ML020580398
| ML020580398 | |
| Person / Time | |
|---|---|
| Site: | North Anna  |
| Issue date: | 02/19/2002 |
| From: | Hartz L Virginia Electric & Power Co (VEPCO) |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| 02-112 | |
| Download: ML020580398 (7) | |
Text
VIRGINIA ELECTRIC AND POWER COMPANY RICHMOND, VIRGINIA 23261 February 19, 2002 United States Nuclear Regulatory Commission Serial No.02-112 Attention: Document Control Desk NLOS/ETS Washington, D.C. 20555 Docket No.
50-339 License No.
NPF-7 Gentlemen:
VIRGINIA ELECTRIC AND POWER COMPANY NORTH ANNA POWER STATION UNIT 2 ASME SECTION XI INSERVICE INSPECTION PROGRAM RELIEF REQUEST PARTIAL 1 During the Spring 2001 refueling outage, North Anna Power Station Unit 2 completed examinations in the third period of the second ten-year interval.
Examinations were conducted to the requirements of the 1986 Edition of ASME Section XI.
Interferences prohibited the complete examination of three reactor nozzle-to-vessel welds.
Pursuant to 10 CFR 50.55a(g)(5), relief is requested from certain requirements of ASME Section XI Code associated with examinations where only partial coverage could be obtained. Relief Request Partial 1 is attached and provides the basis of this request.
A similar relief was approved by the NRC for North Anna Unit 1 on June 15, 2001 (TAC MB0555).
This relief request has been approved by the Station Nuclear Safety and Operating Committee.
If you have any additional questions concerning this request, please contact us.
Very truly yours, Leslie N. Hartz Vice President - Nuclear Engineering Attachment Commitments made in this letter: None
cc:
U. S. Nuclear Regulatory Commission Region II Sam Nunn Atlanta Federal Center 61 Forsyth St., SW, Suite 23T85 Atlanta, Georgia 30303 Mr. M. J. Morgan NRC Senior Resident Inspector North Anna Power Station Mr. M. M. Grace Authorized Nuclear Inspector North Anna Power Station Mr. J. E. Reasor, Jr.
Old Dominion Electric Cooperative Innsbrook Corporate Center 4201 Dominion Blvd.
Suite 300 Glen Allen, Virginia 23060
Attachment Relief Request Partial-1 Virginia Electric and Power Company (Dominion)
North Anna Power Station Unit 2
Virginia Electric and Power Company North Anna Power Station, Unit 2 Second Ten Year Interval Request for Relief Partial 1 IDENTIFICATION OF COMPONENTS Mark/Weld #
Line #
Drawing #
Class 10 2-RC-R-1 12050-WMKS-RC-R-1.1 1
12 2-RC-R-1 12050-WMKS-RC-R-1.1 1
14 2-RC-R-1 12050-WMKS-RC-R-1.1 1
I1.
CODE REQUIREMENTS The 1986 edition of ASME Section XI, Table IWB-2500-1, Examination B-D, Item Number B3.90, does not permit any reduction in the required volumetric examination coverage. Code Case N-460, Alternative Examination Coverage for Class 1 and Class 2 Welds, allows a reduction in coverage if it is less than 10%.
I1l.
CODE REQUIREMENTS FROM WHICH RELIEF IS REQUESTED Pursuant to 10 CFR 50.55a(g)(5),
relief is requested from the volumetric examination coverage requirements of the 1986 edition of ASME Section XI, Table IWB-2500-1, Examination B-D, Item Number B3.90 for the identified reactor vessel outlet nozzle to shell welds.
IV.
BACKGROUND Outlet nozzles to shell welds 10, 12, and 14 were initially examined during the September 1990 refueling outage using the immersion technique and credit was taken for an examination that had less than 10% reduction in coverage. These welds were re-examined during the March 2001 refueling outage to permit these examinations to be performed during the last period of future intervals. However, the immersion technique used in the 1990 examination has been replaced with the contact technique. Although the contact technique, which is the current standard examination method for vessel inspections, provides better sensitivity and improved control of the examination, it further reduces the available examination coverage.
Partial-1 1 of 4
Virginia Electric and Power Company North Anna Power Station, Unit 2 Second Ten Year Interval Request for Relief Partial 1 (continued)
V.
BASIS FOR RELIEF Reactor vessel outlet nozzles to shell welds 10, 12, and 14 have been examined to the extent practical as required by the Code. Due to weld joint geometry, the reduction in coverage for the listed components was greater than 10%.
The protrusion of the nozzle beyond the shell physically restricted access for 100%
coverage of the clockwise and counter-clockwise scans from the vessel shell. One hundred percent of the weld volume was covered from the nozzle bore. Table Partial-1 is provided detailing the limitations experienced during the March 2001 examination. An amplifying sketch is also provided. Although less than the Code required coverage was obtained, this examination provides an acceptable level of quality and safety.
VI.
ALTERNATE PROVISIONS It is proposed that the examinations already completed at the reduced coverage during the March 2001 refueling outage be counted as meeting the Code requirements.
Partial-1 2 of 4
Table Partial 1 North Anna Unit 2 Reactor Vessel Outlet Nozzle to Shell Welds 10, 12, and 14 Aggregate Coverage Percentage Estimates Category B-D, Item B-3.90 Beam 10 Degrees 45 Degrees 50 Degrees 60 Degrees 70 De grees 80 Degrees Direction Weld Volume Weld Volume Weld Volume Weld Volume Weld Volume Weld Volume CCW 100 60.5 100 60.5 100 60.5 100 60.5 CW 100 60.5 100 60.5 100 60.5 100 60.5 Bore Axial 100 100 100 100 Average of Weld = 100% Volume = 60.5%
Combined Average 80.25%
All' 1 The bore exams provide 100% coverage for the axial scan direction, which accounts for 50% of the required scans.
These bore exams combined with the transverse scan average of 60.5% results in a combined coverage for the volume of 80.25%. Weld coverage of 100% was calculated separately.
Partial 1 Page 3 of 4
Sketch Partial 1 North Anna Unit 2 Reactor Vessel Outlet Nozzle to Shell Welds 10, 12, and 14 NOZZLE 0-, 180" VOLUME EXAMINED - 69%
NOZZLE BOSS EXAM VOLUME Partial 1 Page 4 of 4 VOLUMIL