ML15113A054
| ML15113A054 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 12/29/1981 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML15113A055 | List: |
| References | |
| NUDOCS 8201190350 | |
| Download: ML15113A054 (3) | |
Text
o UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D. C. 20555 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION SUPPORTING AMENDMENT NO. 106TO FACILITY OPERATING LICENSE NO.
DPR-38 AMENDMENT NO. 106TO FACILITY OPERATING LICENSE NO. DPR-47 AMENDMENT NO. 103TO FACILITY OPERATING LICENSE NO.
DPR-55 DUKE POWER COMPANY OCONEE NUCLEAR STATION, UNITS NOS.
1, 2 AND 3 DOCKETS NOS. 50-269, 50-270 AND 50-287 1.0 Introduction and Background By letter dated April 17, 1981, Duke Power Company applied for a revision to the Oconee Nuclear Station, Units 1, 2 and 3, Technical Specifications (TSs) related to the Emergency Feedwater System (EFW).
The EFW serves as a backup to the Main Feedwater System (MFW) and is provided to allow cooldown of the Reactor Coolant System (RCS) to temperatures where it is possible to initiate long term decay heat removal.
Each of the three Oconee Units has three EFW pumps installed -
two electric motor driven and one steam turbine driven.
Each of these EFW pumps can take suction from its Unit's condenser o'r upper surge tanks and provide flow to the steam generators. The system is normally aligned for each motor driven pump to provide flow to its associated steam generator while the turbine driven pump is aligned to both steam generators. The system is designed, however, with flexibility to allow any EFW pump to provide flow to either or both steam generators and to take suction from condensate sources at the other two Units.
2.0 Evaluation Duke's April 17, 1981 application proposed increasing the allowable out-of-service (OOS) time for any one EFW pump from the present 60 hours6.944444e-4 days <br />0.0167 hours <br />9.920635e-5 weeks <br />2.283e-5 months <br /> to 7 days, and allowing operations to continue for up to 60 hours6.944444e-4 days <br />0.0167 hours <br />9.920635e-5 weeks <br />2.283e-5 months <br /> with two of the three EFW pumps inoperable. In addition to these requirements, the TSs would continue to require all three EFW pumps and both flow paths to be operable, except for short periods of time, and require immediate corrective action should all three pumps or both flow paths become inoperable.
Duke's bases for concluding that the proposed TSs would continue to result in safe operation are the flow requirements of the EFW during and following postulated plant transients.
Included in.Duke's application was an evaluation of the most probable transients (Loss of MFW, Loss of MFW with loss of electrical power, Plant cooldown, Turbine trip, Main Steam Lsolation Valve closure, MFW line break, Steam Line break and Small Break Loss of Coolant Accident), each of which 8201190350 811229 PDR ADOCK- 05000269 R
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-2 concluded that only one EFW pump was required.
In the event of a complete loss of onsite and offsite AC power, the turbine driven EFW pump would be required since the electric motor drives would be without a power source.
We have reviewed this application and agree that any one EFW pump has sufficient capacity to remove the necessary heat from the RCS if required by the unavailability of MFW. We have also evaluated the advisability of allowing any EFW pump to be 00S for up to 7 days in light of the fact that the turbine driven pump could be 00S concurrent with a complete loss of AC power. We have concluded that such an event is highly unlikely due to the stability of the Duke Power Company electrical distribution system, the probability that the other two Oconee Units will be in operation thus supplying electrical power and the low probability that both conditions (turbine driven EFW pump 00S and complete loss of AC power) would occur at the same time. However, we requested and Duke agreed to limiting the 00S time of the turbine driven pump to 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.
Since any one EFW pump and its associated flow path will satisfy the.requirements of the system, should its use become necessary, the requirement to maintain two flow paths (each with a separate pump) operable, except for short periods of time for testing and maintenance, ensures that sufficient redundancy is maintained to allow for a single failure. By requiring all three EFW pumps to be operable except for maintenance and testing (one motor driven pump OOS for 7 days or the turbine driven pump OS for 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />), added assurance is provided that redundant trains will be available.
In addition to the considerations discussed above, we have reached the following conclusions on the proposed revisions to the EFW pump 0OS requirements:
- 1. This change is consistent with the requirements imposed on other systems contained in the TSs (i.e. high and low pressure safety injection and containment spray) and is, in fact, more restrictive than the require ments for those systems.
- 2. As noted, any one EFW pump could provide sufficient cooling flow; however, each of the Oconee Units' EFW systems are capable of being manually cross-connected to provide EFW from one unit to another. In addition to this capability,.each Unit also has the capability of providing EFW to its steam generators through the use of the Auxiliary Service Water system.
- 3. Duke Power Company is in the process of installing'a separate, independent Standby Shutdown Facility which will be capable of providing sufficient EFW cooling flow to the steam generators in each Unit in the unlikely event of total loss of all offsite and onsite electrical power.
Based on the above considerations, we find that it is acceptable to allow:
- 1) one motor driven EFW pump to be OS for 7 days, 2) one turbine driven EFW pump to be OOS for 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />, and 3) both motor driven pumps to be inoperable for 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.
(These changes to the April 17, 1981 application were agreed to by Duke representatives.) Therefore, we conclude that the modified request is acceptable.
-3 3.0 Environmental Consideration We have determined that the amendments do not authorize a change in effluent types or total amounts nor an increase in power level and will not result in any significant environmental impact. Having made this determination, we have further concluded that the amendments involve an action which is insignificant from the standpoint of environmental impact and,..pursuant to 10 CFR §51.5(d)(4),
that an environmental impact statement, or negative declaration and environ mental impact appraisal need not be prepared in connection with the issuance of these amendments.
4.0 Conclusion We have concluded, based on the considerations discussed above, that:
(1) because the amendments do not involve a significant increase in the probability or consequences of accidents previously considered and do not involve a signi ficant decrease in a safety margin, the amendments do not involve a significant hazards consideration, (2) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, and (3) such activities will be conducte-d in compliance with the Commission's regulations and the issuance of these amendments will not be inimical to the common defense and security or to the health and safety of the public.
Dated:
December 29, 1981