ML16138A822
| ML16138A822 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 11/25/1996 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML16138A821 | List: |
| References | |
| NUDOCS 9611290397 | |
| Download: ML16138A822 (3) | |
Text
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO. 219 TO FACILITY OPERATING LICENSE DPR-38 AMENDMENT NO. 219 TO FACILITY OPERATING LICENSE DPR-47 AND AMENDMENT NO. 216 TO 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 September 17, 1996, as supplemented by letter dated October 23, 1996, Duke Power Company (the licensee) submitted a request for changes to the Oconee Nuclear Station, Units 1, 2, and 3, Technical Specifications (TS).
The requested changes would modify the requirements associated with limiting the peak reactor building pressure by lowering the maximum allowable reactor building pressure, lower the actuation setpoint for actuation of the reactor building spray system, and modify the associated TS Bases requirements. Specifically, the licensee has proposed changes to TS 3.5.3, 3.6.4, and Bases 3.3.
The October 23, 1996, letter provided clarifying information that did not change the initial proposed no significant hazards consideration determination.
2.0 BACKGROUND
Following a high energy line break (and in conjunction with a worst case single failure), the Low Pressure Injection (LPI) coolers, Reactor Building Cooling Units (RBCUs), and the Reactor Building Spray System, must be capable of performing two functions. These two functions are (a) to maintain the Reactor Building temperature less than the environmental qualification (EQ) envelope, and (b) to maintain the Reactor Building internal pressure less than 59 psig. The heat removal capabilities of the LPI coolers and RBCUs are tested at least once per quarter to ensure that these systems are operable.
The acceptance criteria for these tests are based, in part, on the containment pressure/temperature response to a mass and energy release following a high energy line break inside the containment.
The methodology for simulating the mass and energy release from high energy line breaks, and the resulting containment response for the Oconee Nuclear Station, is contained in the Duke Power Company Topical Report, DPC-NE-3003-P, "Mass and Energy Release and Containment Response Methodology," dated August 11, 1993. This methodology was approved by the NRC staff in a Safety Evaluation 9611290397 961125 PDR ADOCK 05000269 PDR
-2 Report dated March 15, 1995. This analysis demonstrates that the EQ requirements and containment pressure acceptance criteria are met for a range of LPI cooler and RBCU performance requirements, and result in less frequent cleaning and testing of these systems. In addition, the analysis indicated that TS changes to the setpoint are necessary based on the input assumptions used in the analysis. These changes are in the more conservative direction and have already been applied administratively.
3.0 EVALUATION The first change would affect TS 3.5.3, "Engineered Safety Features Protective System Actuation Setpoints."
It would reduce the reactor building spray system actuation setpoint on high reactor building pressure from < 30 psig to 5 15 psig.
Justification: The small break loss-of-coolant accident (LOCA) containment pressure response analysis that is described in Topical Report DPC-NE-3003-P requires that the reactor building spray system actuate when reactor building pressure reaches 20 psig. This setpoint, rather than 30 psig, improves the long-term reactor building temperature response following a small break LOCA, since it would result in actuation of the reactor building spray system more quickly on increasing pressure. An allowance of 5 psig is applied to the analysis assumption to provide an additional safety margin, resulting in a proposed setpoint of 15 psig. An additional administrative margin has been applied since 1971 by procedure, so that the setpoint is controlled at < 10 psig. The additional margin has not caused operational concerns.
Since the proposed setpoint is below the maximum setpoint that has been analyzed in the topical report, will enhance the response of the reactor building spray system to a small break LOCA, is consistent with the analysis that covers the entire spectrum of break sizes, is high enough to prevent spurious initiation during normal operation, and is in the more conservative direction, the proposed change is acceptable.
The second proposed change would affect TS 3.6.4, "Reactor Building Pressure."
It would reduce the maximum allowable reactor building internal pressure from 1.5 psig to 1.2 psig when the reactor is critical.
In addition, the lower reactor building pressure limit would be changed from 5 inches of mercury (inches of Hg) to -2.45 psig.
Justification: The post-LOCA reactor building response analysis that is described in Topical Report DPC-NE-3003-P assumes an initial reactor building pressure of 1.2 psig and shows that the peak reactor building pressure remains below the design internal pressure of 59 psig for all reactor building temperatures. Current operating procedures require depressurizing the reactor building if the reactor building pressure indication exceeds 0.6 psig, which represents an additional safety margin that has been administratively applied.
Since the proposed setpoint is consistent with the setpoint assumed in the analysis, and is in the more conservative (safe) direction, it is acceptable.
-3 The proposed change to the lower reactor building pressure limit from a vacuum of 5 inches of Hg to -2.45 psig is merely a straight-forward conversion between units used to specify the pressure. There is no actual change in the allowable negative pressure. Also the units will be consistent with the units and instrument scale used in the control room. Therefore, this change is acceptable.
The third proposed change would affect TS 3.3.5, "Reactor Building Cooling,"
and TS 3.3.6, "Reactor Building Spray," Bases. It would indicate that the containment temperature response following a LOCA or main steam line break accident will be within the equipment qualification analysis conditions with one spray and two coolers operable. This proposed change clarifies the design accident requirements of the reactor building, sprays and coolers to make the description consistent with the topical report description. Therefore, the proposed change is acceptable.
3.0 STATE CONSULTATION
In accordance with the Commission's regulations, the South Carolina State official was notified of the proposed issuance of the amendments. The State official had no comments.
4.0 ENVIRONMENTAL CONSIDERATION
The amendments change requirements 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 (61 FR 55031, October 23, 1996).
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 compliance 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 Contributor: David E. LaBarge Date: November 25, 1996