ML20035H128
| ML20035H128 | |
| Person / Time | |
|---|---|
| Site: | Surry  |
| Issue date: | 04/22/1993 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20035H127 | List: |
| References | |
| NUDOCS 9305030180 | |
| Download: ML20035H128 (2) | |
Text
/po' "G%'o, UNITED STATES NUCLEAR REGULATORY COMMISSION
{
WASHINGTON. D. C. 20555 f
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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO.177 TO FACILITY OPERATING LICENSE NO. CPR-32 AND AMENDMENT NO.176 TO FACILITY OPERATING LICENSE NO. DPR-37 VIRGINIA ELECTRIC AND POWER COMPANY SURRY POWER STATION. UNIT NOS 1 AND 2 DOCKET NOS. 50-280 AND 50-281 l.0 INTRODUCTION By letter dated December 11, 1992, the Virginia Electric and Power Company (the licensee) proposed to change the Surry Power Station Units 1 and 2 Technical Specifications (TS) for the Reactor Coolant System (RCS) Loop Stop Valve Interlocks operability requirement.
The licensee proposed to eliminate the RCS loop stop valve interlocks operability requirements and proposed to modify the TS 3.17 to establish TS requirements governing the operation of the RCS loop stop valves. The existing restrictions were created based on the
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original design basis that included the ability to operate the unit at power with an RCS loop isolated. Although an isolated loop could only be returned to service with the unit shut down, these restrictions and interlocks were established to protect against inadvertent cold water and boron dilution accidents during the startup of an isolated loop. The proposed TS changes restrict the operational modes wherein an RCS loop may be isolated or returned to service to cold shutdown and refueling shutdown only.
2.0 EVALUATION The existing TS 3.17 was originally primarily directed at precluding the J
startup of an isolated loop during power operation; however, it has applicability in cold shutdown and refueling shutdown.
Since power operation with less than all three loops in service is prohibited by TS 3.A.11, the proposed changes to TS 3.17 would remove the interlock operability requirements while maintaining controls which sliminate the potential for a positive reactivity addition accident when performing maintenance operations I
during cold shutdown and refueling shutdown. TS requirements are being-incorporated to. require'that the RCS loop stop valves'be maintained open unless the unit is in cold shutdown or refueling shutdown.- When a loop is isolated the loop stop valves will have their AC power removed and the breakers locked open, thus ensur_ing that a valve is not inadvertently opened.
When returning an isolated loop and a filled loop to service, the revised TS require that the boron concentration of the isolated loop be verified greater than or equal to that of the active loops before opening a hot leg loop 'stop-valve, thus precluding boron dilution. To provide a controlled mixing between the isolated loop and the active loop, the isolated loop will be operated.with 9305030100 930422 PDR ADOCK 05000280 P
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reliei line flow of at least 125 gpm for 90 minutes, while monitoring neutron flux to identify any unexpected reactivity addition. A minimum water level in the RCS is specified to ensure that a loss of shutdown cooling does not occur during the loop backfill evolution.
3.0
SUMMARY
The proposed TS establishes adequate administrative controls to eliminate the potential for an inadvertent valve opening in an isolated loop, causing a boron dilution or cold water addition accident.
Furthermore, startup of an isolated loop is now limited to only cold shutdown or refueling shutdown.
Locking closed the stop valves of an isolated loop with power removed prevents inadvertent opening and potential boron dilution or loss of inventory.
- Thus, the proposed TS administrative controls will meet the operability requirements of the RCS loop stop valves preventing boron dilution and reactivity addition accident.
4.0 STATE CONSULTATION
In accordance with the Commission's regulations, the Virginia State official was notified of the proposed issuance of the amendments. The State official had no comment.
5.0 ENVIRONMENTAL CONSIDERATION
These amendments change a requirement 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 these amendments involve no significant hazards consideration and there has been no public comment on such finding (58 FR 5436). Accordingly, these 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.
6.0 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 these amendments will not be inimical to the common defense and security or to the health and safety of the public.
Principal Contributor:
K. Desai 1
Date: April 22, 1993 t