ML20154J766
| ML20154J766 | |
| Person / Time | |
|---|---|
| Site: | Yankee Rowe |
| Issue date: | 05/18/1988 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20154J758 | List: |
| References | |
| NUDOCS 8805270125 | |
| Download: ML20154J766 (2) | |
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UNITED STATES
[ y.s r(i NUCLEAR REGULATORY COMMISSION 7 ;/ j WASHINGTON, D. C. 20555 gv...../
SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION SUPPORTING AMENDMENT NO. 107 TO FACILITY OPERATING LICENSE NO. DPR-3 YANKEE ATOMIC ELECTRIC COMPANY YANKEE NUCLEAR POWER S1ATION DOCKET N0.50-029 INTRODUCTION AND DISCUSSION I
By letter dated January 5, 1988 Yankee Atomic Electric Company, the licensee for the Yankee Nuclear Power Station submitted a Technical Specification change request pertaining to the first level undervoltage protection for each of the three 480V emergency buses. The change was submitted in response to an NRC request. Presently, testing of the first-level undervoltage protection relays is not included in the Technical Specifications, only in the Operating Procedures (OP-5762).
The proposed change would modify the loss of Voltage (First level) Technical Specification of Table 3.3-2 (limiting condition for operation) including the addition of A: tion Statement 23, and of Table 3.3-3 (trip setpoints). The first-level undervoltage protection relays are set to actuate in 1.8 seconds on a complete loss of voltage, or 3.0 seconds at 276 volts. The second level protection relays are set to actuate at 421 volts in 10 seconds, j
The first level undervoltage protection relays initiate isolation of the a80V i
emergency buses from the non-emergency buses, start the diesel generators, and I
close the diesel generator breakers.
The second level undervoltage protection will only cause an alarm, unless a safety injection actuation signal sir.ultaneously exists or occurs.
EVALUATION The proposed Technical Specifications specify a trip setpoint of 1.8f,0.2 seconds upon complete loss of voltage or 3.010.33 seconds upon a voltage decrease to 276 volts. We find these settings to be reasonable based on a i
balancing of the need for rapid separation of the emergency buses upon loss of voltage while preventing spurious separation during motor starting of the safety injection pumps or during other transient voltage dips.
The proposed W.:Lnical Specifications specify a channel calibration and channel functional test each refueling outage or at least once per 18 months.
This is consisteht with the staff's February 19, 1987 safety evaluation perforced for a previous first level undervoltage protection review, and is therefore acceptable.
For an inoperable condition, the Action Statement requires restoration in eight hours or Hot Standby within the next six hours and Cold Shutdown within the following 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />.
Since surveillance testing is only conducted during shutdown, the Action Statement would nomally be moot. The action would apply only for those rare instances when the inoperability is detected because of a spurious operation or a failure to 8805270125 000S10 DR ADOCK 050 9
2 actuate upon demand.
For those instances, the operators' priorities would be to put the plant into a safe condition before correcting the channel inoperability. Thus, we find that the eight hours permitted to restore the channel to operability is reasonable and acceptable.
The licensee for the Yankee Nuclear Power Station has submitted Technical Specification changes to the Tables 3.3-2 and 3.3-3 for Loss of Voltage (Firsc level) to the 480V emergency ouses.
The staff has reviewed these changes and
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concludes that they are acceptable. We also conclude that the changes upgrade plant reliability by moving these surveillance requirements from the operating procedures to the Technical Specifications.
ENVIRONMENTAL CONSIDERATION An Environmental Assessment for this proposed action was published in the Federal Register on May 16, 1988 (53FR17283).
Therein, it was determined that the proposed changes will not have a significant environmental impact because they will not increase the probability or consequences of accidents, alter the effluents which may be released offsite or cignificantly increase occupational radiation exposure.
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 nnt 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 this amendment will not be inimical to the common defense and security or to the health and safety of the public.
ACKNOWLEDGEMENT Principal Contributor: Argil Toalston, NRC Dated: May 18, 1988 1
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