ML121150247

Memo to File, Verbal Authorization, Relief Request VR-01 from Requirements of ASME OM Code Mandatory Appendix I, One-time Extension Replacement of Main Steam Isolation Valve Actuator Rupture Disks

ML121150247
Person / Time
Site:	Callaway
Issue date:	05/03/2012
From:	Kalyanam N Plant Licensing Branch IV
To:	Office of Nuclear Reactor Regulation
Kalyanam N, NRR/DORL/LPL4, 415-1480
References
TAC ME8319
Download: ML121150247 (3)

Text

May 3, 2012 MEMORANDUM TO: Docket File FROM: N. Kalyanam, Project Manager /RA/

Plant Licensing Branch IV Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation

SUBJECT:

CALLAWAY PLANT UNIT 1 - VERBAL AUTHORIZATION VR-01, PROPOSED ALTERNATIVE REGARDING ASME OM CODE REPLACEMENT INTERVAL FOR MAIN STEAM ISOLATION VALVE ACTUATOR RUPTURE DISKS (TAC NO. ME8319)

By letter dated March 30, 2012, as supplemented by letter dated April 19, 2012 (Agencywide Documents Access and Management System (ADAMS) Accession Nos. ML12090A501 and ML121150347, respectively), Union Electric Company, (the licensee) submitted alternative request VR-01 for the Callaway Plant, Unit 1, for U.S. Nuclear Regulatory Commission (NRC) review and approval.

This request pertains to inservice testing requirements for Main Steam Isolation Valve (MSIV) actuator rupture disks ABPSE0001, ABPSE0002, ABPSE0003, and ABPSE0004 at Callaway Plant, Unit 1. The licensee requested an alternative from the required replacement frequency requirement of the American Society of Mechanical Engineers (ASME) Code for Operation and Maintenance of Nuclear Power Plants (OM Code) Mandatory Appendix I, Paragraph I-1360, Test Frequency, Class 2 and 3 Nonreclosing Pressure Relief Devices, as required and conditioned by Title 10 of the Code of Federal Regulations Section 50.55a.

Specifically, an alternative was requested for the requirement to replace MSIV actuator rupture disks ABPSE0001, ABPSE0002, ABPSE0003, and ABPSE0004 every 5 years. Callaway Plant, Unit 1, had originally scheduled the rupture disks replacement during Refueling Outage 18, which began in October 2011. However, the work was removed from the outage scope based on an initial determination that the work could be done with the plant online subsequent to the outage. The rupture disks were scheduled to be replaced online in the spring of 2012 to meet the ASME OM Code requirement. However, the licensee determined that based on the 8-hour Technical Specification (TS) Limiting Conditions for Operations (LCO) and the time needed to replace the rupture disks online, the TS LCO completion time may be exceeded during this replacement activity. Therefore, the rupture disk replacement activity poses elevated risk to continued plant operations if it is performed online. Therefore, the licensee is proposing an alternative to extend the interval for replacing the rupture disks to the next plant outage providing plant conditions to replace the disks (i.e. Mode 4 or 5), but no later than the end of Refueling Outage 19, which is currently scheduled for June 2013.

Extending the replacement date until Refueling Outage 19 will not affect the functionality of the MSIVs and does not introduce any credible failure mechanism that would prevent the rupture disks from rupturing at a pressure needed for the MSIVs to perform their safety-related purpose.

Conclusion As set forth above, the NRC staff concludes that the proposed alternative described in alternative request VR-01 provides reasonable assurance that the MSIV actuator rupture disks ABPSE0001, ABPSE0002, ABPSE0003, and ABPSE0004 are operationally ready.

Accordingly, the NRC staff concludes that the licensee has adequately addressed all of the regulatory requirements set forth in 10 CFR 50.55a(a)(3)(ii), and is in compliance with the ASME OM Code requirements. Therefore, the NRC staff provides verbal authorization for the proposed alternatives described in request alternative VR-01 until the next plant outage providing plant conditions to replace the MSIV actuator rupture disks (i.e., Mode 4 or 5), but no later than the end of the Callaway Plant, Unit 1, Refueling Outage 19, which is currently scheduled for June 2013.

All other ASME Code requirements for which relief was not specifically requested and approved in this relief request remain applicable, including third-party review by the Authorized Nuclear Inservice Inspector.

The participants in the telephone call were:

NRC Mike Markley, Branch Chief, NRR/DORL/LPL4)

Tony McMurtray, Branch Chief, NRR/DE/EPTB Bob Wolfgang, NRR/DE/EPTB Zach Hollcraft, R-IV/DRP/RPB-B/

Kaly Kalyanam, NRR/DORL/LPL4 UNION ELECTRIC COMPANY Brian Pae, Main Steam System Engineer Ben Oguejiofor, Inservice Testing Engineer Christine Norman, Mechanical Design Engineer Bryan Sprock, Engineering Fix-It-Now Engineer Tom Elwood, Regulatory Affairs and Licensing Supervisor Docket No. 50-483

ML121150247 *via email OFFICE NRR/LPL4/PM NRR/LPL4/LA NRR/DE/EPTB/BC NRR/LPL4/BC NRR/LPL4/PM NAME NKalyanam JBurkhardt AMcMurtray* MMarkley NKalyanam DATE 4/25/12 4/25/12 4/23/12 5/3/12 5/3/12