ML18152B538

SER Accepting Third 10-year Interval Inservice Insp Request for Relief for Surry Power Station,Unit 1.Staff Concludes That Licensee Proposed Alternative Will Provide Acceptable Level of Quality & Safety.Technical Ltr Rept Also Encl

ML18152B538
Person / Time
Site:	Surry
Issue date:	02/16/1999
From:	NRC (Affiliation Not Assigned)
To:
Shared Package
ML18152B537	List: ML18152B536 ML18152B538
References
NUDOCS 9902180338
Download: ML18152B538 (6)

Text

e UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION OF THE THIRD 10-YEAR INTERVAL INSERVICE INSPECTION REQUEST FOR RELIEF

1.0 INTRODUCTION

VIRGINIA ELECTRIC AND POWER COMPANY SURRY POWER STATION, UNIT 1 DOCKET NUMBER: 50-280 lnservice inspection 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 (B&PV) Code and applicable addenda as required by 1 O CFR 50.55a(g),

except where specific written relief has been granted by the Commission pursuant to Title 1 O of the Code of Federal Regulations (1 O CFR) Section 50.55a(g)(6)(i). Section 50.55a(a)(3) states that alternatives to the requirements of paragraph (g) may be used, when authorized by the NRC, if (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 1 O 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 lnservice 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 Section 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 applicable edition of Section XI of the ASME Code for the Surry Power Station, Unit 1 third 10-year inservice inspection (ISi) interval is the 1989 edition of Section XI of the ASME Boiler and Pressure Vessel Code.

By letter dated July 6, 1998, the licensee proposed alternatives to the Code contained in the Request for Relief for Surry Power Station, Unit 1.

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• 2.0 EVALUATION*

The staff, with technical assistance from its contractor, the Idaho National Engineering and Environmental Laboratory (INEEL), has evaluated the information provided by the licensee in support of the licensee-proposed alternative contained in its Request for Relief for Surry Power Station, Unit 1. Based on the results of the review, the staff adopts the contractor's conclusions and recommendations presented in the Technical Letter Report attached to this Safety Evaluation.

Request for Relief: This request for relief involves the use of Code Case N-498-1, Alternative Rules for 10-Year System Hydrostatic Testing for Class 1, 2, and 3 SystemsSection XI, Division 1.

Section IWA-5000 requires pressure-retaining components within each system boundary to undergo system hydrostatic tests for Class 1, 2, and 3 systems under VT-2 visual examination in accordance with IWA-5240 to detect leakages. In accordance with 10 CFR 50.55a(a)(3), the licensee proposes to use Code Case N-498-1, Alternative Rules for 10-Year System Hydrostatic Testing for Class 1, 2, and 3 SystemsSection XI, Division.1. Code Case N-498-1, in part, provides that for Class 1, 2, and 3 systems, prior to performing the VT-2 visual examination, the system shall be pressurized to nominal operating pressure for at least 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> for insulated systems and 10 minutes for noninsulated systems, while maintaining nominal operating pressure during performance of the VT-2 examination.

Code Case N-498 is approved for general use in Regulatory Guide 1.14 7, Revision 11, for Class 1 and 2 systems. Code Case N-498-1 is the revision of Code Case N-498 to include requirements for Class 3 systems that are identical to the Code Case N-498 requirements for Class 2 components for Class 1 and 2 systems. In addition, Class 3 systems will receive inspections commensurate with the function and expected failure mechanisms. Thus, the proposed use of Code Case N-498-1 for Class 1, 2, and 3 systems will provide an acceptable level of quality and safety by providing an adequate means to detect leakage.

3.0 CONCLUSION

The staff evaluated the July 6, 1998, submittal and concludes that the licensee's proposed alternative will provide an acceptable level of quality and safety. Therefore, the licensee's proposed alternative is authorized pursuant to 10 CFR 50.55a(a)(3)(i) for the current interval or

0 e until such time as the revised Code Case has been accepted for general use within Regulatory Guide 1.14 7. 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.

Attachment:

Technical Letter Report Principal Contributor: G. Hatchett Date:

February 16, 1999

e TECHNICAL LETTER REPORT ON THIRD 10-YEAR INTERVAL INSERVICE INSPECTION PROPOSED ALTERNATIVE N-498-1

1.

INTRODUCTION FOR

• VIRGINIA ELECTRIC AND POWER COMPANY SURRY POWER STATION, UNIT 1 DOCKET NUMBER: 50-280 By letter dated July 6, 1998, the licensee, Virginia Electric and Power Company, submitted a proposed alternative to the requirements of the ASME Code,Section XI, for the Surry Power Station, Unit 1, third 10-year inservice inspection (ISi) interval. The Idaho National Engineering and Environmental Laboratory (INEEL) staff's evaluation of the subject request for relief is in the following section.

2.

EVALUATION The information provided by Virginia Electric and Power Company in support of the proposed alternative from Code requirements has been evaluated and the basis for disposition is documented below. The Code of record for the Surry Power Station, Unit 1, third 10-year ISi interval, which began October 14, 1993, is the 1989 Edition of Section XI of the ASME Boiler and Pressure Vessel Code.

Proposed Alternative N-498-1, Use of Code Case N-498-1, Alternate Rules for 1q Year Hydrostatic Pressure Testing for Class 1. 2. and 3 Systems.Section XI. Division 1 Code Requirement: Table IWB-2500-1, Examination Category B-P, Table IWC-2500-1, Examination Category C-H, and Table IWD-2500-1, Examination Categories D-A, D-B and D-C, require system hydrostatic testing of pressure-retaining components in accordance with IWA-5000 once each 10-year interval.

Licensee's Proposed Alternative: Pursuant to 10 CFR 50.55a(a)(3), the licensee has requested authorization to use Code Case N-498-1, Alternate Rules for 10-Year Hydrostatic Pressure Testing for Class 1, 2, and 3 Systems,Section XI, Division 1.

Licensee's Basis for Requesting Relief (as stated):

"Hydrostatic tests are historically difficult to perform. They frequently require extending the duration of the test while non-safety related issues, such as maintenance boundary valve isolation problems, are resolved. This increases the cumulative exposure of test personnel and extends the system tag-out duration. By taking advantage of Code Case N-498-1, increased testing flexibility is provided by permitting testing to be performed at nominal operating pressure. This significantly reduces the number of test blocks, system tag-outs, and corresponding boundary valves required to complete testing. This flexibility is accomplished while maintaining an acceptable level of quality and safety as determined by the ASME Code consensus process.

Attachment

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• Evaluation: The Code requires a system hydrostatic test once per interval in accordance with the requirements of IWA-5000 for Class 1, 2, and 3 pressure-retaining systems. In lieu of the Code-required hydrostatic testing, the licensee has requested authorization to use Code Case N-498-1, Alternative Rules for 10-YearSystem Hydrostatic Testing for Class 1, 2, and 3 Systems, dated May 11, 1994.

The system hydrostatic test, as stipulated in Section XI, is not a test of the structural integrity of the system but rather an enhanced leakage test. 1 Hydrostatic testing only subjects the piping components to a small increase in pressure over the design pressure; therefore, piping dead weight, thermal expansion, and seismic loads present far greater challenges to the structural integrity of a system. Consequently, the Section XI hydrostatic pressure test is primarily regarded as a means to enhance leak detection during the examination of components under pressure, rather than as a method to determine the structural integrity of the components. In addition, the industry experience indicates that leaks are not being discovered as a result of hydrostatic test pressures causing a preexisting flaw to propagate through the wall. In most cases leaks are being found when the system is at normal operating pressure.

Code Case N-498, Alternative Rules for 10-Year System Hydrostatic Testing for Class 1 and 2 Systems, was previously approved for general use on Class 1 and 2 systems in Regulatory Guide 1.147, Rev. 9. For Class 3 systems, Revision N-498-1 specifies requirements identical to those for Class 2 components (for Class 1 and 2 systems, the alternative requirements in N-498-1 are unchanged from N-498). In lieu of 10-year hydrostatic pressure testing at or near the end of the 10-year interval, Code Case N;..498-1 requires a VT-2 visual examination at nominal operating pressure and temperature in conjunction with a system leakage test performed in accordance with paragraph IWA-5000 of the 1992 Edition of Section XI.

Class 3 systems do not normally receive the amount. and/or type of nondestructive examinations that Class 1 and 2 systems receive. While Class 1 and 2 system failures are 1 - S. H. Bush and R. R. Maccary, "Development of In-Service Inspection Safety Philosophy for U.S.A. Nuclear Power Plants," ASME, 1971

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• relatively uncommon, Class 3.leaks occur more frequently and are caused by different failure mechanisms. Based on a review of Class 3 system failures requiring repair during the last 5 years,2 the most common causes of failure are erosion-corrosion (EC),

microbiologically-induced corrosion (MIC), and general corrosion. In general, licensees have implemented programs for the prevention, detection, and evaluation of EC and MIC; therefore, Class 3 systems receive inspection commensurate with their functions and expected failure mechanisms.

Considering that Code Case N-498 was found to be an acceptable alternative for Class 1 and 2 systems, and that Class 3 systems receive inspections commensurate with their function antj expected failure mechanisms, the licensee's proposed alternative, to use Code Case N-498-1, should provide an acceptable level of quality and safety.

3.

CONCLUSION The INEEL staff evaluated the July 6, 1998, submittal and concludes that the licensee's proposed alternative provides an acceptable level of quality and safety. Therefore, it is recommended that the licensee's proposed alternative be authorized pursuant to 10 CFR 50.55a(a)(3)(i). The use of Code Case N-498-1 should be authorized for the current interval or until such time as the Code Case is pubHshed in a future revision of Regulatory Guide 1.147. At that time, if the licensee intends to continue to implement Code Case N-498-1, the licensee should follow all provisions in the Code Case with limitations issued in Regulatory Guide 1.147, if any.

2 - Documented in Licensee Event Reports and the Nuclear Plant Reliability Data System databases.