ML20236K751
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.g 4* cang\ UNITED STATES
+ 8 o NUCLEAR REGULATORY COMM'SSION s t wAsmuctow, n. c. aones
)! January 17, 1992 i
MEMORANDUM FOR: Robert L. Baer, Chief Engineering Issues Branch Division of Safety Issue Resolution, RES FROM: Christopher I. Grimes, Chief Technical Specifications Branch Division of Operational Events Assessment, NRR Scott Newberry, Chief Instrumentation and Control Systems Branch 1 Division of Systems Technology, NRR j
SUBJECT:
GENERIC SAFETY ISSUE 120, *0N LINE TESTABILITY OF PROTECTION SYSTEMS" l I am responding to your request to clarify the NRR technical specification position with regard to at-power testing of subgroup relays. The technical specificatica recommendations of NUREG 1366, " Improvements to Technical Specification:s Surveillance Requirements" were recently approved by the CRGR for )
issuance in ft.741 form and as a generic letter. The NUREG includes a position to perform relay testing on a staggered test basis over a cycle and leave the tests carrying the highest risk to a refueling outage or other cold shutdown.
You stated this position appears to be contrary to the NRR position provided in a memorandum to CRGR dated August 13, 1983 from H.R Denton to V. Stello, Jr.
- regarding review of proposed Revision 3 to the CE-STS. The memorandum position stated that based on relay failure studies, the CE proposed 18-month testing f interval is too long for Engineered Safety Feature Actuation System (ESFAS) subgroup relay testing.
The position in NUREG 1366 is based on staff examination of failure modes of various types of relays which identified age-related failures, but which did not indicate high relay failure rates. Since relay reliability was shown to be generally good, the staff concluded that this is a reasonable basis for relaxing testing requirements. The resulting staff recommendation for quarterly relay testing on a reduced sample size shou' d provide reasonabh assurance that comon-mode failures are detected. In addition, reduced at power testing for certain subgroup relays should reduce the frequency of inadvertent equipment starts and.
reactor trips and is consistent with staff requirements for protection systems design. The August 13,1983 memorandum to the CRGR acknowledged that regulatory guidance prefers, but does not require, a protectior) system design which permits testing of the actuated equipment during operation. Therefore, unless there is a practical system design, at-power testing of actuated equipment and associated devices is not a staff requirement.
Contact:
Carl S. Schulten 504-1192
. 4 9807100070 900624 j PDR FOIA i PDR
, g , 38T98-155
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. January 17, 1992 The monthly ESFAS actuation logic relay testing requirement for CE plants was changed to semi-annually after the staff became aware that licensees tested initiation relays quarterly and subgroup relays at an 18-month interval. As a result, the surveillance interval change was made to the technical specifications for CE plant being licensed as well as to Revision 3 cf the CE-STS. Further, the staff infonned the CRGR that relaxations from 6-months to 18-months for subgroup l relay testing would be allowed only for cases where the relay was associated with actuated equipment that should not be operated during power and where the good relay experience that formed the basis for the position in NUREG 1366 is consistent with plant specific experience.
Thus, we believe that the recommendations in NUREG 1366 to allow limited deferred testing of subgroup relays is consistent with regulatory requirements, current practice and with staff implementation guidance for CE-STS as cut 11ned in the Austtst 1983 memorandum.
Original Sp.ed By Original Signyd Bf Christopher I. Grimes, Chief Scott Newberry, Chief Technical Specifications Branch, Instrumentation and Control Systems Branch Division Of Operational Events Division of Systems Technology, NRR Assessment, NRR cc: W. Russell A. Thadani C. Rossi W. Minners T. Chang i DISTRIBUTION:
0TSB R/F DOEA R/F Central Files WTRussell OTSB Members ACThadani CERossi RLEmch SNewberry CIGrimes CSSchulten AEChaffee CHBerlinger Document Name: SUBRELAY.MEM CSS's Diskette "I&C"
- See previous concurrences -
0TSB:DOEA:NRR OTSB:DOEA:NRR SI C:0TSB:00EA:NRR CSSchulten* RLEnch* 5 erry CIGrimes j 01/16/92 01/16/92 0 /i 92 Olg/92 0FFICIAL RECORD COPY
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,' January 17, 1992 l
The monthly ESFAS actuation logic relay testing requirement for CE plants was changed to semi-annually after the staff became aware that licensees tested initiation relays quarterly and subgroup relays at an 18-month interval. As a result, the surveillance interval change was made to the technical specifications for CE plant being licensed as well as to Revision 3 of the CE-STS. Further, the staff informed the CRGR that relaxations from 6-months to 18-months for subgrous relay testing would be allowed only for cases where the relay was associated witi actuated equipment that should not be operated during power and where the good relay experience that formed the basis for the position in NUREG 1366 is consistent with plant specific experience.
Thus, we believe that the recommendations in NUREG 1366 to allow limited deferred testing of subgroup relays is consistent with regulatory requirements, current practice and with staff implementation guidance for CE-STS as outlined in the August 1983 memorandum.
m =A --
Christopher . Grimes, Chief Scott Newberry, Chief Technical Specifications Branch, Instrumentation and Control Systems Branch Division Of Operational Events Division of Systems Technology, NRR Assessment, NRR cc: W. Russell .
A. Thadani -
C. Rossi
. W. Minners T. Chang l
i I i 1 l
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