ML20150D306
| ML20150D306 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 03/11/1988 |
| From: | NRC OFFICE OF SPECIAL PROJECTS |
| To: | |
| Shared Package | |
| ML20127A683 | List:
|
| References | |
| NUDOCS 8803230306 | |
| Download: ML20150D306 (2) | |
Text
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UNITED STATES g
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NUCLEAR REGULATORY COMMISSION
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a g w,<.....f SAFETY EVALUATION REPORT BY THE OFFICE OF SPECIAL PROJECTS EMPLOYEE CONCFRN ELEMENT REPORT 24105 "WIRE CORROSION AND DETERIORATION OF SEALANT MATERIAL" TENNESSEE VALLEY AUTHORITY SEQU0fAH NUCLEAR POWER PLANT, UNITS 1 AND 2 00CKET NOS. 50-327 AND 50-328 I.
SUBJECT Category:
Engineering (20,000)
Subcategory:
Cable termination and splices (24,100)
Element:
Wire Cerrosion and Deteriorttion of Sealant Paterial (24,105)
Employee Ccncern:
ECTG-6 The basis for Element Repnet 24105, Revision 1, prepared November 23, 1987 is a concern stating:
"Corrosion of wiring thrnugh the penetration, breakdown of the sealant that is potted around the conductor as part of the penetration, resulting from breakdown because of the environment, they either violated --- used the wrong cre, wrcng application ---
a breakdcwn of insulation, wrong application."
II.
SUMMAPY OF ISSUE i
This concern raised two generic problems, one with the corresion of wiring and the other with the deterioration of sealant in peretration modules may exist in the electrical contairrent penetrations.
The contairment penetrations at Sequoyah are manufactured by Westinghouse and Conax to address the concern, TVA reviewed the CAQ (conditions adverse to quality) data base and discovered a report on Watts Bar regarding the crazing and/or cracking of the sealant material vn the end of the Conax penetration.
Conax personnel perforned a walkdown at Matts Bar and determired that cable coating reterial (Vimasco No.
2-B) is not cccpatible with the penetration sealant material (polysulfone).
TVA has determired that the Conax penetrations at Secuoyah have not been encapsulated.
However, Westinghouse penetrations have been encapsulated with a coating raterial (Flamastic 77).
TVA has reviewed the chemical compati-bility of this material and determined that Flamastic 77 will not have a detrirental ef fect on the penetrations.
Since the corrosion of wirirg in penetratien cannot be visually observed, it is believed the concerned orplcyee may have observed the corrosion at the point where pigtails is spliced to the field wiring rather than the wiring in 8803230306 880311 PDR ADOCK 05000328 P
2 the feed through.
Since TVA procedure M&AI-7 specifies the cleaning rethed before splicing, it can be reasonably assured that any corrosion present in the pigtails wculd have been removed.
TVA has also evaluated the response to NRC IE Bulleting 77-07, "Potential Problems with Containment Peretration Assemblies," and concluded that the problem does not exist in the Sequoyah penetrations because of differences in design.
III. EVALUATION NRC and its consultant, SAIC reviewed the erf oyee concern and the TVA findings l
and requested the additional information (Letter from J. Zwolinski, NRC to S. A. White, TVA, dated July 15,1987).
TVA provided the responses to the i
staff's request by their letter of August 13, 1987 from J. R. Russel to NRC.
During a telephor.e conference, NRC staff requested further information j
regarding material compatibility for Conax penetrations and wire corrosien probicm in the penetration assembly.
TVA revised the employee concern report to address the staff concerns.
Based or the information it can be reasonably determined that the document review did not identify any corrosion of wiring problems in the electrical penetratico assembly.
The staff believes that destructive testing of the penetration assemblies is not warranted as the problem with the corrosion of wiring cannot be substentiated. Also TVA evaluetion clearly demonstrates that the problem of deterioration of sealant material due to the inccmpatibility of the coating material is not applicable at Secuoyah.
IV.
CONCLUSION Based on this, the NRC staff concludes that the concern regarding wire corrosion and deter' oration of sealant material is not valid for Sequoyah and that TVA's investigation ar.d evaluation resolves the employee concern.
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