ML20237E069
| ML20237E069 | |
| Person / Time | |
|---|---|
| Site: | Catawba  |
| Issue date: | 08/25/1998 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML20237E061 | List: |
| References | |
| NUDOCS 9808280233 | |
| Download: ML20237E069 (3) | |
Text
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UNITED STATES g
j NUCLEAR REGULATORY COMMISSION
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WASHINGTON, D.C. acce64J01 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO. 169 TO FACILITY OPERATING LICENSE NPF-35 AND AMENDMENT NO.161 TO FACILITY OPERATING LICENSE NPF-52 DUKE ENERGY CORPORATION ET AL.
CATAWBA NUCLEAR STATION. UNITS 1 AND 2 l
DOCKET NOS. 50-413 AND 50-414
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1.0 INTRODUCTION
j By letter dated December 11,1997, Duke Energy Corporation, et al. (the licensee), submitted a request for changes to the Catawba Nuclear Station, Units 1 and 2, Technical Specifications
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(TS). The requested change would revise TS Table 3.3-4, Engineered Safety Feature j
Actuation System Instrumentation Trip Setpoints, to require that suction of the Nuclear Service
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Water System (designated as RN) be swapped from Lake Wylie to the Standby Nuclear Service Water Pond (SNSWP) at a higher water level of Lake Wylie.
I 2.0 DISCUSSION AND EVALUATION The RN design and performance analyses are described in Section 9.2.1 of the Catawba Final Safety Analysis Report and Updated Final Safety Analysis Report, and was evaluated by the staff in Section 9.2.1 of the staff's Catawba Safety Evaluation Report (NUREG-0954). The l
primary function of the RN system is to supply cooling water to various heat loads in both the
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safety and nonsafety portions of each unit. Two bodies of water serve as the ultimate heat sink l
for the components cooled by the RN system. Lake Wylie is the normal water source, while the SNSWP, formed by a Class 1 seismically designed dam, is the alternate source if the water j
level of Lake 'Nylie becomes too low.
RN pump intake pit level transmitters, safety-graded instruments, alert the operators that a low level condition exists in the pumphouse pits and initiate a swap of the pit suction source from Lake Wylie to the SNSWP. Currently, TS Table 3.3-4, item 14.g specifies the swap to occur at a nominal setpoint at elevation (Lake Wylie water level) 2554.4 feet, with an allowed minimum value of 2552.9 feet to accommodate the instrument drift assumed to occur between operational tests and the accuracy to which setpoints can be measure and calibrated.
The licensee proposed to revise the nominal swap setpoint to 2557.5 feet and the allowable value to 2555.4 feet, i.e., increasing the specified values in a conservative direction. The licensee stated that subsequent to the time of initial plant licensing, and as part of the licensee's self-improvement process, the methodology for calculating instrument loop uncertainty was revised to use a more conservative technique. The new method identifies more possible error 9808280233 980825 PDR ADOCK 05000413 P
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,. terms and therefore, yields more conservative numbers. Based on the licensee's revised calculations, the instrument loop error for the RN pump intake pit level transmitters was increased to 1.8 feet from the 1 foot used in the original calculations.
. During the same review, the licensee also identified that the setpoint and allowable value currently specified in the TS may not ensure adequate net positive suction head (NPSH) to the i
RN pumps. The licensee's revised calculations determined that there would be adequate NPSH if the minimum RN pump intake pit level is maintained above the 2555.4 feet elevation.
Therefore, the licensee proposed to revise the RN suction swap setpoint to 2557.5 feet to provide for adequate margin.
In the December 11,1997, submittal, the licensee indicated that the values for the swapover trip setpoint and the minimum allowable lake level had already been incorporated in the plant's Instrument Data Sheets, calculations, and procedures. Incorporation of the revised values into plant procedures and calculations does not contradict the current TS and reflects the licensee's proactive application of conservatism to safety.
The staff has reviewed the licensee's proposed amendment to increase the current setpoint and allowabie minimum values for lake level as recorded by the Nuclear Service Water Pump intake Pit Level Transmitters. The higher trip setpoint and minimum allowable values are based on an updated, more conservative methodology and provide added assurance that sufficient NPSH will be available to the RN system pumps under normal and accident conditions. Therefore, the staff finds the proposed changes acceptable.
3.0 STATE CONSULTATION
in accordance with the Commission's regulations, the South Carolina State official, Mr. Virgil Autrey, 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 and change surveillance requirements. The NRC staff has determined that the amendments involve no significant increase in the amounts, 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 l
that the amendments involve no significant hazards consideration, and there has been no public comment on such finding (63 FR 6983 dated February 11,1998). Accordingly, the amendments meet the eligibikty criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9).- Pursuant to 10 CFR 51.22(b), no envirnnmentalimpact statement or environmental assessment need be prepared in connection with the issuance of the amendments.
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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: Christopher Gratton Peter Tam Date:
August 25, 1998