ML20198P964

SE Granting Relief Request 97-03 for Second 10-yr Interval Inservice Insp Program

ML20198P964
Person / Time
Site:	Catawba
Issue date:	01/15/1998
From:	NRC (Affiliation Not Assigned)
To:
Shared Package
ML20198P948	List: ML20198P945 ML20198P964
References
NUDOCS 9801220302
Download: ML20198P964 (9)

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'4, SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION OF THE SECOND TEN YEAR INTERVAL INSERVICE INSPECTION PLAN REQUESTS FOR REllEF NO. 97-03 DUKE ENERGY CORPORATION CATAWBA NUCLEAR STATION. UNIT 2 DOCKET NO. 50-414

1.0 INTRODUCTION

In order to demonstrate the operability of American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code) Class 1,2, and 3 components, the Technical Specifications (TSs) for Catawba Nuclear Station, Units 1 and 2, state that the inservice inspection of the ASME Code Class 1,2, and 3 components shall be performed in accordance with Section XI of the ASME Code and applicable addenda as required by 10 CFR 50.55a(g),

except where specific written relief has been granted by the Commission pursuant to 10 CFR 50.55a(g)(6)(i).10 CFR 50.55a(a)(3) states that attematives to the requirements of paragraph (g) may be used, when authorized by the NRC, if (i) the proposed attematives would provide an acceptable level of quality and safety, or (ii) compliance with the specified requirements would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety.

Pursuant to 10 CFR 50.55a(g)(4), ASME Code Class 1,2, and 3 components (including supports) shall meet the requirements, except the design and access provisions and the pre-service examination requirements, set forth in the ASME Code,Section XI, " Rules for Inservice inspection of Nuclear Power Plant Components," to the extent practical within the limitations of design, geometry, and materials of construction of the components. The regulations require that inservice examination of components and system pressure tests conducted during the first ten-year interval and subsequent intervals comply with the requirements in the latest edition and addenda of Section XI of the ASME Code incorporated by reference in 10 CFR 50.55a(b) twelve months prior to the start of the 120-month interval, subject to the limitations and modifications listed therein.

ENCLOSURE 9901220302 99011S POR ADOCK 05000414 P

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2-The applicable edition of Section XI of the ASME Code for the Catawba Nuclear Station, Unit 2 second ten-year insory!ce inspection (ISI) interval is the 1989 Edition.

Pursuant to 10 CFR 50.55a(g)(5), if the licensee determines that conformance with an examination requirement of Section XI of the ASME Code is not practkal 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)(i), the Commission may grant relief and may impose altemative requirements that are determined to be authorized by law, will not endanger life, property, or the common defense and security, and are otherwise in the public interest, giving

- due consideration to the burden upon the licenses that could result if the requirements were imposed.

In a letter dated July 29,1997, Duke Energy Corporation (licensee, previously Duke Power Company), submitted Request for Relief 97+, Parts 1 and 2 to ASME Section XI requirements for Catawba Nuclear Station, Unit 2.

2.0 EVALUATION.

The staff, with technical assistance frem its contractor, the Idaho National Engineering and Environmental Laboratory (INEEL), has evaluated the information provided by the licensee la support of its Second Ten Year Inservice inspection Interval Program Plan Request for Relief No. 97 03, Parts 1 and 2 for Catawba Nuclear Station, Unit 2. Based on the information submitted, the staff adopts the contractor's conclusions and recommendations presented in the Technical Letter Repor1 (TLR) attached.

2.1 Request for Relief 97-03, Part 1 Section XI, Examination Category B-A, item B1.22, reactor pressure vessel (RPV) Meridional Head Wolds requires volumetric examination of essentially 100% of the weld length of reactor pressure vessel meridional head welds. Pursuant to 10 CFR 55.55a(g)(6)(i), the licensee requeste.d relief from meeting the volumetric examination coverage requirements as defined in ASME Section XI, Figure IWB-2500 3, Examination Volume E-F-G-H for the Class 1 reactor vessel closure head meridional Wold 2RPV 101-104G.

The licensee proposed as an attemative examination:

. No additional examinations are planned during the current interval for Weld ID Number 2RPV-101-104G..."

o The Code requires 100% ultrasonic examination of reactor vessel closure head welds each inspection interval. However, as shown in the licensee's rubmittal, a lifting lug limits the ultrasonic coverage for Wold 2RPV-101 104G to about 30% of the Code required volume.

Ultrasonic examination from the ins lde surface of the head is not feasible because high radiation exposure would be incurred. Radiography is not a workable altomative because no i

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additional coverage would be obtained. Therefore, the 100% volumetric examination coverage t

is impractical for this RPV meridional head weld To gain access for the Code-required eramination *he lifting lug would have to be removed. Imposition of this requirement would cause a considerable burden on the licensee.

The licenses has ultrasonically examined approximately 30% of the wbject RPV meridional l

head weld. This examination, in combination with the other RPV wolds receiving the Code-required volumetric examination, gives reasonable assurance that any pattoms of degradation would have been detected.

The staff determined that based on the impracticality of meeting the Code requirements for the 7

- subject weld and the inspections performed on the other RPV welds, the licensee's proposed

- altemative provides reasonable assurance of operational readiness of the subject component.

- The staff concludes that relief is granted pursuant to 10 CFR 55.55a(g)(6)(i).

2 2.2 Request for Relief g7-03, Part 2 i

ASME Code Section XI, Examination Category C-A, item C1.10, Containment Spray Heat Exchanger Shell-to-Flange Wold requires volumetric examination of essentially 100% of the weld length of Class 2 circumferential shell welds at gross structural discontinuities each

. inspection interval, in the case of multiple vessels of similar design, size, and service, the required examinations may be limited to one vessel or distributed among the vessels. Pursuant 1

to 10 CFR 55.55a(g)(6)(i), the licensee requested relief from meeting the volumetric examination coverage requirements as defined in ASME Section XI, Figure IWC-2500-1, Examination Volume A-B-C-D for the Class 2 containment spray heat exchanger shell-to flange Wold 2BNSHX 3-5.

i The licensee proposed as an altamative:

"No additional examinations are planned during the current interval for Weld ID Number...

2BNSHX 3-5 (ltem No. C01010.008)."

The Code requires 100% ultrasonic examination of pressure-roteining Class 2 circumferential shell welds at gross structural discontinuities each inspection interval. However, as supported L

by the licensee's submittt*. flange-to-shell Wold 2BNSHX 3 5 is limited to a one-sided examination due to the shell-to-flange configuration. Additionally, ultrasonic scanning in the exial direction was not possible due to the as-welded condit!on. Therefore, the 100% -

volumetric examination is impractical for the subject Containment Spray Heat Exchanger shell weld; To achieve the Cwle-required examination coverage, the weld configuration would have

. to be redesigned to allow for access from both sides of the weld. Imposition of this requirement would cause a considerable burden on the licensee.

g The l6 censes has completed a significar,t portion (53.83%) of the Code-required volumetric

. examination for NS Heat Exchanger sN8 to-flange Wold 2BNSHX-3 5. Therefore, any existing pettoms c' degradation would have boon detected and reasonable assurance of structural integrity has been provided.

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Based on the impract'er ality of meeting the Code coverage requirements for the subject weld, and the reasonable assurance provided by the examinations that were performed, the staff l

concludes that relief is granied pursuant to 10 CFR 55.55a(g)(6)(i).

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- 3.0' CONCLUSIONS i

The staff evaluated the licensee's submittal and concluded that certain inservice examinations cannot be performed to the extent required by the Code at Catawba Nuclear Station, Unit 2, in a

Request for Relief No. 97-03, Parts 1 and 2, the licensee has prevM information to support the determination that the Code volumetric examination coverage requirements are impractical,

-The staff also concluded that the examinations that have been performed provif% reasonable j

assurance of component structuralintegrity of the subject component. Therefore, relief is granted pursuant to 10 CFR 50.55(g)(6)(l). The' relief granted is authorized by law, will not i

endanger life, property or the common defense and security, and is otherwise in the public Interest giving due consideration to the burden upon the licensee that could result if the l

requirements are imposed on the facility, r

Attachment:

Technical Letter Report by INEEL Principal Contributor:

Tom McLellan Date: January 15,1998 k

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TECHNICAL LETTER REPORT

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ON THE StCOND 10. YEAR INTERVAL INSERVICE INSPECTION REQUEST FOR. RELIEF _97 03 f.OR DUKE POWER COMPANY CATAWBA NUCLEAR STATION, UNIT 2 DOCKET NUMBER: 50414

1.0 INTRODUCTION

By letter dated July 29,1997, the licensee, Duke Power Company, requested relief from the requirements of the ASME Code,Section XI, for the Catawba Nuclear Station, Unit 2, second 10 yest inservice inspection (ISI) interval. The Idaho National Engineering and Environmental Laboratory (INEEL) staff has evaluated the subject request for relief in the following section.

2.0 EVALUATION The Code of record for the Catawba Nuclear Station, Unit 2, second 10 year ISI interval, which began August 1996,is the 1989 Edition of Section XI of the ASME Boiler and Pressure Vessel Code. The information provided by the licensee in support of the request for relief from Code requirements has been evaluated and the basis for disposition is documented below.

2.1 Hgouest for Relief 97 03 (Part 11 Examination Cateoorv B A. Item B1.22 RPV Maddional Head Welds Code Reauirement: Section XI, Examination Category B A, item B1.22 requires volumetric examination of omsantially 100% of the weld length of reactor pressure vessel meridional head welds.

ATTACHMENT

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2 Licensee's Raouest for Relief: Pursuant to 10 CFR 55.55a(g)(6)(i), the licensee requested relief from meeting the volumetric examination coverage requirements as defined in ASME Section XI, Figure IW8 2500 3, Examination Volume E F G H for the Class 1 reactor vessel closure heed meridional Wold 2RPV 101 104G.

Licensee's Pronosed Alternative Examination (as stated):

"No additional examinations are planned during the current interval for Wald ID Number 2RPV 101 104G....'

Licensee's Basis for Raouestino Relief (as stated):

"During the ultrasonic examination of the Reactor Vessel Closure Head Meridional Weld 2RPV 101 104G (Item No B01.022.003) shown in Attachment,' coverage of the required examination volume could not be obtained. Causes of these limitations are due to the p:oximity of the lifting lug to the rneridional weld, which limits the ultrasonic coverage to 30.23% of the required volume, in order to achieve greater than 90% coverage of the required volume from the outside surface of the head, the lifting lug would have to be removed. Ultrasonic examination from the inside surface of the head is not feasible because of the high radiation exposure that would be incurred. Radiography would not provide any additional coverage because of the lif ting lug location."

i "Although the examination volume requirements as defined in ASME Section XI 1989 Edition, Figure No IWB 2500 3, Examination Volume E F G H for Weld ID Number 2RPV 101 104G (ltem B01.022.003) could not be met, the amount of coverage obtained for these examinations provides an acceptable level of qualify and integrity. For results of the examinations, reference Attachment 2', Pages 1,2,3,4,5,6,7 of 7.

"The Reactor Vessel (RV) closure head meridional weld is by definition not in the beltline area of the RV; therefore, it is not subject to fluence le rels equal to or greater than 1E17 n/cm'. RV materials not in the highly irradiated beltline region are not prone to negative material property changes (i.e., embrittlement) associated with fuel reactivity neutron bombardment. Based on 10 CFR 50.55a, the ASME Section XI 1975 and 1989 editions, require examination of essentially 100% of the length of beltline welds during every inspection interval. The RV closure head meridional weld The attachments provided in the licensee's original submittal are not included in this report.

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does not meet the requirements of the beltline weld due to a significantly lower fluence exposure, thus resulting in far less potential degradation of ductility. The Catawba Nuclear Station Unit 2 (CNS 2) RV was assembled by Combustion Engineering (CE) and is free from unacceptable fabrication defects. CE performed rigorous state of the art RV inspections following fabrication to ensure no significant flaws existed.

"The location of the RV lifting lu0 over a majority of the RV closure head meridional weld prevents obtaining 100% volumetric examination coverage; therefore, the 100% volumetric examinations are impractical. Removal of the lifting lug is not a viable alternative and would create an undue burden on Duke Energy Corporation."

• Based on these evaluations, it is Duke Energy Corporation's position that the limited coverage will not endanger the health and safety of the general public. Duke Energy Corporation will perform UT examinations to the extent practical using procedures and personnel qualified in accordance with ASME Section XI, Appendix l and Section V, Article 4, for Appendix Ill 1989 Edition for the NS Heat Exchanger."

Evaluation: The Code requires 100% ultrasonic examination of reactor vessel closure head welds each inspection interval. However, as shown in the licensee's subrnittal, a lif ting lug limits the ultrasonic coverage for Weld 2RPV 101 104G to about 30% of the Code required volume. Ultrasonic examination from the inside surface of the head is not feasible because high radiation exposure would be incurred. Radiograpny is not a viable alternative becauso no additional coverage would be obtained. Therefore, the 100% volumetric examination coverage is impractical for this RPV meridional head weld. To gain access for the Code required examination, the lifting lug would have to be removed imposition of this requirement would cause a considerable burden on the licensee.

The licensee has ultrasonically examined approximately 30% of the subject RPV meridional head weld. This examination, in combination with the other RPV welds receiving the Code required volumetric examination, gives reasonable assurance that any patterns of degradation would have been detected.

Based on the impracticality of meeting the Code requirements for the subject wold and the reasonable assurance provided by the examinations completed on other RPV welds, it is recommended that relief be granted pursuant to 10 CFR 55.55a(g)(6)(i).

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2.2 Raa=at far Relief 97 02 (Part 2L framination Ca+--~w C.A. Itam C1.10, i

Cantalnment an,av Ne fweham Shall to-Planna Wald 4

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t pada Manuiramani: Section XI, Examination Category C A, item 31.10 requires i

volumetric examination of essentially 100% of the weld length of Class 2

- circumferential shell welds at gross structural discontinuities each inspection interval.

In the case of multiple vessels of similar design, slae, and service, the' required l

examinations may be limited to one vessel or distributed among the vess,els.

1 Licennan's Manuant for Raliaf: Pursuant to 10 CFR 55.55alg)(6)(i), the licensee requested relief from meeting the volumetric examination coverage requirements as defined in ASME Section XI, Figure IWC 25001, Examination Volume A B C D for j

the Class 2 containment spray host exchanger shell to flange Wold 2BNSHX 3 5.

- Licanmaa's Pronomad Alternative (as stated):

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'No additional examinations are planned during the current interval for Wold ID Number,. 2BNSHX 3 5 (ltem No. CO' 010.008)."

l The Code requires 100% ultrasonic examination of pressure-roteining Class 2 circumferential shell welds at gross structural discontinuities each inspection interval.

However, as supported by the attachments to the licensee's submittal, flange to-shell Wold 2tNSHX 3 5 is limited to a one sided examination due to the shell to-flange configuration. Additionally, ultrasonic scanning in the axial direction was not possible due to the as welded condition. Therefore, the 100% volumetric.

examination is impractical for the subject NS Heat Exchanger shell weld. To achieve i

the Code-required examination coverage, the weld configuration would have to be redesigned to allow for access from both sides of the weld, imposition of this requirement would cause a considerable burden on the licensee.

l The licensee has completed.a significant portion (53.83%) of the Code-required volumetric. examination for NS Heat Exchanger shell to flange Weld 2BNSHX 3 5.

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Therefore, any existing patterns of degradation would have been detected and reasonable assurance of structural integrity has been provided, f

i Based on the impracticality nf meeting the Code coverage requirements for the subject weld, and the reasonable assurance provided by the examinations that were performed, it is recommended that relief be granted pursuant to 10 CFR l

55.55s(g)(6)(i).

3.0 CONCLUSION

The INEEL staff evaluated the licensee's submittal and concluded that certain inservice examinations cannot be performed to the extent required by the Code at i

the Catawba Nuclear Station, Unit 2. In Request for Relief No. 97 03 (Parts 1 and 2), the licensee has provided information to support the determination that the Code

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volumetric examination coverage requirements are impractical, it is also concluded that reasonable assurance of component structuralintegrity has been provided by l

the examinations that have been performed. Therefore, it is recommended that relief be granted pursuant to 10 CFP. 55.55a(g)(6)(1) for Request for Relief No. g7 03.

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