ML20138E441

Safety Evaluation on ASME Code Case N-509 for Crystal River Nuclear Plant,Unit 3

ML20138E441
Person / Time
Site:	Crystal River
Issue date:	04/30/1997
From:	NRC (Affiliation Not Assigned)
To:
Shared Package
ML20138E430	List: ML20138E426 ML20138E441
References
NUDOCS 9705020197
Download: ML20138E441 (5)

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'2 NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 4 ,o 9***** SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION ON ASME CODE CASE N-509 CRYSTAL RIVER NUCLEAR PLANT UNIT N0. 3 FLORIDA POWER CORPORATION 1 DOCKET NO: 50-302 I l

1.0 INTRODUCTION

The Technical . Specifications (TS) for the Crystal River Nuclear Plant, Unit 3 (CR3), state that the inservice inspection and testing 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)(i). 10 CFR 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 1 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 preservice examination requirements, set forth in the ASME Code,Section XI, " Rules for Inservice Inspection of Nuclear Power Plant Components," to the extent practical within the limitations of design, i 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 the ASME Code,Section XI, incorporated by reference in 10 CFR 50.55a(b) on the date 12 months prior to the start of the 120-month interval, subject to the l limitations and modifications listed therein. The applicable ASME Code Section XI edition for CR3, during the second 10-year inservice inspection (ISI) interval is the 1983 Edition though the Summer 1983 Addenda. The j 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.

Pursuant to 10 CFR 50.55a(a)(3), by letter dated March 24, 1997, Florida Power Corporation (FPC or the licensee), requested approval for implementing the alternative rules of ASME Section XI Code Case N-509, " Alternative Rules for  :

the Selection and Examination of Intergrally Welded Atte.hments,Section XI, Division 1," to be applied to the ISI program for CR3. l ENCLOSURE 9705020197 970430 PDR ADOCK 05000302 P PDR l

2 The staff has reviewed and evaluated the licensee's request and supporting information to use Code Case N-509.

2.0 DISCUSSION CODE CASE N-509. ALTERNATIVE EXAMINATION REQUIREMENTS FOR INTEGRAL (?????)

WELDS IN CLASS 1 AND 2 PIPING - SECTION XI. DIVISION 1 Component Identification In . 'ra".j Welded Attachments to piping as specified in Table IWB-2500-1 Catt ...y B-K-1 (Item B10.10); Table IWC-2500-1 Category C-C (Item C3.20); and Table IWD-2500-1 Categories D-A, D-B, and D-C (Items for piping integral attachments only) of ASME Code,Section XI, 1983 Edition through Summer 1983 Addenda.

(a) Examination Category B-K-1 in Table IWC-2500-1, (Class 1), Item No.

B10.10 (Piping) only, (b) Examination Category C-C in Table IWD-2500-1, (Class 2), Item No. C3.20 (Piping) only, (c) Examination Category D-A in Table IWD-2500-1, (Class 3); Items No. i DI.20, DI.30, Dl.40, Dl.50, D1.60, i (d) Examination Category D-B in Table IWD-2500-1, (Class 3); Items No.

D2.20, D2.30, D2.40, D2.50, D2.60, (e) Examination Category D-C in Table IWD-2500-1, (Class 3); Items No.

D3.20, 03.30, D3.40, D3.50, D3.60.

Code Reauirement For Class 1, Examination Category B-K-1, volumetric or surface examinations, as applicable, is required for all integrally-welded attachments exceeding 5/8 inch design thickness during the first and second intervals when implementing Program B. For Class 2, Examination Category C-C, surface examination is required for all integrally-welded attachments exceeding 3/4 inch design thickness. For Class 3, Examination Categories D-A, D-B, and D-C, surface examination is required for all integrally-welded attachments corresponding to those component supports selected by IWF-2510(b).

Reauest for Relief Relief is requested from the existing Code requirements for determining the extent of examination of Class 1, 2, and 3 integrally welded attachments to piping as defined in ASME Section XI, Articles IWB, IWC, and IWD of the ASME Boiler and Pressure Vessel Code, 1983 Edition through Summer 1983 Addenda.

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3 Licensee's Basis for Relief (As stated) a) Florida Power Corporation is requesting relief from the above stated requirements based on ASME Section XI Code Case N-509 which has been issued by the American Society of Mechanical Engineers and has been included in the 1995 Addenda of Section XI.

l b) At Crystal River Unit 3, component supports are selected for examination '

I per ASME Code Case N-491 which was adopted by the 1990 Addenda to ASME Section XI, Subsubarticle IWF-2510. Application of Code Case N-509 defines alternative examination requirements that may be applied to ASME Code Class 1, 2 and 3 integrally welded attachments. The extent of examination as stated in Note 5 of Table 2500-1, Examination Categories B-K, C-C, and D-A of Code Case N-509 reduces the required examinations to 10% of the integral attachments associated with component supports selected for examination under the 1990 Addenda to Section XI, paragraph IWF-2510.

l Crystal River Unit 3 will schedule a minimum of 10% of the total population of integral attachments to piping in non-exempt Code Class 1, 2, and 3 systems. This approach is conservative and would provide an acceptable level of quality and safety.

c) Examination of the Class 1 and some Class 2 integrally welded i attachments can result in radiation exposure of 1.6 to 2.0 mrem per examination. By limiting examinations to 10% of the total population of integral attachments to piping in non-exempt Code Class 1, 2, and 3 ,

systems, the time requirements and the radiation exposure of personnel '

would be reduced. Therefore, compliance with the existing ASME Section XI 1983 requirements would result in higher exposure without a compensating increase in the level of quality or safety.

I d) Industry experience in the United States has also shown that ASME Code integral attachment welds have not experienced degradation that would warrant continued examination to the extent required by the 1983 edition i of ASME Section XI. To date, no significant loading conditions or known material degradation mechanisms have become evident that specifically relate to integral attachment welds in nuclear power plant piping.

Should a service induced defect be detected in these welds, ASME Code Case N-509, specifies examination expansion criteria to ensure degradation in other attachment welds would be detected. Therefore, the health and safety of the public will continue to be maintained while implementing the alternative examination requirements of Code Case N-509.

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4 Licensee's Alternate Examination (As stated)

The following alternative examination requirements will be implemented as defined by ASME Section XI Code Case N-509, exclusive of the selection criteria which is defined by item (d) below:

l a) ASME Code Case N-509 and Table 2500-1, Examination Category B-K, shall

be used for Class 1 integrally welded attachments to piping as defined by Examination Category B-K-1 of ASME Section XI, Article IWB.

b) ASME Code Case N-509 and Table 2500-1, Examination Category C-C, shall be used for Class 2 integrally welded attachments to piping as defined

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by Examination Category C-C of ASME Section XI, Article IWC.

! c) ASME Code Case N-509 and Table 2500-1, Examination Category D-A, shall

, be use? for Class 3 integrally welded attachments to piping as defined by Examination Categories D-A, D-B, and D-C of ASME Section XI, Article

IWD.

i d) In addition to the requirements of ASME Code Case N-509, the extent of scheduled examination shall be a minimum of 10% of the total population

(no thickness exemption) of integral attachments in non-exempt Code i Class 1, 2 and 3 systems.

3.0 EVALUATION l The licensee has proposed, as an alternative to the Code requirements, to apply the requirements of Code Case N-509 for the examination of f integrally-welded attachments on Class 1, 2, and 3 piping and components.

Code Case N-509 provides alternative sampling requirements for the examination

of Class 1, 2, and 3 integral attachments. In addition, the licensee proposed i examine 10% of the integrally attachments in each of the non-exempt Code Class 1, 2, and 3 systems in accordance with Code Case N-509 requirements. Based on industry experience in the United States that no significant loading conditions or known material degradation mechanisms relating to integral attachment welds in nuclear power plant piping have become evident, the licensee concludes that continued examination to the extent required by the i 1983 edition of ASME Section XI is not warranted. The staff finds that a j sampling process, if extended to welded attachments, would provide assurance i that service-related degradation is not occurring and a sample of minimum 10%

of all integral welded attachments in Code Class 1, 2, and 3 systems is

• sufficient to assure that degradation, if occurring, will be detected.

Further, should a service induced defect be detected in these welds, ASME Code Case N-509, specifies examination expansion criteria to ensure degradation in other attachment welds would be detected. Therefore, the staff concludes that the use of alternative contained in Code Case N-509, with a minimum 10%

selection of all integrally-welded attachments in each Code class, will provide an acceptable level of quality and safety.

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4.0 CONCLUSION

i Based on the above discussions, the staff concludes that the licensee's  !

proposed use of Code Case N-509 as. an alternative to the Code requirements, provides an acceptable level of quality and safety. Therefore, the licensee's proposed alternative to use Code Case N-509 is authorized pursuant to 10 CFR 50.55a(a)(3)(1). The licensee is authorized to use Code Case N-509 until such time as the code case is included in a future revision of Regulatory Guide 1.147. At that time the licensee should follow all provisions and any limitations that may be described in the Regulatory Guide 1.147 concerning the use of Code Case N-509.

Principal Contributor: T. McLellan, DE/NRR Date: April 30, 1997 i

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