ML20140D042
| ML20140D042 | |
| Person / Time | |
|---|---|
| Site: | Perry  |
| Issue date: | 12/10/1985 |
| From: | Edelman M CLEVELAND ELECTRIC ILLUMINATING CO. |
| To: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| References | |
| (RDC132-(85)), PY-CEI-DIE-139, PY-CEI-OIE-0139, PY-CEI-OIE-139, NUDOCS 8601290068 | |
| Download: ML20140D042 (3) | |
Text
D p\\ d f THE CLEVELAND ELECTR P.O. BOX 5000 - CLEVELAND, OHIO 44101 - TELEPHONE (216) 622-9800 - lLLUMINATING BLDG.
- 55 PUBLICSQUARE Serving The Best Location in the Nation MURRAY R. EDELMAN VICE PRESIDENT NUCUAR December 10, 1985 PY-CEI/OIE 0139 L Mr. James G. Keppler Regional Administrator, Region III Office of Inspection and Enforcement U.S. Nuclear Regulatory Commission 799 Roosevelt Road Glen Ellyn, Illinois 60137 RE: Perry Nuclear Power Plant Docket Nos. 50-440; 50-441 Class IE Power System During A Loss of Coolant Accident With Degraded Offsite Power
[RDC 132(85)]
Dear Mr. Keppler:
This letter is the final report pursuant to 10CFR50.55(e) on the potentially significant deficiency concerning the starting voltages to some motors in the Class 1E power system during the simultaneous conditions of degraded offsite power and a Loss of Coolant Accident (LOCA).
Mr. James McCormick-Barger of your office was notified on April 1,1985, by Mr E. Riley of The Cleveland Electric Illuminating Company (CEI) that this problem was being evaluated per Deviation Analysis Report 230. An interim report was submitted on April 30, 1985.
In the course of our evaluation, a condition was discovered which has been determined to be reportable pursuant to 10CFR50.55 (e).
Description of Deficiency The Class 1E AC power system provides power to safety-related equipmen: and controls in the plant. The system is divided into three independent d~ visions:
Division 1. Division 2 and Division 3.
Each division distributes power at 4.16kV, 480V and 120V.
Load flow studies of the Class 1E power system had indicated that the starting voltages to some 480V motors may be less than the specified minimum (75 percent of nominal as stated in FSAR Section 8.3.1.1.4.1b) during the simultaneous conditions of degraded offsite power and a LOCA.
8601290063 851210 PDR ADOCK 05000440 10 S
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Mr. James G. Keppler December 10, 1985 4
PY-CEI/OIE 0139 L j
Analysis of Safety Implications Additional load flow analysis was performed on the plant configuration as it i
. existed prior to modifying the sequential loading of the Class 1E loads which are connected following a LOCA with offsite power available. This analysis 4
indicated that the starting voltages to the affected 480V motors, assuming I
offsite power is in a degraded condition, would be less than the specified minimum for only a short time (i.e., less than five seconds).
It is unlikely I
that any equipment damage / failure would occur in this time period should the affected motors fail to start immediately due to low starting voltages.
However, the analysis also indicated that 15 seconds after initiation of the load sequencing, the nominal AC power system voltage would be less than the trip setpoint for the offsite source. At this point, the offsite source would be tripped off and the diesel generators would connect to the 4.16kV safety-
{
related busses when significant decay voltage may still be present. The i
respective voltages have a random phase relationship and if they should be more than 90 degrees apart the potential for overstressing safety-related equipment exists.
Corrective Action l
1 In addition to the load sequencing changes that were identified in our interim report, final transformer tap settings were adjusted to optimize the plant distribution voltage as specified in FSAR Section 8.3.1.1.2.11.
Subsequent analysis performed with the above changes indicated that all 480V motors would receive adequate starting voltages and that the AC system voltage would recover j
adequately to preclude unnecessary tripping of the offsite source and subse-quent diesel generator connection. The analytical model used was verified to 3
i be conservative by comparison with test data. Finally, a modification to the circuit per Design Change Package 85-0499 provides a time delay prior to con-nection of the diesel generators to the 4.16kV safety-related busses following a trip of the offsite source resulting from a degraded voltage condition.
This will eliminate any possibility of overstressing equipment due to out of phase decay voltage.
1 If you have any questions, please call.
i Sincerely, 1
r W
y Murray ht.Edelman Vice Pkesident Nuclear Group j
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..=- - _. ---
.Mr. James G. Keppler Decezbsr 10, 1985 PY-CEI/OIE 0139 L cc:
J. A. Grobe, USNRC Site Office SBB50 Director Office of Inspection and Enforcement U.S. Nuclear Regulatory Commission Washington, D.C.
20555 U.S. Nuclear Reguistory Commission Document Control Desk Washington, D.C.
20555 Records Center, SEE-IN Institute of Nuclear Power Operations 1100 Circle 75 Parkway, suite 1500 Atlanta, Georgia 33039 i
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