ML20246C462

Safety Evaluation Granting Request for Relief from Hydrostatic Testing Requirements of Section XI of ASME Code

ML20246C462
Person / Time
Site:	McGuire, Mcguire
Issue date:	06/29/1989
From:	Office of Nuclear Reactor Regulation
To:
Shared Package
ML20246C452	List: ML20246C448 ML20246C462
References
NUDOCS 8907110026
Download: ML20246C462 (4)

Text

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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION REQUEST FOR RELIEF FROM REGULATORY REQUIREMENTS DUKE POWER COMPANY DOCKET NOS. 50-369 AND 50-370 MCCU1RE NUCLEAR STATION, UNITS 1 AND 2

1.0 INTRODUCTION

Technical Specification 4.0.5 for the McGuire huclear Station, Units 1 and 2, states that the surveillance requirements for inservice inspection of ASME Code Class 1, 2, and 3 components shall be perforred in accordance with Section XI of the ASME Code and applicable Addenda as requireo by 10 CFR 50.55a(g), except where specific written relief has been granted by the Comission pursuant to 10 CFR 50.55a(g)(6)(1).

Pursuant to 10 CFR 50.55a(g)(5), if the licensee determines that conformance with an examinat '* requirement of Section XI of the ASME Code is not practical for tha f acility, infonnation shall be submitted to the Comission 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 Comission may grant relief and may impose alternative requirements as it determines to be authorized by law, will not endanger life or 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.

In letters dated June 27, 1988, and February 16, 1989, Duke Power Comparty (the licensee) requesteo relief f rom hydrostatic testing requirements of Section XI, 1980 Edition, including Winter 1980 Addenda, of the ASME Code, Article IWA-4400 and Article IWD-5000, for the McGuire Nuclear Station, Units 1 and 2. These requests were identified as Pelief Request j Numbers 88-05 and 89-02, respectively. Both requests are associated with modifications to the McGuire Nuclear Service Water (RN) System. The requests and supporting information have been evaluated by the NRC staff, as noted in the following description and evaluation.

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2.0 DESCRIPTION

RELIEF REQUEST NO. 89-02 In its letter of February 16, 1989, the licensee requested relief from ASME Code requirements for six modifications proposed to improve the reliability end maintainability of the RN system. This system is an ASME Code, Class 3 system, providing cooling water to various heat exchdngers during all phases of plant operation. The relief request is for weld and flange corrections associated with six nuclear station modifications (NSM). These six modifications and their planned dates for implementation are:

(a NSM MG-12233, Rev. 0 - January 1,1991 (b NSM MG-22233, Rev. 0 - September 1,1990 NSM MG-12243, Rev. 0 - January 1,1990 NSM MG-22243, Rev. 0 - July 1, 1989 f HSN MG-22130, Rev. 0 - July 1,1989 (f) NSM MG-52128, Rev. 0 - Septenber 1,1989 The purpose of each NSM listed above is discussed below:

1) NSM MG-12233 Rev. O and NSM MG-22233 Rev. O replace flow elements 1RNFE5370, 2RNFE5360, and 2RNFE5370 which provide flow indication for RN system to Component Cooling (KC) Heat Exchangers 18, 2A, and 2B respectively.

2) NSM MG-12243 Rev. O and NSM MG-22243 Rev. O will replace valves 1RN-89A 1RN 190B 2RN-89A and 2RN-190B which are 20-inch Fisher butterfly vr.lves u, sed for flow regulation and isolation of RN system to KC Heat Exchangers.

3) NSM MG-22130 Rev. 0 will replace expansion joints 2RN4A and 2RN4B which are used to minimize pump suction casing loading on RN Pumps 2A and 2B respectively.

4) NSM MG-52128 Rev. O will add piping and valves to allow RN s water to the Control Area HVAC/ Chilled Water system (VC/YC) chiller ystem to be discharged to the comon 36-inch RN header between Unit I and Unit 2. This modification will aid RN system work on Unit 1.

For the above modifications the licensee requested relief because testing is impractical due to the inadequacy of the test boundaries. The hydrostatic test boundary isolation valves include 36-in., 20-in. , and I 18-in. , butterfly valves. These valves have a history of leakage and do I

not offer adequate isolation to permit a hydrostatic test.

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The RN system is a low pressure, low temperature system designed to a pressure of 135 psig and a temperature of 150' F. The required test pressure is 1.1 times design or approximately 150 psig. NSM MG-22130, Rev. O, contains an expansion bellows assenbly having a design pressure of 35 psig. The required test pressure for this section of piping would be 38.5 psig. I In lieu of hydrostatic testing, the licensee proposes that all welds in the modifications be subjected to a dye penetrant (PT) or magnetic particle (MT) examination on the root pass and finished weld. An in-service leak test would also be performed at normal system pressure.

RELIEF REQUEST N0. 88-05 In its letter of June 27, 1988, the licensee requested relief for four additional modifications to be made in the RN system. Eight welded butterfly valves will be replaced with flange end connection valves, four each in the Containment Spray and Component Cooling Systems. Relief from the hydrostatic test requirements was requested for all welds associated with the valves being replaced. The welds connect new flanges to existing pipe. The four modifications and their planned dates for implementation are:

(a) NSM MG-12107, Rev. 0 - February 1,1990 b NSM MG-22107, Rev. 0 - August 1, 1989 c NSM MG-12129, Rev. 0 - February 1,1991 d NSM MG-22129, Rev. 0 - January 1,1991 HSM MG-12107, Rev. O will replace Unit I valves IRN-134A and 1RN-235B and NSM MG-22107, Rev. O will replace corresponding Unit 2 valves 2RN-134A and 2RN-235B. These four valves provide inlet isolation to the four  ;

Containment Spray System heat exchangers. NSM MG-12129, Rev. O will l replace Unit i valves 1RN-86A and 1RN-187B and NSM MG-22129, Rev. O will l replace corresponding Unit 2 valves 2RN-86A and 2RN-187B. These four  ;

valves provide inlet isolation to the KC System heat exchangers. '

The modifications for which relief has been requested will be made during refueling outages. The RN system provices coolant for the Residual Heat l Removal and Spent Fuel Cooling Systems, both of which are needed during j the outage. During the cutage, the supply and discharge header for either j train can be drained and available for work for six days on Unit I and ten days on Unit 2. Unit 1 is more restricted because the control room ventilation and chilled water system discharge to the Unit I discharge header only. Thus, when this header is drained, these systems are inoperable, which places Unit 2 in a seven day operability constraint in compliance ]

with Technical Specification 3.7.6. These short time periods restrict the j allowable time to that required for the modifications. A hydrostatic test ,

is impractical and would add days to the outage scheoule, l

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Since the isolation valves on the system are 36-in butterfly valves, the valves would leak at hydrostatic test pressure. To replace the valves would involve a major undertaking. The licensee stated that the additional manpower, planning, execution expense, and burden required to perform the test would not provide a commensurate increase in operational quality.

In lieu of hydrostatic testing the licensee proposes that the welds be subjected to a liquid penetrant or magnetic particle examination on the root pass and the final welding pass. An inservice leak test at system pressure and temperature would also be nade on the welds involved. The licensee believes that the alternative testing that is planned is adequate to ensure safe ano consistent reliability of the system.

3.0 EVALUATION We have reviewed the licensee's submittels inclucing drawings and descriptions of the modifications. We concur with the licensee that the ASME Code requirements of Article IWA-4400 and Article IWD-5000 are impractical to perform on the modifications at the McGuire Nuclear Station, Units 1 and 2, and that the alternate testing provices an equivalent level of confidence in system integrity. We also find that due to design contraints, compliance with the Code would result in a burden on the licensee.

4.0 CONCLUSION

We conclude from our evaluations of the information submitted by the licensee in support of F,elief Request Nos. 89-02 and 88-05 that the Section XI ASME Code requirements of Article IWA-4400 and Article IWD-5000 are impractical for McGuire Nuclear Station, Units 1 and 2. The alternative weld examinations and inservice leak tests proposed in lieu of the ASME Code requirements will ensure acceptable levels of inservice structural integrity for the RN system.

Accordingly, relief from the hydrostatic test requirements is granted as requested, pursuant to 10 CFR 50.55a(g)(6)(i). This relief is authorized by law and will not endanger life or 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 requirements were imposed on the facility.

Principal Contributor: D. Hood, PD#11-3/DRP-1/II F. L itton, D'EB/ DEST Dated: June 29, 1989 l

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