ML17334B670
| ML17334B670 | |
| Person / Time | |
|---|---|
| Site: | Cook  |
| Issue date: | 12/10/1997 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML17334B669 | List: |
| References | |
| NUDOCS 9712170233 | |
| Download: ML17334B670 (5) | |
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UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON> D.C. 205M-0001 SAFETY EVALUATIONBY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENTNO. 219 TO FACILITYOPERATING LICENSE NO. DPR-58 AND AMENDMENTNO.
203 TO FACILITYOPERATING LICENSE NO. DPR-74 INDIANAMICHIGANPOWER COMPANY DONALDC. COOK NUCLEAR PLANT UNIT NOS.
1 AND 2 DOCKET NOS. 50-315 AND 50-316
1.0 INTRODUCTION
By letter dated September 19, 1997, the Indiana Michigan Power Company (the licensee) requested amendments to the Technical Specifications (TSs) appended to Facility Operating License Nos. DPR-58 and DPR-74 for the Donald C. Cook Nuclear Plant, Unit Nos.
1 and 2.
The proposed amendments would modify TS 4.5.2.d.1 to delete the interlock that would close the Residual Heat Removal (RHR) suction valves ifthe Reactor Coolant System (RCS) pressure were to increase to 600 psig, while retaining the interlock that would prevent the suction valves from opening while the RCS pressure is above the RHR system design pressure.
This change would maintain the open interlock function and allow continued deactivation of the isolation valves to assure RHR availability and provide Low Temperature Overpressure Protection (LTOP).
2.0 EVALUATION Currently, TS 4.5.2.d.1. requires, in Modes 1, 2, and 3, 'Verifying automatic isolation and interlock action of the RHR system from the Reactor Coolant System when the Reactor Coolant System pressure is above 600 psig." TS 4.5.3.1 requires, when T, is less than 350'F, "The ECCS subsystem shall be demonstrated OPERABLE per the applicable Surveillance Requirements (SRs) of 4.5.2," which would include TS 4.5.2.d.1.
FSAR Section 9.3.2, states "The (RHR] suction line valves are interlocked through separate channels of the reactor coolant system pressure signals to provide automatic closure of both valves whenever the RCS pressure exceeds design pressure of the RHR system.
In addition, both valves are interlocked to prevent inadvertent opening under such conditions." and 'When the RCS is open to the atmosphere, power to both suction isolation valves (IMO-128 and ICM-129) is locked out to prevent inadvertent closure of the valves and the potential loss of RHR." This automatic isolation interlock was originally intended to prevent an intersystem loss of coolant accident (LOCA) from a high pressure RCS to the RHR system.
This amendment would not change the interlock that prevents opening the RHR suction valves when the RCS pressure exceeds design pressure of the RHR system.
This amendment would remove the TS requirement for the interlock designed to automatically close the isolation valves ifthe RCS pressure were to increase to 600 psig.
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'I Since June 1980, the licensee has defeated the auto-closure interlock on both units any time the RHR system was operating in the normal cooling configuration.
This was done to prevent inadvertent auto-closing of the valves, which would have resulted in loss of RHR suction during shutdown cooling operation.
In addition, the auto-closure capability, ifactive, renders the LTOP system inoperable in Mode 4 with RHR cooling in service.
This occurs because the RHR suction safety relief valve, as part of the LTOP system in this configuration, would lose communication with the RCS ifeither of the suction valves were to close.
Operation with the auto-closure interlock disabled is consistent with the licensee's response to NRC Bulletin 80-12, "Decay Heat Removal System Operability," with the operational description provided in FSAR Section 9.3.2, and with SR 3.4.12.7. in NUREG-1431, Rev. 1, "Standard Technical Specifications Westinghouse Plants."
However, the disabling of the auto-closure interlock, consistent with the above discussion, is not consistent with TS SR 4.5.2.d.1.
As previously noted, TS 4.5.2.d.1 requires verifying both automatic isolation and interlock of the RHR system from the RCS.
In order to make the TS more accurately reflect plant operation, the licensee has proposed to delete the isolation function surveillance and to add clarification wording that the interlock prevents opening of the suction for the RHR system.
As discussed above, the disabling of the auto-closure interlock is necessary to assure availability/operability of RHR shutdown cooling and for LTOP operation.
Protection against an intersystem LOCA for the high RCS pressure in Modes 1, 2, and 3 is still provided by the interlock that prevents opening of the suction valves when RCS pressure exceeds RHR system design pressure.
The original basis for the auto-closure interlock was to protect the RHR system from an overpressurization event while operating with RHR suction from the normal RCS cooldown line. However, the licensee's analyzed LTOP configuration provides this protection and lowers the potential for inadvertent isolation of decay heat removal capability. Therefore, based on the need to have the interlock disabled during low pressure operation and the continued protection for Modes 1, 2, and 3, the licensee's proposed change is considered acceptable by the staff.
3.0 STATE CONSULTATION
In accordance with the Commission's regulations, the Michigan State official was notified of the proposed issuance of the amendments.
The State official had no comments.
4.0 ENVIRONMENTALCONSIDERATION The amendments involve a change to a requirement with respect to the 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 (62 FR 54861).
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 staff 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.
John B. Hickman Date:
December 10, 1997
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