ML20077C601
| ML20077C601 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 11/30/1994 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20077C596 | List: |
| References | |
| NUDOCS 9412050275 | |
| Download: ML20077C601 (2) | |
Text
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E NUCLEAR REGULATORY COMMISSION f
WASHINGTON, D.C. 20555 4 001
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SAFETY EVACUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO. 98 TO FACILITY OPERATING LICENSE NO. NPF-49 NORTHEAST NUCLEAR ENERGY COMPANY. ET AL.
MILLSTONE NUCLEAR POWER STATION. UNIT NO. 3 DOCKET NO. 50-423
1.0 INTRODUCTION
l By letter dated June 30, 1994, Northeast Nuclear Energy Company, the licensee for Millstone Nuclear Power Station, Unit 3, proposed a change to Technical Specification (TS) Table 3.3-4, " Engineered Safety Features Actuation System >
Instrumentation Trip Setpoints." This request was submitted to resolve an issue raised during the electrical distribution system functional inspection (EDSFI) team evaluation concerning the degraded voltage protection relay l
setpoint on the 4kV safety buses. Also, there were followup teleconferences between representatives of the licensee and the NRC staff on August 15, October 24, and October 26, 1994, to discuss the above change.
The licensee proposes to revise TS Table 3.3-4, by revising the trip setpoint for the 4Kv bus degraded grid (undervoltage) relay from its current value of 23710 volts to its new setting of 23730 volts. This proposed revision is based on the new calculation which was done as a result of the EDSFI team evaluation. The team found that the licensee's original calculation did not account for the potential transformer ratio error of i 0.6% and that no allowance had been made for the relay setpoint tolerance range of i 0.5 volts.
The revision to the calculation affects the TS " Trip Setpoint" only and does not affect the TS " Allowable Value" because the existing value was already set conservatively higher than that required by the calculation.
2.0 EVALUATION Revision to Existino TS Table 3.3-4 Table 3.3-4.8.b:
Fifth column under " TRIP SETPOINT" change "3710" to "3730" volts.
The revision to the calculation, which was done as a result of the EDSFI team evaluation, results in a modification of the degraded grid (undervoltage) relay trip setpoint from 23710 volts to 13730 volts. However, the actual field settings of the undervoltage relays do not require any changes because they are currently conservatively set at 3745 volts. This actual field setting was used to establish additional conservatism, yet still ensures that plant transients would not needlessly occur due to the settings being too
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. high. Therefore, no modification to the actual field setting is required. As a result, the higher trip setpoint value will not cause any additional actuations of the engineered safety features systems.
Branch Technical Position (BTP) PSB-1 " Adequacy of Station Electrical Distribution System Voltages," provides the criteria for determining adequate degraded voltage protection.
The licensee has conducted an engineering review and reanalysis of the Electrical Distribution System, which involved adequately addressing the EDSFI results and the requirements of BTP PSB-1, in order to establish the TS trip setpoint and allowable value for the degraded grid (undervoltage) relays. The proposed revision does not change the design, function or method of operation of Class IE equipment at Millstone, Unit 3.
Staff analysis confirmed the licensee's engineering review.
Based on the above, the staff finds the proposed change to Millstone, Unit 3 TS to be acceptable.
3.0 STATE CONSULTATION
In accordance with the Commission's regulations, the Connecticut State official was notified of the proposed issuance of the amendment. The State official had no comments.
4.0 ENVIRONMENTAL CONSIDERATION
The amendment changes a requirement with respect to 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 amendment involves 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 amendment involves no significant hazards consideration, and there has been no public comment on such finding (59 FR 39594). Accordingly, the amendment meets 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 amendment.
5.0 CONCLUSION
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 ia 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: Charles Thomas Date: November 30, 1994