ML20086K562

Safety Evaluation Supporting Amends 53 & 17 to Licenses NPF-39 & NPF-85,respectively

ML20086K562
Person / Time
Site:	Limerick
Issue date:	12/02/1991
From:	Office of Nuclear Reactor Regulation
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Shared Package
ML20086K546	List: ML20086K543 ML20086K562
References
TAC-M76689, NUDOCS 9112130169
Download: ML20086K562 (6)

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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION SUPPORTING AMENDMENT N05. 53 AND 17 TO FACILITY OPERATING LICENSE N05. NPF 49 AND NPF-85 LIMERICK GENERATING STATION, UNITS 1 AND 2 DOCKET N05. 50-353 1

1.0 INTRODUCTION

By letter dated April 26, 1990, Philadelphia Electric Company (the licensee) requested an amendment to Facility Operating License Nos. NPF-39 and NPF-85 for the Limerick Generatinn Station, Units 1 and 2 (LGS-1&2). These proposed amendments would revise the Technical Specifications (TS) for LGS-1&2 to extend the surveillance test intervals (STIs) and allowable out-of-service times (A0Ts) for instrumentation supporting the Reactor Protection System (RPS) and Emergency Core Cooling System (ECCS), including instrumentation common to the Control Rod Block Function (CRBF), the Reactor Core Isolation Cooling (RCIC) system, and the isolation instrumentation common to RPS and/or ECCS.

These changes are based upon the BWR Owners Group (BWROG) Topical Reports NEDC-30851P, _ " Technical Specification Improvement Analysis for BWR Reactor Protection System," May 1985, which provided a safety analysis for increased surveillance test intervals and allowed out-of-service times for RPS instru-mentation on a generic basis; NEDC-30851P, supplement 1, " Technical Specification Improvement Analysis for BWR Control Rod Block Instrumentation,"

June 1986, which provided a saf ety analysis for extension of on-line test intervals for control rod block instrumentation on a generic basis; and NE0C-30851P, Supplement 2, " Technical Specification Improvement Analysis for BWR Isolation Instrumentation Commen to RPS and ECCS Instrumentation," July 1986, which provided a safety analysis for extension of Surveillance Test Intervals and allow 2d outage times for isolation instrumentation common to RPS and ECCS instrumentation. The NRC staff reviewed NE0C-30851P and its supplements, and issued Safety Evaluation's (SE) on July 15, 1987, September 22, 1988, and Janauary 6, 1989, respectively, approving the reports and providing model TS changes. The stafi's original SE was incorporated into an approved version of the topical report, NEDC-30851P-A, issued April 4, 1988.

The BWROG Topical Report NEDC-30936P, " Technical Specification Improvement Methodology (with demonstration for BWR ECCS actuation Instrumentation) Parts 1 and 2," dated November 1985, provided the justification for increased surveillance test intervals and allowed out-of-service time for ECCS instrumentation on a generic basis.

On December 9, 1988, the NRC staff issued kk h2 P

... a Safety Evaluation'on " Review of BWR Owners Group Report NEDC-30936P (Part 2) on Justification for Extending On-Line Test Intervals and Allowable Out-of-Service Times for BWR Emergency Core Cooling System Instrumentation."

As discussed on page 3 of Attachment 1 of the licensee's application, the NRC staff's evaluation did not cover the RCIC instrumentation or the End-of-Cycle Recirculation Pump Trip (E0C-RPT) instrumentation. To resolve this omission, by letter dated February 19, 1991, the BWR Owners Group submitted two topical reports: GENE-770-06-1, " Bases for Changes to Surveillance Test Intervals and Allowed Out-of-Service Times for Selected Instrumentation Technical Specifications" and GENE-770-06-2, Addendum to " Bases for Changes to Surveillance lest Intervals and Allowed Out of Service Times for Selected Instrumentation Technical Specifications". The latter pro'.ided the results of additional analyses to support changes to the STI and A0T for RCIC instrumentation.

By letter dated September 13, 1991, the NRC staff issued a Safety Evaluation Report (SER) and supporting Technical Evaluation Report (TER) on the topical report GENE-770-06-2. Enclosure 2 to the letter provided model TSs.

The staff concluded that GENE-770-06-2 provided an acceptable basis for extending STEs and A0Ts for RCIC actuation instrumentation.

As noted above, GENE-770-06-1 addresses STI and A0T changes such as the E0C-RPT which were originally proposed in the Improved BWR Technical Specifications but which were not specifically covered by a previous NRC Safety Evaluation. The NRC staff has not completed its review of this topical report. By agreement with the mensee, rather than holdup processing of the subject application any

're mr, the TS changes related to E0C-RPT (pages 3/4 3-46, 3/4 3-48, 3/4 3-51 a.s,,r c of B 3/4 3-3) that were included in the subject apolication of April

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30 are not included in these amendments.

If the proposed TS changes on L?C-F.'T are found to be acceptable when the staff completes its review of the topical report, they will be included in a future, separate snendment.

The staff's generic SER stated that plant specific application of the generic results would require comparison of the plant specific design with the generic design to show that NEDC-30851P-A and NE0C-30936P-A are applicable and that any increase in instrument drift due to the extended STI is properly accounted for in the setpoint calculation methodology.

The licensee's submittal, dated April 26, 1990, included the General Electric Company'(GE) Reports MDE-93-0485-1, dated October 1987, which compared LGS-1&2 RPS design with that used.in NEDC-30851P-A, and RE-019, dated December 1986, which compared LGSl&2 ECCS design with that used in NEDC-30936P-A.

The submittal also provided PECo's response to the plant specific conditions required to be met by the staff's generic SER, and included supplemental data regarding the drift of RPS and ECCS instrumentation.

2.0 EVALUATION The NRC staff has reviewed the licensee's April 26, 1990, submittal. The proposed TS changes reflect those standard TS revisions contained in NEDC-30851P-A

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' and NEDC-30936P-A which, based upon probabilistic analyses, justify the identified time extensions by reducine the potential for (1) unnecessary plant scrams; (2) excessive equipment test cycles and (3) diversion of personnel and resources to conduct unnecessary testing.

The licensee has extended the generic analysis completed by the BWR Owners Group to LGS-1&2 by having General Electric Company complete the required plant specific analysis. As stated in the NRC's SERs for Licensing Topical Repotts, three conditions must be addressed to justify the applicability of the generic analysis to individual plants when specific facility TS are considered for revision.

1.

Confirm the applicability of the generic analysis to the specific facility.

The licensee's submittal GE report MDE-93-0485-1, " Technical Specification Improvement Analysis for the Reactor Protection System for Limerick Generating Station Units 1&2," dated October 1987, identified that the RPS configuration for LGS 1&2 has several differences compared to the RPS-configuration in tne generic evaluation. These differences and the assessment of their effects on the RPS failure frequency were evaluated.

The licensee concluded that these differences would not significantly affect the improvement in plant safety due to the changes in the technical specifications based on the generic analysis. The generic analysis in NEDC-30851P-A is applicable to the LGS 1&2 RPS. The licensee's submittal GE Report RE-19," Technical Spccification Improvement Analysis for Emergency Core Cooling System Actuation Instrumentation for Limerick Generating Station, Units 1&2," dated December 1986 ideni.ified that the ECCS configuration for LGS is similar to the ECCS configuration in the generic evaluation, with only one significant difference-i.e. the generic model has four emergency service water loop while LGS only has two loops.

This difference between LGS and the generic model has been modeled by envelope Case 4A of NEDC-30936P-A which shows that the proposed changes to ECCS Actuation instrumentation Technical Specifications would meet the 4%

acceptance criterion in NEDC-30936P-A. Therefore, the licensee concluded that the generic basis in NEDC-30936P-A is applicable to the LGS 1&2 ECCS actuation instrumentation. The staff has reviewed the comparison documentation in the licensee's submittals and concur with the licensee's conclusion that the generic analyses are applicable to the LGS Units 1&2.

2.

Demonstrate that the drift characteristics for RPS and ECCS channel instrumentation are bounded by the assumptions used in NEDC-30851P-A and NEDC-30936P-A when the functional test interval is extended from monthly to quartarly.

The additional time interval between tests resulting from the changes described in NEDC-30851P-A, NEDC-30936P-A and requested in this submittal, is already factored into the instrument setpoint calculations for the affected instruments. As stated in the Bases to LGS-1&2 TS 3/4.3.1 and TS 3/4.3.3, the difference between each RPS and ECCS instrument trip setpoint and the allowable value is equal to or greater than the drift all wance

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4-assumed for each trip in the plant safety analyses. The setpoint calculations for both the RPS and the ECCS assume an eighteen month calibration interval and the drift based upon vendor supplied values associated with that interval with no credit taken for the currently

_specified 31 day functional test.. This assumption in the setpoint calculations, therefore, bounds any drif t vehich could be e.vpected over the 92 day functional test interval proposed. The licensee has also provided data from surveillance tests at LGS-1 for a representative sample of RPS and ECCS instrumentation and demonstrated that-instrumentation drift characteristics are bounded for the proposed surveillance test interval. Accordingly, revised instrument setpoints or. allowable values are not required to accommodate the longer test intervals requested. Since similar instruments are used at LGS-2, the-data from LGS -1 are applicable to both units.

3.

Confirm tnat the differences between the parts of the RPS (and ECCS) the.t perform the trip functions in the plant and those of the base case plant were included in the specific analysis done using the procedures of

' Appendix K to NEDC-30851P-A.

In the licensee's submittals, GE reports MDE-93-0485-1, and RE-019,-which utilize the procedures of the Licensing Topical Report NE0C-30851P-A Appendix K to identify and evaluate the differences between the parts of RPS_and ECCS that perform the trip functions at LGS-1&2 and those of the base case plant. The results indicate that while the RPS configuration for LGS.4&2 has several differences compared to the configuration in the base case,-the differences and their impact do not significantly affect the applicability of the TS changes developed by the generic efforts of Licensing Topical Report NEDC-30851P-A or NE0C-30936P-A.

The' staff has reviewed the plant specific report for LGS and has verified that-the differences between the LGS-1&2 RPS and ECCS at the time the

= analysis was made and the-generic'RPS and ECCS were included in the plant specific analysis. Since _the plant specific analyses were done (October 1987, and December 1986,) no RPS or ECCS modifications have been made

- which would invalidate the conclusions of these reports. Therefore, the cchclusions reached in NEDC-30851P-A and NEDC-30936P-A apply to LGS-1&2-and the' plant-specific changes contained in this request are bounded by both the generic analyses and the NRC's generic safety evaluations.

The acceptabi_lity of the revised TSs has been addressed in the various staff safety evaluations on the topical reports. The assessment of the

- LC0 action requirements in the revised Section 3.3.1 is addressed below.

For 3.3 la, with the number of operable channels less than required in only one-trip system i.e. any_ number of Functional Units having only one

- inoperable channel in each Function Unit the entire RPS scram capability remains intact, assuming no additional single failure. The condition which allows continued operation for 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> has been evaluated and the reliability of the_ system shown to be acceptable in NEDC-30851P-A, March 1988. Within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> the inoperable channels and/or trip system must be 4

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... placed in the tripped condition. This action restores the RPS capability to accommodate a single failure and allows operation to continue with no further restrictions.

If the inoperable channel (s) and/or trip system is not placed in the tripped condition within the allowed time, then the ACTION required by Table 3.3.1 1 must be taken to place the plant in a condition where the function limits are not required to be OPERABLE.

For 3.3.lb, with the number of operable channels less than required in both trip systems, such that they may have two or more channels inoperable in any Functional Unit, the Reactor Protection System may not be capable of performing its intended f unction (e.g., a loss of scram function may exist), in this condition, during the 12 hour1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> allowance to place the inoperable channels and/or trip system in the tripped condition, if a valid trip signal was received a failure to automatically scram could

result, in order to reduce the probability of this occurrence, the action for this condition requires that steps be taken to ensure each required functional Unit maintains trip capability for each Trip System within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />. This time period allows the operator time to evaluate, to repair or trip the channels. This time period is reasonable considering the diversity of sensors available to provide tr ' signals, and the low probability of an event requiring the initiation of a scram. This time period is also consistent with the current Technical Specifications which address this condition.

In addition, when one channel in each trip system is INOPERABLE, an allowance of 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> is provided in order to restore an additional level of RPS Reliability. The requirement to ensure for each Functional Unit the required channel (s) in one Trip System, or the Trip System are OPERABLE or in the tripped condition limits the time the RPS scram logic for any Functional Unit would not accomodate a single f ailure in either Trip System. The 6 hour6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> time period is considered ac:eptable based on the remaining capability to trip, the diversity available to previde trip signals, the low probability of extensive numbers of inoperabilities affecting all diverse functions, and the low probability allowance, each Functional Unit will have all required channels OPERABLE or in TRIP in one Trip System. This provides a similar level of RPS reliability as found in Action a, above, and evaluated in NEDC-30851P-A to be acceptable for a 12 hour1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> allowed outage time.

Based en the staff's evaluation of the licensee's submittal, the staff finds that LGS-1&2 has met the plant specific conditions needed to apply the results of Gt.'s Topical Report NEDC-30851P to the Limerick Generating Station, Units 1&2. The proposed changes to the TSs are acceptable.

3.0 STATE CONSULTATION

In accordance with the Commission's regulations, the Pennsylvania State official was notified of the proposed issuance of the amendments. The State official had no comments, l.

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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 Part 20.

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 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 amendments involve no significant hazards consideration, and there has been no public comment on such finding (55 FR 21975). Accordingly, the amendments meet the eligibility criteria for categorical exclusion set forth in 10CFR 51.22(c)(9). Pursuant to 10 CFR 51.22(b) no environmental impact statement or environmental assessment need be prepared in connection with the issuance of the amendments.

5.0 CONCLUSION

The Commission has concluded, based on the considerations discussed above, 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 activities will be conducted in compliance with the Conmission's regulations, and (3) the issuance of the amendments will not be inimical to the common defense and security or to ti,e health and safety of the public.

Principal Contributors:

R. Clark H. Li J. Mauck Date:

December 2, 1991

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