ML20238F712

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Forwards Response to NRC 980708 RAI Re Relief Requests NDE-37 Through NDE-41
ML20238F712
Person / Time
Site: North Anna Dominion icon.png
Issue date: 08/28/1998
From: Hartz L
VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:
NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
98-419, NUDOCS 9809040226
Download: ML20238F712 (7)
v • d • e


Text

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VincNir EnzcTunc ANo Powru COWANY memsoso, hoama 232rii August 28, 1998 United States Nuclear Regulatory Commission Serial No.98-419 Attention: Document Control Desk NL&OS/ETS R0 Washington, D.C. 20555 Docket No.

50-338 License No. NPF-4 Gentlemen:

VIRGINIA ELECTRIC AND POWER COMPANY NORTH ANNA POWER STATION UNIT 1 REQUEST FOR ADDITIONAL INFORMATION RELIEF REQUESTS NDE-37 THROUGH NDE-41 in a letter dated December 18,1997 (Serial No.97-713) Virginia Electric and Power Company submitted Relief Requests NDE-37, NDE-38, NDE-39, NDE-40 and NDE-41 for NRC review and approval. The relief requests provided the basis for relief from certain requirements of ASME Section XI Code associated with partial examinations conducted during the 1997 Unit 1 refueling outage. In a letter dated July 8,1998, the NRC requested additional information to complete the review of Relief Requests NDE-39, NDE-40, and NDE-41. Our response to that request is provided in the attachment to this letter.

If you have any additional questions concerning this request, please contact us.

j Very truly yours, f

x L. N. Hartz Vice President - Nuclear Engineering and Services Attachment g

i l

Commitments made in this letter:

None 98o9040226 9808283 e?

DR ADOCK O l

l' cc:

U. S. Nuclear Regulatory Commission Region ll

. Atlanta Federal Center 61 Forsyth St., SW, Suite 23T85 Atlanta, Georgia 30303 Mr. M. J. Morgan NRC Senior Resident inspector North Anna Power Station i

f J

1 Attachment Request For AdditionalInformation Relief Requests NDE-39,40, and 41 1

Virginia Power Electric and Power North Anna Power Station Unit 1

NRC Questions On Relief Request NDE-39 The licensee is seeking relief from the required volumetric examination coverages for welds SW-8, SW-9, and SW-41. It appears from the figures supplied by the licensee that these welds are branch connection welds (Item B9.31). However, the item number listed in the Code Requirements section of the request for relief (89.11) corresponds to piping circumferential welds.

Provide additional information concerning the item classification of the subject welds.

Also, provide additionalinformation concerning the actions (if any) that have been taken to ensure maximum coverage of the subject welds (e.g., has a refracted longitudinal wave been tried or considered?)

Virginia Power Response These welds are branch connection welds. The welds were incorrectly identified in the relief. The correct Code item Number for these welds is B9.31.

As stated in the relief request the piping material is austenitic steel casting (ASTM A-351) and the welds are accessible from only one side. The Code required volumetric examination coverage was reduced due to weld joint geometry and a lifting lug. The beam path could not be extended to examine the weld in two directions, from one side, because of the piping material, which requires the use of focused longitudinal waves (L-waves). The L-waves are focused to the lower section of the weld and tend to defocus after bouncing off the internal diameter (l.D.) surface. In addition, a large percentage of the L-wave is mode converted at the I.D. interface. Because of this defocusing and mode conversion the L-waves are limited to the first sound leg. The welds were examined to the maximum extent practical using 45 L Rontegen Technische Dienst search units from the large pipe side.

1 I

NRC Questions On Relief Request NDE-40 1

The licensee is seeking relief from the required volumetric examination coverages for welds SW-8, SW-31, and SW-38. However, the licensee has not demonstrated that the j

examination requirements are impractical to perform. The licensee's basis for relief states that the welds "have been examined to the extent practical as required by the Code. Due to interference by an existing pipe support, only 6 inches out of 21 were examined." The licensee provided a sketch of the pipe supports and welds; however, it is still unclear why the required examination is impractical. Can the pipe supports be removed to increase the examination coverage?

Explain in more detail why this examination is considered to be impractical or why performing the examination would j

result in a burden or hardship.

l 1

age of 2 L

7 l

Virginia Power Response The information provided in the relief addresses that part of the support that interferes with obtaining full examination coverage of the welds, but does not address the support itself. The support is constructed from the pressurizer up to the safety relief valves, as follows. Two ring strap assemblies (bellybands) are assembled around the pressurizer.

Three (one for each valve) vertical support column assemblies are bolted to the bellybands. A support arm assembly is welded to the vertical support column at a 90-degree angle to the vertical support column. A flange assembly is welded to the support arm assembly and the flange assembly is bolted to the valve flange. The flange assembly extends for 270 around the pipe circumference at the weld. The welds SW-8, SW-31, and SW-38 are on identical lines that run from the pressurizer to the safety relief valves. The supports are attached to the valves restricting examination coverage as shown in the sketches provided as part of the request for relief. That is, the supports (three) would have to be cut to remove them and they would also require welding to reinstall them back into place. An additional drawing is being provided to depict the obstruction.

Thus, the removal of the flange would create an unusual difficulty without a compensating increase in the level of quality and safety.

NRC Questions On Relief Request NDE-41 The licensee is seeking relief from the required surface examination coverage for Weld

31. However, the licensee has not demonstrated that the examination is impractical.

The licensee's basis for relief states that the weld "has been examined to the extent practical as required by the Code. The Code required surface examination coverage was reduced due to a Code name plate band restricting access to the base metal of the pipe." The licensee provided a sketch of the area; however, it is still unclear why the examination is impractical. Can the band be removed to increase the examination coverage? Explain in more detail why this examination is considered to be impractical or why performing the examination would result in a burden or hardship.

Virginia Power Response The sketch provided with the relief does not show that the Code nameplate is welded to the bands; however, this is the case. Additionally, the bands are joined around the pipe by welding.

Therefore, mechanical disassembly is not possible to remove the obstruction. The possibility exists that the piping and the Code nameplate may be damaged during the cutting to remove and the welding to reinstall the nameplate.

Requiring the cutting to remove and welding to reinstall the nameplate to perform the remaining 24% of the weld surface examination causes an unusual difficulty without a compensating increase in the level of quality and safety.

Page 2 of 2

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