ML20134A965
| ML20134A965 | |
| Person / Time | |
|---|---|
| Site: | Calvert Cliffs  |
| Issue date: | 01/23/1997 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML20134A950 | List: |
| References | |
| NUDOCS 9701290196 | |
| Download: ML20134A965 (6) | |
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0 UNITED STATES 4
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,j NUCLEAR REGULATORY COMMISSION l
\\*****l2 WASHINGTON, D.C. 20065 0001 f
SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO.218 TO FACILITY OPERATING LICENSE NO. DPR-53 AND AMENDMENT NO.195 TO FACILITY OPERATING LICENSE NO. DPR-69 BALTIMORE GAS AND ELECTRIC COMPANY CALVERT CLIFFS NUCLEAR POWER PLANT. UNIT NOS. 1 AND 2 i
DOCKET NOS. 50-317 AND 50-318 l
1.0 INTRODUCTION
l By letter dated September 10, 1996, the Baltimore Gas and Electric Company (BGE) submitted an amendment to the operating license of the Calvert Cliffs Nuclear Power Plant, Units 1 and 2.
This amendment proposes to extend the i
automatic actuation logic channel functional test interval of the Engineering j
Safety Features Actuation System (ESFAS) and the surveillance test interval of the containment sump isolation valves from monthly to quarterly.
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The amendment request for the ESFAS actuation logic is primarily based on j
analysis presented in Combustion Engineering Owners Group (CE0G) Topical Reports CEN-327, "RPS/ESFAS Extend Test Interval Evaluation," CEN-327, Supplement 1, and CEN-403, Revision 1-A, "ESFAS Subgroup Relay Test Interval Extension." These topical reports have been approved by the staff. Topical Report CEN-327 and CEN-327, Supplement 1, established that there was a slight i
decrease in core melt frequency in extending ESFAS surveillance intervals from monthly to quarterly by comparing the slight increase in core damage frequency (CDF) from system unavailability and the decrease in CDF from reduced test induced plant transients. Topical Report CEN-403, Revision I-A, supported extending the surveillance test interval for ESFAS actuation relays to each refueling outage on a staggered test basis by considering the mean time i
between failures (MTBF) for these relays in Combustion Engineering (CE) pl ants.
3 The ESFAS design at Calvert Cliffs does not permit testing of the actuation l
relays separately from the automatic actuation logic circuits. The licensee's review of the Calvert Cliffs Units I and 2 Technical Specifications (TSs) i indicates that at present, all ESFAS equipment tests are performed at quarterly or longer intervals except for containment sump isolation valves I
which are tested monthly. To facilitate testing of the ESFAS equipment with j
the actuation logic circuits, the licensee requested extension of the following surveillance tests intervals from monthly to quarterly:
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Channel Functional Test for Automatic Logic of Safety Injection, 4
Containment Spray, Containment Isolation, Main Steam line Isolation, Containment Sump Recirculation, and Auxiliary Feedwater in TS Table 4.3-2, Engineered Safety Feature Actuation System Instrumentation Surveillance Requirements.
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Related surveillance requirements of TS Item 4.5.2 for Emergency Core j
Cooling Systems and TS Item 4.6.2.1 for Containment Spray Systems.
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Bases in TS Items 3/4.3.1 and 3/4.3.2, Protective and Engineered Safety
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Features (ESF) Instrumentation.
In paragraph three of page B 3/4 3-1, the licensee stated, "The quarterly frequency for the channel functional tests I
for these systems is based on analysis presented in the NRC-approved Topical Report CEN-327, "RPS/ESFAS Extended Test Interval Evaluation," as supplemented and CEN-403, "ESFAS Subgroup Relay Test Interval Extension."
The licensee will revise this sentence to indicate that the frequency for
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functional tests is based on analysis presented in CEN-403, Revision 1-A, rather than CEN-403.
i The licensee further requested that the containment sump isolation valve automatic opening verification be extended to preclude having to continue i
monthly testing of the containment sump recirculation automatic actuation j
logic. BGE proposed to extend the surveillance test interval for the j
containment sump isolation valves from monthly to quarterly, to achieve consistency with the ESFAS automatic actuation test. The valves that are f
involved in the evaluation of this proposed TS include containment sump isolation valves 1-MOV-4144, 2-MOV-4144,1-MOV-4145 and 2-MOV-4145.
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2.0 EVALUATION A-ESFAS In Generic Letter 83-28, " Required Actions Based on Generic Implications of i
Salem ATWS Events," dated July 8,1983, NRC requested that licensees review
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the Reactor Protective System (RPS) test intervals to determine if they were 4
consistent with achieving high RPS availability.
Subsequently, in Topical l
Reports CEN-327 and CEN-327, Supplement 1, the Combustion Engineering Owners g
Group (CEPG) presented an analysis of the effects on CDF in extending the j
RPS/ESTM channel functional test interval from monthly to quarterly using fault tree analysis. The report revealed that for Calvert Cliffs there would be a slight decrease in CDF.
4 In a letter dated November 6, 1939, the NRC staff approved these topical reports.
The approval was contingent on the licensee's confirming that instrument drift occurring over the proposed surveillance test interval would not cause the values to exceed the values assumed in the safety analysis and the data specified in the TS. The licensee stated that ESFAS actuation logic circuitry was composed of digital logic gates that were not susceptible to time related instrument drift.
Furthermore, the licensee conducted an instrument drift analysis on each sensor loop which indicated that the l
1 instrument drift for 150 days, including a 25 percent maximum allowable 4
extension permitted by TS, did not exceed the 30-day setpoint assumptions.
The licensee also found that in the last three years, as-found and as-left
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monthly drift data on each channel were within the permissible limits.
l The ESFAS actuation relays were specifically excluded from the CEN-327 and j
CEN-327, Supplement 1, evaluation. Topical Report CEN-403, Revision I-A, provided an analysis based on mean time between component failures which addressed the effe is of the ESFAS actuation relay surveillance test interval extension.
In a i Iter dated February 27, 1996, NRC approved CEN-403, i
Revision I-A whic recommended an extension of the surveillance test interval i
for these relays to each refueling outage on a staggered test basis.
The report identifies the MTBF of ESFAS subgroup relays at Calvert Cliffs, Unit 2 as the longest and the MTBF at Calvert Cliffs, Unit I as the fourth longest i
among all CE plants in the USA. Allowing for a 25 percent margin as permitted i
by TS, the acceptable MTBF for a quarterly surveillance frequency is 3.75 i
months which is far short of the MTBFs reported in the CEN-403, Revision 1-A, for ESFAS subgroup relays at Calvert Cliffs.
1 In a safety evaluation approving CEN-403, Revision I-A, the NRC staff asked that licensees referencing this topical report as a basis for TS license amendments to confirm the applicability of CEN-403, Revision 1-A, to their specific plant, and confirm that the applicable setpoint calculations account for any increase in instrument drift caused by the extended surveillance test interval. NRC also required reevaluation of the adequacy of the surveillance j
test interval in the event two or more ESFAS actuation relays failed within a
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12-month period. Additional restrictions were imposed for plants using Potter 1
and Brumfield type MDR relays in ESFAS actuation. These Potter and Brumfield relays are not used in the Calvert Cliffs ESFAS. The Calvert Cliffs licensee confirmed the applicability of CEN-403, Revision I-A, for Calvert Cliffs.
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addition, the licensee's search of the Nuclear Plant Reliability Data System i
(NPRDS) identified only one ESFAS actuation relay failure in 66 months at i
Calvert Cliffs, Unit 1, which occurred on April 14, 1996.
This failure frequency is substantially below the permissible MTBF of 3.75 months. A plant specific drift analysis indicated that the increased surveillance test 4
interval did not exceed the 30-day setpoint assumptions for ESFAS sensor loops. The ESFAS actuation relays at Calvert Cliffs are Genicom (formerly i
General Electric) series 3SAA13832A relays and are essentially digital devices not susceptible to time related drifts.
The staff has reviewed the licensee evaluations and justifications and finds that the proposed TS changes for extension of the ESFAS logic functional test interval from monthly to quarterly are in conformance with NRC approved CE0G Topical Reports CEN-327, CEN-327, Supplement 1, and CEN-403, Revision I-A.
The licensee has performed a plant specific review to establish the applicability of these topical reports and NRPDS search as to confirm acceptable failure rates of applicable components, and analysis of component drift. The licensees evaluation confirms that the extension of the ESFAS surveillance test interval will slightly reduce the core damage frequency as noted in the above topical reports. Based on our evaluation, the staff
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j concludes that the proposed changes to the Calvert Cliffs, Units 1 & 2 TS are in accordance with the NRC-approved topical reports and are, therefore, acceptable.
B-Containment Sumo Isolation Valves A
The containment sump isolation valves listed above automatically open on receipt of a Recirculation Actuation Signal (RAS).
Single failure criteria is satisfied by two redundant valves on each ' unit. Testing of the automatic opening feature is currently performed monthly in accordance with TS Surveillance Requirements (SR) 4.5.2.b.1 and SR 4.6.2.1.a.1.
Verification of
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valve opening on receipt of an RAS satisfies both specifications, since the containment sump isolation valves are the cnly components in the flow path J
which actuate on RAS.
As discussed above, Calvert Cliffs, Units 1 and 2, ESFAS design does not include features for testing the actuation relays separately from the automatic actuation logic circuits. Becausa of these circumstances, the associated engineered safety features equipinent is actuated each time the ESFAS automatic actuation logic channel functional test is performed.
BGE performed a review of the Units 1 and 2 TS, and found that all associated ESFAS equipment tests are performed at intervals of at least quarterly or greater, with the exception of the containment sump isolation valve test, which is performed monthly as required by BGE's TS SR 4.5.2.b.1 and SR 4.6.2.1.a.l.
Failure to extend the surveillance interval for the containment sump isolation valves would necessitate monthly performance of the ESFAS containment sump recirculation automatic actuation logic channel functional test.
The licensee proposes to change the containment sump isolation valve RAS automatic opening verification surveillance interval from 31 days to quarterly (92 days). This proposed change revises Calvert Cliffs Nuclear Power Plant, Units 1 and 2.
The licensee's justification for extending the containment sump isolation valves test interval from monthly to quarterly is based on review of surveillance test procedures and Nuclear Plant Reliability Data System (NPRDS) data of valve failure history of similar valves.
BGE conducted a historical review of the Units 1 and 2 surveillance test procedures supporting successful completion of TS SR 4.5.2.b.1 and SR 4.6.2.1.a.1.
No failures of the containment sump isolation valves or associated valve operators were identified. Also, review of NPRDS data revealed no failures of these components.
In addition, based on the generic and plant-specific risk evaluations and the demonstrated low failure rate of the components, the licensee determined that the proposed changes do not involve a significant reduction in the margin of safety.
The proposed changes to the surveillance test interval for the subject containment sump isolation valves is in accordance with the inservice testing (IST) requirements of Section XI of the American Society of Mechanical
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i Engineers (ASME) Boiler and Pressure Vessel Code (ASME Code) (1983 Edition).
IST programs are required pursuant to 10 CFR 50.55a.
Valves 1-MOV-4144, 2-MOV-4144, 1-MOV-4145, and 2-MOV-4145 are included in the IST program and are stoke tested quarterly in accordance with the ASME Code. Quarterly inservice testing of power-operated valves has been a long-standing requirement of the ASME Code and is considered adequate to assess the operational readiness of valves. As such, the licensee's proposed change is consistent with t5e level of assurance provided by the IST program requirements. Therefore, based on i
valve perfomance and IST requirements, the staff has determined that the l
licensee's proposed TS SR changes are acceptable.
i Based on the above evaluation, the staff agrees that the licensee has demonstrated the adequacy of the proposed changes for the Calvert Cliffs NPP, Units 1 and 2, TS. The proposed changes to the surveillance test interval to demonstrate proper opening capability of the subject containment sump isolation valves (upon a RAS) is in accordance with Section XI of the ASME Code (1983 Edition). Therefore, the proposed TS changes to TS SR 4.5.2.b.1 j
and SR 4.6.2.1.a.1 for Calvert Cliffs are acceptable.
3.0 STATE CONSULTATION
In accordance with the Commission's regulations, the Maryland State official was notified of the proposed issuance of the amendments. The State official j
had no comments.
4.0 ENVIRONMENTAL CONSIDERATION
The amendments change a requirement with respect to installation or use of a facility component located within the restricted area as defined in 10 CFR l
Part 20 and changes surveillance requirements. The NRC staff has determined that the amendments involve no significant increase in the amounts, and no significant change in the types, of any effluents that may be released i
offsite, and that there is no significant increase in individual or cumulative occupational radiation exposure. The Commission has previously issued a proposed finding that the amendnients involve no significant hazards j
consideration, and there has been no public comment on such finding (61 FR 52963). Accordingly, the amendments meet the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9).
Pursuant to 10 CFR 51.22(b) no environmental impact statement or environmental assessment need be l
prepared in connection with the issuance of the amendments.
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5.0 CONCLUSION
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The Commission has concluded, based on the considerations discussed above, 7
that:
(1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, (2) such l
activities will be conducted in compliance with the Commission's regulations, and (3) the issuance of the amendments will not be inimical to the common defense and security or to the health and safety of the public.
Principal Contributors:
J. Mazumdar j
M. Khanna Date: January 23, 1997 1
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