ML17310B464
| ML17310B464 | |
| Person / Time | |
|---|---|
| Site: | Palo Verde  |
| Issue date: | 07/15/1994 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML17310B463 | List: |
| References | |
| NUDOCS 9407270035 | |
| Download: ML17310B464 (10) | |
Text
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UNITED STATES NUCLEAR REGULATORY COMMISSION WASHlkGTOk, D.C. 20555-0001
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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO. 78 TO FACILITY OPERATING LICENSE NO.
NPF-41 AMENDMENT NO.
64 TO FACILITY OPERATING LICENSE NO.
NPF-51 AND AMENDMENT NO.
TO FACILITY OPERATING LICENSE NO. NPF-74 ARIZONA PUBLIC SERVICE COM ANY ET AL.
PALO VERDE NUCLEAR GENERATING STATION UNIT NOS.
1 2
AND 3 DOCKET NOS.
STN 50-528 STN 50-529 AND STN 50-530
1.0 INTRODUCTION
By letter dated August 5, 1993,,as supplemented by letter dated January 19, 1994, Arizona Public Service Company (APS or the licensee) submitted a request for changes to the Technical Specifications (TS) for the Palo Verde Nuclear Generating Station, Units 1, 2',
and 3 (Appendix A to Facility Operating License Nos.
NPF-41, NPF-51, and NPF-74, respectivel'y).
Arizona Public Service Company submitted this reques't on behalf of itself, the Salt River Project Agricultural Improvement and Power District, Southern California Edison
- Company, El Paso Electric Company, Public Service Company of New
- Mexico, Los Angeles Department of Water and
- Power, and Southern California Public Power Authority.
The proposed changes would extend the surveillance interval for selected channel functional tests from monthly to quarterly for Technical Specification 3/4.3.1, Table 4.3-1, "Reactor Protective Instrumentation Surveillance Requirement,"
and its associated Bases; and selected trip setpoints and allowable values associated with Technical Specification 3/4.3.2, Table 4.3-2, "Engineered Safety Features Actuation System Instrumentation Surveillance Requirement,"
and its associated Bases.
In addition, selected allowable values, associated with Technical Specification 3/4.3.2, Table 3.3-4, "Engineered Safety Features Actuation System Instrumentation Trip Values,"
and selected trip setpoints and allowable values associated with Technical Specification 2.2.1, Table 2.2-1, "Reactor Protective Instrumentation Trip Setpoint Limits, would also be revised.
The additonal information contained in the January 19, 1994, letter was clarifying in nature, was within the scope of the initial notice, and did not affect the NRC staff's proposed no significant hazards consideration determination.
9407270035 940715 PDR ADOCK 05000528t P
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2.0 BACKGROUND
The proposed amendment is based on topical reports CEN-327-A and CEN-327-A, Supplement 1.
Both reports were prepared by Combustion Engineering for the Combustion Engineering Owners Group (GEOG).
The purpose of these reports was to evaluate the safety impact and provide justification for extending the surveillance test intervals from the current 30-days to quarterly for selected components in the reactor protection system (RPS) and the engineered safety features actuation system (ESFAS) instrumentation.
Both reports used probabilistic risk analysis techniques to demonstrate that the proposed surveillance interval extensions do not result in increased plant risk when compared with current technical specification requirements.
The CE analysis estimated a reduced core melt frequency based on a reduction in surveillance test induced transients.
However, the analysis also estimated a slight increase in RPS unavailability as a, result of extending the surveillance test interval.
The result of reduced ESFAS testing on core melt frequency was found to be similar to that for RPS.
The overall effect of the proposed change on safety was determined to be a negligibly small decrease in core melt frequency.
The NRC evaluation and acceptance of the topical reports is documented by the safety evaluation report (SER),
"RPS/ESFAS Extended'est Interval Evaluation" that was issued in November 1989.
As stated in the 1989 SER, the NRC found, that CEN-327-A and its Supplement were acceptable for justifying the proposed'xtensions in surveillance test intervals from monthly to quarterly for the RPS and the ESFAS.
In the generic SER, the NRC agreed that surveil.lance test intervals for the RPS and for the ESFAS could be extended for all CE plants (except Haine Yankee) to the requested interval contingent on the licensee in each case confirming that instrument drift occurring over the proposed surveillance test intervals would not cause the setpoint values to exceed those assumed in the. safety analysis and specified in the Technical Specifications.
The NRC stated that licensees must confirm that they have reviewed instrument drift information for each instrument channel involved. and have determined that drift occurring in that channel over the period of extended surveillance test intervals would not cause the setpoint value to exceed the allowable value as calculated for that channel by the licensee's methodology.
In addition, the licensee should maintain records of the setpoint calculations and associated data to support future staff audits.
The Palo Verde Units 1, 2, and 3 Technical Specification 3/4.3. 1 provides instrumentation operability and surveillance requirements for the RPS.
Surveillance Requirement 4.3. 1. 1 and Table 4.3-1 specify the modes and frequency for the performance of, channel
- checks, channel calibration, and channel functional tests for each RPS channel.
Technical Specification 3/4.3.2 provides instrumentation operability and surveillance requirements for the ESFAS.
Surveillance Requirement 4.3.2. 1 and Table 4.3-2 specify the modes and frequency for the performance of channel
- checks, channel calibration, and channel functional tests for each ESFAS channel.
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The licensee stated that it has performed the required drift setpoint analysis and that it is documented in Calculation 13-JC-SB-200, Rev.
01, "Plant Protection System Bistable Drift Analysis."
The licensee used "as-found" and "as-left" data extracted from surveillance tests performed from 1987 through 1990.
The analysis was performed to determine the drift for 120-day intervals and to identify the components subject to drift which are affected by the proposed increase in the surveillance test intervals.
This calculation evaluated the effects of an extended surveillance test interval on the setpoint drift of the RPS and the ESFAS.
The only RPS equipment that will remain on a monthly testing schedule i's the Reactor Trip Switchgear which is consistent with the Topical Reports.
The ESFAS Automatic 'Actuation Logic (the subgroup relays in the ESFAS Auxiliary Cabinet) and the Loss of Power ESFAS functions were also not in the scope of the analysis and therefore will remain on a monthly,testing schedule.
The instrument drift values were used to recalculate Plant Protection System (PPS)
(RPS and ESFAS) uncertainties and error values.
The new unceriain+'-
and error values were then used to calculate new PPS setpoints.
The licen~
stated that the setpoint calculations were performed using CEN-286 (v),
"Calculation of Trip Setpoint Values-.Plant Protection System,"
an approved setpoint metho'dology.
As a result of the recalculations, the following RPS trip setpoint and allowable values are changed:
The Variable Overpower Trip (VOPT) band trip setpoint is changed from <9.8% of rated thermal power to <9.7% of rated thermal power.
2.
3.
4, As a resul changed:
2.
The VOPT band'llowable value is changed from <10% of rated thermal power to <9.9% of rated thermal power.
The Pressurizer Pressure Low allowable value is changed from >1822.
psi a to >1821 psi a.
The Steam Generator Pressure
-,Low allowable value is changed from
~912 psia to ~911 psia.
t of the recalculations, the following ESFAS allowable values are The Pressurizer Pressure Low allowable value for the Safety Injection Actuation Signal (SIAS)'s changed from >1822 psia to
~1821 psia.
The Steam Generator Pressure
- Low allowable value for the Hain Steam Line Isolation Signal (HSIS) is changed from >912 psia to Z911 psia.
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The Pressurizer Pressure - Low allowable value for. the Containment Isolation Actuation Signal (CIAS) is changed from >1822 psia to
~1821 psia.
Some of the changes are conservative and some are "nonconservative.
The changes to the RPS setpoint and the allowable value for VOPT 'band are conservative and, therefore, there is no reduction in safety margins.
With regard to the RPS and ESFAS allowable values for Pressurizer
.Pressure and Steam Generator
- Pressure, the l.icensee stated these changes are non-conservative but not significant.
The licensee stated that the allowable values are changed to accommodate a small increase in RPS and ESFAS periodic test error.
The increase in test error is due to an, increase in bistable drift allowance for an extended surveillance tqst interval up to 120 days..
The increase in RPS and ESFAS periodic test error,
- however, is insignificant compared,to the process equipment error in the instrument channel.
This results in no change to the total channel error when the errors are combined using the root sum square method as outlined in CEN-286.
Because the total channel error does not change,
.the setpoints for the Pressurizer Pressure and Steam Generator pressure do not change.
Therefore, there is no reduction in the safety margins due to a slight change in allowable values.
The RPS/ESFAS test interval evaluation presented in CEN-327-A.and CEN-327-A Supplement I developed a fault tree model for the four classes of RPS and three classes of ESFAS design.
Each model addressed common mode failures, operator errors, reduced redundancy, and random component failures.
These models were used to evaluate the RPS and ESFAS availability based on both a
30-day and 90-day test interval.
The CE analysis concl'udes that there would be a slight increase in RPS unavailability as a result of extending the test interval'rom monthly to quarterly.
The analysis also concluded that reducing the test interval would reduce the scram and core melt frequency based on the expected reduction in test induced transients/scrams.
The results of the CE analysis regarding reduced ESFAS testing on core melt frequency was found to be similar to RPS.
The staff found these estimates to be acceptable.
The staff SER for CEN-327-A found the overall impact of reduced testing intervals on safety to be a negligibly small decrease, in core melt.frequency.
The staff SER for CEN-327-A required'he licensee to evaluate the effects of drift,on the proposed functional test interval extension.
The licensee reviewed the drift data (as-left and as-found) for the a'ffected instrumentation and performed calculations.for new. PPS setpoints using an approved setpoint methodology.
The evaluation results are acceptable to the staff.
Based on the above, the staff finds the licensee proposal, to incorporate the quarterly surveillance test intervals for RPS and ESFAS instrumentation as referenced by CEN-327-A and CEN-327-A Supplement I to be acceptable.
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4.0 STATE CONSULTATION
In accordance with the Commission's regulations, the Arizona State official was notified of the proposed issuance of the amendment.
The State official had no comments.
- 5. 0 ENVIRONMENTAL CONSIDERATION The amendments change a requirement with respect to the installation or use of a facil.ity component located within the restricted area as defined in 10 CFR Part 20 and change surveillance requirements. 'he 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 (58 FR 48378).
Accordingly, the amendments meet the el'igibility 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 prepared in connection with the issuance of the amendments.
6.0 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'y operation in the proposed
- manner, (2) such activities will be conducted in compliance with the Commission's regulations, and (3) the issuance of the amendment will not be inimical to the common defense and security or to the health and safety of the public.
Principal Contributors:
C. Doutt L. Tran Date:
Oui.y 15, 1994
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