ML20154Q076

Safety Evaluation Supporting 870318 & 880805 Requests for Relief from Inservice Insp Requirements for Pressurizer Support skirt-to-shell Weld

ML20154Q076
Person / Time
Site:	Millstone
Issue date:	09/21/1988
From:	Office of Nuclear Reactor Regulation
To:
Shared Package
ML20154Q069	List: ML20154Q064 ML20154Q076
References
NUDOCS 8810030299
Download: ML20154Q076 (3)

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,E o NUCLEAR REGULATORY COMMISSION

,E WASHINGTON, D. C. 20555 4, O SAFETY EVALUAT_IO,N_ BY T_HE OFFICE OF_ NUCLEAR REACTOR REGULATION RELATED TO REQUESTS FOR RELIEF FROM INSER_V_ ICE _ INSPECTION REQUIREMENTS PRESSURIZER SUPPORT SKIRT-TO-SHELL WELD N_0RTHEAST NUCLEAR ENERGY COMPANY, ET AL.

MILLSTONE NUCLEAR POWER STATI_0N, UNIT NO. 3 DOCKET NO. 50-423 INTRODUCTION Technical Specification 4.0.5a for the Millstone Nuclear Power Station, L' nit No. 3 states that inservice inspection (ISI) of ASME Code Class 1, 2, and 3 components shall be perfonned in accordance with Section XI of required ASME Boiler and Pressure Vessel Code (the Code) and applicable Addenda, as required by 10 CFR 50.55a(g). Title 10 CFR 50.55a(g)(6)(1) authorizes the Comission to grant relief from Code requirenents and to impose such alternative require-ments as it detennines is authorized by law upon taking the necessary findings.

By letter dated March 18, 1987, as supplerented by letter dated August 5, 1988, the licensee requested relief from ASME Code requirements as these requirements related to ISI of the pressurizer support skirt to-shell weld. The licensee proposed an alternative inspection of the weld.

DISCUSSION AND EVALUATION

1. Relief Reques_ _t Pursuant to 10 CFR 50.55a(g)(5)(iii), relief was requested from perfonning the inservice surface examination on the inaccessible portion of the pressurizer support skirt-to-shell weld, area C-D, as shown on Fig. IWB-2500-13 of the 1983 Edition of the Code.

2. Code Requirement A surface examination is required for 100% of the weld length of any integrally-welded attachment to the pressurizer. The examination shall be conducted in accordance with ASME Boiler and Pressure Vessel Code,Section XI,1983 Edition through Sumer 1983 Addenda. '

i 8910030299 800921 PDR G ADOCK 05000423 PNV

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3. l.icensea's Basis For Requesting Relief

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1 The licensee stated that the geometric configuration of the support skirt-  !

to-shell weld limits the surface to be examined to the one accessible side j of the support. In addition, by letter dated August 5, 1988, the licensee i stated that radiation levels in the area to be inspected are high and estimates exposure for scaffolding, weld preparation, and performing the examination at 3.1 man-rem. The infonnation submitted by the licensee meets the requirements of 10 CFR 50.55a(a)(3) regarding the i difficulty / hardship of the existing Code requirement.

4 Licensee's Proposed Alternative l The licensee stated that the subject weld received a surface examination during preservice inspection in accordance with the 1980 Edition through Winter 1980 Addenda of Section XI and would receive an inservice inspection in accordance with Code Case N-323. Code Case N-323 gives acceptable alternative examination requirements for the subject weld.

Stress intensities in Region C-D do not exceed 80 percent of the levels A, B, C, and D service limits (NB-3000) and the usage factor U does not exceed 0.1.. The infomation submitted by the licensee concerning the acceptability of the proposed alternative inspection reets the requirements of 10 CFR 50.55(a)(3).

5. Staff Evaluation i The staff has determined that the geometry of the pressurizer support skirt-to-shell weld at Millstone Unit 3 prevents the licensee from perfoming the required surface examination of area C-D depicted in Fig.

IWB-2500-13 of the 1983 Edition through Sumer 1983 Addenda of Section XI of the ASME Code. In lieu of the required surface examination of the area, the licensee has proposed to use as an alternative the examination and design requirements of Code Case N-323 in which a surface examination of only the accessible side of the support is required to be performed provided the stress intensity factors in region C-D do not exceed 80% of Level A, B, C, and D Service Limits (NB-3000) and the cumulative usage factorV[(NB-322.4e(5)]doesnotexceed0.1. The licensee has stated that a surface examination of the exterior surface of the weld will be performed and the stress intensity and cumulative usage factors do not exceed the limits cited in the Code Case. The staff therefore finds the proposed alternative will provide an acceptable level of quality and safety by providing reasonable assurance of continued weld integrity and concludes that relief from the Code surface examination requirement for area C-D may be granted as requested.

CONCLUSION The NRC staff concludes that the code requirement is impractical, and if imposed, would result in additional radiation exposure. Ar.cordingly, pursuantto10CFR50.55a(g)(6)(1)and 50.55a(a)(3),therelief

requested is granted and the alternative examination is authorized. The NRC staff concludes that the relief granted will not endanger life or  ;

property or the comon defense and security and is otherwise in the  ;

public interest giving due consideration to the burden that would result '

if the requirement were imposed.  !

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Principal Contributor: G. Johnson i D.Jaffe '

Dated: SEP t 1 test i

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