984, was submitted and determined to be to be acceptable. The staff findings reflected in the September 18, 1984, staff memorandum referred to in your memorandum were included in SSER-3, as discussed.above. There has been no change in the staff's position from that stated in SSER-3.

Thomas A. Rehm, Assistant for Operations, E00 D/DIV ED0 o/mt A, RBernero TRehm H centc~ r

/ /86 / /86 /B6 M#4]F) PD#3E PD#4b BWR AD/BWR DD/DIV Krtid EHylton WButler B 4 /g Glainas RHouston

.7 /// /86 / /86J/h/86g/g'/86 / /86 / /86

2-These conclusions assume that the flaw size assumed will not be exceeded significantly. However, service experience on similar castings has disclosed that normal, acceptable shrinkage may be extended by cracking during service. .We, therefore, recc:nmended to the applicant that these valves be inspected for surface cracks on the inside and outside surfaces at the.first refueling outage and at other times when the valve is disassembled for maintenance. The applicant has committed, by letter dated October 12, 1984, to including this augmented inspection by surface examination-or other methods acceptable to the staff, which will be determined during the staff's review of the inservice inspection program.

We have concluded t the results of our evalua[lon and the augmented inservice inspection proEram J for these valves ill provide reasonable ~

assurance of complianceswith the requirements,w'f o GDC-51.

It will be confirmed by the augmented IS!gthat the shrinkage flaws existing in the valve bodies on entering service have/not propagated to either of the surfaces. Should the augment'ed'ISI/ disclose.that these flaws have

.propagated to either of the surface'sy'the valves are then to be replaced by the licensee."

the PEco' letter of October 4,1984, With respect atosurface i.e., whether the issue raised crack of upby/to 3/5 inches in length would be acceptable, the staff's position)(as been and continues to be that if- the valve body inspections disclosefthat internal shfinkage cracks have propagated to either surface,fthe valves are to bet replaced, regardless of the length of the surfacvindication.

/

It should be noted that the alternative approach proposed by PECo in its letter of October 4,1984, was found to be unacceptable by the staff and PECo was so informed; whereupon, the PECo proposed approach described in its letter dated October 12, 1984, was submitted and determined to be to be acceptable. The staff findings. reflected in the September 18, 1984, staff memorandum referred to in your memorandum were included in SSER-3, as discussed above. There has bee no change in the staff's position from that stated in SSER-3.

. Thomas A. Rehm, Assistant for Operations, EDO D/DIV ED0 RBernero TRehm

/ /86 ./ /86

.PD#4 PDll3 _ PD#4 BWR/EB AD/BWR DD/DIV RMartin E on WButler BDLiaw Glainas RHouston

/ 86 i ./86 / /86 / /86 / /86 / /86

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EDO PRINCIPAL' CORRESPONDENCE CONTROL

_- - - - - - - -==

DUE: 03/20/86 EDO CONTROL: 001481 FROM: DOC DT: 02/28/86 FINAL REPLY:

JOHN H. AUSTIN TECHNICAL ASSISTANT TO COMMISSIONER ASSELSTINE TO:

REHM

    • PRIORITY ** SECY NO:

FOR SIGNATURE OF:

+

EXECUTIVE' DIRECTOR ROUTING:

! DESC:

i STELLO LIMERICK COMPLIANE WITH GDC-51 ROE REHM DATE: 03/03/86 SNIEZEK ASSIGNED TO: NRR- CONTACT: DENTON MURLEY

~

TAYLOR GCUNNINGHAM

'SPECIAL INSTRUCTIONS OR REMARKS:

, NRR RECEIVED: 03/04/86 j ACTION: DBL - BERNER0 7 t .
NRR ROUTING: DENTON/EISENHUT PPAS MOSSBURG/ TOMS
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