ML20149L200

SER Granting Requests for Relief NDE-33,34 & 35 Re ISI Program,Per 10CFR50.55a(g)(6)(i)

ML20149L200
Person / Time
Site:	North Anna
Issue date:	07/29/1997
From:	NRC (Affiliation Not Assigned)
To:
Shared Package
ML20149L198	List: ML20149L195 ML20149L200
References
NUDOCS 9707310184
Download: ML20149L200 (13)

Text

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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION REOUEST FOR RELIEF FROM SECTION XI RE0VIREM_fffTS FOR ASME CODE CLASS 1. 2 AND 3 REACTOR COOLANT SERVICE PIPING VIRGINIA ELECTRIC AND POWER COMPANY NORTH ANNA POWER STATION. UNIT 2 DOCKET NO. 50-339

1.0 INTRODUCTION

10 CFR 50.55a(g) requires that the inservice inspection of the American j

Society of Mechanical Engineers (ASME) Code Class 1, 2 and 3 components shall

'i be performed in accordance with Section XI of the ASME Boiler and Pressure Vessel (B&PV) Code and a]plicable addenda, except where specific written relief has been granted Jy the Commission pursuant to 10 CFR 50.55a(g)(6)(i).

10 CFR 50.55a(a)(3) states that alternatives to the r' uirements of paragraph (g) may be used. When authorized by the Director of the Office of Nuclear Reactor Regulation. if (i) the proposed alternatives would provide an acceptable level of quality and safety or (ii) compliance with the specified requirements would result in hardship or unusual difficulties without a compensating increase in the level of quality and safety.

Pursuant to 10 CFR 50.55a(g)(5), if it is determined that conformance with an examination requirement of Section XI of the ASME Code is not practics1 for its facility. information shall be submitted to the Commission in support of that determination and a request made for relief from the ASME Code requirement. After evaluation of the determination. pursuant to 10 CFR 50.55a(g)(6)(1), the Commission may grant relief and may impose alternative re endanger life quirements that are determined to be authorized by law. will not property, or the common defense and security, and are otherwise in the public interest giving due consideration to the burden upon the licensee that could result if the requirements were imposed.

2.0 BACKGROUND

In a letter dated January 28. 1997. Virginia Electric and Power Company (licensee), submitted to the NRC its Second 10-Year Interval Inservice Inspection (ISI) Program Plan Requests for Relief NDE-33. NDE-34, and NDE-35, for North Anna Power Station. Unit 2.

The Code of record for the North Anna Power Station. Unit 2. second 10-year interval ISI is the 1986 Edition of Section XI of the ASME Boiler and Pressure Vessel Code.

9707310184 970729 ENCLOSURE PDR ADOCK 050003 9 P

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t 3.0 LICENSEE *S RELIEF REQUEST Mark /

Line#

Drawing #

Class Weld #

l Relief No. NDE 33 (Reactor coolant pump to loop pipe circumferential welds) 1 l

9 27 1/2"-RC-403-2501R-01 12050-WMKS-109E-1 1

20 31"-RC-405-2501R-01 12050-WMKS-109F-1 1

Code requirement:

100% volumetric and surface examination.

Licensee's Code relief request:

Puruant to 10 CFR 50.55a(g)(5)(iii), licensee has requested relief from examining this weld to the extent required by the Code l

Basis for relief:

The components listed above have been examined to the extent practical as required by the Code.

The Code-required volumetric examination coverage was reduced due to weld joint geometry, and the material j

type from which the components are constructed.

l Relief No. NDE 34 (pipe to flange circumferential weld) l SW-13 6"-RC-437-1502-01 12050-WMKS-110A-1 1

Code requirement:

100's volumetric and surface examination.

Licensee's Code relief request:

Puruant to 10 CFR 50.55a(g)(5)(iii), licensee l

has requested relief from examining this weld to the extent required by the Code.

Basis for relief:

The com)onent listed above has been examined to the extent practical as recuired by tie Code.

The Code-required volumetric examination coverage was recuced due to interference by the existing pipe support.

Relief No. NDE-35 (reactor pressure vessel closure head to flange weld) 1 12050-WMKS-RC-R-1.2 1

l Code requirement:

100% volumetric and surface examination.

Licensee's Code relief request:

Puruant to 10 CFR 50.55a(g)(5)(iii), licensee has requested relief from examining this weld to the extent required by the Code Basis for relief:

The com)onent listed above has been examined to the extent practical as recuired by t1e Code. The Code-required volumetric examination coverage was recuced due to the joint configuration and the lifting lug.

1 i

e

4.0 STAFF EVALUATION The staff, with technical assistance from its contractor, the Idaho National Engineering and Environmental Laboratory (INEEL) has evaluated the information 3rovided by the licensee in support of its Second 10-Year Interval ISI Program )lan Requests for Relief NDE-33. NDE-34 and NDE-35 for North Anna Power Station. Unit 2.

Based on the information submitted, the staff adopts the contractor's conclusions and recommendations (attached).

For Request for Relief NDE 33 the Code requires 100% volumetric examination of the reactor coolant Jump-to-loop pipe circumferential Welds 9 and 20. The staff determined that. aased on a review of the drawings depicting the subject weld joints.100% volumetric examination of the welds is impractical to pc-ferm due to geometrical constraints imposed by the reactor coolant pump nozzle construction.

For the licensee to obtain 100% volumetric examination coverage of the reactor coolant pump inlet and outlet nozzle transition piping would require significant design modifications.

Imposition of this requirement would create an undue burden on the licensee.

The licensee obtained 100% surface examination coverage of 100% of both welds.

Both welds were volumetrically examined using 45 and 60 degree ultrasonic search units from the loop pipe side. Approximately 97% of the lower third of Weld 9 was examined from one side of the weld during the axial scan. The average coverage of all four scans on Weld 9 exceeds 49%. Ap3roximately 100%

of the lower third of weld 20 was examined from one side of t1e weld during the axial and circumferential scans.

The average coverage of the four scans is 75%.

Therefore, the staff determined that any existing patterns of degradation would have been detected, providing reasonable assurance of structural integrity.

Based on the impracticality of meeting the Code coverage requirements for the subject welds, and the reasonable assurance provided by the volumetric and surface examinations that were completed, relief is granted pursuant to 10 CFR 50.55a(g)(6)(i).

For Request for Relief NDE 34 the Code requires 100% volumetric and surface examinations of the pipe-to-flange circumferential weld SW-13.

The staff determined that, based on the review of drawings de)icting the subject weld joint. 100% volumetric and surface examination of t11s weld is impractical to perform due to geometrical constraints imposed by the piping support.

For the licensee to gain access to'this weld for 100% examination, the piping and/or support would recuire significant design modifications.

Imposition of this requirement woulc create an undue burden on the licensee.

The licensee obtained ap3roximately 26% volumetric and 28% surface examination coverage of the weld.

T1e licensee examined the weld to the extent 3ractical:

however, approximately 270 degrees of this circumferential weld is o)scured by the piping support.

The Code requires, and the licensee has performed. 100%

surface and volumetric examination of other Class 1 terminal end pipe welds.

As a result, it is concluded that any existing patterns of degradation would

. have been detected by the examination coverage achieved for this pipe-to-flange weld in combination with the examination of other similar welds.

Therefore, the licensee's alternative provides reasonable assurance of structural integrity of the subject systems.

The staff determined that, based on the impracticality of meeting the Code l

coverage requirements for the subject weld, and the reasonable assurance provided by the surface and volumetric examinations that were completed.

relief is granted pursuant to 10 CFR 50.55a(g)(6)(1).

For Request for Relief NDE 35, the Code requires 100% volumetric and surface examination of the reactor pressure vessel (RPV) closure head-to-flange weld.

The staff determined that based on the review of the drawings depicting the examination area, the proximity of the. lifting lug and the weld's configuration restrict access and make the Code coverage requirements impractical for this weld. To meet the Code coverage requirements, the RPV closure head would require extensive design modifications to allow access for examination.

Imposition of this requirement would create an undue burden on the licensee.

The staff has reviewed the licensee's submittal and determined that the average coverage achieved for this weld exceeds 75%. The licensee utilized beam angles of 45 and 60 degrees for volumetric examinations of both the weld and the base material.

The cumulative average coverage of the weld with the 45 degree beam angle exceeds 83% and with the 60 degree beam angle is 75%.

The average volumetric coverage for the 45 and 60 & gree beam angles on the base is 85%. This volumetric coverage combined with the 96% surface examination coverage, represents a significant portion of the Code requirements. These examinations provide reasonable assurance of structural integrity.

Therefore. based on the impracticality of meeting the Code coverage requirements for the subject weld, and by the volumetric and surface examination coverages obtained, reasonable assurance of the structural integrity is provided. The staff determined that relief is granted pursuant to 10 CFR 50.55a(g)(6)(i).

5.0 Staff Conclusions

-The staff has reviewed the licensee's submittal and concludes that certain inservice examinations cannot be performed to the extent required by the Code at North Anna Power Station. Unit 2.

For Regaests for Relief NDE-33. NDE-34 and NDE-35, the licensee has demonstrated that the Code coverage requirements are imaractical.

Further reasonable assurance of the structural integrity of the su) ject components has been provided by the examinations performed to the extent practical. Therefore, for Requests for Relief NDE-33. NDE-34 and NDE-

35. relief is granted pursuant to 10 CFR 50.55a(g)(6)(i).

Principal Contributor:

T. McLellan Date: July-29, 1997

ATTACHMENT i

l TECHNICAL LETTER REPORT SECOND 10 YEAR INTERVAL INSERVICE INSPECTION REQUESTS FOR RELIEF FOR VIRGINIA ELECTRIC AND POWER COMPANY NORTH ANNA POWER STATION. UNIT 2 DOCKET NUMBER 50-339

1.0 INTRODUCTION

By letter dated January 28,1997, the licensee, Virginia Electric and Power Company, submitted Requests for Relief NDE-33, NDE-34, and NDE-35 for North Anna Power Station, Unit 2. The Idaho National Engineering and Environmental Laboratory (INEEL) staff has evaluated the information provided by the licensee in support of these requests in the following section.

2.0 EVALUATION The Code of record for the North Anna Power Station, Unit 2, second 10-year

)

inservice inspection (ISI)intervalis the 1986 Edition of Section XI of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code. The information provided by the licensee in support of the requests for 4

relief has been evaluated and the bases for disposition are documented below.

A) Bgpuest for Relief NDE-33. Examination Cateoorv B-J. Item B9.11. Reactor Coolant Pomo to-Pioe Welds Code Reauirement: Examination Category B-J, Item B9.11, requires 100% volumetric and surface examination of the weld length for circumferential piping welds as defined by Figure IWB 2500-1.

l l

l Licensee's Code Relief Reauest: Pursuant to 10 CFR 50.55a(g)(5)(iii), the licensee has requested relief from examining the following reactor cooimat pump to pipe circumferential piping welds to the extent required by the Code.

Mark / Weld #

Line#

Drawing #

Class c

9 271/2"-RC-403-2501R-01 12050-Wr.1KS-109E-1 1

l 20 31 "-RC-405-2501 R-01 12050-WMKS-109F-1 1

- Licensee's Basis for Reauestina Relief (as stated):

The components insted above have been examined to the extent practical as required by the Code. The Code required volumetric examination coverage was reduced due to weld joint geometry, and the material type l

from which the components are constructed. The scope of volumetric l

examination coverage completed for the above listed welds is listed in l

Table NDE-33-1. Figures NDE-33-1 and NDE 33-2 are provided detailing the limitations experienced. These welds are classified as terminal ends and are required to be examined by the ISI Program.

i i

Table NDE-33-1 UT Coverage (%)

Surface Scan #'s Examination Coverage (%)

'l Mark / Weld #

2 5

7 8

1 9

97 0

50 50 100 20 0

100 100 100 100 UT Scan Direction Definitions 2 - Axial scan,180 degrees from isometric flow direction (weld count).

5 - Axial scan, the same direction as the isometric flow (weld count).

7 - Circumferential scan, clockwise rotation when viewing in the direction of isometric flow.

8 - Circumferential scan, counterclockwise rotation when viewing in the

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direction of isometric flow.

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1

. - ~...,. -

i Licensee's Pronosed Alternative (as stated):

lt is proposed that the examinations already completed at the reduced coverage be counted as meeting the Code requirements. In addition:

1.

A visual (VT-2) examination will be performed during the normally i

scheduled system leakage test each refueling outage; l

2. Technical Specifications require that the reactor coolant system leak rate be limited to one gallon per minute unidentified leakage. This value is calculated at least once per 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />; and i

3.

Tiw c tainment atmosphere particulate radioactivity is monitored I

The proposed alternative examinations stated ebove will ensure that the overalllevel of plant quality and safety will not be compromised.

l 1

Evaluation: The Code requires'100% volumetric examination of the reactor coolant pump-to-loop pipe circumferential Welds 9 and 20.

However, based on a review of the drawings depicting the subject weld joints, it has been determined that 100% volumetric examination of these welds is impractical to perform due to geometrical constraints imposed by the reactor coolant pump nozzle construction. To obtain 100%

volumetric examination coverage, the reactor coolant pump inlet and outlet nozzle transition piping would require significant design modifications. Imposition of this requirement would create an undue burden on the licensee.

The licensee obtained 100% surface examination coverage of 100% of both welds. Both welds were volumetrically examined using 45 and 60 degree ultrasonic search units from the loop pipe side. Approximately 97% of the lower third of Weld 9 was examined from one side of the weld during the axial scan. The average covarage of all four scans on Weld 9 exceeds 49%. Approximately 100% of the lower third of weld 20 was examined from one side of the weld during the axial and circumferential scans. The average coverage of the four scans is 75%.

Therefore,it cen be concluded that any existing patterns of degradation would have been detected, providing reasonable assurance of structural 3

integrity.

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Based on the impracticality of meeting the Code coverage requirements for the subject welds, and the reasonable assurance provided by the volumetric and face examinations that were completed, it is recommended that relief be granted pursuant to 10 CFR 50.55a(g)(6)(i).

l B) Reauest for Relief NDE-34. Examination Cateaorv B-J. Item B9.11.

Circumferential Pine-to-Flance Wdd il.

Code Reauirement: Examination Category B-J, item B9.11, requires i

100% volumetric and surface examinations of the weld length for 5

pipe-to-flange circumferential welds as defined by Figure IWB 2500-1.

Licensee's Code Relief Reauest: Pursuant to 10 CFR 50.55a(g)(5)(iii), the licensee has requested relief from examining the following pipe-to-flange weld, to the extent required by the Code.

i Mark / Weld #

Line#

Drawing #

Class SW-13 6" RC-437-1502 01 12050 -WMKS 110A-1 1

Licensee's Easis for Reauestina Relief (as stated):

The component listed above has been examined to the extent practical as required by the Code. Due to interference by the existing pipe support, i

only 6 inches out of 21 inches were scanned. The reduction in coverage is detaiLJ in Table NDE-34-1. Figure NDE-34-1 is provided detailing the limitations experienced. The weld is classified as a terminal end and is required to be examined by the ISI Program.

Table NDE-34-1 l

UT Scan Coverage %

Surface l

Examination l

Coverage %

l l

Mark / Weld #

2 1

5 7

8 SW-13 28 26 25 25 28 UT Scan Direction Definitions l

2 - Axial scan,180 degrees from isometric flow direction.

i i

- - - -.- -.--.-.-=_-

l '

5 - Axial scan, the same direction as the isometric flow.

7 - Circumferential scan, clockwise rctation when viewing in the direction of isometric flow.

l 8 - Circumferential scan, counterclockwise rotation when viewing in the direction of isometric flow.

Licensee's Prooosed Altemative (as stated):

It is proposed that the examination already completed at the reduced coverage be counted as meeting the Code requirements. In addition:

1.. A visual (VT-2) axamination will be performed during the normally scheduled system leakage test each refueling outage;

2. Technical Specifications require that the reactor coolant system leak rate be limited to one gallon per minute unidentified leakage. This value is calculated at least once per 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />; and

3. The containment atmosphere particulate radioactivity is monitored l

every 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.

l The proposed alternative examination stated above will ensure that the overall level of plant quality and safety will not be compromised.

Evaluation: The Code requires 100% volumetric and surface examinations of the pipe to-flange circumferential Weld SW-13.

j However, based on the review of drawings depicting the subject weld joint it has been determined that 100% volumetric and surface f

examination of this weld is impractical to perform due to geometrical I

constraints imposed by the piping support. For the licensee to gain access to this weld for 100% examination, the piping and/or support would require significant design modifications. Imposition of this requirement would create an undue burden on the licensee.

The licensee obtained approximately 26% volumetric and 28% surface examination coverage of the weld. The licensee examined the weld to the extent practical, however, approximately 270 degrees of this circumferential weld is obscured by the piping support. The Code i

requires, and the licensee has performed,100% surface and volumetric 3

1 examination of other Class 1 terminal end pipe welds. As a result, it is i

j concluded that any existing patterns of degradation would have been

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detected by the examination coverage achieved for this pipe-to-flange i

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_ _. _ _. _. _. _. _. = _ _ _ _. _ -. _ _ _ _ _ _. _. _ _

l weld in combination'with the examination of other similar welds.

Therefore, reasonable assurance of structural integrity has been provided.

L Based on the impracticality of meeting the Code coverage requirements for the subject weld, and the reasonable assurance provided by the i

surface and volumetric examinations that were completed, it is recommended that relief be granted pursuant to 10 CFR 50.55a(g)(6)(i).

C) Raouest for Relief No. NDE-35. Examination Cateaorv B-A. Item B1.40.

Reactor Pressure Vessel (RPV) Closure Head-to-Flanae Wald l

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Code Raouirement: Examination Category B-A, item B1.40 requires l

100% volumetric and surface examinations of the RPV head-to-flange weld as defined by Figure IWB-2500-5.

Licensee's Code Re!ief Reauest: Pursuant to 10 CFR 50.55a(g)(5)(iii), the l

licensee hac requested relief from performing the surface and volumetric l

examinations of RPV closure head-to-flange Weld 1 to the extent required f-by the Code.

l l

l Licensee's Basis for Reauestina Relief (as stated):

The component listed above has been examined to the extent practical as required by the Code. Due to the joint configuration and a lifting lug the required volume could not be examined. The reductinn in coverage is detailed in Table NDE-35-1. Figures NDE-35-1 and NDE-35-2 are I

provided detailing the limitations experienced.

Table NDE 35-1 Mark / Weld #

Beam Angle ExaAdroa Scan Direction l Exam 1 (120 - 240 )

0 Weld & Base 96 45 Weld 2

48 1

45 Weld 5

96 1

45 Weld 7

95 l

t 45 Weld 8

95 60 W eld 2

15 i

4 i

i i

-,n.

~....

. _ _.. ~. - - -.. - -

.. - -. -.. - - - -. ~ _... -. -

I i

>i 60 Weld 5

96 l

60 W eld 7

95 60 Weld-8 95 i

45 & 60 Base 2

56 45 & 60 Base 5

96 4

l 45 & 60 Base 7

95

~

45 & 60 Base 8

95 i

i l

l Surface coverage 96%

l UT Scan Direction Definitions 2 - Axial scan flange side of weld

)

5 Axial scan head side of weld 7 - Circumferential scan, clockwise (looking down on head) l 8 - Circumferential scan, counterclockwise (looking down on head) i j

Licensee's Pronosed Alternative (as stated):

i it is proposed that the examinations already completed at the reduced i

coverage be counted as meeting the Code requirements, in addition:

1.

A visual (VT-2) examination will be performed during the normally scheduled system leakage test each refueling outage; 2.

Technical Specifications requires that the reactor coolant system leak rate be limited to one gallon per minute unidentified leakage. This value is calculated at least once per 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />; and

3. The containment atmosphere particulate radioactivity is monitored every 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.

The proposed alternative examinations stated above will ensure that the

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overall level of plant quality and safety will not be compromised.

O-i

_ _ _... - ___... _ _ _ _. _... _ ~. _ -.__._.

Evaluation: The Code requires 100% volumetric and surface examination of the RPV closure head-to-flange weld. Based on the review of the drawings depicting the examination area, it has been determined that the proximity of the lifting lug and the weld's configuration restrict access and make the Code coverage requirements impractical for this weld. To meet the Code coverage requirements, the RPV closure head wculd require extensive design modifications to allow access for examination.

Imposition of this requirement would create an undue burden on the licensee.

The INEEL staff has reviewed the licensee's submittal and determined that the average coverage achieved for this weld exceeds 75%. The licensee utilized beam angles of 45 and 60 degrees for volumetric examinations of both the weld and the base. material. The cumulative average coverage of the weld with the 45 degree beam angle exceeds j

83% and with the 60 degree beam angle,is 75%. The average volumetric coverage for the 45 and 60 degree beam angles on the base is 85%. This volumetric coverage, combined with the 96% surface i

examination coverage, represents a significant portion of the Code requirements. These examinations provide reasonable assurance of structural integrity.

Based on the impracticality of meeting the Code coverage requirements i

for the subject weld, and by the volumetric and surface examination coverages obtained, reasonable assurance of the structural integrity is j

provided. Therefore,it is recommended that relief be granted pursuant to 10 CFR 50.55a(g)(6)(i).

3.0 CONCLUSION

l-l The INEEL staff has reviewed the licensee's submittal and concludes that certain inservice examinations cannot be performed to the extent required by the Code j

at North Anna Power Station, Unit 2. For Requests for Relief NDE 33, NDE-34, and NDE-35, the licensee has demonstrated that the Code coverage requirements are impractical. Further, reasonable assurance of the structural integrity of the subject components has been provided by the examinations 4

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i performed to the extent practical. Therefore, for Raquests for Relief NDE 33, NDE-34, and NDE 35 it is recommended that relief be granted pursuant to 10 l

CFR 50.55a(g)(6)(i).

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