ML060480031

Record of Conference Call Re. Preemptive Weld Overlay

ML060480031
Person / Time
Site:	Cook
Issue date:	02/15/2006
From:	Tam P Plant Licensing Branch III-2
To:	Crane R, Scarpello M, Vasey B Indiana Michigan Power Co
References
TAC MC9305
Download: ML060480031 (3)

Text

From: Peter Tam To: Crane, Randy; Scarpello, Michael; Vasey, Bob Date: 2/15/06 4:31PM

Subject:

Cook 2: Record of conference call re. premptive weld overlay (TAC MC9305)

Bob, Randy:

As you requested, I am forwarding my record (below) of the conference call on 2/8/06 in the form of annotations in bold to the 3 draft questions transmitted to you by e-mail on 2/3/06 (ADAMS Accession No. ML060340609). This record also shows what I told you after the conference call.

Peter

>>>>>>>>>>>>>>>>>

(1) On page 8 of the attachment you requested modification to the 100-sq. in. requirement under ASME Code Case N-638-1 (N-638-1) to allow up to 500 sq. in. [The licensee agreed to amend the application for relief, reducing this to 300 sq. in. Consequently, the discussion in this paragraph and the next regarding size requirement no longer applies.]

maximum area of an individual weld for the Preemptive Weld Overlay (PWOL) of selected components. Your bases were that the NRC staff had approved a 300-sq. in. area for the Susquehanna Steam Electric Station and that Code Case N-432-1 allows temper bead welding without limiting the surface area, provided an elevated preheat is applied. You then took exception to applying the preheat due to radiation exposure burden. Please discuss similarities in design between Susquehanna and the D.C. Cook Unit 2 applications in terms of stress differences between the two.

The NRC staff finds that your bases do not sufficiently support your position that this alternative to increase the PWOL surface area to 500 sq. in. provides an acceptable level of quality and safety pursuant to 10 CFR 50.55a(a)(3)(i). It is the NRC staff's understanding that during the conduct of ASME Code proceedings, a white paper was presented as the technical basis for increasing the surface area as you propose, in support of a new Code Case. Please provide a copy of the paper for the NRC staff's information. [The paper had been formally submitted by another licensee; see ADAMS ML060240110. Since the paper is already in NRC possession, there is no need for D.C. Cook to submit it.]

In addition to the submittal of the discussed white paper, please provide stress analyses of each component's configuration to demonstrate that the stresses resulting from the PWOL would not hinder the components from performing their design function. [The NRC staff stated that the stress analyses need to be submitted by the licensee. However, the NRC staff recognizes that the licensee may not be ready to submit the analyses in time to support the tight schedule under which the proposed alternative is needed by the licensee. After the conference call, the NRC staff informed the licensee that the analyses may be submitted on a future date; the NRC staff will, if the alternative is approved, impose a condition that the analyses be submitted before plant restart.]

(2) On page 9 of the attachment you requested modification to the requirement that nondestructive examination (NDE) be performed at least 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> after the welded component has achieved ambient temperature. Specifically, you requested an alternative that allows you to perform NDE at least 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> after completion of welding, which may not be sufficient time for the welded area to reach ambient temperature. You used EPRI document GC-111050 as the basis for this alternative.

The NRC staff had concerns regarding the same alternative under a recently proposed Code Case (N-740) because the alternative was not adequately supported. The subject proposed Code Case was then revised to the original 48 hour5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> [The licensee agreed to amend the application to eliminate this 48-hour provision.] ambient post-NDE requirement as

defined under N-638-1. The NRC staff has not formally reviewed the EPRI document you mentioned in your basis nor has it been submitted to the NRC staff for formal review. You may submit the referenced document for the NRC staff's information. However, this does not guarantee that your alternative will be approved to support your outage schedule. Currently, the NRC staff is reviewing "Technical Basis for Preemptive Weld Overlays for Alloy 82/182 Butt Welds in PWRs" (MRP-169), to assess the use of PWOLs on a generic basis. It has not been determined if the NRC staff's review of this document will support your outage schedule at this time.

Based on the discussion above, the NRC staff finds that your basis does not sufficiently support your position that the alternative to performing NDE 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> after completion of the PWOL welding provides an acceptable level of quality and safety pursuant to 10 CFR 50.55a(a)(3)(i).

(3) On page 9 of the attachment you stated that it was not possible to perform the full UT of the 1.5T band. Your basis was that "it is not possible to perform a meaningful UT of the required band of base material because of the existing nozzle configuration in Figure 1."

Please provide additional information to support your conclusion. The information provided should discuss the achievable amount of area that will be successfully examined for each design configuration you wish to perform a PWOL on. Secondly, clarify whether the UT examination will be performed on the maximum extent achievable.

This e-mail aims solely to prepare you and others for the requested conference call. It does not formally request for information, nor does it convey a formal NRC staff position.

Peter S. Tam, Senior Project Manager Plant Licensing Branch III-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation e-mail: pst@nrc.gov Tel.: 301-415-1451

CC: Gruss, Kimberly; Steingass, Timothy; Tsao, John Mail Envelope Properties (43F39DC8.213 : 12 : 334)

Subject:

Cook 2: Record of conference call re. premptive weld overlay (TAC MC9305)

Creation Date: 2/15/06 4:31PM From: Peter Tam Created By: PST@nrc.gov Recipients Action Date & Time aep.com Transferred 02/15/06 4:32 PM mkscarpello (Michael Scarpello) rgvasey (Bob Vasey) rmcrane (Randy Crane) nrc.gov TWGWPO02.HQGWDO01 Delivered 02/15/06 4:32 PM JCT CC (John Tsao) Opened 02/16/06 6:49 AM TXS3 CC (Timothy Steingass) Opened 02/16/06 2:29 PM nrc.gov twf4_po.TWFN_DO Delivered 02/15/06 4:32 PM KAG1 CC (Kimberly Gruss) Opened 02/15/06 5:17 PM Post Office Delivered Route aep.com TWGWPO02.HQGWDO01 02/15/06 4:32 PM nrc.gov twf4_po.TWFN_DO 02/15/06 4:32 PM nrc.gov Files Size Date & Time MESSAGE 7598 02/15/06 04:31PM Options Auto Delete: No Expiration Date: None Notify Recipients: Yes Priority: Standard Reply Requested: No Return Notification: None Concealed

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