ML040290659

From kanterella
Jump to navigation Jump to search

Unit 1 ASME Section XI Inservice Inspection Program Relief Requests Partial Examination of Reactor Pressure Vessel Head-to-flange Welds
ML040290659
Person / Time
Site: Surry, North Anna  Dominion icon.png
Issue date: 01/22/2004
From: Hartz L
Virginia Electric & Power Co (VEPCO)
To:
Document Control Desk, Office of Nuclear Reactor Regulation
References
03-572, TAC MB7515
Download: ML040290659 (20)
v • d • e


Text

VIRGINIA ELECTRIC AND POWVER COMPANY RICiEMOND, VIRGINIA 23261 January 22, 2004 United States Nuclear Regulatory Commission Serial No.03-572 Attention: Document Control Desk NLOS/ETS Washington, D.C. 20555 Docket Nos. 50-338 50-280 License Nos. NPF-4 DPR-32 VIRGINIA ELECTRIC AND POWER COMPANY (DOMINION)

NORTH ANNA POWER STATION UNIT 1 SURRY POWER STATION UNIT 1 ASME SECTION Xi INSERVICE INSPECTION PROGRAM RELIEF REQUESTS PARTIAL EXAMINATION OF REACTOR PRESSURE VESSEL HEAD-TO-FLANGE WELDS During the Spring 2003 refueling outages, North Anna Power Station Unit 1 and Surry Power Station Unit 1 replaced reactor pressure vessel heads. The preservice examinations for the replacement head were conducted to the requirements of the 1989 Edition of ASME Section Xl. However, interferences due to lifting lugs and the weld configuration prohibited complete examination of the reactor pressure vessel head-to-flange weld.

Pursuant to 10 CFR 50.55a(g)(5)(iii), relief is requested from certain requirements of ASME Section XI Code associated with the examination of the reactor pressure vessel head-to-flange weld where only partial coverage can be obtained. Relief Requests PRT-03 for North Anna Power Station Unit 1 and PRT-01 for Surry Power Station Unit 1 are attached and provide the basis of this request. A similar relief request was approved for North Anna Power Station Unit 2 on November 13, 2003 (TAC MB7515).

In a January 28, 2003 letter (Serial No. 03-050A), Dominion provided reactor vessel head (RVH) fabrication drawings of the North Anna Unit 1 RVH to facilitate the NRC review of the relief request. These drawings are typical of the RVHs fabricated by Framatome for North Anna Units 1 and 2 and Surry Unit 1 and provide the details of the examination interferences. Please use the drawings from this letter to facilitate your review of these relief requests.

These relief requests have been approved by the Station Nuclear Safety and Operating Committees.

,-DY1

Serial No.03-572 Docket Nos. 50-338/339 If you have any additional questions concerning this request, please contact Mr.

Thomas Shaub at (804) 273-2763.

Very truly yours, Leslie N. Hart Vice President - Nuclear Engineering Attachments Commitments made in this letter: None cc: U.S. Nuclear Regulatory Commission Region II Sam Nunn Atlanta Federal Center 61 Forsyth Street, SW Suite 23 T85 Atlanta, GA 30303-8931 Mr. S. R. Monarque U. S. Nuclear Regulatory Commission One White Flint North 11555 Rockville Pike Mail Stop 8-H12 Rockville, MD 20852 Mr. C. Gratton, U. S. Nuclear Regulatory Commission One White Flint North 11555 Rockville Pike Mail Stop 8-G9 Rockville, MD 20852 Mr. M. T. Widmann NRC Senior Resident Inspector North Anna Power Station Mr. G. J. McCoy NRC Senior Resident Inspector Surry Power Station Mr. J. E. Reasor, Jr.

Old Dominion Electric Cooperative Innsbrook Corporate Center 4201 Dominion Blvd.

Suite 300 Glen Allen, VA 23060

03-572 50-338 Attachment 1 Relief Request PRT-03 Examination of Reactor Pressure Vessel Head-To-Flange Weld Virginia Electric and Power Company (Dominion)

North Anna Power Station Unit 1

03-572 50-338 Virginia Electric & Power Company North Anna Power Station Unit 1 Third 10 Year Interval Request for Relief Number PRT-03 I. IDENTIFICATION OF COMPONENT Reactor pressure vessel head-to-flange weld (Weld 1, drawing 11715-WMKS-RC-R-1.2) for the replacement reactor vessel head.

II. CODE REQUIREMENTS North Anna Power Station is currently in the third interval and uses the 1989 Edition of the ASME Code. ASME Section Xi - 1989 Edition, IWB-2200 (c) and Table IWB-2500-1, examination category B-A, item number B13.40 requires volumetric and surface examinations, as defined by Figure IWB-2500-5, of essentially 100 percent of the weld length of the reactor pressure vessel closure head-to-flange weld.

"Essentially 100 percent' as clarified by ASME Code Case N-460, Alternative Examination Coverage for Class 1 and Class 2 Welds, is greater than 90 percent coverage of the examination volume, or surface area, as applicable.

Ill. CODE REQUIREMENT FROM WHICH RELIEF IS REQUESTED In accordance with 10CFR50.55a(g)(5)(iii), relief is requested from the "essentially 100 percent' volumetric examination coverage requirement for the identified reactor pressure vessel head-to-flange weld. This requirement is considered impractical due to the configuration of the reactor pressure vessel head.

IV. BASIS FOR RELIEF The ultrasonic examination of the reactor pressure vessel head-to-flange weld is conducted in accordance with Section Xi, Appendix I of the ASME Code, 1989 Edition. Section Xl, Appendix I states that the ultrasonic examination shall be conducted in accordance with Article 4 of Section V as supplemented by Table I-2000-1 in the Appendix. Article 4,Section V requires the weld and the adjacent base metal be examined using nominal angles of 45 and 60 degrees (deviation is permitted if geometry limits the coverage, however, separation of angles must be 10 degrees) and a straight beam. Four basic scan directions are required for the angle beams; two perpendicular to the weld axis (axial scan) from opposite directions and two parallel to the weld axis (circumferential scan) from opposite directions. These requirements apply for each of the 45 and 60 degree angle beams used. Each of the 45 and 60 degree angle beams is required to pass through all of the weld volume in the four basic scan directions.

The cross-sectional geometry of the component at the reactor pressure vessel head-to-flange weld produces a high transitional angle between the flange and the domed Page 1 of 8

03-572 50-338 head. Scanning from the flange side may not provide the necessary angular orientation to provide full examination coverage. Examination is limited to 0.5 inches from the weld toe due to the flange configuration. The reactor vessel closure head is a carbon steel vessel with stainless steel cladding on the inside surface. Due to this cladding, the ultrasonic beam cannot be 'bounced" from the inside clad surface to increase the examination coverage. Therefore, a full-V examination from the flange side is not possible. Following operational service, radiographic examination of this weld will not be practical due to the projected high radiation levels at the inside surface of the head.

The reduction in preservice volumetric coverage is detailed in Table PRT-03-1.

Sketches PRT-03-1 through PRT-03-5 are provided detailing the configuration limitations experienced. The preservice examination on the component listed above was completed to the extent practical as required by the Code.

Furthermore, three lifting lugs are located 120' apart. Each lug obstructs the volumetric examination for approximately 8 inches, resulting in obstruction of 2 of the 45 feet of total weld length. This limits access to approximately 4 percent of the weld length. However, these lifting lugs result in only a 0.8 percent obstruction during the magnetic particle examination resulting in a 99.2 percent surface examination.

The limited volumetric examination and the surface examination should detect any general patterns of degradation that may occur in the areas covered, therefore providing reasonable assurance of the continued structural integrity of the subject weld.

V. ALTERNATE PROVISIONS One-third of the reactor pressure vessel head-to-flange weld will be examined each period to the extent permitted by the configuration of the reactor pressure vessel closure head.

In addition, it is proposed that the preservice examinations already completed at the reduced coverage be counted as meeting the Code requirements.

Page 2 of 8

03-572 50-338 Table PRT-03-1 North Anna Unit 1 Pre-Service Examination Coverage Summary Reactor Pressure Vessel Closure Head to Flange Weld Category B-A, Item B1.40 Exam Sketch Sketch Weighting Coverage Coverage Factor 45 Weld Metal I PRT-03-1 55% 2 sound beams/9 12.22%

60' Weld Metal I PRT-03-2 52% 2 sound beams/9 11.56%

45 Weld Metal 1 PRT-03-3 100% 2 sound beams/9 22.22%

60 Weld Metal PRT-03-3 100% 2 sound beams/9 22.22%

0 Weld Metal PRT-03-3 100% 1 sound beamn/9 11.11%

Weld Total 79.33%

45/60 Base Metal l; PRT-03-4 88% 2 sound beamsf7 25.14%

45' Base Metal 11 PRT-03-5 54% 2 sound beams/7 15.43%

60' Base Metal PRT-03-5 54% 2 sound beams/7 15.43%

0 Base Metal PRT-03-5 54% 1 sound beanV7 7.71%

Base Total 63.71%

Weld Metal = 11.3% of total exam volume (11.3% x 79.33%) = 9%

Base Metal = 88.7% of total exam volume (88.7% x 63.71 %) = 57%

Total Exam Coverage Achieved = 9% + 57% = 66%

Page 3 of 8

03-572 50-338 Sketch PRT-03-1 North Anna Unit I Pre-Service Examination Coverage Summary Reactor Pressure Vessel Closure Head to Flange Weld Category B-A, Item B1.40 F _

Component: RPV closure head to flange weld Coverage Sketch No: I of 5 Scalb: 50%

Exam: Weld metal. 450 D0 14- 6'

.r-~~~~~~~~~~

EXAM AREA

  • EFGH=0.866X6.6=5.716Winl DIRECTION I
  • Examined EFGH = 100%

DIRECTION 2

  • Examined EFJK - (.886 X .7) + (.
  • (.90915.716)=16%

X .7)12 0.909 Inr

.1. PtKOCTIOic I. .L Vi.EC71bc 2..

M¶1 ti EXAMS +f0.

TOTAL

  • (100%+16%)12=58%
  • 58% X (43'1 45') =55%

Page 4 of 8

03-572 50-338 Sketch PRT-03-2 North Anna Unit 1 Pre-Service Examination Coverage Summary Reactor Pressure Vessel Closure Head to Flange Weld Category B-A, Item B1.40

.- P A ILtr Procedure: 54-ISI-130-38 CA: NA 001 -ROO, NA 001 - ROO Component: RPV closure head to flange weld .0 NN Coverage Sketch No: 2 of 5 Scale: 50%

Exam: Weld metal. 601 M~~~~ rn X I~~~N 1 N.

EXAM AREA

  • EFGH - 0.866 X 6.6 = 5.716 h' 1~~~~~~~~~~~1 DIRECTION I I- 11~~~
  • Examined EFGH = 100 %

DIRECTION 2

  • Examined EFJK (.866 X .3)
  • (.47615.716) w 8 %
  • (.866 X .5)12 -0.476 In' JL rurPcriouI. +/-L VIKEC7WN1 2..

Olun It rxAHS + O'f~

TOTAL

  • (100%*8%)12=54%
  • 64%X(43 145-)m52%

Page 5 of 8

03-572 50-338 Sketch PRT-03-3 North Anna Unit 1 Pre-Service Examination Coverage Summary Reactor Pressure Vessel Closure Head to Flange Weld Category B-A,'Item B1.40 A

0 Component: RPV closure head to flange weld en

'1 Coverage Sketch No: 3 of 5 Scale: 50%

Exam: Weld metal. 451/ 60° ll and 0° m EXAM AREA

  • EFGH = 0.866 X 6.6 = 5.716 Irl EXAMINED D H
  • EFGH=100% C__

TOTAL

  • o0-1000*%
  • 456 1 -ro10%
  • 60° j 100% .1L L'1r7oN I. .L VIREcTIow I.. HFXA IS 4-0*

Page 6 of 8

03-572 50-338 Sketch PRT-03-4 North Anna Unit I Pre-Service Examination Coverage Summary Reactor Pressure Vessel Closure Head to Flange Weld Category B-A, Item B1.40 Component: RPV closure head to flange weld Coverago Sketch No: 4 of 6 Scale: 60%

Exam: Base metal. 4 5 0/ 6 0 .L EXAM AREA

  • AEHD + FBCG =(3.3 x 6.6) + (3.3 x7) = 44.89 ins TWO SOUND BEAMS
  • AEHD + FJLCG
  • = (3.3 x 6.6) 4 (.5 x.7) + (2.8 x 5.4) = 40.4 Ir?
  • (40.4144.88)=90%

ONE SOUND BEAM

  • JKL=(4X8)12=1.6lnh
  • (1.6 144.68) r 4 % .1.pVn.ECTIOU 1.

M

.1.V1t~EcrioU T..

U~~OlE Ii rxRHS + 0'

  • 4 % coverage x 60% credit (for orly one sound beam) 2 %

TOTAL

  • 90%+2%=92%
  • 92%x(43'145)=88%

Page 7 of 8

03-572 50-338 Sketch PRT-03-5 North Anna Unit 1 Pre-Service Examination Coverage Summary Reactor Pressure Vessel Closure Head to Flange Weld Category B-A, Item B1.40 Componont: RPV closure head to flange weld Coverago Skatch No: 5 of 5 Scalo: 50%

Exam: Base metal, 451/60° l and 0' EXAM AREA

  • AEHD + FBCG = (3.3 x 6.6) + (3.3 x 7) =44.8 in' EXAMINED .S6tlllI 111<
  • AEHD + FJKG = (3.3 x 6.6) + (.5 x 7) = 2528 inr
  • (25.2B144.88) 56 %
  • 56%x(43'I45')=54%

0 TOTAL pu cri uI I DiP.Evrion 11. 11FXAM-S + O'

  • 45d10 54%
  • 60I -54%

Page 8 of 8

03-572 50-280 Attachment 2 Relief Request PRT-01 Examination of Reactor Pressure Vessel Head-To-Flange Weld Virginia Electric and Power Company (Dominion)

Surry Power Station Unit 1

03-572 50-280 Virginia Electric & Power Company Surry Power Station Unit 1 Third/Fourth 10 Year Interval Request for Relief Number PRT-01

1. IDENTIFICATION OF COMPONENT Reactor pressure vessel head-to-flange weld (Weld 1-01, drawing 11448-WMKS-RC-R-1.2) for the replacement reactor vessel head.

II. CODE REQUIREMENTS At the time of the preservice examination, Surry Power Station was in the third interval and used the 1989 Edition of the ASME Code. As of October 14, 2003, Unit 1 is in the fourth interval and uses the 1998 Edition, 2000 Addenda of the ASME Code. ASME Section Xi, IWB-2200 (c) and Table IWB-2500-1, examination category B-A, item number B13.40 requires volumetric and surface examinations, as defined by Figure IWB-2500-5, of essentially 100 percent of the weld length of the reactor pressure vessel closure head-to-flange weld. "Essentially 100 percent" as clarified by ASME Code Case N-460, Alternative Examination Coverage for Class 1 and Class 2 Welds, is greater than 90 percent coverage of the examination volume, or surface area, as applicable.

Ill. CODE REQUIREMENT FROM WHICH RELIEF IS REQUESTED In accordance with 10CFR50.55a(g)(5)(iii), relief is requested from the "essentially 100 percent" volumetric examination coverage requirement for the identified reactor pressure vessel head-to-flange weld. This requirement is-considered impractical due to the configuration of the reactor pressure vessel head.

IV. BASIS FOR RELIEF The ultrasonic examination of the reactor pressure vessel head-to-flange weld is conducted in accordance with Section Xl, Appendix I of the ASME Code, 1989 Edition. Section Xl, Appendix I states that the ultrasonic examination shall be conducted in accordance with Article 4 of Section V as supplemented by Table I-2000-1 in the Appendix. Article 4,Section V requires the weld and the adjacent base metal be examined using nominal angles of 45 and 60 degrees (deviation is permitted if geometry limits the coverage, however, separation of angles must be 10 degrees) and a straight beam. Four basic scan directions are required for the angle beams; two perpendicular to the weld axis (axial scan) from opposite directions and two parallel to the weld axis (circumferential scan) from opposite directions. These requirements apply for each of the 45 and 60 degree angle beams used. Each of the 45 and 60 degree angle beams is required to pass through all of the weld volume in the four basic scan directions.

1 of 8

03-572 50-280 The cross-sectional geometry of the component at the reactor pressure vessel head-to-flange weld produces a high transitional angle between the flange and the domed head. Scanning from the flange side may not provide the necessary angular orientation to provide full examination coverage. Examination is limited to 0.5 inches from the weld toe due to the flange configuration. The reactor vessel closure head is a carbon steel vessel with stainless steel cladding on the inside surface. Due to this cladding, the ultrasonic beam cannot be "bounced" from the inside clad surface to increase the examination coverage. Therefore, a full-V examination from the flange side is not possible. Following operational service, radiographic examination of this weld will not be practical due to the projected high radiation levels at the inside surface of the head.

The reduction in preservice volumetric coverage is detailed in Table PRT-01-1.

Sketches PRT-01-1 through PRT-01-5 are provided detailing the configuration limitations experienced. The preservice examination on the component listed above was completed to the extent practical as required by the Code.

Furthermore, three lifting lugs are located 120' apart. Each lug obstructs the volumetric examination for approximately 8 inches, resulting in obstruction of 2 of the 45 feet of total weld length. This limits access to approximately 4 percent of the weld length. However, these lifting lugs result in only a 0.8 percent obstruction during the magnetic particle examination resulting in a 99.2 percent surface examination.

The limited volumetric examination and the surface examination should detect any general patterns of degradation that may occur in the areas covered, therefore providing reasonable assurance of the continued structural integrity of the subject weld.

V. ALTERNATE PROVISIONS One-third of the reactor pressure vessel head-to-flange weld will be examined each period to the extent permitted by the configuration of the reactor pressure vessel closure head.

In addition, it is proposed that the preservice examinations already completed at the reduced coverage be counted as meeting the Code requirements.

2 of 8

03-572 50-280 Table PRT-O1-1 Surry Unit 1 Pre-Service Examination Coverage Summary Reactor Pressure Vessel Closure Head to Flange Weld Category B-A, Item B1.40 -

Exam Sketch Sketch Weighting Coverage Coverage Factor 45 Weld Metal I PRT-01-1 55% 2 sound beams/9 12.22%

60 Weld Metal I PRT-01 52% 2 sound beams/9 11.56%

45 Weld Metal PRT-01-3 100% 2 sound beams/9 22.22%

60 Weld Metal PRT-01-3 100% 2 sound beams/9 22.22%

O0Weld Metal PRT-01-3 100% 1 sound beam/9 11.11%

Weld Total 79.33%

45/60 Base Metal l PRT-01-4 88% 2 sound beams/7 25.14%

45@ Base Metal 11 PRT-01-5 54% 2 sound beams/7 15.43%

604 Base Metal 11 PRT-01-5 54% 2 sound beams7 15.43%

0 Base Metal PRT-01-5 54% 1 sound beamr/7 7.715%

Base Total 63.71%

Weld Metal = 11.3% of total exam volume (11.3% x 79.33%) = 9%

Base Metal = 88.7% of total exam volume (88.7% x 63.71 %) = 57%

Total Exam Coverage Achieved = 9% + 57% = 66%

3 of 8

03-572 50-280 Sketch PRT-01-1 Surry Unit 1 Pre-Service Examination Coverage Summary Reactor Pressure Vessel Closure Head to Flange Weld Category B-A, Item B13.40 Component: RPV closure head to flange weld Coverage Sketch No: I of 5 Scale: 60%

Exam: Weld metal. 450+/-

EXAM AREA

. EFGH=0.866X6.6 =.716nh2 D

DIRECTION I

  • Examined EFGH = 100 %

DIRECTION 2

& Examined EFJK - (.866 X .7) + (.868 X .7)t2

  • (.90915.716)=16%

0.909 In' 0, -

.L riommon 1.

0 L PiREcmm 7, TUR TOTAL

  • (100%*16%)12=58%
  • 58% X (43' I45') =55%

4 of 8

03-572 50-280 Sketch PRT-01-2 Surry Unit 1 Pre-Service Examination Coverage Summary Reactor Pressure Vessel Closure Head to Flange Weld Category B-A, Item B1.40 Procedure: 54-ISI-130-38 CA: NA 001 - ROO, NA 001 - ROO Component: RPV closure head to flange weld Coverage Sketch No: 2 of 5 Scale: 50%

Exam: Weld metal. 60° l EXAM AREA

  • EFGH=0.866X6.6w5.716In' DIRECTION I D ~- - -~
  • ExaminedEFGH=100%

DIRECTION 2

  • Examined EFJK - (.866 X .3) +(.866 x .5)2
  • (.47615.716) w8 %

- 0.476 In'

.1. L'ccriou I.

0 JL VIKECTION 1.

an11 It ixMIS+ O' TOTAL

  • (100%+8%)12=54%
  • 54%X(43'145')m62%

5 of 8

03-572 50-280 Sketch PRT-01-3 Surry Unit I Pre-Service Examination Coverage Summary Reactor Pressure Vessel Closure Head to Flange Weld Category B-A, Item B1.40 A E F-Component: RPV closre head to flange weld 0U Coverage Sketch No: 3of 5 Scale: 50B Exam: Weld metal, 45°160° ll and 0° EXAM AREA a EFGH = 0.866 X6.6 = 5.716 In' EXAMINED D

  • EFGH=100 % - r"-~- ~--- ~

TOTAL 8I 100%

I 450 -100l 60° 1 -100% PL17tCTION I.

M

.L MEC11ON Z-LEDI 11FXAHIS +0 6 of 8

03-572 50-280 Sketch PRT-01-4 Surry Unit 1 Pre-Service Examination Coverage Summary Reactor Pressure Vessel Closure Head to Flange Weld Category B-A, Item B1.40 Component: RPV closure head to flango weld Coverago Skotch No: 4 of 5 Scale: 6o% c Exam: Basermelal. 450/60,+/-

EXAM AREA

  • AEHD + FBCG =(3.3 x 6.6) + (3.3 x7) =44,88 Ir TWO SOUND BEAMS
  • AEHD + FJLCG
  • =(3.3x6.6)+(.5x.7)+(2.8x5.4)-40.4f lH
  • (40.4144.88)=90%

ONE SOUND BEAM

  • JKL=(4X8)/2= 1.61n'"
  • (1.6144.88)=4 % 1 VIrA0c7gM I. 1 mDlEvriom 7IJ I

FX. Rt - 01

  • 4 % coverage x 0 % credit (for only one sound beam)= 2 %

TOTAL

  • 90%+2%=92%
  • 92 % x (43'/45) a88 %

7 of 8

03-572 50-280 Sketch PRT-01-5 Surry Unit 1 Pre-Service Examination Coverage Summary Reactor Pressure Vessel Closure Head to Flange Weld Category B-A, Item B13.40 Component: RPV closure head to flange weld Coverage Sketch No: 5 of S Scale: 50%

Exam: Base metal, 45°160/ and o0 EXAM AREA

  • AEHD 4 FBCG = (3.3 x 6.6) + (3.3 x 7) 44.88 In'

- . N e EXAMINED D ~ H AEHD+FJKG= (3.3x6.6)+(.5x,7)=25281nr

  • (25.28 144.88) 56 %
  • 56%x(43 145 )=54%

TOTAL

  • O°e54%

O'

.L PlitrCrio" 1. I. VAJECTIOI Z..

u~ln 11rXAH5 + O'

  • 4SlR54%
  • 60°g*4rIS4 8 of 8
Retrieved from "https://kanterella.com/w/index.php?title=ML040290659&oldid=2632357"