ML20137G479
| ML20137G479 | |
| Person / Time | |
|---|---|
| Site: | Beaver Valley |
| Issue date: | 03/12/1997 |
| From: | DUQUESNE LIGHT CO. |
| To: | |
| Shared Package | |
| ML20137G377 | List: |
| References | |
| PROC-970312-07, PROC-970312-7, NUDOCS 9704010404 | |
| Download: ML20137G479 (2) | |
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6 PRESSURE TESTING PROGRAM AT BVPS UMIT #1, FOR THE THIRD TEN-YEAR INTERVAL AND BVP2 UNIT #2, FOR THE SECOND TEN-YEAR INTERVAL RELIEF REQUEST BV3-IWA-2, REV. O
SUBJECT:
Class 1,2, and 3 Bolting Removal Due to Leakage 6fd0f97 DEd Date:
Prepared by:
U Supenisor, Inspection and Standards Resiewed by:
/A Date:
3-ll-h 5 Director, Nuclear Analysis and Inspegan Reviewed by:
D -DhC.-b 97 Date:
8/'d /f 7 OSC Meeting No.
Reviewed by:
TNAM4 Mo. $I-I Date:
d/ % /f7 ORC Meeting No.
Approval by:
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DUQUESNE LIGHT COMPANY Beaver Valley Power Station Unit Nos. I and 2 RELIEF REOUEST NO. BV3-lWA-2 Rev. 0 l
COMPONENT i
Class I,2, and 3 pressure retaining bolted connections.
l ASME CODE SECTION XI REOUIREMENT (1989 Edition) i ASME Section XI,1989 Edition, Subparagraph IWA-5250(a)(2) states, "ifleakage occurs at a bolted connection, the bolting shall be removed, VT-3 visually examined for corrosion, and evaluated in accordance with IWA-3100,"
i BASIS OF RELIEF In accordance with 10CFR50.55a(a)(3)(ii) reliefis requested from the ASME bection XI,1989 Edition, Subparagraph IWA-5250(a)(2) requirement that ifleakage occurs at a bolted connection, the bolting shall be removed, VT-3 visually examined for corrosion, and evaluated in accordance with IWA-3100. Compliance with the Code requirements would result in hardship and unusual difficulty without a compensating increase in the level of quality and safety. Leakage at a bolted connection may be a significant variable in the degradation mechanism of bolted connections. However, leakage is not the only variable and in some cases may not be the degradation mechanism. Bolting materials, leaking medium, duration of the leak, and location of the leak are other variables l
to be considered. Removal of bolting at a mechanical connection may not be the most prudent decision to make.
All variables should be considered before disassembling a bolted connection for a sisual VT-3 examination.
Duquesne Light proposes an alternative to the requirements ofIWA-5250(a)(2) that will provide an equivalent level of quality and safety at Class 1,2, and 3 bolted connections.
PROPOSED ALTERNATIVE EXAMINATION Leakage on Code Class I, 2, and 3 bolted connections shall be evaluated to determine the susceptibility of the bolting to corrosion and potential future failure. This review will consider as a minimum, location ofleakage, history ofleakage, bolted connection materials, visual evidence of corrosion with the connection assembled, corrosiveness of the process fluid, history and studies of similar bolted material in a similar emironment, and other components in the vicinity that may be degraded due to the leakage. If the leakage was identified with the bolted connection in senice and the review supports continued senice, the VI' 3 examination may be deferred to the next outage of sufficient duration. If this review warrants further evaluation of the bolted connection, the bolt closest to the leakage source shall be removed, VT-3 examined, and evaluated in accordance with IWA-3100(a). When the removed bolt has rejectable degradation, the remaining bolts will be removed, VT-3 examined and evaluated in accordance with IWA-3100(a). If no degradation is observed on the removed bolt, no further action will be required.
Duquesne Light requests NRC approval of the proposed alternative requirements for Class 1,2, and 3 bolted connections in lieu of those ofIWA-5250(a)(2). NRC approval is requested in a time frame that will support implementation of the alternative requirements for the Unit I twelfth refueling outage currently scheduled to begin in September of 1997 Unit I twelfth refueling outage will be the first outage of the third ten year in crval at Beaver Valley Power Station Unit No.1. The second ten year interval at Beaver Valley Pour Station Unit No. 2 will begin November 17,1997.
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