ML20217A721

Safety Evaluation Supporting Proposed Alternative for ANO-1 to Implement Code Case N-533 (w/4 H Hold Time at Test Conditions Prior to VT-2 Visual Exam)

ML20217A721
Person / Time
Site:	Arkansas Nuclear
Issue date:	04/17/1998
From:	NRC (Affiliation Not Assigned)
To:
Shared Package
ML20217A700	List: ML20217A696 ML20217A721
References
NUDOCS 9804220317
Download: ML20217A721 (5)

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p ps vtoy,k UNITED STATES j

g NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. enana annt SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION REQUEST TO USE CODE CASE N-533 FOR  !

ENTERGY OPERATIONS. INC.

ARKANSAS NUCLEAR ONE. UNIT 1

' DOCKET NO. 50-313 l

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1.0 INTRODUCTION

The Technical Specifications (TSs) for Arkansas Nuclear One, Unit 1 (ANO-1) 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 Title 10 of the Code of Federal Regulations (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). Section 50.55a(a)(3) states that attematives to the requirements of paragraph (g) may be used, when authorized by the NRC, if (i) the proposed altematives would provide an acceptable level of quality and safety, or (ii) compliance with the specified requirements would result in hardship or unusual difficulties  ;

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 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, 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 ANO-1 third 10-year ISI interval is the 1992 Edition, with pressure testing requirements from the 1993 Addenda. 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.

Pursuant to 10 CFR 50.55a(g)(5),if the licensee determines that conformance with an examina-tion requirement of Section XI of the ASME Code is not practical for its facility, information shall be submitted to the Comm!ssion 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)(i), the Commission may grant relief and may impose altemative requirements tc,at 9804220317 900417 DR ADOCK 0500 3 ENCLOSURE

l 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.

2.0 BACKGROUND

in a letter dated June 25,1997, Entergy Operations, Inc. (the licensee), submitted to the NRC its third 10 year ISI plan and requests for altematives for ANO 1. As part of the plan, Request Number 97-005 requested relief from Article IWA-5242(a) of Section XI for Code Class 1 and 2 piping systems. The portion of Request Number 97-005 related to Code Class 1 piping systems pertains to the use of ASME Code Case N-533, "Altemative Requirements for VT-2 Visual Exemination of Class 1 Insulated Pressure-Retaining Bolted Connections,Section XI, Division 1,"

which has been widely requested by licensees and, with the limitations discussed below, has been previously approved by the staff. Given the potential benefits of applying Code Case N 533 during a refueling outage scheduled for early 1998, the staff has opted to separately evaluate the l licensee's request pertaining to Code Case N-533 pending the completion of its review of the remainder of the plan for the third 10 year ISI interval for ANO-1 (including that portion of i Request Number 97-005 pertaining to Code Class 2 piping systems).

1 3.0 EVALUATION i The staff, has evaluated the information provided by the licensee in support of its third 10-yerr interval ISI plan, request to implement Code Case N 533 as an altemative to the Code requirements for ANO-1.

Code Reauirement: l l

i IWA-5242(a) states that for systems borated for the purpose of controlling reactivity, insulation shall be removed from pressure-retaining bolted connections for a direct VT-2 visual examination.

Code cases are periodically published by ASME to either clarify the intent of the Code rules or to i provide altemative rules to existing Code requirements. Use of these nonmandatory Code cases for inservice inspection is subject to general acceptance by the NRC staff and incorporation into Regulatory Guide (RG) 1.147. Pursuant to 10 CFR 50.55a, other Code cases may be used provided specific authorization is granted.

Licensee's Code Reimf Recuest Tne licensee has requested to use Code Case N-533, "A!temative Requirements for VT-2 Visual Examination of Class 1 Insulated Pressure Retaining Bolted Connections,Section XI, Division 1."

Licensee's Basis for Recuesting Relief (as stated)-

" Pursuant to 10 CFR 55a(s)(3)(ii), en altamative is requested on the basis that the original requirements would result in hardship without a compensating increase in the level of quality and safety.

3-Systems which are borated for the purpose of ctw*olling reactivity at ANO-1 include reactor coolant, decay heat removal, high pressure inlede. and make-up. These systems encompass a large portion of the overall181 program and phy" h cover a large expanse of the reactor building. Many areas in which this piping and the m..vciated bolted connections are located are difficult to access (e.g., scaffold and/or ladder installation is required) and many of these areas are located such that significant radiation exposures would be encountered, in order to identify leakage to be repaired during the outage, the preferred time frame to perform this inspection is the beginning of the outage subsequent to depressurization of the reactor coolant system. To perform these inspections at pressure would involve holding the reactor coolant system at operating pressure and temperature for an extended period of time to allow for scaffold construction, insulation removal and VT-2 inspection.

This is normally a relatively short time frame when the unit is transitioning to cold shutdown.

Holding the unit at normal operating temperature and pressure for an extended period of time would result in a significant delay in going to cold shutdown.

Performing this inspection at the end of the outage would be ineffective, since finding leakage at that time would constitute bringing the unit back to cold shutdown to perform the repair and then beginning the start up process over again. Also, in order to reinsulate the reactor coolant system at the end of the outage, the unit would have to remaM at hot standby while the insulation is reinstalled and the scaffolding is removed. Typically, the reinstallation of insulation and removal of scaffolding is performed prior to leaving cold shutdown.

In addition, the removal ani,einstallation of insulation with plant equipment in operation at

. system pressure and temperature increases the rid of personnel injury and presents a safety concem to plant personnel. The personnel risk anc radiation exposure is significant for the removal and reinstallation of insulation at these bol'.ed connections during pressure testing l activities.  !

A VT-2 visual examination with the system depressurized would still provide adequate detection j of leakage because boric acid residue can be easily detected with insulation removed at the bolted connection. ,

I Based on the previously stated reasons, Entergy Operations requests relief from the inspection at operating pressure requirements detailed in IWA 5242(a). In lieu of these requirements, Entergy Operations proposes the altemative examination requirements that follow."

Licensee's Proposed Altemative Examination (as stated):

"A system pressure test with a minimum four hour hold time and VT-2 visual examination shall be performed each refueling outage without the removal of insulation on systems borated for the purpose of controlling reactivity.

Each refuelog outage, the insulation shall be removed from the bolted connections in systems borated for the purpose of controlling reactivity, and a VT-2 visual examination shall be performed on each of the connections. During this VT-2 examination, the connections are not required to be pressurized. Any evidence of leakage shall be evaluated in accordance with IWA-5250.

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These altemative examination requirements are the same as those specified in ASME Section XI Code Case N-533 as approved by the Board of Nuclear Codes and Standards, with the additional four hour hold time provision stated above.

These attematives provide reasonable assurance that safety and integrity will be maintained for bolted connections in systems borated for the purpose of controlling reactivity."

Evaluation:

Paragraph IWA-5242(a) requires the removal of all insulation from pressure-retaining bolted connections in systems borated for the purpose of controlling reactivity when performing VT-2 visual examinations during system pressure tests. The licensee has proposed to use Code Case N 533, which requires (1) performing the Code-required pressure test without removing the insulation, (2) examining Class 1 bolted connections, each refueling outage, at atmospheric or static pressure with insulation removed, and (3) evaluating any evidence of leakage in accordance with IWA-5250.

Paragraph IWA-5242(a) provides requirements to ensure that leakage or evidence of leakage at bolted connections is found. Performing a W-2 visual examination during system pressure tests as required by Code Case N-533, with the insulation in place will likely result in the detection of any significant leakage. The licensee has committed to a 4-hour hold period prior to performing the VT-2 visual examination during system pressure tests. This hold period is consistent with the staff's acceptance of Code Case N-533 for other licensees. Furthermore, performing a VT-2 visual examination after removal of the insulation at atmospheric or static pressure during outages, as specified by Code Case N-533, will allow for examination for evidence of borated water leakage. The Code Case states that any evidence of leakage must be evaluated in accordance with IWA-5250 of Section XI.

The NRC has accepted the use of Code Case N-533 for numerous licensees (provided the 4-hour hold time at test condidtions is observed prior to the VT-2 visual examination) in accordance with 10 CFR 50.55(a)(3)(i) after finding the proposed altemative provides an acceptable level of quality and safety. The licensee has requested the use of an altematve to the ASME Code (the use of Code Case N-533 with the added 4-hour hold period) pursuant to 10 CFR 50.55(a)(3)(ii) on the basis that the original requirement results in hardship without a compensating increase in the level of quality and safety. The hardship associated with the current requirement includes increasing the duration of outages, increasing the risk of personnel injury, and increasing the radiation exposure of plant personnel. Given the staff's finding that the proposed attemative provides comparable assurance of the detection of leakage from borated systems, the staff also agrees that the hardships described by the licensee are witheut compensating increases in the level of quality or safety.

4.0 CONCLUSION

The staff has reviewed the licensee's submittal and concluded that by using Code Case N-533 l the licensee will locate and evaluate leakage, or evidence of leakage, in a manner comparable to j the requirements of the Code, the licensee's proposed altemative provides an acceptable level of i quality and safety and that the existing requirement results in hardship without a compensating j l

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increase in the level of quality or safety. Therefore, the licensee's proposed attemative for ANO-1 to implement Code Case N-533 (with a 4-hour hald time at test conditions prior to the VT-2 visual examination), is authorized pursuant to 10 CFR 50.55a(s)(3)(ii). The use of this Code Case is authorized for the duration of the respective current applicable 10-year ISI

interval, or until the Code Case is approved for general use by reference in RG 1.147. After that l time, the licensee may continue to use Code Case N-533 with the limitations, if any, listed in RG 1.147.

Principal Contributors: T. McLellan W. Reckley l Date: April 17, 1998

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