ML20034G324
| ML20034G324 | |
| Person / Time | |
|---|---|
| Site: | Diablo Canyon  |
| Issue date: | 03/02/1993 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20034G301 | List: |
| References | |
| NUDOCS 9303090339 | |
| Download: ML20034G324 (3) | |
Text
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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO. 76 TO FACILITY OPERATING LICENSE NO. DPR-80 AfLD AMENDMENT NO. 75 TO FACILITY OPERATING LICENSE NO. DPR-82 PACIFIC GAS AND ELECTRIC COMPANY DIABLO CANYON NUCLEAR POWER PLANT. UNITS 1 AND 2 DOCKET NOS. 50-275 AND 50-323 1.0 INTRODUCT16N Pacific Gas and Electric Company (PG&E), by letter dated October 30, 1992 proposed that the facilities operating licenses DPR-80 and DPR-82 be amended to rrodify Diablo Canyon Unit I and 2 Technical Specifications (TS) Section 3/4.:8.1, "A.C. Sources." This change is for a one-time extension of the 7-day diesel generator allowed outage time (A0T) to complete modifications and associated testing to support installation of a new sixth emergency diesel generator (2-3), implement Appendix R modifications, and perform preplanned maintenance / testing during the Unit 2 refueling outage.
The staff has reviewed the license's submittal and provides the following evaluation.
2.0 BACKGROUND
The Diablo Canyon Power Plant (D PP) electrical power system consists of an offsite system and a:, onsite system. The offsite power system is comprised of a 230 kV and 500 kV tvansmission system.
The onsite power system consists of a distribution system normally supplied by the offsite power system.
In the event of a loss of offsite power, the onsite power system will be available to supply power via five emergency diesel generators.
Two of the emergency diesel generators (EDGs) are dedicated to Unit 1, two of the EDCs are dedicated to Unit 2, and a fifth EDG (swing) is shared between both units.
Each EDG consists of a self-contained diesel engine directly connected to an alternating current generator.
Each EDG supplies a vital bus, with the swing EDG supplying either a Unit 1 or 2 vital bus.
3.0 EVALUATION During the Unit 2 fifth refueling outage, EDG l-3 will be removed from service for 14 days while Unit 1 is anticipated to be operating at 100 percent power.
As part of the installation of EDG 2-3, EDG l-3 will be separated from Unit 2 9303090339 930302 PDR ADOCK 05000275 P
PDR 1
. i and preoperational testing will be performed to verify proper operation in the new configuration.
During this time, EDG 1-3 will be inoperable. The Appendix R modifications consist of: (1) Addition of manual transfer switch contacts to the diesel generator control circuitry. This would isolate all fuses that could be affected by a control room or cable spreading room fire.
(2) Addition a second set of contacts to connect power to the diesel generator-control circuit through a different set of fuses. This will ensure positive transfer and operability of the diesel generator control circuit from the local diesel control panel. The Appendix R modifications are corrective actions described in the Licensee Event Report (LER) 2-92-001-01, submitted to the NRC in PG&E letter DCL-92-156, dated July 8,1992.
In addition, prior to taking EDG 1-3 out of service for the proposed activities with Unit 2 down and the present five EDG configuration, PG&E will verify that Unit 2 is in Mode 5, Mode 6, or in a defueled condition and verify the motor-operated disconnect for Unit 2 is disconnected. Also, the operability of the offsite circuits required by TS 3.8.1.1 for operating unit and TS 3.8.1.2 for the shutdown unit will be verified by checking for the correct breaker alignments and availability of indicated power.
The licensee will perform the Surveillance Requirements 4.8.).l.la and 4.8.1.1.2a.4 within 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> prior to removing EDG l-3 from service and the operability of the Unit I auxiliary feedwater pumps will be verified. With the present five EDG configuration, PG&E will also ensure that the following conditions are met during-the time that EDG 1-3 is out of service:
- 1. No preventative maintenance will be performed on the remaining EDGs.
- 2. The remaining four EDGs will be verified operable once every 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.
- 3. The capability for cross-connecting of the vital busses between units using the operable EDGs in accordance with the provisions of Emergency Procedure (EP) ECA-0.3 " Restore 4kV Bus," will be verified.
The term " verify" as used above, means to administratively check by examining I
logs or other information to determine if certain components are out-of-service for maintenance or other reascas.
It does not mean performance of the surveillance requirements needed to demonstrate the operability of the components.
In addition to the compensatory measures outlined above, Administrative Procedure AD8.DC55, " Outage Safety Scheduling," has been developed specifically to address plant safety issues during outage conditions. This procedure was developed using the guidance provided by Nuclear Utility Management and Resource Council (NUMARC), " Shutdown Management Guidelines." The control established for the shutdown unit's vital electrical sources during outage conditions as described in AD8.DC55 exceed minimum l
shutdown requirements.
In addition, the guidance provided in AD8.DC55 ensures the operability of two 4 kV vital buses at all times.
The NRC has previously approved a change to the DCPP TS to increase the EDG 1-3 allowed outage time (A0T) from 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> to 7 days for scheduled maintenance once per calendar year (License Amendments 43 and 43 for Units 1 and 2, respectively). The incremental risk increase associated with the one time i
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extension of the A0T from 7 to 14 days is 3.2E-6/yr, or approximately a 1.6 percent increase in total core damage frequer;cy for the year in which the A0T would be implemented. The PRA for the increased A0T results determined that the probability of an accident previously evaluated does not significantly change by increasing the EDG A0T from 7 to 14 days. Additionally, the DCPP i
staff has determined that increasing the EDG l-3 A0T will not involve physical l
alterations of any plant equipment and will not effect analytical assumptions regarding functioning of equipment designed to mitigate the consequences of accidents.
It is the opinion of the staff that based on the information submitted by the licensee the above change will not create the possibility of a new or different kind of accident from any previously evaluated. Therefore, the proposed change is found not to involve a reduction in a margin of safety and j
is acceptable to the staff.
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4.0 STATE CONSULTATION
In accordance with the Commission's regulations, the California State official was notified of the proposed issuance of the amendments.
The State official had no comments.
5.0 ENVIRONMENTAL CONSIDERATION
These amendments change a requirement with respect to the installation or use i
of a facility component located within the restricted area as defined in
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10 CFR Part 20 and changes surveillance requirements. The NRC staff has determined that the amendments involve ao significant increase in the amounts, d
and no significant change in the types, of any effluents that may be released 2
offsite, and that there is no significant increase in individual or cumulative
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j occupational radiation exposure. The Commission has previously issued a proposed finding that the amendments involve no significant hazards considera-i tion, and there has been no public comment on such finding (57 FR 58247).
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 i
connection with the issuance of the amendments.
6.0 CONCLUSION
l 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 amendment will not be inimical to the common defense and security or to the health and safety of the public.
Principal Contributor: M. Pratt I
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Date:
March 2, 1993 I
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