ML20071P810
| ML20071P810 | |
| Person / Time | |
|---|---|
| Site: | North Anna  |
| Issue date: | 07/25/1994 |
| From: | Ohanlon J VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.) |
| To: | Ebneter S NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| References | |
| 94-425, NUDOCS 9408100197 | |
| Download: ML20071P810 (2) | |
Text
_
VinoixtA ELI:cTunc Asi> Pown:n Co.sil'ANY l{ ICit ht O N D, VI H OINI A 2006I l
f.3 *, 5 D
,,;-._o July 25, 1994 l
Mr. Stewart D. Ebneter, Regional Administrator Serial No.
94 425 U.S. Nuclear Regulatory Commission NL&P/MPW/GSS R3 Region 11 Docket Nos.
50 338 101 Marietta Street, N. W.
50 339 Suite 2900 License Nos. NPF-4 Atlanta, Georgia 30323 NPF 7
Dear Mr. Ebneter:
VIRGINIA ELECTRIC AND POWER COMPANY NORTH ANNA POWER STATION UNITS 1 & 2 METEOROLOGICAL TEMPERATURE RECORDER itiOPERABLE GREATER THAN 7 DAYS SPECIAL REPORT l
Pursuant to the North Anna Power Station Technical Specification 3.3.3.4, a Special Report is required due to the control room differential temperature recorder for the meteorological tower being declared inoperable for greater than 7 days. On July 14, 1994, it was determined the temperature recorder had been Inoperable from June 30, 1994 through July 8,1994.
On June 28,1994, a new differential temperature recorder was installed in accordance with a design change package. On June 29,1994 the recorder loop was calibrated with no problems present. Subsequently, a severe thunderstorm occurred on the night of June 29,1994 whereby the abnormal procedure for severe weather was entered.
At 0100 hours0.00116 days <br />0.0278 hours <br />1.653439e-4 weeks <br />3.805e-5 months <br /> on June 30,1994, the abnormal procedure was exited.
Upon review of the meteorological tower data on July 10,1994, a change was noted in the differential temperature stability class which corresponded with the time the new recorder was returned to service. This stability data was inconsistent with actual weather conditions measured from the meteorological tower for the time period from June 30,1994 to July. 8,1994.
Subsequent troubleshooting and investigation -
determined that the output module on the signal conditioning card for the differential temperature recorder had failed. The module was replaced and the differential temperature recorder was recalibrated and returned to service on July 8,1994. The cause of the module failure was attributed to the severe thunderstorm on the night of June 29,1994.
s fp 1
9408100197 940725
\\
gDR ADOCK 05000338 PDR
[
During the time period that the control room differential temperature recorder was Indicating an incorrect stability class, the backup meteorological tower was available to determine the stability class using sigma theta.
Likewise, the differential temperature from the dual output at the primary meteorological tower was being transmitted correctly to the corporate Air Quality Department. Either of those sources could have been used to provide the correct stability class during the time that the primary indication was out of service.
This Special Report has been reviewed by the Station Nuclear Safety and Operating Committee and will be provided to the Management Safety Review Committee.
Should you have any questions regarding this report, please contact us.
Very truly yours, h.m c,.,
l,'
~
' James P. O'Hanlon Senior Vice President - Nuclear cc:
U.S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, D.C. 20555 Mr. R. D. McWhorter NRC Senior Resident inspector North Anna Power Station c
v e--