ML20035C693
| ML20035C693 | |
| Person / Time | |
|---|---|
| Site: | Catawba  |
| Issue date: | 03/30/1993 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20035C692 | List: |
| References | |
| NUDOCS 9304080323 | |
| Download: ML20035C693 (3) | |
Text
_.
[ [pH aECg h
UNITED STATES j
4 i
NUCLEAR REGULATORY COMMISSION
.s,
g,'
/, lC W ASHING TON. D. C. 20555 p
SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO.108 TO FACILITY OPERATING LICENSE NPF-35 AND AMENDMENT NO.102 TO FACILITY OPERATING LICENSE NPF-52 DUKE POWER COMPANY. ET AL.
CATAWBA NUCLEAR STATION. UNITS 1 AND 2 DOCKET NOS. 50-413 AND 50-414
1.0 INTRODUCTION
By letter dated June 7, 1990, as supplemented April 22 and November 4, 1992, the Duke Power Ccmpany, et al. (the licensee), submitted a request for changes to the Catawba Nuclear Station, Units 1 and 2, Technical Specifications (TS).
The Standby Nuclear Service Water Pond (SNSWP) limiting condition for operation (LCO) would be changed to require an average water temperature less than or equal to 91.5 *F at the 568 foot elevation.
The April 22 and November 4,1992, letters provided clarifying information that did not change the initial proposed no significant hazards consideration determination.
The initial submittal of June 7,1990, proposed that TS 3.7.5b. be revised to 92 *F at the 563 foot elevation.
fhe staff noted from its earlier review of this issue in the Safety Evaluation Report (NUREG-0954) for issuance of the operating license, that there was a 2.4 *F difference in the NRC staff's calculation of pond temperature and the licensee's calculation.
The staff discussed this difference with the licensee and, consequently, the licensee revised its proposed TS 3.7.5b. in its April 22, 1992, submittal to a value of 91.5 "F at 568 feet elevation. This results in a maximum licensee calculated temperature of 97.5 *F, which when combined with the 2.4 *F difference, is less than 100 *F which is the qualification temperature for operation of the Nuclear Service Water (RN) System in this mode.
The proposed change reflects a more conservative approach to ensuring that the SNSWP can meet its design basis safety function, which is to provide an adequate source of cooling water to dissipate waste heat rejected during a unit LOCA plus a unit cooldown. The previous TS required that the temperature for the SNSWP, which serves as the ultimate heat sink in the event of the loss of Lake Wylie, be monitored at the intake pipe level (540 feet). This is not conservative because that monitoring point is near the bottom of the SNSWP, where cooler water exists. There is the opportunity for warmer, less dense water to exist at levels above the monitoring point.
It is assumed in the Final Safety Analysis Report (FSAR) analysis that the entire pond is at the same initial temperature as measured at the indicated level in the pond with 9304080323 930330 PDR ADOCK 05000413 P
~
. no stratification. Therefore, the licensee concludes that it is not conservative for the LC0 to specify a maximum allowed SNSWP temperature which is measured at the intake level.
2.0 EVALUATION The proposed SNSWP change, as revised, requires that the average water temperature be less than or equal to 91.5 *F at an elevation of 568 feet in the SNSWP. This reflects a change from 86.5 'F at an elevation of 540 feet, and offers a more conservative approach in ensuring that the SNSWP can perform' its design basis function as the ultimate heat sink, when required.
The licensee performed an analysis to qualify the SNSWP at a more conservative (91.5 *F) initial temperature and evaluate its impact on station structures, systems, and equipment.
Preliminary steps in the analysis included verifying that the FSAR and SNSWP input parameters (i.e., area, volume) remained valid; and performing temperature surveys during summer months to come up with a reasonably conservative SNSWP temperature.
Westinghouse then performed a containment analysis to determine the effects of the higher water temperature on peak containment pressure during a LOCA.
Results of this analysis were reported in the initial June 7, 1990, application based on the 92 *F limit then proposed.
Two input parameters--the initial SNSWP temperature and the assumed temperature of the Refueling Water Storage Tank (RWST)--were changed to reflect this proposed change and to more closely represent the TS i
requirements for the RWST temperature.
The resulting peak analyzed pressure was 14.05 psig (which is below the assumed containment peak design pressure of 14.7 psig). This was reached 12.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> from the start of the LOCA sequence.
The licensee stated that the water temperature is conservatively assumed to remain at 92 *F for the first 12.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> and that the volume of water needed to supply the RN system for those 12.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> is available below the 557 feet
- i elevation. This demand volume determination was revised in the April 22, 1992, submittal to be consistent with the F5AR 9.2.5 methodology in which two i
trains of essential components are assumed to be shut down after 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />.
The licensee stated that, following the initial turnover of the SNSWP volume through tha RN system assuming an initial unstratified temperature of 91.5 *F, the predicted peak SNSWP temperature is 97.5 *F.
When the 2.4 *F difference between the DPC analytical model results and the NRC staff's independent analysis is added to this, the predicted maximum pond temperature remains at or below the 100 *F limit.
This is the SNSWP temperature for which safety-related components were designed and assured makeup demands were based.
Records show that the highest surface water temperatures in the Catawba SNSWP observed under warm weather conditions were below the value of the revised TS limit.
The licensee also stated that test acceptance criteria have been implemented for the major RN system heat exchangers to ensure that the actual LOCA heat rejection rates used in the Westinghouse containment peak pressure analysis can be attained with margin for fouling.
Equipment qualification analyses for long-term containment temperatures have been revised to account for 92 *F initial SNSWP temperature followed by 100 *F RN cooling water temperature.
i
- Based on its review of the licensee's proposed TS changes related to the SNSWP, the staff concludes that the licensee's analysis adequately demonstrates that the SNSWP will continue to meet its design basis safety function and satisfy the requirements of General Design Criterion 44.
The staff, therefore, finds the proposed TS changes acceptable.
3.0 CONSULTATION In accordance with the Cummission's regulations, the South Carolina State official was notified of 1he 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 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 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 (55 FR i
28474 dated July 11, 1990). 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 environdental 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 Contributors:
R. Hartin D. Roberts Date: March 30, 1993 v
,v.
- -