AEP-NRC-2011-15, Response to Second Request for Additional Information Regarding Amendment Request Associated with the Large-Break Loss-of-Coolant Accident Analysis Methodology

Response to Second Request for Additional Information Regarding Amendment Request Associated with the Large-Break Loss-of-Coolant Accident Analysis Methodology

ML110680210
Person / Time
Site:	Cook
Issue date:	02/24/2011
From:	Gebbie J Indiana Michigan Power Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
AEP-NRC-2011-15, CAW-10-3034, TAC ME1017
Download: ML110680210 (82)

Text

z INDIANA PROPRIETARY INFORMATION MICHIGAN Enclosures 3 and 4 to this letter contain proprietary information.

IA!OER Withhold from public disclosure under 10 CFR 2.390.

A unit ofAmerican Electric Powflpon removal of Enclosures 3 and 4, this letter is decontrolled.

Indiana Michigan Power Cook Nuclear Plant One Cook Place Bridgman, Mi 49106 AEP~com February 24, 2011 AEP-NRC-2011-15 10 CFR 50.90 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001

References:

Donald C. Cook Nuclear Plant Unit 2 Docket No. 50-316 Response to Second Request for Additional Information Regarding a License Amendment Request Associated With the Large-Break Loss-Of-Coolant Accident Analysis Methodology (TAC No. ME1017)

1) Letter from L. J. Weber, Indiana Michigan Power Company (I&M), to U.S.

Nuclear Regulatory Commission (NRC)

Document Control

Desk, "Donald C. Cook Nuclear Plant Unit 2, Docket No. 50-316, License Amendment Request Regarding Large Break Loss-of-Coolant Accident Analysis Methodology," AEP-NRC-2009-23, dated March 19, 2009 (ADAMS Accession Number ML090930453).

2) Letter from T. A. Beltz, NRC, to J. N. Jensen, I&M, "Donald C. Cook Nuclear Plant, Unit 2 - Request for Additional Information (RAI)

Regarding the License Amendment Request Associated With the Large-Break Loss-of-Coolant Accident Analysis Methodology (TAC No. ME1017)," dated September 22, 2009 (ADAMS Accession Number ML092610029).

3) Letter from L. J. Weber, I&M, to NRC Document Control Desk, "Donald C. Cook Nuclear Plant Unit 2, Docket No. 50-316, Response to Request for Additional Information Regarding a License Amendment Request Associated With the Large-Break Loss-Of-Coolant Accident Analysis Methodology (TAC No.

ME1017)," AEP-NRC-2009-71, dated November 20, 2009 (ADAMS Accession Number ML093360524).

4) Electronic mail from P. S. Tam, NRC, to M. K. Scarpello, H. L. Etheridge, and J. R. Waters, I&M, et al., "D.C. Cook Unit 2 - Second Set of Formal RAI on the Proposed LBLOCA Amendment (TAC ME1017)," dated January 20, 2011 (ADAMS Accession Number ML110210006).

Dear Sir or Madam:

This letter provides Indiana Michigan Power Company's (l&M's) response to a second U. S. Nuclear Regulatory Commission (NRC) request for additional information (RAI) regarding l&M's proposed license amendment to adopt a new*.-large break loss-of-coolant accident (LBLOCA)

U. S. Nuclear Regulatory Commission AEP-NRC-2011-15 Page 2 analysis for Donald C. Cook Nuclear Plant (CNP) Unit 2. This letter also describes two errors in the new analysis that were identified subsequent to its submittal, and describes I&M's current plans for resolution of the errors. The resolution of these errors will not alter the methodology used for the new LBLOCA analysis or the RAI responses provide by this letter.

By Reference 1, I&M proposed to amend Appendix A, Technical Specification (TS), to the CNP Unit 2 Facility Operating License, DPR-74.

I&M requested NRC approval to adopt a new LBLOCA analysis for CNP Unit 2, and proposed to modify the associated TS.

The new LBLOCA analysis uses a plant-specific adaptation of the NRC-approved methodology documented in Westinghouse Electric Company LLC (Westinghouse) Topical Report WCAP-16009-P-A, "Realistic Large-Break LOCA Evaluation Methodology Using the Automated Statistical Treatment of Uncertainty Method (ASTRUM)." By Reference 2, the NRC transmitted an RAI regarding the proposed amendment.

By Reference 3, I&M provided the information requested by Reference 2. By Reference 4, the NRC transmitted a second RAI regarding the proposed amendment. This letter provides l&M's response to the second RAI. to this letter provides an affirmation statement. provides l&M's response to the second NRC RAI. Enclosures 3 and 4 are Westinghouse reports that provide information requested by the second NRC RAI.

These reports contain information that is proprietary to Westinghouse. Accordingly, Enclosures 5 and 6 are Westinghouse applications for withholding these reports from public disclosure.

Enclosures 7 and 8 are non-proprietary versions of these reports. Enclosure 9 provides a discussion of the two errors identified in the new LBLOCA analysis.

Copies of this letter and its enclosures are being transmitted to the Michigan Public Service Commission and the Michigan Department of Natural Resources and Environment, in accordance with the requirements of 10 CFR 50.91. This letter contains no new or modified NRC commitments.

Should you have any questions, please contact Mr. Michael K. Scarpello, Regulatory Affairs Manager, at (269) 466-2649.

Sincerely, Joel, P. Gebbie Site Vice President JRW/jmr

U. S. Nuclear Regulatory Commission AEP-NRC-2011-15 Page 3

Enclosures:

1.

Affirmation

2.

Response to Second NRC RAI Regarding License Amendment Request Associated With the Large-Break Loss-Of-Coolant Accident Analysis Methodology for Donald C.

Cook Nuclear Plant Unit 2.

3.

Westinghouse Report, "D. C. Cook Unit 2 (AMP) Post-LOCA Responses to Request for Additional Information (RAI)," Proprietary Version.

4.

Westinghouse Report, "Supplemental Information to Support Informal NRC Audit of 12 Downcomer Channel Model Validation," Proprietary Version.

5.

Application for Withholding Proprietary Information from Public Disclosure for.

6.

Application for Withholding Proprietary Information from Public Disclosure for.

7.

Westinghouse Report, "D. C. Cook Unit 2 (AMP) Post-LOCA Responses to Request for Additional Information (RAI)," Non-Proprietary Version.

8.

Westinghouse Report, "Supplemental Information to Support Informal NRC Audit of 12 Downcomer Channel Model Validation," Non-Proprietary Version.

9.

Discussion of Two Errors in the New LBLOCA Analysis.

c:

J.T. King, MPSC S. M. Krawec, Ft. Wayne AEP, w/o enclosures MDNRE - WHMD/RPS NRC Resident Inspector M. A. Satorius, NRC Region III P. S. Tam, NRC, Washington DC to AEP-NRC-2011-15 AFFIRMATION I, Joel P. Gebbie, being duly sworn, state that I am Site Vice President of Indiana Michigan Power Company (I&M), that I am authorized to sign and file this request with the Nuclear Regulatory Commission on behalf of I&M, and that the statements made and the matters set forth herein pertaining to I&M are true and correct to the best of my knowledge, information, and belief.

Indiana Michigan Power Company Joel P. Gebbie Site Vice President SWORN TO AND SUBSCRIBED BEFORE ME THIS DAY OF "f'Ce1(1

,2011 My Commission Expires L Iol 10 1

to AEP-NRC-2011-15 Response to Second NRC RAI Regarding License Amendment Request Associated With the Large-Break Loss-Of-Coolant Accident Analysis Methodolo-gy for Donald C. Cook Nuclear Plant Unit 2 The documents referenced in this enclosure are identified on page 5.

By Reference 1, Indiana Michigan Power Company (I&M) proposed to amend Appendix A, Technical Specification (TS), to the Donald C. Cook Nuclear Plant (CNP) Unit 2 Facility Operating License, DPR-74. I&M requested NRC approval to adopt a new large break loss-of-coolant accident (LBLOCA) analysis for CNP Unit 2, and proposed to modify the associated TS.

The new analysis uses a plant-specific adaptation of the U.S. Nuclear Regulatory Commission (NRC)-approved methodology documented in Westinghouse Electric Company LLC (Westinghouse) Topical Report WCAP-16009-P-A, "Realistic Large-Break LOCA Evaluation Methodology Using the Automated Statistical Treatment of Uncertainty Method (ASTRUM)." By Reference 2, the NRC transmitted a Request for Additional Information (RAI) regarding the proposed amendment.

By Reference 3, I&M provided the information requested by Reference 2.

By Reference 4, the NRC transmitted a second RAI regarding the proposed amendment. This enclosure provides I&M's response to the second RAI. Each RAI question in Reference 4 is restated below followed by the corresponding I&M response.

In some cases, I&M's response refers to the Westinghouse reports provided in Enclosure 3 or Enclosure 4 to this letter. These Westinghouse reports were informally provided to the NRC on November 29, 2010, and December 17, 2010, respectively. These reports are proprietary to Westinghouse. and Enclosure 8 to this letter provide non-proprietary versions of these reports.

NRC RAI Question I Please provide the results of the boric acid precipitation analysis (i.e., analysis report) that supports the D.C. Cook Unit 2 power level of 3479.8 MWt. The analysis should show the boric acid concentration versus time assuming no switch to simultaneous injection. The analysis should also list all of the key parameter inputs and assumptions applicable to the model used to identify the emergency operating procedure timing for switching to hot-leg injection.

I&M Response A boron precipitation analysis report for CNP which compiles the requested information in a single concise document was not prepared when the analyses were performed. I&M considers that the response to Questions 3, 4, and 5 will resolve the concern involved with Question 1.

NRC RAI Question 2 Please comment if the boron precipitation analyses and assumptions referenced in WCAP-15302, "Donald C. Cook Nuclear Plant Units 1 and 2, Modifications to the Containment Systems," dated September 1999, are still valid to support the loss-of-coolant-accident analysis and assumptions that are the basis for this large-break loss-of-coolant accident license amendment request.

to AEP-NRC-2011-15 Page 2 I&M Response I&M confirms that the boron precipitation inputs and assumptions referenced in WCAP-15302 (transmitted by Reference 5) are still valid to support the analysis and assumptions that are the basis for the LBLOCA amendment request.

NRC RAI Question 3 Please provide the following information regarding the D.C. Cook Unit 2 nuclear steam supply system:

a. Volume of the lower plenum, core and upper plenum below the bottom elevation of the hot leg, each identified separately. Also provide heights of these regions.

b. Loop friction and geometry pressure losses from the core exit through the steam generators to the inlet nozzle of the reactor vessel. Also, provide the locked rotor RCP k-factor. Please provide the mass flow rates, flow areas, k-factors, and coolant temperatures for the pressure losses provided (upper plenum, hot legs, steam generators (SG), suction legs, reactor coolant pumps, and discharge legs). Please include the reduced SG flow areas due to plugged tubes. Please also provide the loss from each of the intact cold legs through the annulus to a single broken cold leg. Please also provide the equivalent loop resistance for the broken loop and separately for the intact loop.

c. Capacity and boron concentration of the refueling water storage pool.

d. Capacity of the condensate storage tank

e. Flushing flow rate at the time of switch to simultaneous injection

f. HPSI [high pressure safety injection] runout flow rate

g. Capacities and boron concentrations for BIT [boron injection tank] storage tanks

h. Flow rate into the reactor coolant system from the BIT I&M Response I&M's response is provided by Items 1.a through 1.h on pages 2 through 5 of the Westinghouse report provided by Enclosure 3 to this letter:

NRC RAI Question 4 Please provide the following elevation data:

a. Bottom elevation of the suction leg horizontal leg piping, cold leg diameter

b. Top elevation of the cold leg at the reactor coolant pump discharge

c. Top elevation of the core (also height of core)

d. Bottom elevation of the downcomer to AEP-NRC-2011-15 Page 3 I&M Response I&M's response is provided by Items 2.a through 2.d on page 6 of the Westinghouse report provided by Enclosure 3 to this letter.

NRC RAI Question 5 Please provide the limiting bottom and top skewed axial power shapes.

I&M Response I&M's response is provided by Item 3 on pages 6 through 8 of the Westinghouse report provided by Enclosure 3 to this letter.

NRC RAI Question 6 Please provide information if you considered using the Idlechik Handbook recommended expression for pressure loss coefficients along a curved channel (diagram 6-2). If so, please explain why it was not used in the calculation for the k-factor.

I&M Response The Idelchik Handbook recommended expression for pressure loss coefficients was not used.

The reason it was not used is provided by Supplemental Response #1 and #2 on pages 7 through 11 of the Westinghouse report provided by Enclosure 4 to this letter.

NRC RAI Question 7 Please provide the values of the lateral k-factors used for the downcomer lateral flow paths for the plant.

I&M Response I&M's response is provided by Figure 3 and Figure 5 of Supplemental Response #1 and #2 on pages 7 through 11 of the Westinghouse report provided by Enclosure 4 to this letter.

NRC RAI Question 8 Please provide the method used to compute the azimuthal lateral k-factors and the values used in the plant calculations. The staff notes that the "Idlechik" reference for calculating k-factors presents a method to compute k-factors in annuli of various radii. Please provide the results of a k-factor study for the lateral flow paths in the downcomer if it was performed.

to AEP-NRC-2011-15 Page 4 I&M Response Response #2 on pages 4 through 5 of the Westinghouse report provided by Enclosure 4 to this letter presents the method used to compute the azimuthal lateral k-factors.

Figure 3 and Figure 5 of Supplemental Response #1 and #2 on pages 7 through 11 of the same enclosure provide the k-factor values used in the WCOBRAITRAC runs.

As indicated in telephone discussions with the NRC staff, a k-factor sensitivity was not performed as part of the WCOBRAITRAC Code Qualification Document. Subsequent to those discussions, a CNP-specific k-factor sensitivity study was performed.

As described in the response to NRC RAI Question 11, the results of this sensitivity study are presented by Supplemental Response #3 on pages 12 through 45 of the Westinghouse report provided by to this letter.

NRC RAI Question 9 Please describe the azimuthal nodalization and results from the approved best-estimate WCOBRAITRAC model. Also provide the results of other nodalization studies applied to the azimuthal detail in the downcomer (other than the four and 12 azimuthal node studies)

I&M Response The azimuthal nodalization and results from the approved best-estimate WCOBRAITRAC model are provided by Response #3 on page 6 of the Westinghouse report provided by Enclosure 4 to this letter. The results of other nodalization studies (e.g., 3 - 9 node) applied to the azimuthal detail in the downcomer were discussed with the NRC staff during an audit at the Westinghouse office in Rockville Maryland.

NRC RAI Question 10 Please provide the plant nodalization scheme for DC Cook Unit 2.

I&M Response I&M's response is provided by Response #1 on pages 1 through 3 of the Westinghouse report provided by Enclosure 4 to this letter.

NRC RAI Question 11 The NRC staff completed its sensitivity study on downcomer boiling and the effect of lateral k-factor on this phenomenon. The case with zero lateral k-factor in the downcomer cross flow paths joining the azimuthal cells resulted in a 400 degrees F reduction in peak clad temperature.

This was due to the maximization of mixing between the downcomer azimuthal cells which severely limited downcomer boiling. The cold water entering the downcomer during the long term readily mixed into the adjacent downcomer volumes and reduced boiling and the resulting core uncover and clad temperature. ECC bypass and liquid sweep-out that dominate the very early portion of the event (the first 100-200 seconds) does not prevail during the longer term to AEP-NRC-2011-15 Page 5 when the downcomer fills with liquid and vapor velocities are no longer high enough to entrain and sweep out the injected liquid.

Based on these results, the NRC staff needs to request that an additional analysis of downcomer boiling be performed for D. C. Cook Unit 2 with the lateral k-factors based on Idelchik included in the downcomer resistance model in the WCOBRA/TRAC model. The additional comparative study should show the impact of the lateral k-factor on PCT during downcomer boiling following a large break LOCA.

I&M Response I&M's response is provided by Supplemental Response #3 on pages 12 through 45 of the Westinghouse report provided by Enclosure 4 to this letter. Note that second to last sentence in Section 4, "Single Failure Assumption," on page 15 of Enclosure 4, mentions a discrepancy in the containment pressure calculation for the LBLOCA analysis.

I&M plans to address this discrepancy as described in Enclosure 9 to this letter.

References

1. Letter from L. J. Weber, I&M, to NRC Document Control Desk, "Donald C. Cook Nuclear Plant Unit 2, Docket No. 50-316, License Amendment Request Regarding Large Break Loss-of-Coolant Accident Analysis Methodology," AEP-NRC-2009-23, dated March 19, 2009 (ADAMS Accession Number ML090930453).

2. Letter from T. A. Beltz, NRC, to J. N. Jensen, I&M, "Donald C. Cook Nuclear Plant, Unit 2 -

Request for Additional Information (RAI) Regarding the License Amendment Request Associated With the Large-Break Loss-of-Coolant Accident Analysis Methodology (TAC No.

ME1017)," dated September 22, 2009 (ADAMS Accession Number ML092610029).

3. Letter from L. J. Weber, I&M, to NRC Document Control Desk, "Donald C. Cook Nuclear Plant Unit 2, Docket No. 50-316, Response to Request for Additional Information Regarding a License Amendment Request Associated With the Large-Break Loss-Of-Coolant Accident Analysis Methodology (TAC No. ME1017)," AEP-NRC-2009-71, dated November 20, 2009 (ADAMS Accession Number ML093360524).

4. Electronic mail from P. S. Tam, NRC to M. K. Scarpello, H. L. Etheridge, and J. R. Waters, I&M, et al., "D.C. Cook Unit 2 - Second Set of Formal RAI on the Proposed LBLOCA Amendment (TAC ME1017)," dated January 20, 2011 (ADAMS Accession Number ML110210006).

5. Letter from R. P. Powers, I&M, to NRC Document Control Desk, "Donald C. Cook Nuclear Plant Units 1 and 2, Technical Specification Change Request - Containment Recirculation Sump Water Inventory," C1 099-08, dated October 1, 1999.

to AEP-NRC-2011-15 Application for Withholding Proprietary Information from Public Disclosure for Enclosure 3

W esting-ouse Westinghouse Electric Company Nuclear Services 1000 Westinghouse Drive Cranberry Township, PA 16066 USA U.S. Nuclear Regulatory Commission Direct tel: (412) 374-4643 Document Control Desk Direct fax: (724) 720-0754 Washington, DC 20555-0001 e-mail: greshaja@westinghouse.com Proj letter ref NF-AE-10-92 CAW-1 0-3034 November 24, 2010 APPLICATION FOR WITHHOLDING PROPRIETARY INFORMATION FROM PUBLIC DISCLOSURE

Subject:

"D. C. Cook Unit 2 (AMP) Post-LOCA Responses to Request for Additional Information (RAI)," (Proprietary)

The proprietary information for which withholding is being requested in the above-referenced report is further identified in Affidavit CAW-10-3034 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 American Electric Power.

Correspondence with respect to the proprietary aspects of the application for withholding or the Westinghouse affidavit should reference this letter, CAW-10-3034 and should be addressed to J. A. Gresham, Manager, Regulatory Compliance and Plant Licensing, Westinghouse Electric Company LLC, Suite 428, 1000 Westinghouse Drive, Cranberry Township, PA 16066.

Very truly yours, ham, Manager Regulatory Compliance and Plant Licensing Enclosures

CAW-10-3034 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:

A. Gresham, Manager Regulatory Compliance and Plant Licensing Sworn to and subscribed before me this 2 4'h day of November 2010 Vito Public COMMONWEALTH OF PENNSYLVANIA q

Notarial Sewal Kristin Joy Schade, Notary Public North Huntingdon Twp.. Westmoreland County My Commission Expires March 11, 2013 Member, Pennsylvania Association of Notaries

2 CAW-10-3034 (1)

I 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)

I 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 Proprietary Information from Public Disclosure accompanying this Affidavit.

(3)

I 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

3 CAW-10-3034 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.

(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.

4 CAW-10-3034 (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 information, any one component 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 "D. C. Cook Unit 2 (AMP) Post-LOCA Responses to Request for Additional Information (RAI)," (Proprietary) for submittal to the Commission, being transmitted by American Electric Power letter and Application for Withholding Proprietary Information from Public Disclosure, to the Document Control Desk. The proprietary information as submitted by Westinghouse is that associated with the NRC review of the D. C.

Cook Unit 2 Best Estimate ASTRUM Large Break LOCA Reanalysis.

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

(a) Assist the customer in obtaining NRC review of the D. C. Cook Unit 2 Best Estimate ASTRUM Large Break LOCA Reanalysis.

5 CAW-10-3034 Further this information has substantial commercial value as follows:

(a) Westinghouse plans to sell the use of this information to its customers for purposes of plant specific LOCA analysis for licensing basis applications (b) Its use by a competitor would improve their competitive position in the design and licensing of a similar product for Best Estimate ASTRUM Large Break LOCA analyses.

(c) The information requested to be withheld reveals the distinguishing aspects of a methodology which was developed by Westinghouse.

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 calculations 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.

to AEP-NRC-2011-15 Application for Withholding Proprietary Information from Public Disclosure for Enclosure 4

OWestinghouse Westinghouse Electric Company Nuclear Services 1000 Westinghouse Drive Cranberry Township, Pennsylvania 16066 USA U.S. Nuclear Regulatory Commission Document Control Desk Washington, DC 20555-0001 Direct tel: (412) 374-4643 Direct fax: (724) 720-0754 e-mail: greshaja@westinghouse.com Proj letter. NF-AE-10-145 W/AEP2-1645 CAW-10-3061 December 17, 2010 APPLICATION FOR WITHHOLDING PROPRIETARY INFORMATION FROM PUBLIC DISCLOSURE

Subject:

"Supplemental Information to Support Informal NRC Audit of 12 Downcomer Channel Model Validation," (Proprietary)

The proprietary information for which withholding is being requested in the above-referenced report is further identified in Affidavit CAW-10-3061 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 American Electric Power.

Correspondence with respect to the proprietary aspects of the application for withholding or the Westinghouse affidavit should reference this letter, CAW-10-3061, and should be addressed to J. A. Gresham, Manager, Regulatory Compliance and Plant Licensing, Westinghouse Electric Company LLC, Suite 428, 1000 Westinghouse Drive, Cranberry Township, Pennsylvania 16066.

Very truly yours, J. A. Gresham, Manager Regulatory Compliance and Plant Licensing Enclosures

CAW-10-3061 AFFIDAVIT COMMONWEALTH OF PENNSYLVANIA:

ss COUNTY OF BUTLER:

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:

VJ.A. Gresham, Manager Regulatory Compliance and Plant Licensing Sworn to and subscribed before me this J._L day of1 p

m 2010 Nota4Wic COMMONWEALTH OF PENNSYLVANIA Notarial Seal Kristin Joy Schade, Notary Public North Huntlngdon Tw., Westmorelanl County My Commission Expires March 11. 2013

-'Member. Pennsylvania Association of Notaries

2 CAW-10-3061 (1)

I 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)

I 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 Proprietary Information from Public Disclosure accompanying this Affidavit.

(3)

I 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

3 CAW-10-3061 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.

(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.

4 CAW-10-3061 (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 information, any one component 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 "Supplemental Information to Support Informal NRC Audit of 12 Downcomer Channel Model Validation," (Proprietary) for submittal to the Commission, being transmitted by American Electric Power letter and Application for Withholding Proprietary Information from Public Disclosure, to the Document Control Desk. The proprietary information as submitted by Westinghouse is that associated with the NRC review of the D. C. Cook Unit 2 Best Estimate Large Break LOCA Reanalysis and may be used only for that purpose.

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

5 CAW-10-3061 (a) Assist the customer in obtaining NRC review of the D. C. Cook Unit 2 Best Estimate Large Break LOCA Reanalysis.

Further this information has substantial commercial value as follows:

(a) Westinghouse plans to sell the use of this information to its customers for purposes of plant specific LOCA analysis for licensing basis applications (b) Its use by a competitor would improve their competitive position in the design and licensing of a similar product for Best Estimate Large Break LOCA analyses.

(c) The information requested to be withheld reveals the distinguishing aspects of a methodology which was developed by Westinghouse.

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 calculations 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.

to AEP-NRC-2011-15 Westinghouse Report "D. C. Cook Unit 2 (AMP) Post-LOCA Responses to Request for Additional Information (RAI)"

Non-Proprietary Version

Westinghouse Proprietary Class 3 Non-proprietary Attachment to NF-AE-10-1 39 Page 1 of 8 D. C. Cook Unit 2 (AMP) Post-LOCA Responses to Request for Additional Information (RAI)

@ 2010 Westinghouse Electric Company LLC All Rights Reserved

Westinghouse Proprietary Class 3 Non-proprietary Attachment to NF-AE-1 0-139 Page 2 of 8 D. C. Cook Unit 2 (AMP) Post-LOCA Responses to Request for Additional Information (RAI)

1.

Information regarding the D.C. Cook Unit 2 NSSS:

a.

Volume of the lower plenum, core and upper plenum below the bottom elevation of the hot leg, each identified separately. Also provide heights of these regions.

Table la-1: Lower Plenum, Core, and Upper Plenum Volumes Volume (ft3)

Lower Plenum

[

]a,c Core

[

]a'c Upper Plenum Below the Bottom Elevation of the Hot Leg

[

]aj Table la-2: Lower Plenum, Core, and Upper Plenum Heights Height (ft)

Lower Plenum

[

]a,c Core 12.000 Upper Plenum Below the Bottom Elevation of the Hot Leg

[

],c

Westinghouse Proprietary Class 3 Non-proprietary Attachment to NF-AE-1 0-139 Page 3 of 8

b. Loop friction and geometry pressure losses from the core exit through the steam generators to the inlet nozzle of the reactor vessel. Also, provide the locked rotor RCP k-factor.

Please provide the mass flow rates, flow areas, k-factors, and coolant temperatures for the pressure losses provided (upper plenum, hot legs, SGs, suction legs, RCPs, and discharge legs). Please include the reduced SG flow areas due to plugged tubes. Please also provide the loss from each of the intact cold legs through the annulus to a single broken cold leg. Please also provide the equivalent loop resistance for the broken loop and separately for the intact loop.

Table lb-1: Loop Friction and Geometry Pressure Losses from the Core Exit Through the Steam Generators to the Inlet Nozzle of the Reactor Vessel 0% SGTP Loss 1 0 %(s) SGTP Loss (dimensionless)

(inF )

Coefficient Coefficient (ft/gpm2 )

(ft/gpm2 )

Upper Plenum to Hot Leg

]a,c

]ac

[

]3,C Same Nozzle Hot Leg Nozzle

[

]ac

[

]ac

[

]a~c Same Hot Leg N/A N/A

[]ac Same Steam Generator Inlet N/A N/A

[]ac Same Steam Generator Tubes, N/A N/A ac

[

Inlet to U-Bend N/A_/A__]___[]_,

Steam Generator U-Bend N/A N/A

[

]a,c

[

]a,c Steam Generator Tubes, N/A N/A

]a~c

[

]a.t U-Bend Outlet Steam Generator Outlet N/A N/A

[]a,c Same Pump Suction Leg N/A N/A

[]ac Same Cold Leg N/A N/A

[]ac Same Cold Leg Nozzle

[

]a,

[

]c

[]c Same Intact Cold Leg to Broken

][,

[

].,C

]ame Cold Leg

[I[

=

Same Table lb-2: Locked Rotor Reactor Coolant Pump (RCP) k-factor k

Flow 0% SGTP Loss 10% SGTP Loss Area Coefficient Coefficient (dimensionless)

(in2)

(ft/gpm 2)

(ft/gpm 2)

Locked Rotor (Forward Flow)

N/A N/A

[,c Same Locked Rotor (Reverse Flow)

N/A N/A

[]a,c Same

Westinghouse Proprietary Class 3 Non-proprietary Attachment to NF-AE-1 0-139 Page 4 of 8 Table lb-3: Mass flow rates, flow areas, k-factors, and coolant temperatures for the pressure losses provided Mass Flow 0% SGTP 10% SGTP Coolant Rate (Ibm/hr)

Flow Area (in2)

Flow Area (in2) k-factor (ft/gpm2 )

Temperature

(°F)

Upper Plenum to Hopeg Nlen

]a,c

[

a,c Same

[

]a,c 581.9 Hot Leg Nozzle Hot Leg Nozzle

[

]ac

[

]ac Same

[]'c 581.9 Hot Leg

[

]axc

[

]ac Same

[

jaxc 581.9 Steam Generator

[

]

[

Same 581.9 Inlet Steam Generator Tubes, Inlet to U-

[

]a,c

[

]a,c

[

]a,c

[]a' 547.6 Bend Steam Generator

]ac

[

]a~c

]a~C

[

547.6 U-Bend Steam Generator Tubes, U-Bend

[

]a

[

]a'c

[

]a'c

[

]a*c 547.6 Outlet Steam Generator Ia'c

[

Same

[

513.0 Outlet Pump Suction Leg

[

]a,c

[

]ac Same

[],c 513.0 Cold Leg

[

]ac

]a,c Same

[]a' 513.3 Cold Leg Nozzle

[

]ac

[]a,c Same

[

]ac 513.3 Intact Cold Leg to Not Modeled

[

]a,c Same

[]a,c 513.3 Broken Cold Leg

c.

Capacity and boron concentration of the RWST.

Table ic-1: Capacity and boron concentration of the RWST Capacity (gal)

Boron Concentration (ppm)

RWST, Minimum 280,000 2350 ("

RWST, Maximum 420,000 (2) 2600

'l Technical Specification SR 3.5.4.3 states to verify the RWST boron concentration is greater than 2400 ppm. The value of 2350 ppm accounts for 50 ppm of B-10 depletion.

(2)

The 420,000 gal value conservatively bounds the RWST maximum capacity including tank uncertainties. Actual RWST volume delivered to the containment sump may be less.

Westinghouse Proprietary Class 3 Non-proprietary Attachment to NF-AE-1 0-139

d. Capacity of the condensate storage tank Page 5 of 8 Table ld-1: Capacity of the condensate storage tank Volume (ft3)

Condensate Storage Tank, Post-LOCA Analysis Not Modeled

e.

Flushing flow rate at the time of switch to simultaneous injection Table le-1: Flushing Flow Rate Flushing Flow Rate (lbbm/sec)

Flsin lw at HI.SO ()9 I Flushing flow is calculated as Ms] -

1 Mboil

f.

HPSI runout flow rate Table lf-1: High Head Safety Injection System-Runout Minimum Resistance Pump Flow (gpm) 1 675

g. Capacities and boron concentrations for BIT storage tanks Table ig-1: Capacities and boron concentrations of the BIT storage tanks Capacity (gal)

Boron Concentration (ppm)

Boron Injection Tank (4) 900 2,600

14)

Since the BIT is non-functional, the BIT volume can be conservatively represented as additional ECCS piping volume, modeled at the RWST maximum concentration.

h.

Flow rate into the RCS from the BIT Table lh-1: Flow rate into the RCS from the BIT Flow Rate (gpm)

Boron Injection Tank Not Modeled (5)

(5) Since the BIT is non-functional and remains in the ECCS piping volume, flow from the BIT has the RWST as the source.

Westinghouse Proprietary Class 3 Non-proprietary Attachment to NF-AE-1 0-139

2.

Please provide the following elevation data:

a. bottom elevation of the suction leg horizontal leg piping, cold leg diameter

b. top elevation of the cold leg at the reactor coolant pump discharge

c. top elevation of the core (also height of core)

d. bottom elevation of the downcomer Page 6 of 8 Table 2-1: Elevation Data Elevation (ft) (6)

Bottom of Suction Leg Horizontal Piping

[

]a,c Top of Cold Leg at Reactor Coolant Pump Discharge

[

]axc Top of the Core (also Core Height)

[

]a,c (12.000)

Bottom of the Downcomer

[

aC (6)

All elevations referenced from the bottom of the reactor vessel.

3.

Please provide the limiting bottom and top skewed axial power shapes.

The limiting bottom skewed actual power shape is shown in Figure 3-1 with an axial offset of

-15.482%. The limiting top skewed power shape is shown in Figure 3-2 with an axial offset of 15.041%.

Westinghouse Proprietary Class 3 Non-proprietary Attachment to N F-AE-1 0-139 Page 7 of 8 BOTTOM SKEWED 0

0 0

AVGPWR 1.4' 1.2'1

• N 0.8__

0 2

4 6

8 10 Elevation (ft) 12 Figure 3-1 Limiting Bottom Skewed Power Shape for Average Power Rod

Westinghouse Proprietary Class 3 Non-proprietary Attachment to NF-AE-1 0-139 Page 8 of 8 TOP SKEWED 0

0 0

AVGPWR 1.4.

1.2' 1*

_N "

LA_

0 2

4 6

8 10 Elevation (ft) 12 Figure 3-2 Limiting Top Skewed Power Shape for Average Power Rod to AEP-NRC-2011-15 Westinghouse Report "Supplemental Information to Support Informal NRC Audit of 12 Downcomer Channel Model Validation" Non-Proprietary Version

Westinghouse Non-Proprietary Class 3 NF-AE-10-145 NP-Attachment Response to NRC Request for Additional Information on BELOCA ASTRUM Reanalysis Supplemental Information to Support Informal NRC Audit of 12 Downcomer Channel Model Validation December 2010 Westinghouse Electric Company LLC 1000 Westinghouse Drive Cranberry Township, PA 16066 D 2010 Westinghouse Electric Company LLC All Rights Reserved

Westinghouse Non-Proprietary Class 3 NF-AE-10-145 NP-Attachment (Page 1 of 45)

Supplemental Information to Support Informal NRC Audit of 12 Downcomer Channel Model Validation Action Item #1 Please provide a noding diagram for the D. C. Cook Unit 2 vessel model.

Response #1 The noding diagram for D. C. Cook Unit 2 with twelve downcomer channel stacks is presented as Figure 1 (on a later page).

In Figure 1, the numbers enclosed in squares represent channel numbers. Channels are used to make vertical connections in the vessel model. The numbers enclosed in circles represent gap numbers. Gaps are used to make lateral connections in the vessel model. The gap numbers which have a horizontal arrow through them connect the channels shown at the start and end of the horizontal arrow. The gaps which have a diagonal arrow through them have a corresponding numbered gap shown elsewhere on the noding diagram. These gaps connect the channels with the matching gap numbers shown.

The downcomer channels are modeled with the long channel stacks shown on the outer portion of the noding diagram (Figure 1).

A cross-section of the vessel noding at the Section 6 elevation is presented in Figure 2. The cold leg connection locations can be seen in Figure 2, as well as

©20 70 Westinghouse Electric Company LLC All Rights Reserved

Westinghouse Proprietary Class 3 NF-AE-10-145 P-Attachment (Page 2 of 45)

Figure 1: D. C. Cook Unit 2 Vessel Noding Diagram for the Twelve Downcomer Channel Stack Model 496.4 I

61 1F Channel Q Gap Section 9 (48.4')

Section 8 (22.8")

447.9 425.2 389.8 56 S,-

.59 5..

.63i DC DC DC DC: DC DC

.9 51

1.

-]

57]:E -&*[

I.

=

=

i....

53-

=2 OHISC/FM DC: DC DC DC DCDC Section (82 5")

55 52..9.....53.9..19..

17.7.

I-56 57 GT 7

342.7 HL 465 CL c

~

4! 161 1114 1

147 45 11H) 313.7

~

~

-i) 1

~

~

293

.2*--....

S tion 5 278.2 2-78~ 10_

23 m

31 34

...24...

.4..

79.24 Section 3o' -L

9 2

~

36 33 24 3~193 13 94 9

1 (13.2")

257.5 F......................

21~

LIP OHISCIFM

'HA 'OH/'

G L

2500 239.7 r-b

[

..................... i.....

.. i.

. i...

.... r SD.8......

15*~

i 12 925 2209.

-:.4..................

4R........

I.....

198

-9 178 1-89I 13 1829

,16I 7

E i.

161 3

7 4

7 157.5 147.3 20.9 i:2 8

2.

Section 2 12 68......4

(. 689 17.....

.... ]..... *.

167.

I..............

88..

2]

Section 2

12 4o 1~

.....................(6 I

U.0 m

AMP

Westinghouse Non-Proprietary Class 3 NF-AE-10-145 NP-Attachment (Page 3 of 45)

Figure 2: D. C. Cook Unit 2 Section 6 Cross-Section Diagram

Lc

Westinghouse Non-Proprietary Class 3 NF-AE-1 0-145 NP-Attachment (Page 4 of 45)

Action Item #2 Please describe the model/correlation/technique used to calculate the lateral (cross-flow) K-factor in the downcomer. Also, please provide the value calculated for a plant application with the twelve downcomer channel stack model, and the results of a K-factor study if one was performed.

Response #2 Form and wall drag in gap K is specified for the transverse momentum equations using the parameters WKR(K) and FWALL(K). WKR(K) is the form drag loss coefficient (velocity head)

[a The single-phase pressure drop between two adjacent channels though the gap is then calculated as:

I I a,c II

] a-C I

ac The friction factors for the liquid and vapor fields

]ac a~c I

Westinghouse Non-Proprietary Class 3 NF-AE-10-145 NP-Attachment (Page 5 of 45)

The lateral drag coefficient is calculated as:

[

ac

]a.C Please refer to Section 4-2 of the CQD (Reference 1) for additional information.

No K-factor study was completed for the model with revised noding; rather, consistency was used between the test facility models and the PWR model. [

]aC Reference(s)

1. Bajorek, S. M., et al., March 1998, "Code Qualification Document for Best Estimate LOCA Analysis," Volume 1 Revision 2, and Volumes 2 through 5, Revision 1, WCAP-12945-P-A (Proprietary).

Westinghouse Non-Proprietary Class 3 NF-AE-I 0-145 NP-Attachment (Page 6 of 45)

Action Item #3 Please describe the azimuthal noding and results from the approved best-estimate WCOBRA/TRAC model. Also provide the results of any other nodalization studies applied to the azimuthal detail in the downcomer (i.e. other number of nodes besides one-per-loop and three-per-loop).

Response #3 The results of the CCTF Test 62, UPTF Test 6, and UPTF Test 25A simulations for the approved CQD methodology are described in Sections 14-2-6-1, 14-4-5 through 14-4-9, and 14-4-11 of the CQD (Reference 1), respectively. The results of these same simulations with four downcomer channel stacks per loop (twelve total stacks) are described in Reference 2. These test simulations were not executed with any other number of downcomer channel stacks to support the revised downcomer noding in the PWR.

[

Ia.c Reference(s)

1. Bajorek, S. M., et al., March 1998, "Code Qualification Document for Best Estimate LOCA Analysis," Volume I Revision 2, and Volumes 2 through 5, Revision 1, WCAP-12945-P-A (Proprietary).

2.

Letter from Jensen, J. N. to USNRC, December 27, 2007, "License Amendment Request Regarding Large Break Loss-of-Coolant Accident Analysis Methodology," Enclosure 3, AEP:NRC:7565-01.

Westinghouse Non-Proprietary Class 3 NF-AE-10-145 NP-Attachment (Page 7 of 45)

Supplemental Request #1 Did you consider using the Idlechik Handbook recommended expression for pressure loss coefficients along a curved channel (diagram 6-2)? And, if so, why was it not used in the calculation for the k-factor?

Supplemental Request #2 What are the values of the lateral k-factors used for the downcomer lateral flow paths for a specific 4 loop plant? We would like to see typical values used in a plant analysis for these lateral k-factors in the downcomer.

Supplemental Response #1 and #2 Since these two questions are related to each other, they are addressed in a single response.

The total lateral K-factor is made up of two components; the loss due to the curvature in the downcomer (form loss) and the frictional loss. The lateral K-factor resulting from application of Diagram 6-2 from Idelchik (Reference 1) is determined, and then compared to the lateral K-factor for a 4-loop PWR. A number of boundary conditions are necessary for this calculation.

1) [

]" Also note that the geometry used for the PWR calculation was taken from D. C. Cook Unit 2.

The K-factor from the frictional losses and losses due to the curvature of the downcomer from WCOBRA/TRAC for a 4-loop PWR are presented in Figure 3 as a function of Reynolds number. Since the azimuthal flow rate in the downcomer and the fluid properties change significantly throughout a Large Break LOCA transient, it is desirable to compare the losses over a range of Reynolds numbers. [

Westinghouse Non-Proprietary Class 3 NF-AE-10-145 NP-Attachment (Page 8 of 45)

]"C is discussed later in this response.

The total loss calculated from Idelchik (including both frictional and curvature losses) is presented in Figure 4 as a function of Reynolds number. It is noted that the loss is higher for low Reynolds numbers in the laminar flow regime, and decreases as the regime transitions to turbulent flow.

The total loss calculated from WCOBRA/TRAC for a 4-loop PWR, the total loss calculated from Idelchik, and the difference between the two losses are presented in Figure 5.

]a.c Reference(s)

1. Idelchik, I. E., 1994, "Handbook of Hydraulic Resistance," 3 rd Edition, CRC Press, Inc.

Westinghouse Non-Proprietary Class 3 NF-AE-10-145 NP-Attachment (Page 9 of 45)

Figure 3: K-Factor for Frictional and Curvature Losses from WCOBRA/TRAC a~c

Westinghouse Non-Proprietary Class 3 NF-AE-10-145 NP-Attachment (Page 10 of 45)

Figure 4: Total K-Factor for Losses Calculated from Idelchik 3.-

2.5 2

0 1.5 -

.1 0.5 0*

0 10000 20000 30000 40000 50000 60000 70000 80000 90000 100000 Reynolds Number (-)

Westinghouse Non-Proprietary Class 3 NF-AE-10-145 NP-Attachment (Page 11 of 45)

Figure 5: Comparison of Losses from WCOBRA/TRAC and Idelchik a~c

Westinghouse Non-Proprietary Class 3 NF-AE-10-145 NP-Attachment (Page 12 of 45)

Supplemental Request #3 The NRC staff completed its sensitivity study on downcomer boiling and the effect of lateral k-factor on this phenomenon. The case with zero lateral k-factor in the downcomer cross flow paths joining the azimuthal cells resulted in a 400 degrees F reduction in peak clad temperature. This was due to the maximization of mixing between the downcomer azimuthal cells which severely limited downcomer boiling. The cold water entering the downcomer during the long term readily mixed into the adjacent downcomer volumes and reduced boiling and the resulting core uncover and clad temperature. ECC bypass and liquid sweep-out that dominate the very early portion of the event (the first 100-200 seconds) does not prevail during the longer term when the downcomer fills with liquid and vapor velocities are no longer high enough to entrain and sweep out the injected liquid.

Based on these results, the NRC staff needs to request that an additional analysis of downcomer boiling be performed for D. C. Cook Unit 2 with the lateral k-factors based on Idelchik included in the downcomer resistance model in the WCOBRA/TRAC model. The additional comparative study should show the impact of the lateral k-factor on PCT during downcomer boiling following a large break LOCA.

Supplemental Response #3

1. Introduction Westinghouse has previously put forth that [

]

In order to support this statement, a sensitivity study was performed for D. C. Cook Unit 2 with WCOBRA/TRAC to determine the sensitivity of WCOBRA/TRAC to the azimuthal loss coefficient in the downcomer. The reference case was initially selected to perform the sensitivity study since it is a representative case for the plant. The reference case (or reference transient) refers to a case where many of the potential uncertainty contributors are set to their nominal value, while some are skewed in a limiting direction. Some of the boundary conditions of interest for this sensitivity study are as follows.

The safety injection flow rate as a function of pressure is given by Tables IA and lB.

The safety injection temperature is 87.57F.

The containment backpressure as a function of time is presented in Figure 6.

As previously discussed in the responses to Action Item #2 and Supplemental Request #2, the form losses in the downcomer azimuthal gaps were [

I

&~C

Westinghouse Non-Proprietary Class 3 NF-AE-10-145 NP-Attachment (Page 13 of 45)

The results of the lateral K-factor sensitivity study are discussed in Section 2. Some additional discussion regarding the validation of the WCOBRA/TRAC condensation prediction is provided in Section 3.

Information regarding the single-failure assumption for this sensitivity study is presented in Section 4, and all references called out in these discussions are cited in Section 5.

2. Sensitivity Study Results Discussion I

I axc

Westinghouse Non-Proprietary Class 3 NF-AE-10-145 NP-Attachment (Page 14 of 45)

] as

Westinghouse Non-Proprietary Class 3 NF-AE-10-145 NP-Attachment (Page 15 of 45)

3. Validation of WCOBRA/TRAC Condensation Prediction The WCOBRA/TRAC prediction of condensation during reflood is addressed in Section 15-3 of the CQD (Reference 1). The degree to which condensation occurs in the cold leg and downcomer is important in calculating the steam flowrate and temperature of the water flowing into the vessel during reflood. If the condensation rate is high, the steam flow will be reduced and the water temperature will be increased.

The hotter water will reach saturation and begin to boil sooner in the downcomer, lower plenum, and core. The lower steam flow may entrain less water from the downcomer out the break, and may result in a smaller pressure drop across the broken cold leg nozzle. This in turn will reduce the downcomer pressure (allowing liquid to boil at a lower temperature, and potentially reducing the reflood rate to some small degree). If the condensation rate is low, the colder water will contribute to continued subcooling of the water in the downcomer.

The WCOBRA/TRAC predicted condensation rates were evaluated by comparing the predicted and available fluid temperature measurements for UPTF Tests 8 and 25A, and by calculating an overall condensation efficiency. The predicted liquid temperatures at the exit of the cold leg for both UPTF Test 8 and Test 25A [

]pc Condensation efficiency is defined as the actual condensation rate divided by the potential condensation rate. Analysis of the tests indicates that the condensation efficiency for these large scale tests

]" (Reference 2). The predicted condensation efficiencies for these tests

]Ic with the measured efficiency.

4. Single-Failure Assumption The NRC specifically requested information regarding the single-failure assumption in the sensitivity study discussed in Section 2. As such, the information on the limiting single-failure assumption is provided in this section.

The limiting single-failure assumed

]ac It should be noted that a discrepancy was identified in the containment pressure calculation for the D C Cook Unit 2 analysis which is the subject of ongoing evaluation. It is expected that this discrepancy would not impact the conclusions drawn from the downcomer lateral K-factor sensitivity study.

5. References

1) WCAP-12945-P-A, Volume I (Revision 2) and Volumes 2 through 5 (Revision 1), "Code Qualification Document for Best Estimate LOCA Analysis," March 1998.

2) MPR-1208, "Summary of Results from the UPTF Cold Leg Flow Regime Separate Effects Tests, Comparison to Previous Scaled Tests, and Application to U.S. Pressurized Water Reactors," October 1992.

Westinghouse Non-Proprietary Class 3 NF-AE-10-145 NP-Attachment (Page 16 of 45)

Table IA: RHR and High Head Safety Injection Flow Rates for Downcomer Lateral K-Factor Sensitivity Study a"c

Westinghouse Non-Proprietary Class 3 NF-AE-10-145 NP-Attachment (Page 17 of 45)

Table IB: Charging Safety Injection Flow Rates for Downcomer Lateral K-Factor Sensitivity Study ac

Westinghouse Non-Proprietary Class 3 NF-AE-10-145 NP-Attachment (Page 18 of 45)

Figure 6: Containment Pressure Boundary Condition for Downcomer Lateral K-Factor Sensitivity Study a-c

Westinghouse Non-Proprietary Class 3 NF-AE-10-145 NP-Attachment (Page 19 of 45)

Figure 7: Comparison of Sensitivity Study Downcomer Lateral K-factors to Idelchik a.*c

Westinghouse Non-Proprietary Class 3 NF-AE-1 0-145 NP-Attachment (Page 20 of 45)

Figure 8: Vessel Fluid Inventory Comparison through 60 Seconds a,c

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Figure 9: Peak Cladding Temperature Comparison

Westinghouse Non-Proprietary Class 3 NF-AE-10-145 NP-Attachment (Page 22 of 45)

Figure 10: Vessel Fluid Inventory Comparison "

ax

Westinghouse Non-Proprietary Class 3 NF-AE-1 0-145 NP-Attachment (Page 23 of 45)

Figure 11: Core Collapsed Liquid Level Comparison ac

Westinghouse Non-Proprietary Class 3 NF-AE-10-145 NP-Attachment (Page 24 of 45)

Figure 12: Break Flow Comparison from 170 to 250 Seconds ax

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Figure 13: Integrated Break Flow Comparison from 170 to 250 Seconds ax

Westinghouse Non-Proprietary Class 3 NF-AE-10-145 NP-Attachment (Page 26 of 45)

Figure 14: Average Liquid Subcooling Comparison in the Downcomer at the Nozzle Elevation a,c

Westinghouse Non-Proprietary Class 3 NF-AE-10-145 NP-Attachment (Page 27 of 45)

Figure 15: Comparison of Liquid Subcooling in the Downcomer Cell Attached to Intact Cold Leg

1. 2 ac

Westinghouse Non-Proprietary Class 3 NF-AE-10-145 NP-Attachment (Page 28 of 45)

Figure 16: Comparison of Liquid Subcooling in the Downcomer Cell Attached to Intact Cold Leg

1. 3 ac I

Westinghouse Non-Proprietary Class 3 NF-AE-1 0-145 NP-Attachment (Page 29 of 45)

Figure 17: Comparison of Liquid Subcooling in the Downcomer Cell Attached to Intact Cold Leg

1. 4 a~c

Westinghouse Non-Proprietary Class 3 NF-AE-10-145 NP-Attachment (Page 30 of 45)

Figure 18: Average Liquid Subcooling Comparison in the Downcomer at Vessel Section 5 a,c

Westinghouse Non-Proprietary Class 3 NF-AE-10-145 NP-Attachment (Page 31 of 45)

Figure 19: Average Liquid Subcooling Comparison in the Downcomer at Vessel Section 4 ac

Westinghouse Non-Proprietary Class 3 NF-AE-10-145 NP-Attachment (Page 32 of 45)

Figure 20: Average Liquid Subcooling Comparison in the Downcomer at Midplane of Vessel Section 3 a~c

Westinghouse Non-Proprietary Class 3 NF-AE-10-145 NP-Attachment (Page 33 of 45)

Figure 21: Comparison of Liquid Subcooling at the Bottom of the Downcomer (1 of 12) a,c

Westinghouse Non-Proprietary Class 3 NF-AE-10-145 NP-Attachment (Page 34 of 45)

Figure 22: Comparison of Liquid Subcooling at the Bottom of the Downcomer (2 of 12) ac

Westinghouse Non-Proprietary Class 3 NF-AE-10-145 NP-Attachment (Page 35 of 45)

Figure 23: Comparison of Liquid Subcooling at the Bottom of the Downcomer (3 of 12) a,c

Westinghouse Non-Proprietary Class 3 NF-AE-10-145 NP-Attachment (Page 36 of 45)

Figure 24: Comparison of Liquid Subcooling at the Bottom of the Downcomer (4 of 12) a,c

Westinghouse Non-Proprietary Class 3 NF-AE-10-145 NP-Attachment (Page 37 of 45)

Figure 25: Comparison of Liquid Subcooling at the Bottom of the Downcomer (5 of 12) a,c

Westinghouse Non-Proprietary Class 3 NF-AE-10-145 NP-Attachment (Page 38 of 45)

Figure 26: Comparison of Liquid Subcooling at the Bottom of the Downcomer (6 of 12) ac

Westinghouse Non-Proprietary Class 3 NF-AE-10-145 NP-Attachment (Page 39 of 45)

Figure 27: Comparison of Liquid Subcooling at the Bottom of the Downcomer (7 of 12) ac

Westinghouse Non-Proprietary Class 3 NF-AE-10-145 NP-Attachment (Page 40 of 45)

Figure 28: Comparison of Liquid Subcooling at the Bottom of the Downcomer (8 of 12) a,c

Westinghouse Non-Proprietary Class 3 NF-AE-10-145 NP-Attachment

.(Page 41 of 45)

Figure 29: Comparison of Liquid Subcooling at the Bottom of the Downcomer (9 of 12) ac

Westinghouse Non-Proprietary Class 3 NF-AE-10-145 NP-Attachment (Page 42 of 45)

Figure 30: Comparison of Liquid Subcooling at the Bottom of the Downcomer (10 of 12) ac 7

Westinghouse Non-Proprietary Class 3 NF-AE-10-145 NP-Attachment (Page 43 of 45)

Figure 31: Comparison of Liquid Subcooling at the Bottom of the Downcomer (11 of 12) a,c

Westinghouse Non-Proprietary Class 3 NF-AE-10-145 NP-Attachment (Page 44 of 45)

Figure 32: Comparison of Liquid Subcooling at the Bottom of the Downcomer (12 of 12) a,c

Westinghouse Non-Proprietary Class 3 NF-AE-10-145 NP-Attachment (Page 45 of 45)

Figure 33: Pressure and Saturation Temperature in Cell 2 of Channel 72 for Sensitivity Run a,c to AEP-NRC-2011-15 Discussion of Two Errors in the New LBLOCA Analysis

Reference:

Letter from L. J. Weber, Indiana Michigan Power Company (I&M), to U.S.

Nuclear Regulatory Commission (NRC)

Document Control

Desk, "Donald C. Cook Nuclear Plant Unit 2, Docket No. 50-316, License Amendment Request Regarding Large Break Loss-of-Coolant Accident Analysis Methodology," AEP-NRC-2009-23, dated March 19, 2009 (ADAMS Accession Number ML090930453).

By the referenced letter, I&M requested NRC approval to adopt a new large break loss-of-coolant accident (LBLOCA) analysis for Donald C. Cook Nuclear Plant (CNP) Unit 2, and proposed to modify the associated Technical Specifications. The new analysis uses a plant-specific adaptation of the NRC approved methodology documented in Westinghouse Electric Company LLC (Westinghouse) Topical Report WCAP-16009-P-A, "Realistic Large-Break LOCA Evaluation Methodology Using the Automated Statistical Treatment of Uncertainty Method (ASTRUM)." Subsequent to submittal of the referenced letter, two errors were identified in the new LBLOCA analysis. These errors and I&M's current plans for their resolution are described below along with the basis for I&M's conclusion that neither the methodology used in the new Unit 2 LBLOCA analysis nor the responses to the request for additional information transmitted by this letter will be affected by the resolution of these two errors.

The ASTRUM evaluation model utilizes a computer code called LOTIC2 to determine a containment back-pressure boundary condition for the WCOBRAFFRAC program used to calculate the peak cladding temperature (PCT). The ASTRUM methodology requires that the value for containment backpressure that is input to the WCOBRA/TRAC code be lower than the LOTIC2 predicted backpressure, since a lower back pressure assumption is conservative.

Subsequent to submittal of the referenced letter requesting approval to use the ASTRUM evaluation model, Westinghouse determined that the LOTIC2 calculations did not account for the mass and energy of the ECCS water spilling from the broken pipe. Accounting for the addition of the relatively cooler ECCS water to the containment would cause the LOTIC2 predicted containment backpressure to decrease below that assumed in the WCOBRA/TRAC calculations. The second error in the new LBLOCA analysis involved use of an incorrect energy conversion factor for mass and energy releases into containment, which produced non-conservative results. The impact of the second error is significantly less than that of the first error. I&M plans to pursue resolution of both errors by using available margin in the LOTIC2 analysis, without altering the ASTRUM (including WCOBRA/TRAC) calculations.

The planned resolutions will not alter the methodology used in the new LBLOCA analysis.

Similarly, resolution of these two errors will not alter the RAI responses provided by this letter.

I&M plans to provide the NRC a description of the final resolution of these errors within 90 days of the date of this letter.

I&M will inform the NRC Licensing Project Manager if there are significant changes to that schedule.