ML042940366
| ML042940366 | |
| Person / Time | |
|---|---|
| Site: | Surry  |
| Issue date: | 10/12/2004 |
| From: | Hartz L Virginia Electric & Power Co (VEPCO) |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| 04-337A | |
| Download: ML042940366 (11) | |
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VIRGINIA ELECTRIC AND POWJER COMPANY RICHMOND, VIRGINIA 23261 October 12, 2004 U.S. Nuclear Regulatory Commission Serial No.
04-337A Attention: Document Control Desk NL&OS/GDM RO Washington, D.C. 20555 Docket No.
50-281 License No.
DPR-37 VIRGINIA ELECTRIC AND POWER COMPANY (DOMINION)
SURRY POWER STATION UNIT 2 INSERVICE INSPECTION THIRD INTERVAL RELIEF REQUEST NO. SR-004. REV. 2 RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION In a letter dated June 29, 2004 (Serial No.04-377), Dominion submitted revised Relief Request SR-004, Rev. 2, for Surry Power Station Unit 2. This relief request provides proposed alternative inspection requirements for the Category C-G pressure-retaining pump casing welds associated with the outside recirculation spray (ORS) and low head safety injection (LHSI) pumps.
During the course of their review, the NRC staff determined that they required additional information to complete their review of the relief request. Consequently, the NRC Project Manager for Surry, Mr. Stephen Monarque, provided Dominion questions associated with the request for relief.
A conference call was held on September 29, 2004, to discuss the NRC's questions as well as Dominion's responses.
At the conclusion of the call, Dominion agreed to provide a response to the NRC's questions on the docket. Consequently, Dominion's response is provided in the enclosure.
If you have any questions or require additional information, please contact Mr. Gary D.
Miller at (804) 273-2771.
Very truly yours, Leslie N. Hartz Vice President - Nuclear Engineering Enclosure Commitments made by this letter: None
,*\\OI
V SN 04-337A Docket No. 50-281 Page 2 of 2 cc:
U.S. Nuclear Regulat6ry Commission Region II Sam Nunn Atlanta Federal Center 61 Forsyth Street, SW, Suite 23 T85 Atlanta, GA 30303-3415 Mr. S. R. Monarque U. S. Nuclear Regulatory Commission One White Flint North 11555 Rockville Pike Mail Stop 8H12 Rockville, MD 20852 Mr. N. P. Garrett NRC Senior Resident Inspector Surry Power Station Mr. R. A. Smith Authorized Nuclear Inspector Surry Power Station
Serial No. 04-337A Docket No. 50-281 Enclosure Revised Third Interval Relief Request Outside Recirculation Spray and Low Head Safety Iniection Pumps Casing Welds SR-004, Rev. 2 Response to NRC Request for Additional Information Surry Power Station Unit 2 Virginia Electric and Power Company (Dominion)
V Serial No. 04-337A Docket No. 50-281 Enclosure Revised Third Interval Relief Request Outside Recirculation S~rav and Low Head Safety Iniection Pumps Casing Welds SR-004, Rev. 2 Response to NRC Request for Additional Information NRC Question 1 In page 2 of 2 of the attachment, the proposed alternative to use IWC 1223 stated, "As detailed in Note (1) of Table IWC-2500-1, examination of only one pump in a group is requiredper interval,"and then the last sentence says but ".. one examination per pump group is required, regardless of the number of times the pumps are disassembled."
This statement contains the licensee's interpretation of Note (1%. Is this interpretation different than the ASME Code requirement?
Discuss the reasoning behind the examination of only one pump upon disassembly even if the other pumps are disassembled and the welds are accessible.
Is VEPCO requesting the NRC staff validate the interpretation?
Dominion's Response As discussed during the September 29, 2004 conference call with the NRC staff, Dominion is not requesting NRC validation of our interpretation of code requirements.
The discussion in our June 29, 2004 letter noted above was simply provided as background information regarding how we will meet the ASME Section Xi Code requirement for pump examination. Dominion will perform pump weld examinations in accordance with applicable ASME Section Xl Code requirements.
NRC Question 2 On page 2 of 4 of the submittal, VEPCO stated that the pump casing welds are inaccessible. Accessibility is based on the 1995 Edition with 1996 Addenda,Section XI paragraph IWC 1223 which identifies "inaccessible" as being encased in concrete, buried underground, located inside a penetration or encapsulated by guard pipe, and you interpret this definition as applying to the subject pump casing welds.
Please provide a sketch showing the inaccessibility of the subject welds, explain the inaccessibility aspects of the installed component pump, and discuss the accessibility for other NDE methods.
Dominion's Response See the attached drawings of the Surry Unit 2 low head safety injection (LHSI) and outside recirculation spray (ORS) pumps. The discharge elbow section of the LHSI pumps is welded to the flange face at weld 0-08. This flange is bolted to the top of the 24-inch suction can in which the pump rests. The bolted connection is broken only Page 1 of 2
Serial No. 04-337A Docket No. 50-281 Enclosure when the pump internals are required to be lifted for maintenance. Consequently, there is no physical access to insert any type of NDE visual probe down into the pump well to inspect the welds on the pump column except when the pump is disassembled for maintenance. Likewise, the top discharge section on the ORS pumps is one integral piece with a weld at location 0-08. Again, there is no physical access to the space between the exterior of the pump casing and the interior of the suction can without disassembling and lifting the pump shaft.
Upon disassembly of a pump for maintenance, Dominion will perform the code required surface exam (liquid penetrant) on the exterior welds as they are made accessible in accordance with ASME Section Xl Code requirements.
NRC Question 3 Page 2 of 4 of the submittal states that "...sufface examination of the accessible pump casing welds on one pump of a similar group is required each interval only if a pump is disassembled for maintenance rendering the welds accessible for examination." In the event that no pump in a similar group of pumps is disassembled, how will the 95 Edition of Section IWC 2500-1, Examination Category CG, Frequency of Examination Requirements, be satisfied?
Dominion's Response As long as the pumps remain intact, the welds in question are "inaccessible" and therefore exempt from code examination requirements pursuant to paragraph IWC-1223, "Inaccessible Welds," of the 1995 Addenda of the 1995 Code Edition.
Consequently, if a pump is not required to be disassembled, the pump welds remain inaccessible and do not require examination. However, Dominion would consider these welds accessible for examination if a pump were disassembled for maintenance, and we would perform the code required examination provided this Category and Item Number code requirement had not been previously met.
Also, please note that the first paragraph under Section III, "Basis for Relief," of Relief Request SR-004, Revision 2, has been revised to refer to the 1995 Addenda of the 1995 Edition for the applicable section heading "Inaccessible Welds" versus "Integral Attachments" under IWC-1223.
A revised copy of the relief request including this change is attached.
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Serial No. 04-337A Docket No. 50-281 Attachment Virginia Electric and Power Company Surry Power Station Unit 2 Third Ten Year Interval RELIEF REQUEST SR-004, Rev. 2 I.
Identification of Components:
Systems: Recirculation Spray (RS) and Safety Injection (SI)
Components: Pump casing welds Component Drawing Weld No.
2-RS-P-2A 11548-WMKS-RS-P-2A Pump casing welds*
2-RS-P-2B 11548-WMKS-RS-P-2B Pump casing welds*
2-SI-P-1 A 11548-WMKS-SI-P-1A Pump casing welds*
2-SI-P-1 B 11548-WMKS-SI-P-1 B Pump casing welds*
Drawings will be changed accordingly.
II.
Code Requirements: -
Section Xl of the ASME Boiler and Pressure Vessel Code, 1989 Edition, Category C-G, Item Number C6.10, requires that a surface examination be performed on 100% of the welds each inspection interval. For a ten-year interval the examination can be limited to one pump in the case of multiple pumps of similar design, size, function and service in a system. The examination may be performed from either the inside or outside surface of the component.
Ill.
Basis for Relief:
In the 1995 Addenda of the ASME Section Xl 1995 Code Edition, paragraph IWC-1223 in section IWC-1220, "Components Exempt From Examination," was changed to read 'Welds or portions of welds that are inaccessible due to being encased in concrete, buried underground, located inside a penetration, or encapsulated by guard pipe" in the definition of "Inaccessible Welds".
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W Serial No. 04-337A Docket No. 50-281 Attachment These pumps are vertical, two-stage, centrifugal pumps with an extended shaft and casing that allows suction from the containment sump. This pump casing extends subgrade for more than 40 feet. The pump column consists of bolted flange sections of pipe.
Circumferential welds exist at the pipe to flange locations. The pump is suspended in a suction can container, which renders the welds inaccessible while the pump is in operational standby. Only when the pump is disassembled for maintenance do the pressure retaining casing welds become accessible.
The 1995-96, and subsequent 1998-2000, edition of the ASME Section XI Code requires that a surface examination be performed on the pump casing welds only when the pump is removed from the suction can for maintenance; thus, allowing accessibility to the welds.
The later edition of the code does not require disassembly of the pump for the sole purpose of performing the code specified surface examination. To remove the pumps only to perform the Section Xl examination is inconsistent with the requirements of the later code edition and is considered an unnecessary burden.
IV.
Proposed Alternate Examination In accordance with 10 CFR 50.55a(g)(4)(iv), Dominion requests approval to use paragraph IWC-1223 of the 1995-96 edition of the ASME Section Xl Code to perform the inspections of Category C-G pump casing welds on the Outside Recirculation Spray and Low Head Safety Injection pumps. When a pump is removed for maintenance activities, the code required surface examination of 100% of the accessible welds would be performed in accordance with Table IWC 2500-1 Category C-G, Item C6.10. Related requirements of the 1995-96 code edition regarding the Category C-G, Item C6.10 will be met.
As detailed in Note (1) of Table IWC-2500-1, examination of only one pump in a group is required per interval. Thus, when one recirculation spray pump and one safety injection pump receives examination, the ten-year interval code requirement will be met.
Only one examination per pump group is required, regardless of the number of times the pumps are disassembled.
As accepted in the more recent 1995-1996, and the 1998-2000, Code editions, the proposed alternative will not compromise the overall level of plant quality and safety.
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