ML20198C106
| ML20198C106 | |
| Person / Time | |
|---|---|
| Site: | Catawba  |
| Issue date: | 06/20/1991 |
| From: | Tuckman M DUKE POWER CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NUDOCS 9106280128 | |
| Download: ML20198C106 (2) | |
Text
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DUKE POWER June 20,1991 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555 i
Subject:
Catawba Nuclear Station Docket Nos. 50-413 and 50-414 Special Report Cathodic Protection System Inoperable Pursuant to Technical Specification 3.8.1.1 ACTION statement "g" and 6.9.2, find attached a Special Report concerning the inoperability of the Cathodic Protection System for Catawba. The system was dec!ared inoperable on May 21,1991 and remained inoperable for more than 10 days.
Very truly yours, c7 u 4 9' < r. w) y' 4
b M. S. Tuckman i CRUSR62091.2 Attachment xc: S. D. Ebneter Regional Administrator, Region II R. E. Martin, ONRR W. T. Orders Senior Resident Inspector I
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1 SPECIAL REPORT CATAWBA NUCLEAR STATION CATHODIC PROTECTION SYSTEM INOPERABLE On May 21,1991, while performing the sixty day surveillance on Rectifier #7 (Unit 1 Diesel Generator (D/C) Fuel Storage Tank Cathodic Protection), the reading for test station TS-12 was below the acceptance criteria indicating inadequate cathodic protection of the D/G Fuel Storage Tank piping.
The system was declared inoperable and Design Engineering was contacted.
During this same time frame, the implementation of Station Modification 50385/00 was taking place. This modification resolves the deterioration problem with Rectifier #7 by installing another Rectifier (#10) near Rectifier #7 Burn in time for voltage stabilization of Rectifier #10 and voltage adjustments to Rectifier #7 corrected the low voltage reading on TS-12. With the addition of Rectifier #10, no further failures are anticipated.
Based on the above, the following actions are either planned or have already been taken:
1)
The output voltage of Rectifier #10, which is located near Rectifier #7, was adjusted to the appropriate voltage setting. This action increased the voltage potential at TS-12. With the addition of Rectifier #10, the voltage potential of Rectifier #7 was lowered to extend it's life expectancy.
2)
Procedure IP/0/B/3550/01 will be revised to reflect the addition of Rectifier #10 and the associated test stations prior to the next scheduled surveillance.
Even though the system did not meet the acceptance criteria for a period of 21 days, the system was providing adequate protection to the D/G Fuel Storage Tanks and the fuel tank pipes.
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