ML16138A714
| ML16138A714 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 12/05/1990 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML16138A713 | List: |
| References | |
| NUDOCS 9012120163 | |
| Download: ML16138A714 (3) | |
Text
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NUCLEAR REGULATORY COMMISSION WASHINGTON, D. C. 20555 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO. 186TO FACILITY OPERATING LICENSE DPR-38 AMENDMENT NO.186 TO FACILITY OPERATING LICENSE DPR-47 AMENDMENT NO. 183TO FACILITY OPERATING LICENSE DPR-55 DUKE POWER COMPANY OCONEE NUCLEAR STATION, UNITS 1, 2 AND 3 DOCKET NOS. 50-269, 50-270 AND 50-287
1.0 INTRODUCTION
By letter dated July 19, 1990, Duke Power Company (the licensee) proposed changes to the Technical Specifications (TSs) for the Oconee Nuclear Station, Units 1, 2 and 3. The proposed changes would revise pages 2.3-1 and 2.3-7 of TS 2.3 to establish a revised reactor trip setpoint for the reactor coolant pump monitors.
Specifically, this revision would require the pump monitors to cause a reactor trip when two pumps are inoperable and the reactor is operating at greater than 2.0% full power instead of the current requirement which considers a power level greater than-0.0% of the rated power as the setpoint. This change was prompted by a recent event (Licensee Event Report 269/90-06, May 30, 1990) when a reactor trip was caused by electrical noise in the excore detector signal.
This electrical noise caused the 0.0% full power setpoint to be exceeded. The revision will increase the setpoint to greater than 2.0% full power for the pump monitor trip function and assure avoidance of future spurious reactor trips during cooldowns with two reactor coolant pumps in operation.
2.0 EVALUATION The NRC staff has evaluated the proposed change to TS 2.3 which would require pump monitors to produce a reactor trip when less than three pumps are operating and the reactor is at power operation greater than 2.0% full power as compared to the current 0.0% full power level setpoint. The licensee has determined that the proposed change would provide adequate margin to account for electrical noise in the excore detection signal during subcritical conditions.
The licensee has evaluated the effects of the reduction of coolant flow as a result of reactor coolant pump failures by addressing the applicable analyses addressed in Section 15.6 of the Final Safety Analysis Report (FSAR). The evaluation of loss of reactor coolant flow resulting from malfunction of reactor coolant pumps or their power supply establishes the minimum departure from nucleate boiling ratio (DNBR) as the controlling reactor protection criterion.
Specifically, the DNBR is to be not less than 1.3 at any time during the transient. The accident evaluated in Section 15.6 of the FSAR considers the loss of all four reactor coolant pumps leading to the loss of all forced flow from a beginning power level of 108%. Operation at 2% power with two reactor coolant pumps is well below what the equivalent power for this flow rate would 9oi2120263 90120!5
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-2 be. Therefore, loss of all forced flow from a power level of 2% with two reactor coolant pumps is clearly bounded by the accident analysis in Section 15.6, which shows that DNBR dces not decrease below 1.3 as a result of the transient.
Therefore, the proposed changes to TS 2.3 will not cause a condition during which the DNBR will reach a value of 1.3 or less.
In addition, the licensee has evaluated partial pump coastdowns and has established that the limiting transient for the determination of the flux/flow ratio is the coastdown of two reactor coolant pumps from full power initial conditions. However, the pump monitor trip function generates a reactor trip signal earlier than the flux/flow trip function. Since the analysis of a partial loss of flow accident with a trip generated by the pump monitor is more conservative than the analysis for a reactor trip on flux/flow alone, the proposed increase in the pump monitor setpoint will have no impact on the partial loss of reactor coolant flow analyses, and the proposed setpoint change will have no impact on the licensing basis safety analyses for the Oconee Nuclear Station. Therefore, the TS changes are acceptable.
3.0 ENVIRONMENTAL CONSIDERATION
These amendments involve a change in the requirements with respect to the installation or use of facility components located within the restricted area as defined in 10 CFR Part 20. We have 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 these amendments involve no significant hazards consideration, and there has been no public comment on such finding.
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 these amendments.
4.0 CONCLUSION
The Commission's proposed determination that the amendments involve no significant hazards consideration was published in the Federal Register (55 FR 34368) on August 22, 1990. The Commission has consulted with the State of South Carolina.
No public comments were received, and the State of South Carolina did not have any comments.
We have 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, and (2) such activities will be conducted in compliance with the Commission's regulations, and the issuance of these amendments will not be inimical to the common defense and security or to the health and safety of the public.
Principal Contributor:
Frank Rinaldi, PDII-3/DRP-I/II Leonard A. Wiens, PDII-3/DRP-1/II Dated:
December 5, 1990
DATED:
December 5, 1990 AMENDMENT NO. 186TO FACILITY OPERATING LICENSE DPR Oconee Nuclear Station, Unit 1 AMENDMENT NO. 186TO FACILITY OPERATING LICENSE DPR Oconee Nuclear Station, Unit 2 AMENDMENT NO. 183TO FACILITY OPERATING LICENSE DPR Oconee Nuclear Station, Unit 3 DISTRIBUTION:
Docket File NRC PDR Local PDR PD 11-3 R/F Oconee R/F S. Varga 14-E-4 G. Lainas 14-H-3 D. Matthews 9-H-3 R. Ingram 9-H-3 L. Wiens 9-H-3 F. Rinaldi 9-H-3 OGC-WF 15-B-18 D. Hagan MNBB 4702 E. Jordan MNBB-3701 G. Hill (12)
P1-37 W. Jones P-130A J. Calvo 11-F-22 ACRS (10)
P-135 GPA/PA 17-F-2 OC/LFMB MNBB 4702 R.Jon e-s