ML17310B358
| ML17310B358 | |
| Person / Time | |
|---|---|
| Site: | Palo Verde  |
| Issue date: | 06/07/1994 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML17310B357 | List: |
| References | |
| NUDOCS 9406170269 | |
| Download: ML17310B358 (8) | |
Text
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON. D.C. 20555-0001 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO.
77 TO FACILITY OPERATING LICENSE NO.
NPF-41 MENDMENT NO.
63 TO FACILITY OPERATING LICENSE NO.
NPF-51 AND AMENDMENT NO. 49 TO FACILITY OPERATING LICENSE NO. NPF-74 ARIZONA PUBLIC SERVICE COMPANY 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 February IS,
- 1994, as supplemented by letter dated Hay 16, 1994, the 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, respectively).
The Arizona Public Service Company submitted this request 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 modify Technical Specification (TS) Figure 3.2-1, "REACTOR COOLANT COLD LEG vs CORE POWER LEVEL," of TS 3/4.2.6, "REACTOR COOLANT COLD LEG TEMPERATURE," for Units 1 and 3 to include the cold leg temperature between 552'F and 562'F at core power levels between 90 percent and 100 percent within the AREA OF ACCEPTABLE OPERATION.
Also, the proposed amendments modify TS 3/4. 1.1.4, "MINIMUMTEMPERATURE FOR CRITICALITY," and BASES 3/4.1.1.4, "MINIMUMTEMPERATURE FOR CRITICALITY,"for all three units.
These changes allow the minimum temperature for criticality to be established
-at 545 F, rather than the current value of 552'F, establish the surveillance temperature at 552'F, rather than the current 557'F, and clarify the BASES for this TS.
These TS changes would permit reactor operation at full power with a lower reactor coolant temperature to minimize potential steam generator tube degradation due to primary water stress corrosion cracking.
The additional information contained in the May 16,
- 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.
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2.0 BACKGROUND
Currently, Figure 3.2-1 of the Palo Verde Units 1 and 3 Technical Specifications (TS) specifies a minimum cold leg temperature of 562'F for core power levels between 90% and 100%.
In addition, TS 3/4. 1. 1.4 and its associated BASES for Palo Verde Units 1, 2, and 3 specify a minimum temperature of 552'F for criticality.
These TS requirements are supported by the safety analyses documented in the Updated Final Safety Analysis Report (UFSAR).
Operation of the Palo Verde units is currently restricted by an administratively imposed 10'F reduction in the reactor coolant cold leg temperature with reactor power restricted to 85% of rated core power to satisfy the current TS requirements.
The licensee requested changes to. the TS to allow Units 1 and 3 to operate at full power with a 10'F deduction in the reactor coolant cold and hot leg temperatures.
The hot leg temperature reduction is needed to minimize the steam generator tube degradation, (e.g.,
primary water stress corrosion cracking (PWSCC)).
3.0 EVALUATION In support of its proposed changes to the TS, the licensee submitted the results of an evaluation for all transients and accident analyses documented in the UFSAR with the reduced cold leg temperature.
For events that were no longer bounded by the analyses presented in UFSAR, new analyses were performed to ensure that the acceptance criteria are still met for each event.
For transients involving an increase in heat removed by the secondary system or a decrease in reactor coolant flow rate, the UFSAR analysis covers cold leg temperatures of 550'F and above; and therefore no new analysis is needed.
Regarding transients involving a decrease in heat removal by the secondary
- system, the loss of condenser vacuum event is affected by a reduction in cold leg temperature and was reanalyzed assuming a cold leg temperature of 550'F.
The results of the analysis are acceptable.
The consequences of a main feedwater line break are more limiting with higher values of cold leg temperature; and therefore it was not reanalyzed.
Transients involving reactivity and power distribution anomalies were reviewed for power levels above '90%.
Acceptable results are assured because adequate thermal-margin remain available with the reduced cold leg temperature.
The transients involving an increase in reactor coolant system inventory are determined to be independent of the value of cold leg temperature.
Similarly, transients involving a decrease in reactor coolant system inventory are not
-'ffected because either a higher cold leg temperatur'q....is more limiting or the results of analysi's are independent of cold leg temperature.
The licensee also performed a reanalysis for a postulated main steam line break with induced multiple steam generator tube ruptures, assuming cold leg temperatures of 550'F and 540'F.
The results demonstrate that the Palo Verde administrative limits for primary iodine activity will ensure that the dose consequences remain acceptable.
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Additionally, cycle specific LOCA evaluations were performed for Unit 2, Cycle 5.
These evaluations include a reduction in cold leg temperature of 10'F.
The resultant peak clad temperature remains less than the current analysis of record limit of 2091'F, and the licensing basis limit of 2200'F.
Based on the results of the Unit 2 evaluation and similarity among the three
- units, and the evaluations discussed
- above, a 10'F reduction in cold leg temperature is acceptable for Units 1 and 3.
Technical Specification 3/4. 1. 1.4 specifies a minimum temperature for criticality and establishes a minimum temperature for criticality for its associated surveillance requirements.
This TS ensures:
(1) the moderator temperature coefficient is within its analyzed temperature range; (2) the protective instrumentation is within its normal operating range; (3) a minimum temperature is provided for special test exception 3/4. 10.4; and (4) the reactor vessel is above its minimum RT ndt temperature.
The licensee has evaluated the effects of the proposed TS changes against the above stated criteria and determined that a reduction of the minimum temperature for criticality to 545'F, with its associated surveillance requirement set at 552'F, is adequate for the Palo Verde units.
The staff has reviewed the licensee's submittal and finds that the proposed TS changes are supported by appropriate analysis and are acceptable.
4.0 STATE CONSULTATION
In accordance with the Commission's regulations, the Arizona State official was notified of the proposed issuance of the amendments.
The State official had no comments.
5.0 ENVIRONMENTAL CONSIDERATION
The amendments change a requirement with respect to the installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20 and change 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 offsite,,and that there is no significant increase in individual or cumulative occupationa]
radiation exposure.
The Commission has previously issued a
proposed finding that the amendments involve no significant hazards considera-
- tion, and there has been no public comment on such finding (59.FR 14886).
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 prepared in connection with the issuance of the amendments.
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- 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 publ.ic will not be endangered by,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 publ,ic.
Principal Contributor:
C. Liang Date:
June 7,
1994
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