ML20005A153
| ML20005A153 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 06/19/1981 |
| From: | Papay L SOUTHERN CALIFORNIA EDISON CO. |
| To: | Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| References | |
| 10CFR-050.55E, NUDOCS 8106290456 | |
| Download: ML20005A153 (3) | |
Text
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Southern Calitbrnia Edison Company
[G a o..ox.co 2244 WALNUT GROVE AVENUC RCSEMEAD. CALIFORNIA 91770
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7' June 19, 1981 w
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N Mr. R. H. Engelken, Director 3
Office of Inspection and Enforcement
/g Aj U. S. Nuclear Regulatory Commission bl y o 6gg\\F D l
Region V rq
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Suite 202,~ Walnut Creek Plaza
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f 1990 North California Boulevard o.S*
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Walnut Creek, California 94596 O
Dear Mr. Engelken-l
Subject:
Docket Nos. 50-361 and 50-362 San Onofre Nuclear Generating Station, Units 2 and 3 In a letter to your office dated May 26, 1981 we j
identified a condition which we consider reportable in accord-ance with 10CFR50.55(e).
The condition involves the solder-ing of terminal lugs for Thermon Heat Trace System RTD instal-lations by unqualified personnel without a qualified soldering procedure.
Enclosed in accordance with 10CFR50.55(e) are twenty-five (25) copies of a Final Report entitled, " FINAL REPORT ON UNQUALIFIED SOLDERING PROCESS IN THERMON HEAT TRACE SYSTEM INSTALIATION, San Onofre Nuclear Generating Station, Units 2 and 3."
If you have any questions regarding this report, we would be pleased to discuss this matter with you at your con-venience.
Very truly yours, W77 rew Enclosures
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cc:
Victor Stello (NRC, Director I&E)
R. J. Pate (NRC San Onofre, Units 2 and 3)
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FINAL REPORT ON UNQUALIFIED SOLDERING PROCESS IN THERMON HEAT TRACE SYSTEM INSTALLATION San Onofre Nuclear Generating Station, Units 2 and 3 INTRODUCTION This report is submitted pursuant to 10CFR50.55(e)(3).
It describes a condition concerning the use of the wrong size wire termination lugs and use of unqualified personnel and procedures to correct this deficiency in the Thermon Heat Trace System installation.
It includes a description of the deficiency, analysis cf the safety implications and a summary of the cor-rective artlon taken or to be taken.
By letter dated May 26, 1981, Edison confir:ned notification to the NRC of this condition.
BACKGRCvND 2
During installation of Resistance Temperature Detectors (RTD) i in the heat trace systems, a number of previously terminated wire leads required shortening to avoid excess coiling in the terminal boxes.
During the re-termination process, it was observed that some of the crimp type lugs could be pulled off the wire leads.
Measurement of the wire leads determined their
- size to be 24AWG.
Measurement of the lugs determined them to be 22AWG.
These lugs were provided by both Bechtel and Thermon.
An attempt was made to asse:nble lugs by soldering to the wire leads after crimping.
The soldering and crimping process demonstrated a high rejection rate.
DESCRIPTION OF THE DEFICIENCY 1
The lugs utilized on the RTD wire leads for Heat Tr' acing System were the wrong size.
The process of soldering after crimping was not controlled in that neither the personnel nor the pro-cedure were qualified prior to performance.
ANALYSIS OF SAFETY IMPLICATIONS The failure of a Thermon RTD could potentially cause a safety problem in the delivery of boric acid into the primary system.
If the RTD failed in an "open" mode this would appear to the con-trol logic as an overtemperature condition, causing the heaters to be-turned off.
That could result in a drop in the fluid
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FINAL REPORT ON UNQUALIFIED SOLDERING PROCESS IN Page Two THERMON HEAT TRACE SYSTEM INSTALIATION San Onofre, Units 2 and 3 temperature below the crystallization point, resulting in pre-cipitation of boric acid crystals.
This could cause fluid blockage in delivery lines or result in delivery of less boron to the Reactor Coolant System than required.
CORRECTIVE ACTION 1)
A nonconformance report has been issued for each heat trace system.
2)
All RTD wire leads will be reinspected for use of proper size lug and correct use of the crimping tool as evidenced by a visual examination of the crimp indentation.
All improperly crimped lugs and all soldered lugs which have been applied in the. field will be reworked using the proper lug and crimping tool.
Rework will be performed in accord-ance with established procedures for crimped terminals.
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