ML20070G774
| ML20070G774 | |
| Person / Time | |
|---|---|
| Site: | Cooper  |
| Issue date: | 03/07/1991 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20070G773 | List: |
| References | |
| NUDOCS 9103120397 | |
| Download: ML20070G774 (2) | |
Text
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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AHENDMENT NO. i37 TO FACILITY OPERATING LICENSE NO DPR-46 NEBRASKA PUBLIC POWER DISTRICT COOPER NUCLEAR STATION DOCKET NO. 50-298
1.0 INTRODUCTION
By letter dated May 31, 1989, Nebraska Public Power District (the licensee) requested an amendment to the Technical Specifications appended to Facility Operating License No. DPR-46 for the Cooper Nuclear Station.
The proposed amendment would delete the 20 second minimum stroke time requirement for the Reactor Recirculation Pump Discharge Valve.
2.0 DISCUSSION The Reactor Recirculation Pump Discharge Valves close during Los; of Coolant Accidents (LOCA) in order zo ensure successful injection of the Low Pressure Coolant Injection (LPCI) Mode of the Residual Heat Removal (RHR) system.
The closure of the discharge valve would isolate the LPCI flow from possible pipe ruptures in the recirculation suction line and prevent the loss of the LPCI makeup water through the break.
The existing Technical Specification 4.5.A.3.e requires testing of the discharge valves every refueling outage to verify that the time required for the valves stroke from full open to full closed is greater than 20 seconds and less than 26 seconds.
The maximum valve stroke time, 26 seconds, was an assumption in the design basis LOCA analysis for the LPCI injection time and would remain a requirement in the revised Technical Specification.
The minimum stroke time, 20 seconds, is not a design basis assumption but was intended to prevent attempted valve closure against differential pressures in excess of the valves design value of 200 psid.
Protection of the discharge valve by preventing attempted closure against high differential pressures is provided by a logic permissive which prevents valve closure until the reactor pressure decreases to a specified value.
This permissive is required to be maintained between reactor pressures of 185 and 235 psig by Technical Specification Table 3.2.B.
The permissive and the reactor depressurization which occurs as a result of the rupture of a recirculation pipe are sufficient to ensure that the valves will be able to perform the isolation function.
The minimum valve stroke time of 20 seconds is therefcre considered to be an unnecessary requirement to ensure the operability of the discharge valves.
9103120397 910307 PDR ADDCK 05000298 P
.' In addition to the protection of the discharge valves, the licensee's safety evaluation addressed the flow coastdown in the unbroken recirculation loop as a potential concern for the discharge valves minimum stroke time requirement.
The permissive which prevents valve closure before reactor pressure decreases to approximately 200 psig is sufficient to ensure the heat transfer associated with the recirculation flow coastdown during the initial 5-10 seconds of a LOCA is unaffected by the closure of the discharge valves.
Based on its review, the staff finds the licensee's prooosed Technical Specification change to be acceptable.
3.0 STATE CONSULTATION
In accordance with the Commission's regulations, efforts were made to contact the Nebraska State representative.
The state representative was contacted and had no comment.
4.0 ENVIRONMENTAL CONSIDERATION
The amendment involves a change in 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 and changes in surveillance requirements.
The staff has determined that the amendment involves no significant increase in the amounts, and no significant cha",ge in the types, of any effluents that may be released offsite, anr'. that there is no significant increast in individual or cumulative occupational radiation exposures.
The Commission has previously issued a aroposed finding that the amendment involves no significcnt hazards ccasideration and there has been no public comment on such finding.
Accortingly, the amendment meets the eligibility criteria for categorical exclusion set forth in 10 CFR Sectlon 51.22(c)(9).
Pursuant to 10 CF1 51.22(b),
no environmental impact statenient or environmental assessment need be prepared in connection with the issuance of the amendment.
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, and (2) such activities will be conducted in compliance with the Commission's regulations, and the issuance of the amendment will not be inimical to the common defense and security or to the health and safety of the public.
Principal Contributor:
W. Reckley, NRR Date: March 7, 1991
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