ML20246J837
| ML20246J837 | |
| Person / Time | |
|---|---|
| Site: | LaSalle, 05003738  |
| Issue date: | 07/07/1989 |
| From: | Diederich G COMMONWEALTH EDISON CO. |
| To: | Davis A NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| References | |
| NUDOCS 8907170463 | |
| Download: ML20246J837 (1) | |
Text
_ _ _ -
Commonwealth Edison LaSalle County Nuclear Station RuralRoute #1, Box 220 Marseilles, Illinois 61341 Telephone 815/357-6761 July 7, 1989 l
Mr. A. B. Davis Regional Administrator Region III U.S. Nuclear' Regulatory Coesnission 799 Roosevelt Road l
Glen Ellyn, Illinois 60137 i
Dear Sir:
l This special report is being submitted in accordance with LaSalle Unit 1 l
Operating License NPF-11 and Unit 2 Operating License NPF-18, Appendix A and l
Technical Specifications 3.3.7.2 and 6.6.C due to the Seismic Monitoring i
System Being inoperable for greater than 30 days.
On May 29, 1989, at 0239 hours0.00277 days <br />0.0664 hours <br />3.95172e-4 weeks <br />9.09395e-5 months <br />, during an electrical storm, the seismic 3
It was believed that Monitoring System actuated and would not stay reset.Further investigation revealed
- i tape deck #4 was the cause for the failure. The master and slave cards were
?
that the master and slave cards had failed.During an instrumental functional test, the replaced and the skew adjusted.
The voltage regulator was replaced voltage regulator was found inoperable.Three sensors were found inoperable. The spare and the system rotested.
Upon their arrival, the sensors were installed, sensors were still on order.
During another retest, a snd another order for three more spares was sent.The replacement order was late in a vertical sensor failed.
site, therefore the seismic monitoring system was inoperable for more than 30 days.
Following the installation of the vertical sensor and appropriate testing, the 28, 1989, at 0545 Seismic Monitoring System was restored to operable on June hours.
A G/ J. Diederich Station Manager LaSalle County Station GJD/MMT/kg U.S, NRC Document Control' Desk xc:
l INPO - Records Center l
File - NRC Resident h hs o
S
(
_