Text

Response to Request for Additional Information Regarding Application for Steam Generator Tube Integrity Technical Specification
	ML070880464
Person / Time
Site:	Byron, Braidwood
Issue date:	02/15/2007
From:	Benyak D; Exelon Corp, Exelon Generation Co, Exelon Nuclear
To:	; Document Control Desk, Office of Nuclear Reactor Regulation
References
	RS-07-022
	Download: ML070880464 (84)
	v • d • e

Exelon Generation www.exeloncorp.com Exelkn,. Nuclear 4300 Winfield Road Warrenville, IL60555 10 CFR 50.90 RS-07-022 February 15, 2007 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555-0001 Braidwood Station, Units 1 and 2 Facility Operating License Nos. NPF-72 and NPF-77 NRC Docket Nos. 50-456 and 50-457 Byron Station, Units 1 and 2 Facility Operating License Nos. NPF-37 and NPF-66 NRC Docket Nos. 50-454 and 50-455

Subject:

Response to Request for Additional Information Regarding Application for Steam Generator Tube Integrity Technical Specification

References:

(1) Letter from J. A. Bauer (Exelon Generation Company, LLC) to U. S.

NRC, "Application for Technical Specification Improvement Regarding Steam Generator Tube Integrity," dated November 18, 2005 (2) Letter from S. J. Campbell (U. S. NRC) to C. M. Crane (Exelon Generation Company, LLC), "Byron Station, Unit Nos. 1 and 2, and Braidwood Station, Unit Nos. 1 and 2 - Request for Additional Information Related to Technical Specification Improvement Regarding Steam Generator Tube Integrity," dated August 4, 2006 (3) Letter from D. M. Benyak (Exelon Generation Company, LLC) to U. S. NRC, "Response to Request for Additional Information Regarding Application for Steam Generator Tube Integrity Technical Specification," dated August 18, 2006 (4) Letter from R. F. Kuntz (U. S. NRC) to C. M. Crane (Exelon Generation Company, LLC), "Byron Station Unit Nos. 1 and 2 and Braidwood Station, Unit Nos. 1 and 2 - Request for Additional Information Related to Application for Technical Specification Improvement Regarding Steam Generator Tube Integrity," dated December 13, 2006

February 15, 2007 U.S. Nuclear Regulatory Commission Page 2 In Reference 1, Exelon Generation Company, LLC (EGC) requested an amendment to Appendix A Technical Specifications (TS), of Facility Operating License Nos. NPF-72, NPF-77, NPF-37, and NPF-66 for Braidwood Station, Units 1 and 2, and Byron Station, Units 1 and 2, respectively. The proposed changes were to revise the TS requirements related to steam generator tube integrity. The change was consistent with NRC approved Revision 4 to Technical Specification Task Force (TSTF) Standard Technical Specification Change Traveler, TSTF-449, "Steam Generator Tube Integrity."

In the course of their review the NRC determined that additional information was required. This request was provided in Reference 2. The response to this initial request for additional information (RAI) was provided in the Reference 3 submittal. Reference 4 requested additional information specific to the Braidwood Station Unit 2 and Byron Station Unit 2 alternate repair criteria analyses. The propriety version of seven of the eight RAI question responses are provided in Attachment 1. Question 6 of the RAI suggested changes to the wording of Braidwood Station and Byron Station TS 5.5.9, "Steam Generator (SG) Tube Surveillance Program," paragraph (c)1. Updated TS pages 5.5-8, including the requested changes, for Braidwood Station and Byron Station are provided in Attachments 7A and 7B.

The attached request for additional information is subdivided as shown below.

Attachment 1 provides Westinghouse Electric Company, LLC (Westinghouse) document LTR-CDME-07-13 P-Attachment, "Response to NRC Request for Additional Information Related to the Application for Technical Specification Improvement Regarding Steam Generator Tube Integrity for Byron Units 1 and 2 and Braidwood Units 1 and 2" (Proprietary).

Attachment 2 provides affidavit CAW-07-2235, signed by Westinghouse, the owner of the proprietary information for withholding the information provided in Attachment 1.

Attachment 3 provides Westinghouse document LTR-CDME-07-13 NP-Attachment, "Response to NRC Request for Additional Information Related to the Application for Technical Specification Improvement Regarding Steam Generator Tube Integrity for Byron Units 1 and 2 and Braidwood Units land 2" (Non-Proprietary).

Attachment 4 provides Westinghouse document SG-CDME-07-02-P-Attachment, "White Paper Addressing Changes to B* and H* Analysis due to New Crevice Pressure and Divider Plate Information," (Proprietary).

Attachment 5 provides affidavit CAW-07-2234, signed by Westinghouse, the owner of the proprietary information for withholding the information provided in Attachment 4.

Attachment 6 Westinghouse document SG-CDME-07-02-NP-Attachment, "White Paper Addressing Changes to B* and H* Analysis due to New Crevice Pressure and Divider Plate Information," (Non- Proprietary).

February 15, 2007 U.S. Nuclear Regulatory Commission Page 3 Attachment 7A provides the typed TS page 5.5-8 with the proposed changes incorporated for Braidwood Station Attachment 7B provides the typed TS page 5.5-8 with the proposed changes incorporated for Byron Station Attachments 1 and 4 contain information proprietary to Westinghouse and it is supported by an affidavit signed by Westinghouse, the owner of the information. The affidavits provided in Attachments 2 and 5 set forth the basis on which the information may be withheld from public disclosure by the NRC and addresses with specificity the considerations listed in paragraph (b)(4) of 10 CFR 2.390, "Public inspections, exemptions, requests for withholding." Accordingly, it is respectfully requested that the information which is proprietary to Westinghouse be withheld from public disclosure in accordance with 10 CFR 2.390.

Correspondence with respect to the copyright or proprietary aspects of the items listed above or the supporting Westinghouse affidavit should reference CAW-07-2234 and/or CAW-07-2235 and should be addressed to J. A. Gresham, Manager, Regulatory Compliance and Plant Licensing, Westinghouse Electric Company LLC, P.O. Box 355, Pittsburgh, Pennsylvania 15230-0355.

The information provided in this letter does not affect the supporting analysis for the original license amendment request as described in Reference 1. No other information contained in the referenced letter is affected by this additional information. The No Significant Hazards Consideration and the Environmental Consideration provided in Attachment 1 of the Reference 1 letter are not affected by this additional information.

In accordance with 10 CFR 50.91(b), "State consultation," EGC is providing the State of Illinois with a copy of this letter and its attachments to the designated State Official.

EGC requests that this proposed license amendment change be approved by April 1, 2007, to support the inspection activities for Byron Unit 2, Refueling Outage 13.

If you have any questions about this letter, please contact Mr. David Chrzanowski at (630) 657-2816.

I declare under penalty of perjury that the foregoing is true and correct. Executed on the 1 5 th day of February 2007.

Respectfully, Darin Benyak Manager - Licensing

Attachment 1 Westinghouse Electric Company, LLC LTR-CDME-07-13 P-Attachment Response to NRC Request for Additional Information Related to the Application for Technical Specification Improvement Regarding Steam Generator Tube Integrity for Byron Units 1 and 2 and Braidwood Units 1 and 2 (Proprietary)

Attachment 2 Westinghouse Electric Company, LLC Affidavit CAW-07-2235 Request to Withhold Proprietary Information Contained In LTR-CDME-07-13 P-Attachment

9Westinghouse Nuclear Services Westinghouse Electric Company P.O. Box 355 Pittsburgh, Pennsylvania 15230-0355 USA U.S. Nuclear Regulatory Commission Direct tel: (412) 374-4643 Document Control Desk Direct fax: (412) 374-4011 Washington, DC 20555-0001 e-mail: greshaja@westinghouse.com Our ref: CAW-07-2235 February 8, 2007 APPLICATION FOR WITHHOLDING PROPRIETARY INFORMATION FROM PUBLIC DISCLOSURE

Subject:

LTR-CDME-07-13 P-Attachment, "Response to NRC Request for Additional Information Related to the Application for Technical Specification Improvement Regarding Steam Generator Tube Integrity for Byron Units I and 2 and Braidwood Units I and 2 (TAC NOS.

MC8966, MC8967, MC8968, and MC8969)," dated February 6, 2007 (Proprietary)

The proprietary information for which withholding is being requested in the above-referenced report is further identified in Affidavit CAW-07-2235 signed by the owner of the proprietary information, Westinghouse Electric Company LLC. The affidavit, which accompanies this letter, sets forth the basis on which the information may be withheld from public disclosure by the Commission and addresses with specificity the considerations listed in paragraph (b)(4) of 10 CFR Section 2.390 of the Commission's regulations.

Accordingly, this letter authorizes the utilization of the accompanying affidavit by Exelon Generation Company, LLC.

Correspondence with respect to the proprietary aspects of the application for withholding or the Westinghouse affidavit should reference this letter, CAW-07-2235, and should be addressed to J. A. Gresham, Manager, Regulatory Compliance and Plant Licensing, Westinghouse Electric Company LLC, P.O. Box 355, Pittsburgh, Pennsylvania 15230-0355.

Very truly yours,

/

/ J. A. Gresham, Manager Regulatory Compliance and Plant Licensing Enclosures cc: Jon Thompson (NRC O-7E1A)

CAW-07-2235 AFFIDAVIT COMMONWEALTH OF PENNSYLVANIA:

ss COUNTY OF ALLEGHENY:

Before me, the undersigned authority, personally appeared J.A. Gresham, who, being by me duly sworn according to law, deposes and says that he is authorized to execute this Affidavit on behalf of Westinghouse Electric Company LLC (Westinghouse), and that the averments of fact set forth in this Affidavit are true and correct to the best of his knowledge, information, and belief:

/."

iJ.A. Gresham, Manager Regulatory Compliance and Plant Licensing Sworn to and subscribed before me this 8th day of February, 2007 Notary Public COMMONWEALTH Or PENNSYLVANIA Notarial Seal Sharon L. Markle, Notarj Public Monroeville Boro, Allegheny County My Commission Expires Jan. 29, 2011 Member, Pernsv!vania Association of Notaries

2 CAW-07-2235 (1) 1 am Manager, Regulatory Compliance and Plant Licensing, in Nuclear Services. Westinghouse Electric Company LLC (Westinghouse), and as such, I have been specifically delegated the function of reviewing the proprietary information sought to be withheld from public disclosure in connection with nuclear power plant licensing and rule making proceedings, and am authorized to apply for its withholding on behalf of Westinghouse.

(2) 1 am making this Affidavit in conformance with the provisions of 10 CFR Section 2.390 of the Commission's regulations and in conjunction with the Westinghouse "Application for Withholding" accompanying this Affidavit.

(3) 1 have personal knowledge of the criteria and procedures utilized by Westinghouse in designating information as a trade secret, privileged or as confidential commercial or financial information.

(4) Pursuant to the provisions of paragraph (b)(4) of Section 2.390 of the Commission's regulations, the following is furnished for consideration by the Commission in determining whether the information sought to be withheld from public disclosure should be withheld.

(i) The information sought to be withheld from public disclosure is owned and has been held in confidence by Westinghouse.

(ii) The information is of a type customarily held in confidence by Westinghouse and not customarily disclosed to the public. Westinghouse has a rational basis for determining the types of information customarily held in confidence by it and, in that connection, utilizes a system to determine when and whether to hold certain types of information in confidence. The application of that system and the substance of that system constitutes Westinghouse policy and provides the rational basis required.

Under that system, information is held in confidence if it falls in one or more of several types, the release of which might result in the loss of an existing or potential competitive advantage, as follows:

(a) The information reveals the distinguishing aspects of a process (or component, structure, tool, method, etc.) where prevention of its use by any of Westinghouse's competitors without license from Westinghouse constitutes a competitive economic advantage over other companies.

3 CAW-07-2235 (b) It consists of supporting data, including test data, relative to a process (or component, structure, tool, method, etc.), the application of which data secures a competitive economic advantage, e.g., by optimization or improved marketability.

(c) Its use by a competitor would reduce his expenditure of resources or improve his competitive position in the design, manufacture, shipment, installation, assurance of quality, or licensing a similar product.

(d) It reveals cost or price information, production capacities, budget levels, or commercial strategies of Westinghouse, its customers or suppliers.

(e) It reveals aspects of past, present, or future Westinghouse or customer funded development plans and programs of potential commercial value to Westinghouse.

(f) It contains patentable ideas, for which patent protection may be desirable.

There are sound policy reasons behind the Westinghouse system which include the following:

(a) The use of such information by Westinghouse gives Westinghouse a competitive advantage over its competitors. It is, therefore, withheld from disclosure to protect the Westinghouse competitive position.

(b) It is information that is marketable in many ways. The extent to which such information is available to competitors diminishes the Westinghouse ability to sell products and services involving the use of the information.

(c) Use by our competitor would put Westinghouse at a competitive disadvantage by reducing his expenditure of resources at our expense.

(d) Each component of proprietary information pertinent to a particular competitive advantage is potentially as valuable as the total competitive advantage. If competitors acquire components of proprietary infomiation, any one component

4 CAW-07-2235 may be the key to the entire puzzle, thereby depriving Westinghouse of a competitive advantage.

(e) Unrestricted disclosure would jeopardize the position of prominence of Westinghouse in the world market, and thereby give a market advantage to the competition of those countries.

(f) The Westinghouse capacity to invest corporate assets in research and development depends upon the success in obtaining and maintaining a competitive advantage.

(iii) The information is being transmitted to the Commission in confidence and, under the provisions of 10 CFR Section 2.390, it is to be received in confidence by the Commission.

(iv) The information sought to be protected is not available in public sources or available information has not been previously employed in the same original manner or method to the best of our knowledge and belief.

(v) The proprietary information sought to be withheld in this submittal is that which is appropriately marked in LTR-CDME-07-13 P-Attachment, "Response to NRC Request for Additional Information Related to the Application for Technical Specification Improvement Regarding Steam Generator Tube Integrity for Byron Units I and 2 and Braidwood Units I and 2 (TAC NOS. MC8966, MC8967, MC8968, and MC8969),"

dated February 6, 2007 (Proprietary), for submittal to the Commission, being transmitted by Exelon Generation Company, LLC Application for Withholding Proprietary Information from Public Disclosure to the Document Control Desk. The proprietary information as submitted for use by Westinghouse for Byron Unit 2 and Braidwood Unit 2 is expected to be applicable to other licensee submittals in support of implementing a limited inspection of the tube joint within the tubesheet region of the steam generators and is provided in response to a NRC request for additional information on LTR-CDME-05-32-P, Rev. 2, "Limited Inspection of the Steam Generator Tube Portion Within the Tubesheet at Byron 2 and Braidwood 2," dated August 2005.

This information is part of that which will enable Westinghouse to:

5 CAW-07-2235 (a) Provide documentation of the analyses, methods, and testing for the imp lementation of an alternate repair criteria for the portion if the tubes within the tubesheet of the Byron Unit 2 and Braidwood Unit 2 steam generators.

(b) Assist the customers in the licensing and NRC approval of the Technical Specification changes associated with the alternate repair criteria.

Further this information has substantial commercial value as follows:

(a) Westinghouse plans to sell the use of similar information to its customers for the purposes of meeting NRC requirements for licensing documentation.

(b) Westinghouse can sell support and defense of the technology to its customers in the licensing process.

Public disclosure of this proprietary information is likely to cause substantial harm to the competitive position of Westinghouse because it would enhance the ability of competitors to provide similar calculation, evaluation and licensing defense services for commercial power reactors without commensurate expenses. Also, public disclosure of the information would enable others to use the information to meet NRC requirements for licensing documentation without purchasing the right to use the information.

The development of the technology described in part by the information is the result of applying the results of many years of experience in an intensive Westinghouse effort and the expenditure of a considerable sum of money.

In order for competitors of Westinghouse to duplicate this information, similar technical programs would have to be performed and a significant manpower effort, having the requisite talent and experience, would have to be expended.

Further the deponent sayeth not.

PROPRIETARY INFORMATION NOTICE Transmitted herewith are proprietary and/or non-proprietary versions of documents furnished to the NRC in connection with requests for generic and/or plant-specific review and approval.

In order to conform to the requirements of 10 CFR 2.390 of the Commission's regulations concerning the protection of proprietary information so submitted to the NRC, the information which is proprietary in the proprietary versions is contained within brackets, and where the proprietary information has been deleted in the non-proprietary versions, only the brackets remain (the information that was contained within the brackets in the proprietary versions having been deleted). The justification for claiming the information so designated as proprietary is indicated in both versions by means of lower case letters (a) through (f) located as a superscript immediately following the brackets enclosing each item of information being identified as proprietary or in the margin opposite such information. These lower case letters refer to the types of information Westinghouse customarily holds in confidence identified in Sections (4)(ii)(a) through (4)(ii)(f) of the affidavit accompanying this transmittal pursuant to 10 CFR 2.390(b)(1).

COPYRIGHT NOTICE The reports transmitted herewith each bear a Westinghouse copyright notice. The NRC is permitted to make the number of copies of the information contained in these reports which are necessary for its internal use in connection with generic and plant-specific reviews and approvals as well as the issuance, denial, amendment, transfer, renewal, modification, suspension, revocation, or violation of a license, permit, order, or regulation subject to the requirements of 10 CFR 2.390 regarding restrictions on public disclosure to the extent such information has been identified as proprietary by Westinghouse, copyright protection notwithstanding. With respect to the non-proprietary versions of these reports, the NRC is permitted to make the number of copies beyond those necessary for its internal use which are necessary in order to have one copy available for public viewing in the appropriate docket files in the public document room in Washington, DC and in local public document rooms as may be required by NRC regulations if the number of copies submitted is insufficient for this purpose. Copies made by the NRC must include the copyright notice in all instances and the proprietary notice if the original was identified as proprietary.

Attachment 3 Westinghouse Electric Company, LLC LTR-CDME-07-13 NP-Attachment Response to NRC Request for Additional Information Related to the Application for Technical Specification Improvement Regarding Steam Generator Tube Integrity for Byron Units 1 and 2 and Braidwood Units 1 and 2 (Non-Proprietary)

Westinghouse Non-Proprietary Class 3 LTR-CDME-07-13 NP-Attachment Exelon Generation Company, LLC Response to NRC Request for Additional Information Related to the Application for Technical Specification Improvement Regarding Steam Generator Tube Integrity for Byron Units 1 and 2 and Braidwood Units 1 and 2 (TAC NOS. MC8966, MC8967, MC8968, AND MC8969)

February 2, 2007 Westinghouse Electric Company LLC P.O. Box 158 Madison, PA 15663

Westinghouse Non-Proprietary Class 3 Response to Request for Additional Information Regarding Application for Steam Generator Tube Integrity Technical Specification NRC Question 1:

RegardingEGC's response' to Attachment 6,2 Question 5 in the requestfor information (RAI),

provide aplot of crack opening areafor circumferentialcracks located 4-inchesfrom the bottom of the tubesheet as afunction of crack lengthfor normal operating and main steam line conditions. Also, provide a plot of leak rate as afunction of the same parameters,neglecting the effect of crevice resistance.

Exelon Generation Company, LLC (EGC) response to Question 1:

As requested, Figure 1.0 and Figure 2.0 are plots of the circumferential and axial crack opening area (COA), as a function of crack length, for both the normal operating (NOp) and main steam line break (SLB) conditions (Reference 1). The crack opening area models are independent of tubesheet (TS) radius. The results shown below are for a crack 4.0 inches above the bottom of the TS. In the figures, the term "guided" refers to the mechanical and kinematic constraint provided by the tubesheet that acts to limit the crack opening for both circumferential and axial cracks.

Note that Figures 1.0 and 2.0 show that the crack opening area for a realistic circumferential or axial crack less than about 0.30 inches in total length (i.e., crack length = 2a) and below H* is on the order of 10-6 in2 or less. Also, the response to NRC RAI No. 5 concludes that no load is transmitted below a distance of less than H*; therefore, crack opening area is minimal (i.e., only a result of pressure on the crack face).

Figures 3.0 and 4.0 show the predicted leak rate for a freespan crack in the axial and circumferential orientations to eliminate the crevice resistance. These predictions were made using the CRACKFLO code.

1 The Exelon Generation Company, LLC response to the RAI was provided in a letter from D. M. Benyak (Exelon Generation Company, LLC), to U.S. NRC, "Response to Request for Additional Information Regarding Application for Steam Generator Tube Integrity Technical Specification," dated August 18, 2006.

2 Attachment 6 to the EGC RAI response provided the proprietary version of SG-SGDA-06-20-P, "Response to Request for Additional Information on FP&L Seabrook License Amendment Request 05-08 'Limited Inspection of the Steam Generator Tube Portion Within the Tubesheet."' Attachment 7 to the RAI provided the non-proprietary version of this report.

Page 2 of 36 LTR-CDME-07-13 NP-Attachment

Westinghouse Non-Proprietary Class 3 Response to Request for Additional Information Regarding Application for Steam Generator Tube Integrity Technical Specification 6.OE . ....

5.7E-04 [ I _____

5.7E-04 _

5.1 E 4.8E-04 I 4.5E-04_I 4.2E-04 _ ___,_

"m 3.9E-04 _

S 3.6E-04 3.3E-04 //

. 3.OE-04 _

w 2.7E-04 S2.4E-04 _

2.1E-04 AF F 1.8E-04 _

(J 1.5E-04 - OF 1.2E-04 "

9.OE LCO 6.0E NOp COA 3.OE-05 __I_

0.OE+00 -'_ _j 0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 1.00 Crack Half-Length, a [in]

Figure 1.0: Plot of Guided Circumferential Crack Opening Area vs. Circumferential Crack Length for a Crack 4.0 inches above the Bottom of the Tubesheet Page 3 of 36 LTR-CDME-07-13 NP-Attachment

Westinghouse Non-Proprietary Class 3 Response to Request for Additional Information Regarding Application for Steam Generator Tube Integrity Technical Specification 5.5E-04 5.3E-04 5.OE-04 4.8E-04 4.5E-04 4.3E-04

= 4.0E-04 3.8E-04

3.5E-04

. 3.3E-04 3.0E-04

2.8E-04 0 2.5E-04

. 2.3E-04 2.OE-04 1.8E-04 1.5E-04 1.3E-04 1.0E-04 7.5E-05 5.OE-05 2.5E-05 0.0E+00 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 Crack Half-Length, a [in]

Figure 2.0: Plot of Guided Axial Crack Opening Area vs. Axial Crack Length for a Crack 4.0 inches above the Bottom of the Tubesheet Page 4 of 36 LTR-CDME-07-13 NP-Attachment

Westinghouse Non-Proprietary Class 3 Response to Request for Additional Information Regarding Application for Steam Generator Tube Integrity Technical Specification a,c,e Figure 3.0: Freespan Axial Crack, Crack Only Resistance a,c,e Figure 4.0: Freespan Circ Crack, Crack Only Resistance Page 5 of 36 LTR-CDME-07-13 NP-Attachment

Westinghouse Non-Proprietary Class 3 Response to Request for Additional Information Regarding Application for Steam Generator Tube Integrity Technical Specification NRC Question 2:

Regarding EGC'sresponse to Attachment 6, RAI question 5, provide revised versions of Figures 3 and 4 to include the leak rate ratiosfor cracks in the range of 0. 1 inches in length. It would seem from Figures3 and 4, that if crack resistancedominates crevice resistance, then leakage ratios may exceed 2for through wall crack lengths less than 0.5 inchesfor tubes near the periphery of the bundle, particularlyfor circumferentialcracks. Also, provide similarfiguresfor the near radius and mid-radius locations.

EGC response to Question 2:

The plots of leak rate as a function of crack length that were requested using the results from new test data (Reference 19) and input from CRACKFLO are shown below. In order to obtain these plots the leakage resistances during normal and accident conditions were determined for:

1. A freespan axial crack (See response to Question 1.0 above)

2. A freespan circumferential crack (see response to Question 1.0 above)

3. An axial crack in series with a crevice

4. A circumferential crack in series with a crevice The viscous effects have not been included in this analysis. Therefore, these results should be considered as conservative estimates of the potential leak rate through a crack in series with a crevice (e.g., Q=AP/R). The sum of the leakage resistance in the freespan crack and in the crevice only conditions equals the resistance of the crack in series with a crevice. In all cases, the leak rates shown in the plots below are for a crack 4.00 inches above the bottom of the TS. See the table below for the set of conditions and pressures used in the models and in response to NRC RAI Questions 1 and 2. The leak rate ratio (abbreviated as LRR) in the tables and plots below refers to the ratio of the leak rate through a given crack during the SLB condition to the leak rate through the same crack during the NOP condition. a,c,e

_____ I

__ I__ I__ .1

__ .1__ J__ J___ J

Steam Generator primary side (Pri), secondary side (Sec), crevice (Crev), crack, and crack with crevice (C+C) pressures are expressed in pounds force per square inch (psi)

- Using test data found in Reference 19, a slope is defined to linearly interpolate the NOP crevice pressure ratio at 4 inches from the bottom of the tubesheet. The crevice pressure ratio used in this case is [ ]a...e

- - Using test data found in Reference 19, a slope is defined to linearly interpolate the SLB crevice pressure ratio at 4 inches from the bottom of the tubesheet. The crevice pressure ratio used in this case is [ ]a...e Page 6 of 36 LTR-CDME-07-13 NP-Attachment

Westinghouse Non-Proprietary Class 3 Response to Request for Additional Information Regarding Application for Steam Generator Tube Integrity Technical Specification The resistance of the crevice for a given TS radius, depth and differential pressure across the tube wall is the same regardless of crack orientation. Table 1, summarizes the predicted leak rate for the drop in pressure across the tube wall with the resistance of the crevice only. The crevice resistance is calculated using the values given in Reference 17.

Table 1: Crevice Only Leak Resistance Figures 5.0 through 10.0 show the leak rate and leak rate ratio for an axial or circumferential crack 17.03 inches below the top of the tubesheet (TTS) at different TS radii. The "near", "mid" and "peripheral" terms in each plot refer to TS radii. The TS radii for each range are: Near (2.0774 inches), Mid (33.101 inches), Peripheral (60.2475 inches) (Reference 1).

Figures 5.0 through 10.0 show that for any crack length, the SLB leakage is calculated not to exceed 2 times the leakage during normal operating conditions for any significant crack length (see response to question #3) at an elevation of 17.03 inches below the TTS.

Page 7 of 36 LTR-CDME-07-13 NP-Attachment

Westinghouse Non-Proprietary Class 3 Response to Request for Additional Information Regarding Application for Steam Generator Tube Integrity Technical Specification a,c,e Figure 5.0: Axial Crack, Crack Plus Crevice Resistance, Near Radius Page 8 of 36 LTR-CDME-07-13 NP-Attachment

Westinghouse Non-Proprietary Class 3 Response to Request for Additional Information Regarding Application for Steam Generator Tube Integrity Technical Specification a,c,e Figure 6.0: Circumferential Crack, Crack Plus Crevice Resistance, Near Radius a,c,e Figure 7.0: Axial Crack, Crack Plus Crevice Resistance, Mid Radius Page 9 of 36 LTR-CDME-07-1 3 NP-Attachment

Westinghouse Non-Proprietary Class 3 Response to Request for Additional Information Regarding Application for Steam Generator Tube Integrity Technical Specification a,c,e Figure 8.0: Circumferential Crack, Crack Plus Crevice Resistance, Mid Radius a,c,e Figure 9.0: Axial Crack, Crack Plus Crevice Resistance, Peripheral Radius Page 10 of 36 LTR-CDMF-07-13 NP-Attachment

Westinghouse Non-Proprietary Class 3 Response to Request for Additional Information Regarding Application for Steam Generator Tube Integrity Technical Specification ace Figure 10.0: Circumferential Crack, Crack Plus Crevice Resistance, Peripheral Radius The draft response to the draft NRC RAI provided to Seabrook included a response to a question similar to the current question regarding leak rate as a function of crack opening area. In that response, a figure was provided that led to a remaining'issue of leak rate vs. crack opening area.

This figure is reproduced here as Figure 11, which shows the leak rate reaching a maximum at some crack area and then declining with further increase in crack area. This peak in the curve is referred to as the "sweet spot". The character of the curve is highly dependent on the assumptions incorporated in the DENTFLO model. Similarly, the crack only leak rate plots also provided in the prior draft response are also highly dependent on similar model assumptions. The assumptions in the model pertaining to the relationship between the crevice resistance and the crack resistance were used to algebraically manipulate the DENTFLO output for a leak through a crack in series with a crevice. New test data (Reference 19) has changed the assumptions that were used to identify the crack-only and crevice-only leak rate conditions previously provided to the NRC for consideration. Therefore, the concerns with the "sweet spot" effects are no longer relevant to the current discussion.

Page II of 36 LTR-CDME-07-13 NP-Attachment

Westinghouse Non-Proprietary Class 3 Response to Request for Additional Information Regarding Application for Steam Generator Tube Integrity Technical Specification a,c,e Figure 11.0: Typical Result Displaying a Peak in the Predicted Leak Rate as a Function of Circumferential Crack Length The results shown in Figure 11.0 describe the interaction between two opposing phenomena: the ability of a crack to discharge fluid and the ability of a crack to maintain a pressure drop with increasing crack length. As the crack length increases, the crack opening area increases, and more fluid can be discharged through the crack. However, under isothermal conditions, a larger crack opening area reduces the pressure drop across the crack. Similar effects caused by the interaction of these opposing phenomena have been studied in flow through a converging orifice and discharge coefficients through sharp edged orifices (Reference 2). The new test data (Reference 19) has changed the assumptions that were used to calculate the leak rates shown in Figure 11.0. As displayed in Figures 4.0, 6.0, 8.0 and 10.0, the SLB leak rate is now calculated to increase with increasing circumferential crack length during a postulated steam line break event.

Page 12 of 36 LTR-CDME-07-13 NP-Attachment

Westinghouse Non-Proprietary Class 3 Response to Request for Additional Information Regarding Application for Steam Generator Tube Integrity Technical Specification NRC Question 3:

The discussion accompanying Figures3 and 4 in Attachment 6 to the RAI response states that cracks less than 0. 5 inches in length are not expected to cause any "relative significant leakage."

Pleaseexplain basisfor concluding the leakage contributionfrom the population of circumferentialcracks of through wall length less than 0.5 inches is small, relative to the leakage contributionfrom the population of through-wall cracks greaterthan 0. 5 inches in length such that the leakage ratio between normal operatingconditions and accident conditions is dominated by the leakage ratio (which is less than 2) exhibited by the population of cracks large than 0.5 inches. This explanationshould consider any relevant operatingexperience regarding probabilitydensity function of 100 percent through wall crack lengths and, in addition, the plots provided in response to 2 above.

EGC response to Question 3:

The bellwether principle addresses the concern regarding crack size because the leakage from even a very small crack under a postulated SLB event is limited to twice that of the normal operating condition (see, for example, Figure 5 through Figure 10 and the response to RAI #2).

The bellwether principle applies for the "True" value of B* which is the axial distance from the TTS where the flow resistance is the same at NOp and SLB conditions. The proposed inspection depth of 17 inches includes significant margin to the true B* value.

The maximum volumetric leak rate, Q, is based on Darcy's model for flow through porous media and is a function of the driving pressure, the inverse values of viscosity, the loss coefficient and the length of the crevice. Below 17 inches from the top of the tubesheet, the maximum leak rate from all significant indications would be limited to less than 2 times the leakage during normal operating conditions because the driving head at SLB conditions is twice that at NOp conditions and the leak resistance is greater below B*, the equal resistance point. It has already been pointed out by the NRC staff that the use of Darcy's formula is conservative relative to alternative models such as Bernoulli or orifice models, which assume leak rate to be proportional to the square root of differential pressure. As an example of the behavior under discussion, Figure 12.0 shows the crevice only and cumulative crack plus crevice resistance for the normal and accident conditions at the peripheral radius (i.e., TS radius of 60.2475 inches) 17.03 in. below the TTS (Reference 1).

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Westinghouse Non-Proprietary Class 3 Response to Request for Additional Information Regarding Application for Steam Generator Tube Integrity Technical Specification a,c,e Figure 12.0: Calculated Leakage Resistance for the Crevice Only and Crack Plus Crevice Conditions at the Peripheral Radius 17.03 in. Below the Top of the Tubesheet In regard to the probability density function of a 100% TW crack, it is noted that there are no data for A600TT tubing. The available data for the population of circumferential cracks are from the 1999 inspection record of the circumferential cracks at Callaway Unit 1 in mill-annealed Alloy 600 tubing. The tubing in the Byron and Braidwood steam generators is Alloy 600TT , which is significantly less sensitive to cracking initiation and propagation than the mill annealed tubing.

The available data were provided in WCAP-15932, the Callaway docket, NRC Accession No. ML022910436. The total data set included 40 circumferential cracks observed, with an average crack angle of 40.180 +/- 21.620, a maximum angle of 1080 and a minimum angle of 200. Of this population, 87.5% of the cracks were less than 0.5 inch in arc length, and 75% of the cracks covered an angle of 400 or less. In the data set, 25% of the circumferential cracks were 95%

through wall or greater; only a single crack was identified as 100% through wall. The depths of the indications were consistent with the data from prior inspections and suggest very little crack depth growth occurred.

For a tube with a 0.688 inch outer diameter (Model F SG), a crack angle of 400 corresponds to a crack arc length of approximately 0.24 inches. The predicted crack opening area for a guided circumferential crack (constrained from bending, crack opening constrained) 0.24 inch in length, using the models described in WCAP-15932 (Callaway docket, NRC Accession No. ML022910436) and illustrated in Figure 2, is approximately 1.03e-5 in2 for the NOp condition and 1.77e-5 in2 for the SLB condition.

Page 14 of 36 LTR-CDME-07-13 NP-Attachment

Westinghouse Non-Proprietary Class 3 Response to Request for Additional Information Regarding Application for Steam Generator Tube Integrity Technical Specification It is reasonable to consider a value for crack opening area on the order of 10-5 in2 as negligible.

This conclusion is consistent with the values for crack opening area that can be calculated using the alternate approach of calculating the kink angle compatibility via methods described in The Stress Analysis of Cracks Handbook ( 2 dEdition) by Tada. The result of such calculations, given in case 33.1 and 33.2 of the text, show that the crack opening area for circumferential cracks with an angle of less than 40' is expected to be zero. If the crack opening area is negligible, the potential flow through the crack should likewise be negligible. Therefore, since 75% of the cracks in the available database have crack angles less than 40', corresponding to a crack length of 0.24 inch, these cracks would not contribute significantly to any observed leakage.3 This analysis also validates the prior conclusion that for any crack that would contribute significantly to leakage, the ratio of leakage at SLB condition to that at NOp conditions will always be less than 2.

From the available database, the probability of a crack having an angle of 400 or greater, but still less than 0.5 inch arc length, is 12.5%. The probability of a circumferential crack having an arc length of 0.5 inch or greater is also 12.5%. Since the probability in the available data of cracks greater than 0.5 inch length is the same as the probability of occurrence of cracks less than 0.5 inch length is the same, and it is not possible for the crack opening area of constrained shorter cracks (<0.5 in.) to be greater than that of constrained longer (>0.5 in.) cracks, it is concluded that the leakage from the population of shorter cracks must be less than that from the population of longer cracks.

In summary:

0 The bellwether principle (QSb/QNop< 2 ) applies for all significant cracks.

Significant cracks (those that would be expected to contribute significantly to observed leakage) are those longer than 0.24 inch (a=0.12 inch).

The available data for tube cracking in the TS expansion region applies for A600MA tubing. The Byron/Braidwood tubing is A600TT which is much less susceptible to crack initiation and propagation.

0 75% of the cracks in the available database are less than 0.24 inch long and would, therefore, not contribute significantly to observed leakage.

0 Based on available data, the probability of cracks existing >0.5 inch length is the same as the probability of cracks <0.5 inch length. Therefore, the contribution of leakage from cracks <0.5 inch long is less than that from cracks >0.5 inch long.

3 Although cracks of this size do not contribute to leakage, the detection of any cracks from the top of the tubesheet (TTS) to 17 inches below the TTS will be cause for removing a tube from service.

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Westinghouse Non-Proprietary Class 3 Response to Request for Additional Information Regarding Application for Steam Generator Tube Integrity Technical Specification NRC Question 4:

Regardinga statement in the discussion underneathFigure 4 in Attachment 6 to the RAI response that reads, "The resultsfrom the crack-only analyses show that in the absence of the dent the resistance to flow is increasedand each crack type produces a lower leak rate ratio,"please clarify what is meant by the "dent, " and the impact on this statement. Additionally, please qualify what the increase in resistance to flow and lower leak rates are relative to.

EGC response to Question 4:

The reference to "dent" in the original response was erroneous. The underlying logic of the response was taken from a prior, similar response to an RAI which dealt with a licensing amendment request that concerned the presence of dents in conjunction with cracks and crevices.

Further, the reference to increased flow resistance for a crack-only analysis, absent another contributor to flow resistance (i.e., a dent) is incorrect and should read "...the resistance to flow is decreased..." since the model is resistances in series in which the resistances add to form the total resistance. Thus, as noted in the response to questions no. 2, the total resistance of the tubesheet region is the sum of the crack flow resistance and the resistance of the crevice.

Hypothetically, if a dent were involved in the tubesheet expansion region, the dent would represent an additional flow resistance.

This issue is also discussed in the response to question 2. In an attempt to respond to the original question as stated, which referenced leakage calculation methods that the NRC previously questioned, the response was developed using those specific methods. To simulate the crack-only and crack-plus-crevice conditions requested, an attempt was made to simulate the requested information using the same methods by artificially adjusting crack opening areas and boundary conditions in the computer code. Further study showed that this approach could lead to physically impossible results which were not recognized at the time, and it was concluded that this approach could not be used to provide the requested information.

NRC Question 5:

In Attachment 6 to the RAI response, the paragraphtitled "Analysis of Circumferential Cracking",states that the circumferentialcrack model was developed in WCAP-15932-P, Revision 1, "ImprovedJustificationof PartialLength RPC Inspection of Tube Joints of Model F Steam GeneratorsofAmeren-UE CallawayPlant," dated May 2003. WCAP-15932-P, Appendix C states that the main loadings on the circumferentialcrack below the H* distance are the pressure loads acting on the crackface. It is also stated in the WCAP that the internalpressure end cap load is not transmittedbelow about 1/3 the H* distance. Assuming that the H* is determined correctly, the NRC staff agrees that this statement is true for normal operating pressureprovidedthe tube is severed immediately below the 1/3 H* distance. Similarly, the 3 delta P end cap load does not extend below the H* distance assuming the tube is severed immediately below the H* distance.

If the tube is not severed, then much of the end cap load will be transmittedbelow the H*

distance. Taking an extreme example, the calculatedH* distance is based in part on pullout tests Page 16 of 36 LTR-CDME-07-13 NP-Attachment

Westinghouse Non-Proprietary Class 3 Response to Request for Additional Information Regarding Application for Steam Generator Tube Integrity Technical Specification (on specimens that were basically severed at the bottom) where the pullout criterionwas an axial displacement of 0.25 inches at the bottom of the specimen. If the tube is intact below the H*

distance, then the tube must be able to stretch by 0.25 inches between the weld and the H*

location which means there must be considerableforce transmittedbelow the H* distance. For smaller end cap loads where no slippage takes place, a severed tube end would be expected to displace upward due to the accumulatedstrains in the tube to tubesheetjointabove the severed location. If the tube is not completely severed, the tube below the crack would be expected to resist this displacement and thus resistsome of the pullout load. The tube to tubesheetjoint (where the tube is not severed inside the tubesheet) is a redundant structure. How much of the end cap load that gets transmittedbelow the crack location (assumed to be 17 inchesfrom the top of the tubesheet) depends on the stiffness of the frictionjoint above the crack relative to the stiffness of the tube below the crack.

It is not clearfrom the NRC staff's review of the model that this effect has been evaluated. Thus, it is not clear to the NRC staff that an axial load acting on the circumferentially cracked cross section is limited solely to the pressure acting on the crack faces and that no portion of the internal pressure end cap load is acting on the cross section. Please address this concern, including how the stiffness of the tube to tubesheetfriction joint above the crack relative to the stiffness of the tube below the crack have been specifically accountedfor. Has a detailedanalysis (e.g., finite element analysis) been performed to determine how much of the full internalpressure end cap load is actually transmitted to the cracked cross-section under normal operating and accident conditions. If so, describe the analysis and results.

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Westinghouse Non-Proprietary Class 3 Response to Request for Additional Information Regarding Application for Steam Generator Tube Integrity Technical Specification EGC response to Question 5:

A detailed finite element analysis, other than described in the technical justification to support the Byron/Braidwood License Amendment Request, has not been completed by Westinghouse to determine if any of the end cap load may be transmitted to a cracked tube cross-section at or below the H*distance. However, based on the analyses performed to determine the H* distance using the updated crevice pressure data detailed in Reference 19, it is concluded that no end-cap loads are transmitted below H*. The reasons follow:

a) The results of pull out tests coupled with those from finite element evaluations of the effects of temperature and primary-to-secondary pressure on the TS interface loads have been used to demonstrate that an engagement length of less than or equal to 8.61 inches (8.91 inches with 0.3 inch eddy current uncertainty) is sufficient to equilibrate axial loads resulting from the consideration of 3 times the normal operating pressure and 1.4 times the limiting accident pressure differences for the Byron/Braidwood steam generators.

The current license amendment request for the Byron/Braidwood steam generators is a 17 inch permanent inspection length criterion that contains ample structural margin to the full internal end cap load.

b) The proposed 17 inch inspection length is well below the length of engagement needed for the leak rate during a postulated steam line break event to be bounded by twice the leakage experienced during normal operating conditions. The contact pressure increases across the tubesheet for all radial locations relative to normal operating conditions during a postulated SLB at a depth of 17 inches into the tubesheet.

c) The Theory of Elasticity model was used to calculate the contact pressure preload associated with the test pullout forces. The full details of the model are discussed in Callaway docket, NRC Accession No. ML022910436. The value of the contact pressure was then converted to an average force per unit length using the gross area of contact.

The quantitative analysis follows the method published in Reference 3 and makes use of the flexibility expressions provided in Reference 4. The variations of the nomenclature used for the analysis are illustrated on Figure 15 and 16. For this discussion, the inside radius of the tube is designated a, the outside radius is b, and the outside radius of the TS simulating collar is c. When each radius is designated as r, the subscripts refer to the component, tube or collar, and the surface, inside or outside, respectively. For example, rto refers to the outside radius of the tube. The collar is sized to provide an average radial stiffness equal to that of the TS. The use of the theory of elasticity is desired because there will be a decrease in the contact pressure between the tube and the TS due to Poisson contraction of the tube in response to the application of the axial load.

Conversely, an increase in the contact pressure would result from the application of axial load tending to push on the tube; a push load arises from pressure on the crack flanks in operation. The decrease in contact pressure results in a radial inward springback of the TS and a radial outward springback of the tube outside radius. Resistance to pullout of the tube is manifested as a shear stress from the frictional contact pressure between the tube and the TS. The pullout resistance incrementally decreases along the interface as the axial load is applied. Not all of the axial load is transmitted downward into the TS because of the resistance provided by the shear stress, thus the Poisson contraction is Page 18 of 36 LTR-CDME-07-13 NP-Attachment

Westinghouse Non-Proprietary Class 3 Response to Request for Additional Information Regarding Application for Steam Generator Tube Integrity Technical Specification progressively less with distance into the TS. One observation from this discussion is that the tube does not behave as a rigid body, thus stretching deformation occurs as the load is progressively transmitted down the tube.

The result of the first principles derivation of the pullout force as a function of depth into the tubesheet is provided below:

The load carrying capability of the joint, F, is calculated by considering the force equilibrium diagram (Figure 16) for a short cylindrical element of the tube with length dz to establish a differential equation involving the axial stress, oz, and the net contact pressure, Pc. Compatibility and force-deformation relations are used to express the contact pressure as a function of depth in the tubesheet resulting in a first order differential equation (DE) for the contact pressure. When the contact pressure is constant through the tubesheet the DE is homogeneous. When the contact pressure is a function of depth into the tubesheet the DE is not homogeneous. By considering the initial contact pressure to be linear through the tubesheet, which is approximately the case per the results in Reference 5, a linear first order DE results.

The axial force equilibrium for an element of the tube with a length of dz and a cross-section area of A, illustrated on Figure 16.0, is given by, a,c,e E ] (1) where b is the outside radius of the tube, lt is the coefficient of friction between the tube and the tubesheet, and Pc is the contact pressure between the tube and tubesheet. So, a,c,e E J Force Equilibrium (2) is the differential equation of equilibrium. Note that the contact pressure is not known at this point. The contact pressure is the net value from the initial installation of the tube, thermal expansion and internal pressure associated with operation, and relaxation associated with dilation of the tubesheet holes as the result of bowing from the primary-to-secondary pressure differential.

The compatibility condition is that the reduction in the radius of a tubesheet hole due to the decrease in contact pressure must be equal to the expansion of the tube as a result of the decrease in contact pressure minus the Poisson contraction of the tube due to the application of the axial load. The magnitudes of the terms to be considered for compatibility come from the force-deformation relations.

The force-deformation relations will be used next to develop expressions for the respective deformations of the tube and tubesheet hole radii. Ifpo is the initial contact pressure, the decrease in TS hole radius from the decrease in the contact pressure can be found from, Page 19 of 36 LTR-CDME-07-13 NP-Attachment

Westinghouse Non-Proprietary Class 3 Response to Request for Additional Information Regardinq Application for Steam Generator Tube Integrity Technical a,c,e ition I I TS Radius Decrease (3) where the subscript on the radius indicates if it is for the tubesheet collar. Absolute relations are considered since the accounting of the directions of movement can be accounted for later. The flexibility of the inside radius of the collar relative to an internal pressure is given by, Collar Flexibility (4)

I I where v is Poisson's ratio for the tubesheet and E is the modulus of elasticity. This is obtained from the application of the theory of elasticity to a thick-walled, open ended cylinder, see Reference 4 for example.

The corresponding relation for the effect of the change in pressure on the outside radius of the tube is given by, a,c,e I I Tube Radius Increase (5)

Because of the application of the axial tensile stress, there is a radial contraction (Poisson effect) of the tube given by the following expression, a,c,e I I Tube Radius Decrease (6)

If the axial stress is compressive, the radius of the tube increases due to the Poisson effect.

Applying the compatibility condition that the tube must remain in contact with the tubesheet leads to the following solution for the average axial stress acting on the tube element (See Figures 15 and 16 for the tube element) of the form:

a,c,e I I Tube Stress (7)

Equation 7 is a combination of Equations 3, 4, 5 and 6 above according to the compatibility condition with some algebraic manipulation.

Page 20 of 36 LTR-CDME-07-13 NP-Attachment

Westinghouse Non-Proprietary Class 3 Response to Request for Additional Information Regarding Application for Steam Generator Tube Integrity Technical Specification If the modulus of elasticity of the tube and the tubesheet, or collar, are not the same, the expression for pullout force is: a,c,e 1K (8)

By iterative solution of equation 8, it can be demonstrated that the force, F, does not penetrate below H*. Indeed, the value of H* includes significant margin below the predicted distance into the tubesheet where the NOp end cap load is equilibrated.

In equation 8, Af is the difference in radial flexibilities between the tubesheet and the tube relative to the application of the interface pressure, i.e., Af=fe-f where the respective flexibility expressions are, a,c,e 1 (9) 1 Note thatf is negative, indicating that the radius of the tube decreases in response to an external pressure. The difference between the two quantities is then the same as the sum of their absolute values. The difference is frequently referred to as the influence coefficient between the tube and the tubesheet. Moreover, A is the cross section area of the tube given by:

A = rt(b2 -a2)

Based on an incremental analysis completed for a Model F SG it is calculated that the normal operating pressure end cap loads are not transmitted below about 1/2 of the H*

depth based on the calculation documented in the technical justification. The only source of forces acting to extend a circumferential crack at or below the H* distance is the primary pressure acting on the crack flanks.

d) Since the tube is captured within the tubesheet, there are additional forces acting to resist the opening of a crack. The contact pressure between the tube and tubesheet results in a friction induced shear force acting to oppose the direction of cracking opening, and the force on the crack flanks is compressive on the material adjacent to the plane of the cracks. Hence, Poisson's ratio radial expansion of the tube material in the immediate vicinity of the crack plane is induced that acts to restrain the opening of the crack.

Further, the differential thermal expansion of the A600TT tube is greater than that of the carbon steel tubesheet, thereby inducing a compressive stress in the tube below the H*

length.

Page 21 of 36 I.TR-CDME-07-13 NP-Attachment

Westinghouse Non-Proprietary Class 3 Response to Request for Additional Information Regarding Application for Steam Generator Tube Integrity Technical Specification Axial Force Tube

/Potential Leak Path Crack or Sever Location Figure 13.0: Tube with Circumferential Crack or Sever Within the Tubesheet Page 22 of 36 LTR-CDME-07-13 NP-Attachment

Westinghouse Non-Proprietary Class 3 Response to Request for Additional Information Regarding Application for Steam Generator Tube Integrity Technical Specification Figure 14.0: Tube-to-Tubesheet Pullout Testing Page 23 of 36 LTR-CDME-07-13 NP-Attachment

Westinghouse Non-Proprietary Class 3 Response to Request for Additional Information Regarding Application for Steam Generator Tube Integrity Technical Specification I _ t -

b,r~ r.

Ia, r 1 Tube and Collar Centerline Figure 15.0: Tube & Collar Radii Designations Page 24 of 36 LTR-CDME-07-13 NP-Attachment

Westinghouse Non-Proprietary Class 3 Response to Request for Additional Information Regarding Application for Steam Generator Tube Integrity Technical Specification a,c,e Figure 16.0: Tube Wall Element For Elastic Analysis Page 25 of 36 LTR-CDME-07-13 NP-Attachment

Westinghouse Non-Proprietary Class 3 Response to Request for Additional Information Regarding Application for Steam Generator Tube Integrity Technical Specification NRC Question 6:

The Reference 1 application included the following provision in TS 5.5.9c: "For Unit 2 only, degradationfound in the portion of the tube from the top of the hot leg tubesheet to 17 inches below the top of the tubesheet shall be plugged or repaired on detection." In the example accompanying the NRC staff's draft RAI No. 4, the NRC staff inadvertently left this sentence out.

It wasn't the NRC staff's intent to suggest this sentence should be deleted. Describeyour plan for re-includingthis sentence as part of TS 5.5.9c. Also, as a point of consistency and clarification, the word "degradation" in the above sentence and in TS 5.5.9c.4.1 shall be replacedby the word

'flaws" consistent with the rest of the technical specifications. Please describe your plan for making this change as well.

EGC Response to Question 6:

EGC to provide response.

NRC Question 7:

Did any of the hydraulic expansions in the Model D5 SGs experience a stress relief during fabrication, directly or indirectly (e.g., as a result of stress relieving the shell to tubesheet welds)? If so, how was this reflected in the pullout and leakage tests in support of the tubesheet amendment requests.

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Westinghouse Non-Proprietary Class 3 Response to Request for Additional Information Regarding Application for Steam Generator Tube Integrity Technical Specification EGC Response to Question 7:

The tube-to-TS joint is completed prior to welding the channel head to the TS and therefore the joint necessarily experiences a thermal cycle during the subsequent post weld heat treatment of the weld seam. In order to determine the temperature which the expanded tube joints experience, thermocouples were installed in tubes in the region of the TS in one of the replacement steam generators prior to PWHT of the weld seam (Reference 6). Two types of thermocouples (TCs) were used. For type 1 TCs, Ia,c,e Figure 17.0 shows examples of temperature-time plots for the select TCs. The upper curve represents the TS to weld seam. Of the various TCs on the weld seam, TC 19 was the first one to reach the "soak temperature" of [ .. The lower curves were

]ac for the three thermocouples in the tube Row 1 Column 1 on the hot leg side of the channelhead.

Figures 18.0, 19.0, and 20.0 show the locations of tubes that were equipped with thermocouples and the peak tube temperatures achieved. As expected, the highest temperatures occurred at the periphery of the tube bundle on the primary side of the TS. The peak temperatures observed were I

]apc`e These temperatures are judged to be representative of the temperatures that would be expected in the Model D5 steam generators during post weld heat treatment of the Z-seam weld due to similarity in the steam generator dimensions (tubesheet thickness, diameter, channelhead thickness, etc) and the type of materials used in the fabrication of the replacement SG that was instrumented and the Model D5 steam generator (Reference 18).

As a result, the Model D5, Model 44F, and Model 5 IF, H* testing programs did consider a 9000 F stress relief cycle on the tube-to-TS test specimens (References 7 and 8). As noted in Reference 6, a soak temperature as low as [ ]a,c,e can be justified as being typical, but also on the conservative side, for most of the joint lengths. However, the data packages for the H*

pullout and leakage testing for the Model F SGs has no indication that a stress relief was either considered or implemented in test specimen preparation (Reference 9). As the Model F loss coefficients were used as applicable loss coefficients for the Model D5 SGs, the purpose of this response is to show that the test results used to develop the H*and B* distances for the Model F steam generators are acceptable even though the [ ]a,c, stress relief cycle may not have been applied to the test specimens.

The impact of the PWHT of the TS to channelhead weld (called the Z-seam weld) on joint tightness between the expanded tube and TS has been assessed analytically in terms of impact on residual contact pressure and experimentally by pull tests, leak rate tests and fluid dye-penetration tests. It is concluded that is was [

]apc based on the following reasons:

0 The temperatures which the tubes experience are too low to effect stress relief of the tube joint and are not expected to have any effect on joint leak tightness. The tubes may become discolored to some extent with a thin heat tint oxide film. Such heat tint films Page 27 of 36 LTR-CDME-07-13 NP-Attachment

Westinghouse Non-Proprietary Class 3 Response to Request for Additional Information Regarding Application for Steam Generator Tube Integrity Technical Specification have been observed on various studies related to in-situ stress relief of U-bends and tube support plate intersections. In these studies Alloy 600 Row I U-bend tubes and reverse U-bend tube samples were stress relieved in air at temperatures up to [ ]a,c, (Reference 10).

The contact pressure strength of hydraulically expanded tubes with the expansion pressure of around [ ],,,ce The residual contact pressure is not the greatest contributor to tube joint pullout strength. Thermal growth mismatch between the Alloy 600 tubing and carbon steel TS, primary side pressure and TS bow effects are much more significant contributors to joint strength (Reference 10).

" It has been shown analytically that the exposure to elevated temperatures below I ]axc does not significantly effect tube joint contact pressure.

Tube pullout testing shows that the breakaway load is essentially the same before and after PWHT for both Alloy 600 and Alloy 690 tubing. The maximum load after PWHT is [

]a,c,c

The tubes that are affected most by heat treatment of the Z-seam weld are

]a,c,e

" Helium leak testing does not show a

]a,c,

" Dye penetrant testing of tube joints shows that

]a,c,e Page 28 of 36 LTR-CDME-07-13 NP-Attachment

Westinghouse Non-Proprietary Class 3 Response to Request for Additional Information Regarding Application for Steam Generator Tube Integrity Technical Specification a,c,e Figure 17.0 Examples of Temperature Time Plots Page 29 of 36 LTR-CDME-07-13 NP-Attachment

Westinghouse Non-Proprietary Class 3 Response to Request for Additional Information Regarding Application for Steam Generator Tube Integrity Technical Specification a,c,e Figure 18.0: Peak Tube Temperatures (TF) at the Primary Side Face of the Tubesheet Page 30 of 36 LTR-CDME-07-13 NP-Attachment

Westinghouse Non-Proprietary Class 3 Response to Request for Additional Information Regarding Application for Steam Generator Tube Integrity Technical Specification a,c,e Figure 19.0: Peak Tube Temperatures (°F) at the Secondary Side Face of the Tubesheet Page 31 of 36 LTR-CDMF-07-13 NP-Attachment

Westinghouse Non-Proprietary Class 3 Response to Request for Additional Information Regarding Application for Steam Generator Tube Integrity Technical Specification a,c,e Figure 20.0: Peak Tube Temperatures (°F) 8-Inches Beyond the Secondary Side of the Tubesheet Page 32 of 36 LTR-CDME-07-13 NP-Attachment

Westinghouse Non-Proprietary Class 3 Response to Request for Additional Information Regarding Application for Steam Generator Tube Integrity Technical Specification NRC Question 8:

The tubesheet bow analysis describedin Westinghouse report,LTR-CDME-05-32-P, Rev. 2,4 submitted as Attachment 7 to the originallicense amendment request,5 takes creditfor resistance against tube bow provided by the dividerplate. Cracks in the welds connecting the tubesheet and divider plate have been found by inspection at certainforeign steam generators. Please describe how such cracks, ifpresent in the Byron/Braidwoodunits, could affect the conservatism of the proposed17-inch tubesheet inspection distance requirementfor ensuringstructuraland leakage integrity.

EGC Response to Question 8:

Indications of cracks in the divider plates have been reported in several steam generators located in France. These indications have been observed in steam generators located at the Chinon, Saint-Laurent, Dampierre and Gravelines nuclear power stations. The cracks were observed on the hot leg side of the divider plate in the stub runner divider plate weld, stub runner base metal and also at or in the divider plate itself. See Figure 21.0 for a sketch of the region where cracking has been observed to occur.

The divider plate has typically been accounted for in B* and H* analyses via a divider plate factor, which is the ratio of the maximum vertical tubesheet displacements with an intact divider plate compared to the maximum vertical displacements of a tubesheet with no divider plate present. The factor is based on the ASME Code Stress Report provided for the SGs, which considered both to conservatively calculate stresses in the tubesheet and stresses in the components attached to the tubesheet. The ratio of the maximum tubesheet displacement with and without the benefit of the divider plate is [

]a,c,e The divider plate factor from the ASME stress report was determined by [

]a..ce The finite element models utilized for the code stress report to determine the divider plate effect were overly conservative because they did not account for features in the lower steam generator assembly that act to increase the resistance of the tubesheet to vertical deflections. For example, in the early analysis models used to calculate tubesheet displacements, the tubelane and the channel head to divider plate weld were not modeled. Research by Terakawa (Reference 13) indicates that the presence of the tube material within the tubesheet acts to stiffen the tubesheet with respect to bending and vertical deflection. A more detailed finite element model than that 4The title of this report is: "Limited Inspection of the Steam Generator Tube Portion Within the Tubesheet at Byron 2 & Braidwood 2."

5The original request for a license amendment was provided in a letter from J. A. Bauer (Exelon Generation Company, LLC) to U. S. NRC, "Application for Technical Specification Improvement Regarding Steam Generator Tube Integrity," dated November 18, 2005.

Page 33 of 36 LTR-CDME-07-13 NP-Attachment

Westinghouse Non-Proprietary Class 3 Response to Request for Additional Information Regarding Application for Steam Generator Tube Integrity Technical Specification used in the original stress analysis shows that the impact of a non-degraded divider plate on tubesheet deflection is significantly greater and that the appropriate value to use for the divider plate factor in H* and B* analyses is [ )]a,c,c, that is, the tubesheet deflection with an intact divider plate is significantly less than originally estimated.

The effect of a reduced divider plate factor with a non-degraded divider plate will [

]a,c,e To evaluate the effect of a degraded divider plate, a bounding analysis was performed which assumed that the divider plate provides no restraint against tubesheet deflection (i.e. DP = 1.00).

The structural model used in this bounding analysis was the improved finite element model. The bounding value for H* and B* using the previous model assumptions (with the secondary side pressure in the crevice) was estimated to be 12 inches (Reference 15). Therefore, significant margin is available between the requested 17" inspection depth and the justifiable value of H*/B*. a,c,e Figure 21.0: Sketch of Divider Plate, Channel Head and Tubesheet with Potential Cracking Areas Highlighted Page 34 of 36 LTR-CDME-07-13 NP-Attachment

Westinghouse Non-Proprietary Class 3 Response to Request for Additional Information Regarding Application for Steam Generator Tube Integrity Technical Specification

References:

1. LTR-CDME-07-15, Rev. 1, "Identification of Byron 2 and Braidwood 2 Microsoft Excel Worksheets Supporting LTR-CDME-07-13-P Attachment," February 2007. (Proprietary)

3. Goodier, J., and Schoessow, G., "The Holding Power and Hydraulic Tightness of Expanded Tube Joints: Analysis of Stress and Deformation," Transactions of the ASME, New York, New York, USA (July, 1943).

4. Formulasfor Stress and Strain, Fifth Edition, Roark, R., and Young, W., McGraw-Hill Book Company, New York, New York, USA (1975).

5. CN-SGDA-02-127, "Evaluation of Tube/Tubesheet Contact Pressures for Wolf Creek, Seabrook, and Millstone 3 Model F Steam Generators," Westinghouse Electric Company, Madison, PA, USA (August, 2002).

6. WNEP-9725, The Westinghouse Tube-to-Tubesheet Joint Hydraulic Expansion Process -

Design, Qualification, Manufacturing, and Performance," July 1997.

7. DP-SGDA-03-1, "Model D5 Tube-to-Tubesheet Joint Determination of Pullout Resistance for H-Star Program for Comanche Peak 2/TCX, Catawba 2/DDP, Byron 2/CBE and Braidwood 2/CCE," October 2003.

8. DP-SGDA-05-2, "Data Package for H-Star Pull Test of 7/8 Inch Tubing from Simulated Tubesheet, PA-MSC-0 199 WOG Program for Steam Generator Models 44F and 5 IF,"

November 2005.

9. STD-DP-1997-8015, Rev. 0, "Data Package for Leak Testing of Vogtle Unit 1 Steam Generator Tube to Tubesheet Joint per STD-TP-1997-7951, Rev. 1," 6/3/97.

10. Nuclear Engineering and Design 143 (1993) 159-169 North-Holland, "Residual Stresses Associated with the Hydraulic Expansion of Steam Generator Tubing into Tubesheets," W.B.

Middlebrooks, D.L. Harrod, and R.E. Gold.

11. NCE-88-27 1, "Assessment of Tube-to-Tubesheet Joint Manufacturing Processes for Sizewell B Steam Generators Using Alloy 690 Tubing," November 1988.

12. WNEP-8448, "Hydraulic Expansion of Steam Generator Tubes into Tubesheets," December 1983.

13. Terakawa, T., Imai, Yagi, Kazushige, Fukada, Y., Okada, K., "Stiffening Effects of Tubes in Heat Exchanger Tube Sheet," Journal of Pressure Vessel Technology Transactions, ASME, Vol. 106, No. 3, August 1984.

14. CN-SGDA-07-6, C.D. Cassino, "Finite Element Analysis of a Degraded Alloy 600 Stub Runner to Divider Plate Weld in Non-Center Stayed Steam Generator," January 2007.

Page 35 of 36 LTR-CDME-07-13 NP-Attachment

Westinghouse Non-Proprietary Class 3 Response to Request for Additional Information Regarding Application for Steam Generator Tube Integrity Technical Specification

15. LTR-SGDA-06-157, C.D. Cassino, "B*/H* Bounding Cracked Divider Plate Analysis,"

8/31/06.

16. LTR-SGDA-06-156, "Potential Effect of Cracks in Westinghouse Steam Generator Divider Plates Considering EDF Cracking History," August 29, 2006.

17. LTR-CDME-05-32-P, Rev. 2, "Limited Inspection of the Steam Generator Tube Portion Within the Tubesheet at Byron 2 and Braidwood 2," August 2005. (Proprietary)

18. LTR-SGDA-03-191, "H* Testing of Model D5 and F Tube-to-Tubesheet Joint Specimens,"

August 3, 2003.

19. LTR-SGDA-07-4, "Letter Summary of Changes to B* and H* Analysis due to New Crevice Pressure and Divider Plate Data," January 17, 2007.

Page 36 of 36 LTR-CDME-07-13 NP-Attachment

Attachment 4 Westinghouse Electric Company, LLC SG-CDME-07-02-P-Attachment White Paper Addressing Changes to B* and H*

Analysis due to New Crevice Pressure and Divider Plate Information (Proprietary)

Attachment 5 Westinghouse Electric Company, LLC Affidavit CAW-07-2234 Request to Withhold Proprietary Information Contained In SG-CDME-07-02-P-Attachment

( )Westinghouse Westinghouse Electric Company Nuclear Services P.O. Box 355 Pittsburgh, Pennsylvania 15230-0355 USA U.S. Nuclear Regulatory Commission Direct tel: (412) 374-4643 Document Control Desk Direct fax: (412) 374-4011 Washington, DC 20555-0001 e-mail: greshaja@westinghouse.com Our ref CAW-07-2234 February 8, 2007 APPLICATION FOR WITHHOLDING PROPRIETARY INFORMATION FROM PUBLIC DISCLOSURE

Subject:

SG-CDME-07-2-P Attachment, "White Paper Addressing Changes to B* and H* Analyses Due to New Crevice Pressure and Divider Plate Information," dated February 2, 2007 (Proprietary)

The proprietary information for which withholding is being requested in the above-referenced report is further identified in Affidavit CAW-07-2234 signed by the owner of the proprietary information, Westinghouse Electric Company LLC. The affidavit, which accompanies this letter, sets forth the basis on which the information may be withheld from public disclosure by the Commission and addresses with specificity the considerations listed in paragraph (b)(4) of 10 CFR Section 2.390 of the Commission's regulations.

Accordingly, this letter authorizes the utilization of the accompanying affidavit by Exelon Generation Company, LLC.

Correspondence with respect to the proprietary aspects of the application for withholding or the Westinghouse affidavit should reference this letter, CAW-07-2234, and should be addressed to J. A. Gresham, Manager, Regulatory Compliance and Plant Licensing, Westinghouse Electric Company LLC, P.O. Box 355, Pittsburgh, Pennsylvania 15230-0355.

Very truly yours,

.,J. A. Gresham, Manager Regulatory Compliance and Plant Licensing Enclosures cc: Jon Thompson (NRC O-7E IA)

CAW-07-2234 AFFIDAVIT COMMONWEALTH OF PENNSYLVANIA:

ss COUNTY OF ALLEGHENY:

Before me, the undersigned authority, personally appeared J.A. Gresham, who, being by me duly sworn according to law, deposes and says that he is authorized to execute this Affidavit on behalf of Westinghouse Electric Company LLC (Westinghouse), and that the averments of fact set forth in this Affidavit are true and correct to the best of his knowledge, information, and belief:

" J.A. Gresham, Manager Regulatory Compliance and Plant Licensing Sworn to and subscribed before me this 8 th day of February, 2007 Notary Public COMMONWEALTH OF PeNNSYLVANIA Notarial Seal Sharon L. Markle, Notary Public Monroeville Boro, Allegheny County My Commission Expires Jan. 29, 2011 Member, Pennsylvania Association of Notaries

2 CAW-07-2234 (1) 1 am Manager, Regulatory Compliance and Plant Licensing, in Nuclear Services, Westinghouse Electric Company LLC (Westinghouse), and as such, I have been specifically delegated the function of reviewing the proprietary information sought to be withheld from public disclosure in connection with nuclear power plant licensing and rule making proceedings, and am authorized to apply for its withholding on behalf of Westinghouse.

(2) 1 am making this Affidavit in conformance with the provisions of 10 CFR Section 2.390 of the Commission's regulations and in conjunction with the Westinghouse "Application for Withholding" accompanying this Affidavit.

(3) 1have personal knowledge of the criteria and procedures utilized by Westinghouse in designating information as a trade secret, privileged or as confidential commercial or financial information.

(4) Pursuant to the provisions of paragraph (b)(4) of Section 2.390 of the Commission's regulations, the following is furnished for consideration by the Commission in determining whether the information sought to be withheld from public disclosure should be withheld.

(i) The information sought to be withheld from public disclosure is owned and has been held in confidence by Westinghouse.

(ii) The information is of a type customarily held in confidence by Westinghouse and not customarily disclosed to the public. Westinghouse has a rational basis for determining the types of information customarily held in confidence by it and, in that connection, utilizes a system to determine when and whether to hold certain types of information in confidence. The application of that system and the substance of that system constitutes Westinghouse policy and provides the rational basis required.

Under that system, information is held in confidence if it falls in one or more of several types, the release of which might result in the loss of an existing or potential competitive advantage, as follows:

(a) The information reveals the distinguishing aspects of a process (or component, structure, tool, method, etc.) where prevention of its use by any of

3 CAW-07-2234 Westinghouse's competitors without license from Westinghouse constitutes a competitive economic advantage over other companies.

(b) It consists of supporting data, including test data, relative to a process (or component, structure, tool, method, etc.), the application of which data secures a competitive economic advantage, e.g., by optimization or improved marketability.