ML071720528

Use of Weld Overlays (TAC Nos. MD3903/3904)

ML071720528
Person / Time
Site:	North Anna
Issue date:	05/24/2007
From:	Siva Lingam NRC/NRR/ADRO/DORL/LPLC
To:	Shaub T Dominion Resources Services
Lingam, Siva NRR/DORL 415-1564
References
TAC MD3903, TAC MD3904
Download: ML071720528 (3)

Text

From: Siva Lingam To: Tom.Shaub@dom.com Date: 5/24/2007 8:07:23 AM

Subject:

Re: USE OF WELD OVERLAYS AS AN ALTERNATIVE REPAIR TECHNIQUE (TAC NOS. MD3903/3904)

Please note the clarification for Question 2.

>>> David Tarantino 5/24/2007 7:58 AM >>>

Siva, Thank you for arranging and forwarding the RAI below.

As a point of clarification for the licensee Question 2 (last sentence in parentheses) is posed as a statement in lieu of a question; however, we are seeking the licensee's standpoint on this matter.

I hope this clears up any potential confusion and if the licensee requires any additional clarification or explanation please let me know.

Thanks again, Dave

>>> Siva Lingam 5/23/2007 10:05 AM >>>

Tom, The following questions relate to the relief request CMP022/023 that has been verbally approved by NRC on March 29, 2007. Due to ongoing NRC and Industry issues, we need further clarifications.

The following questions refer to Enclosure 1 of the Licensee's Alternative Request CMP-022R1/023R1 dated March 13, 2007.

The Licensee may review the Dominion response to the staff Request for Additional Information regarding a similar Relief Request for Millstone Unit 3 in Letters dated March 28 and April 23, 2007.

Question 1:

Section 2(a)(2)(c) does not specify the depth of the base metal that ultrasonic (UT) testing would be qualified to detect flaws after weld overlay installation. The staff believes that a region of the base metal MAY not be qualified. In such case, the staff considers that the initial flaw size assumed in the crack growth calculation should be the as-found flaw depth plus the postulated worst-case flaw in the unqualified region of the base metal. The postulated worst-case flaw size should be the depth of the base metal that UT is not qualified (to examine). The initial flaw size should be clarified. See Millstone's response; ATTACHMENT 1 to DOMINION LETTER SERIAL NO. 07-0116A dated 04/23/2007.

Question 2:

IN Section 2(a)(2)(d), the current UT is not qualified to inspect inner 75% of the base metal once the weld overlay is installed on the pipe. Therefore, UT is not capable of detecting any indication that is connected to the inside surface of the pipe during pre-service inspection (the staff believes that the pre-service inspection is the post-installation pre-service inspection, not pre-installation inspection). See Millstone's response; ATTACHMENT 1 to DOMINION LETTER SERIAL NO. 07-0116A dated

04/23/2007.

Question 3:

In Section 3(b)(2), THE LICENSEE STATED THAT .......if flaws are found in the outer 25%

of the existing base metal or original weld and cannot be determined to be isolated from the inside diameter (ID) of the existing base metal or weld, will the flaw depth be conservatively sized by adding the thickness of the remaining 75% of the original existing base metal or weld thickness to the through wall dimension for any flaw growth calculations performed.

The Staff's position is that the Licensee will use the actual UT determined through wall dimension in the crack growth analysis for those flaws that do not intrude on the interface between the outer 25% of the original base metal or weld thickness and the inner 75% of the same existing materials and that can be determined by the qualified UT examination to not be connected to the interface between the outer 25% and the inner 75% of the base metal or weld. FOR THE ACTUAL UT DETERMINED FLAW IN THE OUTER 25% OF THE BASE METAL THAT IS CONNECTED TO THE INTERFACE BETWEEN THE OUTER 25% AND THE INNER 75% OF THE PIPE WALL THICKNESS, THE INITIAL FLAW SIZE WOULD BE THE AS-FOUND FLAW SIZE PLUS THE INNER 75% PIPE WALL THICKNESS. Clarify the initial flaw size that will be used in the crack growth calculation.

Question 4:

Section 3(c)(4) relating to accept flaws found in weld overlay. The licensee should add that IWB-3600 is not permitted to accept PWSCC flaws.

Siva P. Lingam Project Manager (NRR/DORL/LPL2-1)

North Anna and Surry Nuclear Stations Location: O8-D5 Mail Stop: O8-G9 Telephone: 301-415-1564 Fax: 301-415-1222 E-mail address: spl@nrc.gov CC: David Tarantino; John Tsao; Terence Chan Mail Envelope Properties (46557FFB.E55 : 13 : 35786)

Subject:

Re: USE OF WELD OVERLAYS AS AN ALTERNATIVE REPAIR TECHNIQUE (TAC NOS. MD3903/3904)

Creation Date 5/24/2007 8:07:23 AM From: Siva Lingam Created By: SPL@nrc.gov Recipients Action Date & Time dom.com Transferred 5/24/2007 8:07:43 AM Tom.Shaub (Tom.Shaub@dom.com)

nrc.gov OWGWPO03.HQGWDO01 Delivered 5/24/2007 8:07:31 AM TLC CC (Terence Chan) Opened 5/24/2007 3:33:35 PM nrc.gov TWGWPO02.HQGWDO01 Delivered 5/24/2007 8:07:28 AM DMT2 CC (David Tarantino) Opened 5/24/2007 8:07:34 AM JCT CC (John Tsao) Opened 5/24/2007 8:33:19 AM Post Office Delivered Route dom.com OWGWPO03.HQGWDO01 5/24/2007 8:07:31 AM nrc.gov TWGWPO02.HQGWDO01 5/24/2007 8:07:28 AM nrc.gov Files Size Date & Time MESSAGE 5861 5/24/2007 8:07:23 AM Options Auto Delete: No Expiration Date: None Notify Recipients: Yes Priority: Standard ReplyRequested: No Return Notification: None Concealed

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