ML20086A492
| ML20086A492 | |
| Person / Time | |
|---|---|
| Site: | Comanche Peak  |
| Issue date: | 11/11/1991 |
| From: | William Cahill TEXAS UTILITIES ELECTRIC CO. (TU ELECTRIC) |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| CP-91-007, CP-91-7, TXX-91413, NUDOCS 9111190174 | |
| Download: ML20086A492 (2) | |
Text
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1UELECTRIC November 11, 1991 William J. Cahill. Jr.
omn,rmwe V. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555
SUBJECT:
COMANCHE PEAK STEAM ELECTRIC STATION UNIT 2 DOCKET NO. 50-4h LAMINAR INDICA 110NS IN PIPE SDAR CP 91 007 (FINAL REPORT)
Gentlemen:
-On October 10, 1991, TV Electric orally notified the NRC of a potentially reportable deficiency in which laminar indications were discovered in piping installed in the Auxiliary Feedwater ( AFW) System.
While performing ultrasonic inspection on AFW piping in an area of pipe lug removal, readings were obtained which suggested a laminar indication.
Further inspection using an 'A-scan
- ultrasonic scope revealed an area of lamination approximately seven inches long by six inches wide.
Readings taken in the axial-di_rection for a distance of approximately three feet showed numerous small indications in the pipe wall.
Two pieces-of the pipe were removed from the system and the UT was performed using a second, more advanced 'A-scan
- scope.
This inspection showed no laminar indications.
Reinspection was performed using the initial "A scan
- scope and the laminar indications were again present.
Disassembly of the initial scope revealed a loose jam nut in the transducer lead connection inside the scope itself.
This caused interference in the sound path when the scope was used in the multi-echo mode.
This interference caused a false echo to appear between the second and third back reflection on the CRT.
Because the scope had not been used in the multi-echo mode during the current calibratiun period, other readings taken by this scope are not in question.
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TXX-91413 Page 2 of 2 The transducer, lead, and connection were all replaced in the initial scope, it was recalibrated and the pipe was reinspected using the repaired scope.
No indications of laminations were found.
However, the final acceptance of the pipe was based on the second, more advanced scope.
Based on the actions stated above, no deficiency or reportable condition exists.
Sincerely, n-William J. Cahi 1 Jr.
JTC/fds c
Mr. R. D. Martin, Region IV Resident inspectors CPSES (2)
Mr. M. B. fields, NRR l
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