ML17311B192
| ML17311B192 | |
| Person / Time | |
|---|---|
| Site: | Palo Verde  |
| Issue date: | 09/20/1995 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML17311B191 | List: |
| References | |
| NUDOCS 9509250326 | |
| Download: ML17311B192 (6) | |
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UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 205550001 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO.
100 TO FACILITY OPERATING LICENSE NO.
NPF-41 AMENDMENT NO.
88 TO FACILITY OPERATING LICENSE NO.
NPF-51 AND AMENDMENT NO.
71 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 application dated December 7,
- 1994, as supplemented by letter dated August 1, 1995, the Arizona Public Service Company (APS or the licensee) requested changes to the Technical Specifications (Appendix A to Facility Operating License Nos.
NPF-41, NPF-51, and NPF-74, respectively) for the Palo Verde Nuclear Generating Station, Units 1, 2, and 3.
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 the Technical Specifications (TS) to allow the use of generic shape-annealing matrix (SAM) elements in the core protection calculators (CPCs).
Presently, cycle-specific SAM elements are determined during startup testing after each core reload.
Use of a generic SAM would eliminate several hours of critical path work after a refueling outage.
The staff questioned the licensee about the data used for the generic SAM and the monitoring of CPC synthesized axial shapes.
The licensee responded to these questions by letter dated August 1, 1995.
This information clarified the original submittal and did not expand the scope of the original no significant hazards determination published in the Federal
~Re ister on January 4,
1995 (60 FR 495).
2.0 EVALUATION The CPCs rely upon the excore detector signals to trip the reactor in the event of an anticipated operational occurrence (AOO) to ensure that the specified acceptable fuel design limits on minimum departure from nucleate boiling ratio (DNBR) and peak linear heat rate are not violated.
To do this, each CPC channel synthesizes the core average axial power shape from three levels of excore detector signals.
The relative excore detector readings are 950925032b 950'gI20 PDR ADQCK 05000528 P
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subsequently adjusted within the CPCs by a set of channel dependent shape annealing constants.
These SAM constants are typically measured during the reload startup power ascension and installed into the CPC channels.
Incore and excore signal data are taken at regular intervals during the initial startup power ascension and the incore data is subsequently processed through a computer code to determine the relative power at the core periphery.
An automated data reduction code is then used to verify the data, calculate the SAM constants, and determ'ine whether the measured SAM meets a set of review and acceptance criteria to justify its implementation into the CPC channels.
The licensee has proposed to change Note 5 of Table 4.3-1 in TS 3/4.3. 1 to allow either a determination of a cycle-dependent SAM or verification of the acceptability of a generic SAM to be used in the CPCs.
The cycle-specific SAMs from previous cycles have been found not to be reload dependent and, in fact, would have been acceptable for other cycles, even other units.
In addition, since the cycle-specific SAM is only measured once during reload
- startup, the representation has been observed to be less accurate as the cycle progresses and the power shape evolves from a flattened cosine to a saddle shape.
The generic SAM would be based on middle-of-cycle data and, therefore, would be more representative of the entire cycle.
If a generic SAM is used, the matrix elements will be validated each cycle during startup testing and must meet the same acceptance criteria as the cycle-specific SAM elements.
This ensures that the axial power shapes generated by the CPCs will still
=-
remain within the required uncertainties and that the CPCs will trip the reactor so that minimum DNBR and peak linear heat rate are not violated in the event of an A00. If these criteria are not met, APS would calculate a cycle-specific SAM to be used in the CPCs.
In response to a staff concern, APS has confirmed that it intends to monitor the CPC synthesized axial shapes at least quarterly during each cycle to verify the continued acceptability of the CPC axial shape synthesis.
Based on the above review, the staff finds the proposed TS change to provide the option of using generic SAM elements in the CPCs acceptable.
- 3. 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.
4.0 ENVIRONMENTAL CONSIDERATION
The amendments change a surveillance requirement.
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
0
consideration, and there has been no public comment on such finding (60 FR 495).
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.
- 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 compl:iance 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:
L. Kopp B. Holian Date:
September 20, 1995
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