ML13330A573

Verbal Authorization of Relief Request 51, Alternative to ASME Code for Flaw Removal, Reactor Vessel Bottom-mounted Instrumentation Nozzle, Third 10-Year ISI Interval

ML13330A573
Person / Time
Site:	Palo Verde
Issue date:	12/05/2013
From:	Jennivine Rankin Plant Licensing Branch IV
To:	Plant Licensing Branch IV
George A
References
TAC MF3051
Download: ML13330A573 (3)

Text

December 5, 2013

MEMORANDUM TO: File

FROM: Jennivine K. Rankin, Project Manager /RA/ Plant Licensing Branch IV-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation

SUBJECT:

PALO VERDE NUCLEAR GENERATING STATION, UNIT 3 -

SUMMARY

OF TELEPHONE CONFERENCE RE: VERBAL AUTHORIZATION FOR RELIEF REQUEST 51 (TAC NO. MF3051)

This memorandum summarizes the telephone discussion on November 21, 2013, between the U.S. Nuclear Regulatory Commission (NRC) staff and Arizona Public Service Company (APS, the licensee). The discussion related to the licensee's Relief Request 51 for Palo Verde Nuclear Generating Station (PVNGS), Unit 3. Participants in the discussion included Messrs. David Van Allen, Thomas Weber, Winston Borrero, Dwight Mims, Paul Horn, Robert Roehler, Mike Hooshmand, Donald Buth, Carl Stephenson, and Del Elkinton from APS; Ms. Stacey Rosenberg and Mr. Simon Sheng from the NRC's Office of Nuclear Reactor Regulation, Division of Engineering, Vessels and Internals Integration Branch (NRR/DE/EVIB);

and Ms. Jennivine Rankin (LPLIV-1 Acting Branch Chief) and Ms. Andrea George from NRR's Division of Operating Reactor Licensing, Plant Licensing Branch IV-1 (NRR/DORL/LPLIV-1).

On October 6, 2013, APS found small white boric acid deposits around the annulus of reactor vessel (RV) bottom mounted instrument (BMI) nozzle No. 3 for PVNGS, Unit 3, during the planned visual examinations pursuant to American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code) Case N-722-1, "Additional Examination for PWR Pressure Retaining Welds in Class 1 Components Fabricated with Alloy 600/82/182 Materials," in accordance with Title 10 of the Code of Federal Regulations (10 CFR) Section 50.55a. The licensee attributed the through-wall flaw to primary water stress-corrosion cracking (PWSCC).

The licensee proposed to perform a "half-nozzle" repair technique where the lower portion of the

existing nozzle penetration assembly near the outer diameter (OD) surface of the RV would be cut and removed by machining, and replaced with an Alloy 690 nozzle resistant to PWSCC.

By letter dated November 8, 2013 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML13317A071), the licensee submitted Relief Request 51 which requested NRC approval to implement an alternative to certain requirements of the 2001 Edition through 2003 Addenda of Section XI of the ASME Code regarding removal and characterization of the presumed flaw for the unit. The alternative was requested under the provisions of 10 CFR 50.55a(a)(3)(i).

Relief Request 51 and the supplements dated November 18 and November 20, 2013 (ADAMS Accession Nos. ML13323A763 and ML13325A098, respectively), were intended to demonstrate that the proposed alternative would maintain an acceptable level of quality and safety under all licensing basis conditions of operation for one operating cycle. The flaw evaluation used conservative assumptions regarding the flaw size, stress state, and potential for flaw growth during one cycle, and determined that the postulated flaw would meet the structural margins required by the ASME Code,Section XI, under all normal, upset, emergency, and faulted conditions.

The NRC staff completed its review and concluded that the information provided by the licensee is consistent with the provisions of 10 CFR 50.55a(a)(3)(i) and supports the granting of the proposed alternative to the ASME Code requirements described in Relief Request 51, with the exception of the relief from subsequent examinations required by IWB-2420(b). Since these examinations would not be required until after the current cycle, any alternative to the requirement for subsequent examinations will be addressed in a future request for alternative.

As set forth above, the NRC staff determined that the proposed alternative in Relief Request 51 provides an acceptable level of quality and safety.

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)(i) and is in compliance with the ASME Code,Section XI requirements.

Therefore, the NRC staff authorized the proposed alternative as described in Relief Request 51, with the exception of the relief from subsequent examinations required by IWB-2420(b) at PVNGS, Unit 3, in accordance with 10 CFR 50.55a(a)(3)(i). The proposed alternative is authorized for use for the duration of the next Unit 3 operating fuel cycle (U3C18).

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

Docket No. 50-530

ML13330A573 OFFICE NRR/DORL/LPL4-1/PM NRR/DORL/LPL4-1/PM NRR/DORL/LPL4-1/LA NRR/DORL/LPL4-1/BC NRR/DORL/LPL4-1/PM NAME AGeorge JRankin JBurkhardt MMarkley JRankin DATE 12/4/13 12/4/13 12/3/13 12/5/13 12/5/13