ML20198H554

SER Accepting Request for Approval of ASME Case N-498,rev 1, as an Alternative to Required Hydrostatic Pressure Test for Plant,Unit 2

ML20198H554
Person / Time
Site:	North Anna
Issue date:	12/29/1997
From:	NRC (Affiliation Not Assigned)
To:
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ML20198H526	List: ML20198H520 ML20198H554
References
NUDOCS 9801130337
Download: ML20198H554 (4)

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• j ,j UNITED STATES

. NUCLEAR REGULATORY COMMISSION

\ /s nswisaton. o.c. nosoooi 1Aff,J1EVALUAT10N BY THE OFFICE OF NUCLEAR REACTOR REGULATION REQUEST FOR APPROVAL TO USE CODE CASE N 498-1 VIRGINIA ELECTRIC ann POWER COMPANY NORTH ANNA POWER STAT 10N. UNIT 2 DOCKET NO. 50-339

1.0 INTRODUCTION

The Technical Specifications for riorth Anna Power Station, Unit 2, (NAPS 2),

state that the inservice inspection (ISI) 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)(1). 10 CFR 50.55a(a)(3) states that alternatives to the requirenents of paragraph (g) may be used, when authorized by the NRC if (1) the proposed alternatives would provide an acceptable level of quality end 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 areservice examination requirements, set forth in the ASME Code.Section XI. " Rules for Inservice Inspection of Nuclear Power Plant Congonents." 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 cnd subsecuent intervals comply with the requirements in the latest edition and addenca of 3ection XI of the ASME Code incorporated by reference in 10 CFR 50.55a(b) 12 months prior to the start of the 120 month interval, subject to the limitations and modifications listed therein. The a)plicable ASME Code.Section XI. for NAPS-2 second 10-year 151 interval is t1e 1986 Edition. The components (including supports) may meet the requirements set forth in subsequent editions and addenda of the ASME Code incorporated by reference in 10 CFR 50.55a(b) subject to the limitations and modifications listed therein and subject to Commission approval.

Enclosure SR H O 339 P__ PDR

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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 practical 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)(1), the Comission may grant relief and may impose alternative 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 licensee that could result if the requirements were imposed.

By letter dated October 14, 1997, Virginia Electric and Power Company, the licensee for NAPS 2, submitted to the NRC their request for relief from the examination requirement of the 1986 edition of the ASME Code,Section XI, in regard to conducting the 10 year system hydrostatic test and proposed to implement Code Case N 498-1 as an alternative, for the second inservice inspection interval examinations. The Civil Engineering and Geosciences Branch, Division of Engineering, has reviewed and evaluated the licensee's proposed alternative to use Code Case N 498-1, "Alterr.ative Rules for 10 Year System Hydrostatic Testing for Class 1, 2, and 3 Systems.Section XI. Division 1" during the second 10-year inservice inspection interval of NAPS 2.

2.0 D.lSCUSS10N:

a. Component

Description:

Hydrostatic Testing of Class 1, 2 and 3 Systems - Request for Approval to use Code Case N 498 1

b. ASM". Code Class:

ASME Section XI Class 1, 2, and 3

c. ASME Examination Requirements. ASME Section XI, 1986 Edition:

Table IWB-2500 1. Examination Category B-P, Table IWC-2500-1 Examination Category C-H and Table IWD-2500-1. Examination Categories 0-A, 0 B, and D C.

require hydrostatic testing of pressure retaining components during each inspection interval.

d. Basis for Relief:

ASME Code Case N-498 1, " Alternative Rules for 10-Year System Hydrostatic Testing for Class 1, 2, and 3 Systems,Section XI Division 1," was approved by ASME on May 11, 1994. This Code Case has not yet been approved for use by Regulatory Guide 1.147, inservice Inspection Code Case Acceptability ASME Section XI Division 1. Therefore, pursuant to 10 CFR 50.55a(6)(3), it is requested that Code Case N-498 1 be approved for use at NAPS-2 to complete its second interval requirements.

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3 NAPS 2 is' scheduled to begin its second interval, third period. 10 year  !

inservice ins >ections durin  !

scheduled to >egin April 5,g its next refueling outage, which isancurrently '

1998. Code Case N 498 1 now provides '

alternative to the Class 3. as well as the Class 1 and 2 (Code Case N 498) hydrostatic test Code requirements (ASME Section XI 1986 Edition). Proper '

advance planning for this upcoming outage necessitates that advance approval for use of Code Case N 4981 be obtained in lieu of the normal Regulatory Guide 1.147 revision process.

Hydrostatic tests are historically difficult to perform. They frequently ,

require extending test durations while non safety related issues such as maintenance boundary valve isolation problems are resolved. This increases the-cumulative exposure of test personnel and sy:, tem tag out daration. By taking advantage of Code Case N 498 1. increased testing flexibility is provided,  ;

allowing testing to be >erformed at nominal o>erating pressure. in turn, this i significantly reduces tie number of test bloccs, system tag outs, and {

corresponding bou;1dary valves required to complete testing. This flexibility is accomplished while maintaining an acceptable level of safety and quality as determined by the ASME Code.

Code Case N 498-1 will continue to provide assurance of component structural integrity as intended by the ASME Code and, as such, it is requested that interim use of the Code Case be a proved for the upcoming NAPS-2 outage, currently scheduled to commence A ril 1998,

e. Alternative Examination:

Alternative provisions of Code Case N 498 1 will be used in lieu of the requirements of Table IWB 2500-1. Table IWC 2500-1. and Table IWD 2500-1 of t ie 1986 Edition. ASME Code.Section XI, for the 10 year system hydrostatic test of Class 1. 2. and 3 systems.

3.0 EVALUATION

The licensee has requested approval for the implementation of the alternative  !

rules of ASME Section XI Code Case N 498-1 dated May 11, 1994. " Alternative Rules for 10 year System Hydrostatic Testing for Class 1. 2, and 3 Systems." in lieu of 10 year hydrostatic testing of Class 1. 2 and 3 systems. Use of Code Case N 498 for Class 1-and 2 systems was previously approved by the NRC in  :

Regulatory Guide 1.147, Rev. 11. The rules for Class 1 and 2 in N-498-1 are unchanged from N 498. The staff found the use of N 498 to be acceptable since the alternative provided-reasonable assurance of operational readiness and compliance with the specified Code requirements would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety. < Code Case N 4981, however, encompasses Class 3 compenents and

- specifies requirements for Class 3 that are identical to those for Class 2 components. In lieu of the 10 year hydrostatic pressure testing at or near the end of the 10 year interval. Code Case N-4981 requires that a visual ,

examination (VT-2) be performed in conjunction with system leakage testing in accordance with paragraph IWA-5000. Class 3 systems do not normally receive the amount and/or type of non-destructive examinations that Class 1 and 2 systems receive. khile Class 1 and. 2 system failures are relatively uncomon.

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Class 3 leaks occur more frequently and the failure mode typically differs.

The most common cause failures in Class 3 systems are errosion-corrosion, microbiological 1y induced corrosion, and general corrosion. The licensees generally have programs in place for prevention, detection, and evaluation of these degradation mechanisms. The industry experience further demonstrates

- that leaks are seldom discovered as a result of hydrostatic test pressure driving a pre-existing flaw throv jh wall: rather, they are found in most cases at normal operating condition.

Licensees incur considerable t1 9 and radiation dose to conduct a hydrostatic test in comparison to a system I skage test for a minimal amount of increased ,

assurance of structural integrity orovided by a slightly higher pressure '

associated witn hydrostatic test of Class 3 systems. Therefore, the staff i finds that compliance with the ASME Section XI hydrostatic testing requirements l as opposed to system leakage test of Class 3 systems results in hardship and/or i unusual difficulty to licensees without a compensating increase in the l w el of {

- quality and safety. '

4.0 CONCLUSION

The staff has evaluated the information provided by the licensee in support of its request for relief to implement Code Case N 498-1 as an alternative to the '

10-XI. year Thesystem staff has hydrostatic determined test required that the proposed by the applicable testing in ..cordance VsME Code. withSection the rules of Code Case N 4981 provides reasonable assurance of operational  ;

i readiness without and compliance a compensating increase with the in quality Code requirement and safety. would Therefore resultlicenseein hardship's  !

proposed alternative to use Code Case N-498 1 in lieu of the Code required 10- i ear hydrostatic test is authorized, pursuant to 10 CFR 50.55a(a)(3)(11) for ,

APS-2. during the second inspection interval. The use of Code Case N 498 1 is '

authorized for the second inspection interval until such time as the Code case is approved by reference in 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 498-1 with limitations issued in .

Regulatory Guide 1.147 if any.  :

Principal Contributor: P. Patnaik Date: December 29, 1997

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