ML20217B524

SE Accepting Licensee Request for Approval to Use Alternative Exam Requirement for Brunswick,Unit 1,reactor Vessel Stud & Bushing During Second 10-yr ISI Interval Per 10CFR50.55a(a)(3)(ii)

ML20217B524
Person / Time
Site:	Brunswick
Issue date:	04/20/1998
From:	NRC (Affiliation Not Assigned)
To:
Shared Package
ML20217B521	List: ML20217B514 ML20217B524
References
NUDOCS 9804230062
Download: ML20217B524 (4)

Text

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1. 44 9 y & UNITED STATES

" g NUCLEAR REGULATORY COMMISSION 4"

WASHINGTON. D.C. 2066&O001

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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION ON ASME CODE. SECTION XI RE0UEST TO USE ALTERNATIVE FOR INSERVICE INSPECTION OF REACTOR VESSEL STUD AND BUSHING DURING SECOND 10-YEAR INTERVAL FOR BRUNSWICK STEAM ELECTRIC PLANT UNIT NO.1 CAROLINA POWER & LIGHT COMPANY l DOCKET NO- 50-325

1. INTRODUCTION.

I The Technical Specifications (TS) for the Brunswick Steam Electric Plant. Unit No.1. states that the inservice inspection and testing of the American  !

Society of Mechanical Engineers (ASME) Code Class 1, 2. and 3 components shall be performed in accordance with Section XI of the ASME Boiler and Pressure Vessel 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 alternatives to the requirements of paragraph (g) may be used, when authorized by the NRC. if l (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 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 preservice 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 10-year interval and subsequent intervals comply with the requirements in the latest edition and addenda of the ASME Code.

Section XI. incorporated by reference in 10 CFR 50.55a(b) on the date 12 months prior to the start of the 120-month interval, subject to the limitations and modifications listed therein. The applicable ASME Code.

l Section XI. for Brunswick Unit 1. during the second 10-year inservice l inspection (ISI) interval is the 1980 Edition though the Winter 1981 Addenda.

The components (including supports) may meet the requirements set forth in l subsequent editions and addenda of the ASME Code incorporated by reference in l 10 CFR 50.55a(b) subject to the limitations and modifications listed therein and subject to Commission approval, y 2gooI! $ oo$025 h PDR

i l Pursuant to 10 CFR 50.55a(a)(3)(11), by letter dated January 27. 1998.

l Carolina Power & Light Company (CP&L or the licensee), requested approval of an alternative to the ASME Code.Section XI. for inservice inspection of one l of the reactor vessel studs and its associated bushing to be applied to the ISI program during the second 10-year interval for Brunswick Unit 1. The ,

staff's review and evaluation of the licensee's request and supporting i information is noted below.

2. D_ISCUSSION 1

l Comoonent Identification: l Reactor Vessel closure stud number 19 including its associated bushing ASME Code.Section XI Reauirement:

ASME Code.Section XI 1980 Edition, including the Winter 1981 Addendum.  !

, Examination Category B-G-1 requires a volumetric examination and a surface examination of the reactor vessel closure stud when removed. The Code l requires a VT-1 visual examination of the closure bushing surfaces when connections are disassembled.  ;

Licensee's Procosed Alternative:

o Volumetric examination of each of the 64 reactor vessel studs in place from top of the stud.

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o Surface examination of four out of the five closure studs which have been j removed during the current 10-year inspection interval.

o VT-1 visual examination of four out of the five closure bushing surfaces j

which have been made accessible during the current 10-year inspection interval, and o VT-2 visual examination of the Class 1 reactor coolant pressure boundary, including the reactor vessel top head and flange areas, during each refueling outage.

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Licensee's basis for relief:

The inservice inspection of five reactor vessel studs and their associated bushings was deferred until the end of the second 10-year inspection interval as permitted by the Code. Four closure studs out of five were removed from

F the vessel and inspected in accordance with the applicable ASME Code,Section XI. In addition, a VT-1 visual examination was performed on the bushing associated with each of the four closure studs. However, one remaining '

closure stud identified as No.19 could not be removed from the vessel using normal means. Therefore, its associated bushing also could not be visually )

examined in accordance with the Code. Extraordinary means can be employed to support removal of stud 19. However. such means have the potential to result in damage to the stud. Nevertheless, the stud 19 was volumetrically examined l in place with no indications found. Therefore, the licensee concluded that l removal of stud 19 solely to comply with ASME Code requirements-for-surface examination of the stud and visual examination of its associated bushing for j .

the remainder of the second 10-year interval that ends on May 10, 1998, i

creates a hardship without a compensating increase in the level of quality and i sa fety. However. if the reactor vessel closure stud 19 requires removal for maintenance or repair during the remainder of the current 10-year interval, i the licensee will perform the surface examination of the stud and the VT-1

! visual examination of the associated bushing surfaces in accordance with ASME Code,Section XI, Table IWB-2500-1.

3. EVALUATION The licensee has stated that one closure stud identified as stud 19 could not be removed from the vessel flange by normal means to perform the Code-required surface examination and the VT-1 visual examination of the associated bushing surfaces. However, as required by the Code, volumetric examination was performed on all 64 closure studs including stud 19 during the current inspection interval and there were no unacceptable indications found.

Furthermore, four out of five closure studs designated for removal were subject to a surface examination in accordance with the Code and were found to i be acceptable. The staff, therefore. determined that if a degradation mechanism existed, the volumetric examination of the closure studs would have detected it with high degree of confidence. The leak-tight integrity of the reactor vessel head to flange joint has also been ensured by VT-2 visual examination after each refueling outage, and hence the alternative proposed by ,

the licensee provides a reasonable assurance of operational readiness. The '

staff has further determined that if the licensee were to comply with the Code 4 requirement for the remainder of the inspection interval, the stud 19 has to l be removed by unusual means with the potential for damaging the stud and causing hardship to the licensee without a compensating increase in the level i

of quality and safety. '

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4. CONCLUSION The staff has concluded that it is acceptable to implement the proposed alternative to the applicable ASME Code.Section XI. for the remainder of the

, second 10-year inspection interval, since there is no evidence of any active l degradation mechanism or existence of any defect in the reactor vessel closure studs based on the results of the volumetric examination of all closure studs and the surface examination of four studs. The licensee's proposed alternative, however provides a reasonable assurance of operational readiness and compliance to the applicable Code would result in hardship to the licensee j without a compensating increase in the level of quality and safety.

Therefore, the licensee's proposed alternative to the ASME Code.Section XI.

l l i 1980 Edition with the Winter 1981 Addendum, is authorized pursuant to 10 CFR 50.55a(a)(3)(11) for the remainder of the second 10-year inspection interval '

of Brunswick. Unit 1.

Principal Contributor: P. Patnaik. DE/ECGB 1

Date: April 20, 1998 l

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