ML20141D050

Safety Evaluation Supporting Requests for Relief to Use ASME Code Case N-508-1 for Plant

ML20141D050
Person / Time
Site:	Wolf Creek
Issue date:	06/23/1997
From:	NRC (Affiliation Not Assigned)
To:
Shared Package
ML20141D048	List: ML20141D042 ML20141D050
References
NUDOCS 9706260249
Download: ML20141D050 (4)

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NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20666-0001 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION l

RELATED TO REQUESTS FOR RELIEF TO USE ASME CODE CASE N-508-1 WOLF CREEK NUCLEAR OPERATING CORPORATION WOLF CREEK GENERATING STATION DOCKET NO. 50-482

1.0 INTRODUCTION

The Code of Federal Regulations.10 CFR 50.55a, requires that inservice inspection (ISI) of certain ASME Code Class 1, 2, and 3 components be performed in accordance with Section XI of the ASME Boiler and Pressure Vessel (B&PV) Code applicable Edition and Addenda, except where s)ecific written relief has been requested by the licensee and granted by t1e Commission pursuant to paragraph 10 CFR 50.55a(g)(6)(1), or alternatives approved pursuant to 10 CFR 50.55a(a)(3). In proposed alternatives. the licensee must demonstrate that: (i) the proposed alternatives provide an acceptable level I of quality and safety; or (ii) compliance would result in hardship or unusual '

difficulty without a compensating increase in the level of quality and safety. I In requesting relief, pursuant to 10 CFR 50,55a(g)(5), the licensee must i demonstrate that the requirement is impractical for their facility.

Section 50.55a of Title 10 of the Code of Federal Regulations authorizes the Commission to grant relief from, and authorize alternatives to ASME Code requirements upon making the necessary findings. The NRC staff's finding with respect to whether to grant the relief request as part of the licensee's ISI program or authorize an alternative is contained in this Safety Evaluation (SE).

This SE covers a request for approval to use the ASME Boiler and Pressure Vessel (B&PV) Code Case N-508-1, for Wolf Creek Generating Station (WCGS), as an alternative to the ASME B&PV Code,Section XI, requirements submitted by the Wolf Creek Nuclear Operating Corporation (WCNOC) letter dated January 2, 1997. The licensee's ISI program for the current interval is based on the repair and replacement requirements of Section XI of the ASME B&PV Code.

Section XI. 1989 Edition for the second ten-year ISI program at WCGS,

2.0 BACKGROUND

l ASME Code Section XI Reauirement: Article IWA-7000 Replacement, specifies l the rules and recuirements to be used when replacing, among other items, l relief valves anc snubbers. In th6t article the owner's responsibilities are

! defined and require the owner to develop a replacement program that meets the

requirements of Section IWA-7130. Replacement Program. When a component is replaced under this program, IAW-7000 requires the preparation of a 9706260249 970623 PDR ADOCK 05000482 P PDR

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replacement plan and Form NIS-2, performance of specific Section XI reviews and evaluations, and review and concurrence of the Authorized Nuclear Inspector. These requirements a) ply even when removing and installing relief valves and snubbers solely for t1e purpose of testing.

Code Case N-508-1. " ROTATION OF SERVICED SNUBBERS AND PRESSURE RELIEF VALVES FOR THE PURPOSE OF TESTING. SECTION XI. DIVISION 1" Reauirements: Code Case N-508-1 provides an alternative to Article IWA-7000 when pressure relief valves and snubbers are rotated from stock and installed on components (including piping systems) within the Section XI boundary. Specific requirements, that are detailed in Code Case N-508-1, must be met when rotating components from stock for the purpose of testing. These requirements include: the items must be of the same design and construction:- the items shall have no evidence of failure at the time of removal; items being rotated shall be removed and installed only by mechanical means: items being installed shall previously have been in service: preservice inspections and pressure tests shall be performed as required by IWA-7000; traceability of inservice inspection and testing shall be maintained: the use of an NIS-2 form is not required except for repair or replacement of the rotated item: testing of removed snubbers and pressure relief valves, including required sample expansions, shall be in accordance with the owner's test program: and repair or replacement of removed items shall be performed in accordance with IWA-7000.

Staff Review of Code Case N-508-1: The staff has reviewed Code Case N-508-1 for acceptability and inclusion in Regulatory Guide 1.147. The staff concluded that it would not approve the generic use of the Code Case. The staff's concern was the Code Case did not provide assurance that its application would not adversely impact the existing snubber service life monitoring program. Specifically, when snubbers are rotated between stock and installation, without involving the preparation of a Section XI repair / replacement plan and the subsequent submittal of a Form NIS-2, traceability of the snubbers service life could be compromised.

3.0 RELIEF REQUEST The licensee requests ap3roval to use Code Case N-508-1 for snubbers and pressure relief valves tlat are rotated from stock for the purposes of testing as an alternative to the requirements of ASME Section XI Article IWA-7000, 3.1 Licensee's Basis for Reauested Relief When a snubber or relief valve is removed for the purposes of testing and when -

adequate spares are available. WCNOC rotates a replacement item into its place and tests the removed item at a later time. However, WCNOC could declare the system inoperable, remove the component, perform the test, reinstall the component and then declare the system operable. By rotating the components, WCNOC minimizes the time that the system is inoperable or out-of-service.

Currently, the activity of rotating components is required to be treated as a Section XI replacement activity meeting the requirements of Article IWA-7000.

The requirements of Article IWA-7000 are detailed above. The provisions of I

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3-Article IWA-7000 are appropriate when items are replaced because of a design i change or a nonconformance, but they are excessive for the removal and l

i installation of snubbers and relief valves solely for the purpose of testing.

I The licensee has stated that when performing the rotation of the item in accordance with IWA-7000 or Code Case N-508-1, the following will be required:

(1) a work package will be prepared to control the effort of removing and installing the replacement component from spares: (2) upon installation, the replacement component will receive the recuired inspections and tests: (3) the removed component will be tested in accorcance with required WCNOC test programs for snubbers and relief valves: (4) the work package for relief valves will provide the method for tracking the required inspections and tests: (5) for snubbers the managed maintenance data base will provide the method of tracking the required inspections and tests; and (6) if the removed component requires repair or replacement, these activities will be performed in accordance with Section XI, IWA-4000 or IWA-7000. As required by Code Case f1-508-1, if the item being removed shows evidence of failure, use of the Code  !

Case is not acceptable and the removal will be performed and documented in l accordance with IWA-7000. The use of the Code Case only eliminates i unnecessary administrative controls and documentation requirements associated with a Section XI replacement when an item is rotated from stock.

The snubber service life monitoring program is contained in the WCGS Updated Safety Analysis Report (USAR) (previously contained in the technical specifications) which requires inspection and testing of snubbers. Snubbers l are tracked by serial number and are tracked independently from the Section XI l Repair / Replacement Program. Use of Code Case N-508-1 will have no impact on l the implementation of that program. The snubber program will continue to meet '

all requirements contained in the USAR.

3.2 Evaluation Code Case N-508-1 provides an alternative to the current ASME B&PV Code,Section XI, Article IWA-7000 requirement to generate a Repair / Replacement Program when removing snubbers or 3ressure relief valves from a system for testing. The Code Case allows snu)bers and pressure relief valves to be rotated from stock and installed on components and piping systems within the Section XI boundary, provided all the requirements stated in the Code Case are met. The use of the Code Case eliminates only certain administrative controls and docu,nentation requirements associated with a Section XI replacement.

The licensee has agreed to meet all of the Code Case requirements. Further, if the component being removed shows evidence of failure, the licensee will not use Code Case N-508-1, but will use Section XI Article IWA-7000 of the ASME B&PV Code for repair or replacement activities.

In response to the staff's concern about the impact of the use of Code Case 1 N-508-1 on the snubber service life monitoring program, the licensee has I

stated the snubber service life monitoring program as contained in the WCGS USAR will be continued. Snubbers will continue to be tracked by serial number independently of the Section XI Repair / Replacement Program. Further, the

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-licensee states that. "Use of Code Case N-508-1 will have no impact on the implementation of the snubber service life monitoring program,"

The licensee's proposed alternative to use the Code Case for the purpose of testing snubbers and pressure relief valves will eliminate unnecessary administrative and documentation requirements, minimize the time during which the affected system is out-of-service, and component reliability will be maintained in that previously tested components will be used for rotation.

In considering the proposed use of Code Case N-508-1 for the WCGS, and the licensee's argument in addressing the staff's concerns with regard to an adverse impact on the existing snubber service life monitoring program, the staff has determined that the application is acceptable. The use of Code Case N-508-1, with the provision that the snubber service life monitoring program is not changed. provides and acceptable level of quality and safety.

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3.0 CONCLUSION

S The staff concludes that the licensee's proposed alternative to use Code Case N-508-1 for rotation of serviced snubbers and pressure relief valves for the purpose of testing in lieu of ASME B&PV Code,Section XI, Article IWA-7000 requirements provides an acceptable level of quality and safety for Wolf Creek i Generating Station in that it only affects the administrative and l documentation requirements of Section XI. Therefore, the licensee's proposed alternative with the clarification of the snubber service life monitoring program contained in the request for approval, is authorized by law, pursuant to 10 CFR 50.55a(a)(3)(i), for the first and second 10-year ISI interval, provided that all requirements of Code Case N-508-1 are satisfied. Use of Code Case N-508-1 is authorized until such time as the Code Case is published in a future revision of Regulatory Guide 1.147. At that time, if the licensee intends to continue to implement this Code Case, the licensee is to follow all provisions in Code Case N-508-1 with the limitations issued in Regulatory Guide 1.147, if any.

l Principal Contributor: F. Grubelich I J. Stone l

Date: June 23, 1997 I

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