ML18153A471
| ML18153A471 | |
| Person / Time | |
|---|---|
| Site: | Surry, North Anna  |
| Issue date: | 06/24/1996 |
| From: | Kansler M VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.) |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| 96-167, NUDOCS 9606270094 | |
| Download: ML18153A471 (10) | |
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VIRGINIA ELECTRIC AND POWER COMPANY RICHMOND, VIRGINIA 23261 June 24, 1996 United.States Nuclear Regulatory Commission Attention: Document Control Desk Washington, D.C. 20555 Gentlemen:
VIRGINIA ELECTRIC AND POWER COMPANY SURRY POWER STATION UNITS 1 AND 2 NORTH ANNA POWER STATION UNIT 2 REVISED ASME SECTION XI RELIEF REQUESTS Serial No.96-167 NL&OS/ETS Docket Nos. 50-280 50-281 50-339 License Nos. DPR-32 DPR-37 NPF-7 Surry Power Station Units 1 and 2 are presently in the first period of the third ten year interval.
Surry Power Station Units 1 and 2 examinations are conducted to the requirements of the 1989 Edition of ASME Section XI. North Anna Unit 2 is currently in the second period of the second ten year interval. North Anna Unit 2 examinations are conducted to the requirements of the 1986 Edition of ASME Section XI. Pursuant to 10 CFR 50.55a (g) 5, relief is requested from certain requirements of the ASME Section XI Code associated with system pressure tests.
If leakage at a bolted connection occurs during system pressure testing, Paragraph IWA-5250 (a) (2) requires, affected bolting be removed, VT-3 visually examined for corrosion and evaluated in accordance with IWA-3100. NRC approved relief requests, RR-10 and RR-5 for Surry Units 1 and 2 (SE Rs dated July 19, 1995 and August 30, 1995) and relief request SPT-14 for North Anna Unit 2 (SER dated August 8, 1995),
reduced the bolting removal and examination requirement to only the bolt closest to the source of leakage.
Upon further consideration, we have concluded that imposing a condition to remove the bolt closest to the source of leakage regardless of the circumstances (operating history, material, etc.) may yet represent restrictions not commensurate with a corresponding 9606270094 960624 PDR ADOCK 05000280 P
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increase in the level of quality or safety.
Therefore, we are requesting that the approved relief request be revised to permit an evaluation of the leakage and removal o'f the closest bolt only if the evaluation concludes additional evaluation is necessary.
The revised relief requests for Surry Units 1 and 2 and North Anna 2 are attached.
These relief requests have been approved by the stations Nuclear Safety and Operating Committees.
If you have -any additional questions concerning these requests, please contact us.
Very truly yours, resident - Nuclear Engineering Services Attachments cc:
U.S. Nuclear Regulatory Commission Region II 101 Marietta Street, N. W.
Suite 2900 Atlanta, Georgia 30323 Mr. M. W. Branch NRG Senior Resident Inspector Surry Power Station Mr. R. D. McWhorter NRG Senior Resident Inspector North Anna Power Station Surry Power Station Units 1 and 2 ASME Section XI Relief Requests
Relief Request No. RR-10 (Unit 1)
Revision 1 I.
Identification of Component Class 1, 2 and 3 pressure retaining bolting II.
Impractical Code requirements IWA-5250 (a) (2) states, "if leakage occurs at a bolted connection, the bolting shall be* removed, VT-3 visually examined for corrosion, and evaluated in accordance with IWA-3100;"
111.
Basis for Relief
- Leaking conditions at a bolted connection may be an important variable in the
.degradation. of fasteners. However, leakage.is not the only variable, and some cases may not be the degradation mechanism. Other variables to be considered are: bolting materials, leaking medium, duration of the leak, and orientation of the leak (not all bolts may be wetted). These variables are important to consider before disassembling a bolted connection for a visual VT-3 examination.
Removal of bolting at a mechanical connection may not be the most prudent decision and may cause undue hardship without a compensating increase in the level of quality or safety.
Virginia Power proposes an alternative to the requirements of IWA-5250 (a) (2) that will provide an equivalent level of quality and safety at Class 1, 2, and 3 bolted connections.
IV:
Alternate Requirements Leakage discm,ered at a bolted connection by visual VT-2 examination during a system pressure test will be evaluated to determine the susceptibility of the bolting to corrosion and potential failure.
This evaluation will consider the following variables:
1.
Location of leakage;
- 2.
History of leakage;
- 3.
Fastener materials;
- 4.
Evidence of corrosion with the connection assembled;
- 5.
Corrosiveness of the process fluid;
- 6.
History and studies of similar fastener material in a similar environment; and
- 7.
Other components in the vicinity that may be degraded due to the
. leakage.
When* evaluation of the above variables is concluded and the evaluation
. determines that the leaking condition has_not.degraded the. fasteners, then no.
further action is necessary.
If evaluation of the variables above indicates the need for further evaluation, or no evaluation is performed, then the bolt closest to the source of leakage will be removed. The bolt will receive a visual VT-3 examination, and be evaluated in accordance with IWA-3100 (a). This visual VT-3 examination may be deferred to the next outage of sufficient duration if the evaluation supports continued service. When the removed bolting shows evidence of rejectable degradation, all remaining bolts shall be removed and receive a visual VT-3 examination and evaluation in accordance with IWA-3100 (a).
e Relief Request No. RR-5 (Unit 2)
Revision 1 I.
Identification of Component Class 1, 2 and 3 pressure retaining bolting
- 11.
Impractical Code requirements IWA-5250 (a) (2) states, "if leakage occurs at a bolted connection, the bolting shall be removed, VT-3 visually -examined for corrosion, and evaluated in accordance with IWA-3100;"
Ill.
Basis for Relief Leaking conditions at a bolted connection may be an. important variable in the
.... degradation of Jasteners. __.However,. leakage is not the only variable, and.some cases may not be the degradation mechanism. Other variables to be considered are: bolting materials, leaking medium, duration of the leak, and orientation of the leak (not all bolts may be wetted). These variables are important to consider before disassembling a bolted connection for a visual VT-3 examination.
Removal of bolting at a mechanical connection may not be the most prudent decision and may cause undue hardship without a compensating increase in the level of quality or safety.
Virginia Power proposes an alternative to the requirements of IWA-5250 (a) (2) that will provide an equivalent level of quality and safety at Class 1, 2, and 3 bolted connections.
IV:
Alternate Requirements Leakage discovered-at a bolted connection byvisual VT-2 examination during a system pressure test will be evaluated to determine the susceptibility of the bolting to corrosion and potential failure.
This evaluation will consider the following variables:
1.
Location of leakage;
- 2.
History of leakage;
- 3.
Fastener materials;
- 4.
Evidence of corrosion with the connection assembled;
- 5.
Corrosiveness of the process fluid;
- 6.
History and studies of similar fastener material in a similar environment; and
- 7.
Other components in the vicinity that may be degraded due to the leakage.
When evaluation of the above variables - is concluded and the evaluation
__ determines.that the leaking. condition has_noLdegraded _the_ fasteners, then_ no further action is necessary.
If evaluation of the variables above indicates the need for further evaluation, or no evaluation is performed, then the bolt closest to the source of leakage will be removed. The bolt will receive a visual VT-3 examination, and be evaluated in accordance with IWA-3100 (a). This visual VT-3 examination may be deferred to the next outage of sufficient duration if the evaluation supports continued service. When the removed bolting shows evidence of rejectable degradation, all remaining bolts shall be removed and receive a visual VT-3 examination and evaluation in accordance with IWA-3100 (a).
North Anna Power Station Unit 2 ASME Section XI Relief Request
e Relief Request SPT-14 (Unit 2)
Revision 1 I.
Identification of Component Class 1, 2 and 3 pressure retaining bolting II.
Impractical Code requirements IWA-5250 (a) (2) states, "if leakage occurs at a bolted connection, the bolting shall be removed, VT-3 visually examined for corrosion, and evaluated in accordance with IWA-3100;"
Ill.
Basis for Relief Leaking conditions at a bolted connection may be an important variable in the
-- - degradation of.fasteners. However, _leakage is not the only variable, and some cases may not be the degradation mechanism. Other variables to be considered are: bolting materials, leaking medium, duration of the leak, and orientation of the leak (not all bolts may be wetted). These variables are important to consider before disassembling a bolted connection for a visual VT-3 examination. Removal of bolting at a mechanical connection may not be the most prudent decision and may cause undue hardship without a compensating increase in the level of quality or safety.
Virginia Power proposes an alternative to the requirements of IWA-5250 (a) (2) that will provide an equivalent level of quality and safety at Class 1, 2, and 3 bolted connections.
IV:
e
~lternate Requirements Leakage discovered at a bolted connection by visual VT-2 examination during a system pressure test will be evaluated to determine the susceptibility of the bolting to corrosion and potential failure.
This evaluation will consider the following variables:
1.
Location of leakage;
- 2.
History of leakage;
- 3.
Fastener materials;
- 4.
Evidence of corrosion with the connection assembled;
- 5.
Corrosiveness of the process fluid;
- 6.
History and studies of similar fastener material in a similar environment; and
- 7.
Other components in the vicinity that may be degraded due to the leakage.
When evaluation of the above variables is concluded and the evaluation determines that the leaking condition has not degraded the fasteners, then no further action is necessary.
If evaluation of the variables above indicates the need for further evaluation, or no evaluation is performed, then the bolt closest to the source of leakage will be removed. The bolt will receive a visual VT-3 examination, and be evaluated in accordance with IWA-3100 (a). This visual VT-3 examination may be deferred to the next outage of sufficient duration if the evaluation supports continued service. When the removed bolting shows evidence of rejectable degradation, all remaining bolts shall be removed and receive a visual VT-3 examination and evaluation in accordance with IWA-3100 (a).