ML20206K377
| ML20206K377 | |
| Person / Time | |
|---|---|
| Site: | LaSalle  |
| Issue date: | 04/14/1987 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20206K345 | List: |
| References | |
| NUDOCS 8704160336 | |
| Download: ML20206K377 (2) | |
Text
o UNITED STATES
~
o NUCLEAR REGULATORY COMMISSION
,E 4
WASHINGTON. D. C. 20555
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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION SUPPORTING AMENDMENT N0. 31 TO FACILITY OPERATING LICENSE N0. NPF-18 COMMONWEALTH EDIS0N COMPANY LA SALLE COUNTY STATION, UNIT 2 DOCKET NO. 50-374
1.0 INTRODUCTION
To ensure satisfactory resolution of outstanding concerns regarding the adequacy of station electrical distribution system voltages, the La Salle Unit 2 Operating License contains License Condition 2.C.(11) regarding low and/or degraded grid voltage. The license condition requires the Comonwealth Edison Company (licensee) to install a secon.d level of undervoltage protection prior to startup from the first refueling outage. The concern was that the original design provided no protection for the engineered safety feature (ESF) buses against a degraded voltage condition between the trip setpoint of the normal (first level) of undervoltage relays (60 to 69 percent of rated volt-age) and 90 percent of rated voltage.
By letter dated February 26, 1987, the licensee requested an amendment to the La Salle Unit 2 Technical Specifications to include this low and/or degraded grid voltage modification in the Division I of the electrical divisions.
The modifications and the changes to the Technical Specifications have been com-pleted for the other electrical divisions, Divisions II and III, and accepted in Amendment 22. This modification will include two undervoltage relays and a time delay relay to each 4.16kV bus which provides protection against degraded grid voltage. The undervoltage relays are connected in a two-out '.f-two logic arrangement to prevent spurious trips. The undervoltage relays se set to trip at 92 percent of bus voltage and have a 10 second time delay to prevent momentary voltage drops (e.g., motor starts) from actuating the system. The ESF bus will automatically disconnect from the offsite power sources, shed loads, and transfer to the diesel generator if a degraded voltage condition exists for more than five minutes during normal plant conditions or immediately upon receipt of an emergency core cooling system initiation signal (neither time includes the 10 second sensor time delay).
2.0 EVALUATION The licensee proposed revisions to the Technical Specification Tables 3.3.3-1, 3.3.3-2, and 4.3.3.1-1 to add the second level of undervoltage protection for Division I.
The staff has reviewed the licensee's submittal and concludes that the degraded grid voltage design for Division I of Unit 2 conforms to the previously approved design, see Amendment No. 22 dated May 9, 1986, and is, therefore, acceptable.
The staff has also reviewed the licensee's proposed Technical Specification changes and finds that they appropriately address the actuation sensor, trip setpoints and surveillance requirements for the Division I change made to degraded voltage logic circuit and are, therefore, acceptable.
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3.0 ENVIRONMENTAL CONSIDERATION
This amendment involves a change in the installation and 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 this 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 cumula-tive occupational radiation exposure.
The Commission has previously issued a proposed finding that this amendment involves no significant hazards consideration and there has been no public comment on such finding. Accord-ingly, this 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 this amendment.
4.0 CONCLUSION
The Commission made a proposed determination that this amendment involves no significant hazards consideration which was published in the Federal Register (52 FR 7879) on March 12, 1987, and consulted with the state of Illinois. No public comments were received, and the state of Illinois did not have any comments.
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 comaliance with the Commission's regula-tions 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.
Principal Contributor:
A. Bournia, BWR Project Directorate No. 3, DBL Dated: April 14, 1987
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