ML18130A619
| ML18130A619 | |
| Person / Time | |
|---|---|
| Site: | Surry  |
| Issue date: | 08/20/1979 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML18130A618 | List: |
| References | |
| NUDOCS 7909200174 | |
| Download: ML18130A619 (5) | |
Text
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SAFETY EVALUATION BY THE OFFICE -OF NUCLEAR REACTOR REGULATION RELATED TO MODIFICATION FOR 480V EMERGENCY POWER SYSTEM VIRGINIA ELECTRIC AND POWER COMPANY SURRY POWER STATION, UNIT 1 DOCKET NO. 50-280 INTRODUCTION By letter dated May 3, 1979, Virginia Electric and Power Company (the licensee) proposed modification to the 480V emergency power system on Surry Unit 1. The modification consists of adding one 480V Class lE load center to each train of the emergency power system.
The justification and adequacy of this modification are established by the licensee 1 s submittal of June 18, 1979, consisting of a load and voltage analysis and integrated test program and relay coordination data.
BACKGROUND
- Based on our review of Surry Unit 1, LER#79-008 dated April 5, 1979, we requested the licensee by letter dated April 16, 1979, to provide its modification plan and a testing program to correct the reported underpower capacity conditions on the station 480V emergency busses.
The licensee
- submitted the modification plan dated May 3, 1979.
The plan consists of adding a 1333 KVA (fan cooled r~ting) 480V load center to each of the two trains of the emergency power systems.
All 480V large motors (200 HP and above) will be powered from the existing load center on each train whereas the motor control center (MCC) feeders will be from the added load center.
The existing ijKV feeder breaker shall be common to both load centers.
Details of the modification are shown on the enclosed sketch.
We discussed
.the modification with the licensee in a meeting held on May 3', 1979.
In response to our request at the meeting, the licensee submitted a detailed study containing the load capability of the modified system and the voltage profile on Class lE busses during various modes of plant operation as specified in the FSAR, and integrated test program and relay coordination data on June 18, 1979, to establish the adequacy of the proposed modification.
EVALUATION The addition of another load center to each of the two trains and transferral of two MCCs from each existing load center to the one added, resulted in reduced loading of the existing load center to approximately 75 percent of its fan-cooled rating from the original loading of almost 12§ percent.
The new load center serves only two MCCs and is loaded to approximately 50 percent of its fan-cooled rating.
The addition of a load center to each train and the sharing of the existing connected load have adequately improved voltage conditions on the 480V Class lE busses for all plant operating conditions.
The steady state voltages on 480V Class lE equipment terminals remain within the design limit of plus 10 percent for light load conditions and minus 10 percent for heavy loa0 conditions of the plant for anticipated switch-yard voltage variations.
-2.:.
The starting voltage on the 480V Class lE equipment remains above 70 percent of the name plate rating during the worst condition of simultaneous low grid.
voltage and heavy bus loading.
The current carrying capacity of the cable between the 4KV breaker and the load center transformer is 150 percent of air cooled amperage rating of the load center.
One of the new load centers has a disconnect switch on the primary side of the load center transformer.
In the May 3, 1979 meeting, the licensee informed us that there is a single kirk key which is used to close both the disconnect switch and the load center bus supply breaker.
This feature ensures closure of the disconnect switch before the supply breaker is closed.
The proposed test program for the modified 480V Class lE system is sufficient for verifying the system's design capability to perform its safety functions.
The program is capable of testing 480V Class lE equipment ratings and performances.
CONCLUSIONS The analysis*, data and other information provided by the-1 icensee demonstrate the following features of the modified 480V Class lE systems:
- a.
The total load on the existing load center is within its self-cooled rating.
~.
The new load center is only 50 percent loaded.
- c.
Ampacity of the 4KV cable connecting the 4KV breaker to load centers is adequ_ate.
- d.
Starting and steady state voltages on the 480V Class lE equipment are within design limits.
- e.
The integrated test program for the modified 480V Class lE system is adequate.
Therefore, based on our review and evaluation, we conclude that the proposed modification to the 480V Class lE system is acceptable.
ENVIRONMENTAL CONSIDERATIONS We have determined that this action (i.e. finding the proposed modification acceptable) does not authorize a change in effluent types or total amounts nor an increase in power l~vel and will not result in any significant environmental impact.
Having made this determination, we have further con-cluded that the action 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 environmental impact appraisal need not be prepared in connection with this action.
'* CONCLUSION We have concluded, based on the considerations discussed above, that:
(1) because the action does not involve a significant increase in the probability or consequences of accidents previously considered and does not involve a significant decrease in a safety margin, the action does 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 conducted in compliance with the Commission 1s regulations and.this action will not be inimical to the common defense and security or to the health and safety of the public.
Date: August, 20, 1979
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~.fr. W. L. Proffitt Virginia Electric and Power Company cc:
Mr. Mi chae 1 W. Maupin Hunton and Williams Post Office Box 1535 Richmond, Virginia 23213 Swem Library College of William and Mary Williamsburg, Virginia 23185 Donald J. Burke U. S, Nuclear Regulatory Commission Region II Office of Inspection and Enforcement 101 Marietta Street, Suite 3100 Atlanta, Georgia 30303 Mr. Sherlock Holmes, Chairman Board of Supervisors of Surry County Surry Cou~ty Courthouse, Virginia 23683 Commonwealth of Virginia Council on the Environment 903 Ninth Street Office Building Richmond, Virginia 23219 Attorney General 1101 East Broad Street Richmond, Virginia 23219 Mr. James R. Wittine Commonwealth of Virginia State Corporation Commission Post Office Box 1197 Richmond, Virginia 23209 Director, Technical Assessment Division*
Office of Radiation Programs (AW-459)
U. S. Environmental Protection Agency Crystal Mall #2 Arlington, Virginia 20460 U. S. Environmental Protection Agency Region III Office ATTN:
EIS COORDINATOR Curtis Building - 6th Floor 6th and Walnut Streets Philadelphia, Pennsylvania 19106