ML20085M602
| ML20085M602 | |
| Person / Time | |
|---|---|
| Site: | Fort Saint Vrain  |
| Issue date: | 10/13/1975 |
| From: | Hillyard H, Lambert D, Swart F PUBLIC SERVICE CO. OF COLORADO |
| To: | Howard E NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| Shared Package | |
| ML20085M605 | List: |
| References | |
| RO-50-267-75-13, NUDOCS 8311090044 | |
| Download: ML20085M602 (4) | |
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October 13, 1975 is %[af-Mr. E. Morris Howard, Director
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Nuclear Regulatory Commission Region IV
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- Facility Operating License " -
No. DPR-34 Docket No. 50-267 IE FILE COPY;
Dear Mr. Howard:
Enclosed please find a copy of Unusual Event Report No. 50-267/75/13A, Final, submitted per the requirements of the Technical Specifications.
This report is being issued in order to correct a minor omission in the
" Identification of Occurrence" given in Unusual Event Report No. 50-267/
75/13.
Very truly yours, N<a h
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Frederic E. Swart Superintendent, Nuclear Production Fort St. Vrain Nuclear Generating Station FES/alk cc:
Mr. Roger S. Boyd
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e311090044 751013
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PDR ADOCK 05000267 g
PDR COPY SENT REGION _
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REPORT DATE:
October 13. 1975 UNUSUAL EVENT 75/13A Page 1 of 3 OCCURRENCE DATE: September 11 1975 2
70RT ST. VRAIN NUCLEAR CENERATING STATION PUBLIC SERVICE COMPANY OF COLORADO P.O. Box 361 PLATTEVILLE, COLORADO 80651 REPORT NO. 50-267/75/13A Final IDENTIFICATION OF
_0CCURRENCE:
Failure of the fan start relay for 480 V Transformer 1B.
This is identified as an Unusual Event per Section 7.6 paragraph C(3) of the Technical Specifications.
CONDITIONS PRIOR
_TO OCCURRENCE:
Steady State Power Routine Shutdown ~
Hot Shutdown Routine Load Change Cold Shutdown X
Other (specify)
Refueling Shutdown '
' None specified because conditions varied and did not contribute to Routine Startup the failure the major plant parameters at the time of the event were as follows:
Power RTR Eth ELECT We Secondary Coolant Pressure psig f
Temperature
- F Flow f/hr.
Primary Coolant Pressure psig Temperature
- F Core Inlet
- F Core Outlet Flow f/hr.
- Not listed since they have no bearing on problem.
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i UNUSUAL EVENT 75/13 A Page 2 of 3 DESCRIPTION OF OCCURRENCE:
On 8/27/75, it was reported by the plant operating personnel that 460 V either automatically on high transformer 1B cooling fans failed to start, Operations temperature, or by manual operation of fan start hand switch.
personnel determined by local indication that the cooling fans w In order to prevent damage due to overheating, it was necessary f.
The fans returned to requirements.
to replace the fan start relay on an emergency basis.
normal operation with replacement of the relay.
Unusual Service Cond.
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APPARENT CAUSE
' X Design Including Environ.
l OF OCCURRENCE:
X Component Failure Manufacture InstallationIConst.
"Other (specify)
Operator 9
Procedure ANALYSIS OF OCCURRENCE:
From A search of essential 480 V transformer maintenance records was cond this search it was noted that a history existed of trouble with this particular control.
an analysis and test'of the fan control scheme was completed.
On September 11, 1975,
- The results of this study were that the control scheme was unsatisfactory in three
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respects:
We type relay used to actuate the cooling fans had a tendency to hang
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1) up with slight changes in orientation.
%e start circuit relay logic was undesirable in that it was necessary 2) to energize the relay to start the fans.
Failure of the fans to start on high transformer temperature was not 3) alarmed in the control room.
. CORRECTIVE ACTION:
For the five air cooled 480 V transformers (3 essential and 2 non ne'unsuitabic relays will be repinced with a better application.
1)
7 o
o UNUSUAL EVENT 75/13A Page 3 of 3
- 2) The relay logic circuitry will be reverned so that it requires a de-energized relay to start the cooling fans.
- 3) An alarm on high temperature will be installed in the control room.
- 4) The local handswitches will be rewired to bypaan the fan start relay and start the fans directly.
Thenc corrective actionn have aircady been completed for 480 V Transformer 18.
FAlt.URE DATA / SIMII.AR REPORTED OCCURPINCES:
None PROGRAMMATIC IMPACT:
None EDP. IMPACT:
Nonc '.
A Submitted by:
kJ hr Harvey W. (tillyard', J h.
Technical Services Supervisor Reviewed by:
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Duane L. Lambert V
f Supervisor, Denvor Plant Electriciana f/ '
Approved by:
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[ Superintendent, rederic E. Swart Nuclear Production e
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