ML110880506

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Final Safety Analysis Report (FSAR) - Response to Requests for Additional Information (Rais) Concerning the Nuclear Steam Supply System (NSSS)
ML110880506
Person / Time
Site: Watts Bar Tennessee Valley Authority icon.png
Issue date: 03/25/2011
From: Stinson D
Tennessee Valley Authority
To:
Document Control Desk, Office of Nuclear Reactor Regulation
References
Download: ML110880506 (30)
v • d • e


Text

Attachment 1 is to be withheld from public disclosure under 10 CFR 2.390.

When separated from this attachment, this letter is decontrolled.

Tennessee Valley Authority, Post Office Box 2000, Spring City, Tennessee 37381-2000 March 25, 2011 10 CFR 50.4(b)(6) 10 CFR 50.34(b)

U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C. 20555-0001 Watts Bar Nuclear Plant, Unit 2 NRC Docket No. 50-391

Subject:

Watts Bar Nuclear Plant (WBN) Unit 2 - Final Safety Analysis Report (FSAR) - Response to Requests for Additional Information (RAIs)

Concerning the Nuclear Steam Supply System (NSSS)

An NRC e-mail dated March 2, 2011, contained three RAls concerning the NSSS. These three RAIs had a total of 12 parts. The questions and responses thereto for all except RAI 1.d.

are provided in Attachment 1.

RAI 1.d. and the response thereto are as follow:

RAI 1.d.

1. Please provide the following information for the Watts Bar Unit 2 NSSS:
d. Capacity of the condensate storage tank.

TVA's Response The Condensate Storage Tank (CST) has a normal capacity of 385,000 gallons, of which 210,548 gallons are reserved for the Auxiliary Feedwater (AFW) System (

Reference:

System Design Description N3-2-4002, Revision 15, "Condensate System," Section 2.2.2, "Process and Operational Requirements"). Unit 2 FSAR 9.2.6.2, "System Description,"states "... A minimum of 200,000 gallons in each tank is reserved for the auxiliary feedwater system.

Each tank has a capacity of 385,000 gallons with an overflow at 395,000 gallons." Technical Specifications LCO 3.7.6, "Condensate Storage Tank (CST)," requires that the CST level be "greater than or equal to 200,000 gallons."

103

U.S. Nuclear Regulatory Commission Page 2 March 25, 2011 contains information proprietary to Westinghouse Electric Corporation (WEC).

TVA requests that the WEC proprietary information be withheld from public disclosure in accordance with 10 CFR § 2.390. Attachment 2 contains the corresponding non-proprietary version of the document. The corresponding affidavit for withholding proprietary information from public disclosure is contained in Attachment 3.

The response to RAI 1.c. provided on page 4 of Attachment 1 provides a value of "250,000" gallons for the minimum capacity of the Refueling Water Storage Tank (RWST). The following information clarifies the capacity:

value (in gallons)

Maximum RWST volume at overflow 380,000 Minimum Technical Specifications RWST Volume (TS SR 3.5.4.2) 370,000 Minimum RWST Injection to RCS / Containment 203, 000 / 245,000 (See Note 1)

Maximum RWST Injection to RCS / Containment 304, 000 /351,000 (See Note 2)

Notes:

1. 203,000 gallons assumes injection to the Reactor Coolant System (RCS) / Containment from Safety Injection (SI) and Containment Spray (CS) is terminated at the upper value for the SI switchover setpoint.

245,000 gallons assumes injection to the RCS I Containment from Safety Injection (SI) and Containment Spray (CS) is terminated at the lower value for the SI switchover setpoint.

2. 304,000 gallons assumes the CS system continues to inject to the containment until reaching the upper value for the CS switchover setpoint.

351,000 gallons assumes the CS system continues to inject to the containment until reaching the lower value for the CS switchover setpoint.

During a public meeting on March 15, 2011, the NRC staff requested additional information concerning Unit 2's Boric Acid Precipitation Analysis. The requested information is provided in .

U.S. Nuclear Regulatory Commission Page 3 March 25, 2011 This letter does not contain any new regulatory commitments. If you have any questions, please contact Bill Crouch at (423) 365-2004.

I declare under penalty of perjury that the foregoing is true and correct. Executed on the 25L day of March, 2011.

Respectfully, David Stinson Watts Bar Unit 2 Vice President

Enclosure:

List of Attachments cc (Enclosure):

U. S. Nuclear Regulatory Commission Region II Marquis One Tower 245 Peachtree Center Ave., NE Suite 1200 Atlanta, Georgia 30303-1257 NRC Resident Inspector Unit 2 Watts Bar Nuclear Plant 1260 Nuclear Plant Road Spring City, Tennessee 37381

ENCLOSUREI Tennessee Valley Authority - Watts Bar Nuclear Plant - Unit 2, Docket No. 50-391 List of Attachments

1. Westinghouse Electric Company WBT-D-2995 P, "Watts Bar Unit 2 (WBT) Responses to Request for Additional Information (RAI) - Plant Data for Transmittal to NRC," (Proprietary)
2. Westinghouse Electric Company WBT-D-2995 NP, "Watts Bar Unit 2 (WBT) Responses to Request for Additional Information (RAI) - Plant Data for Transmittal to NRC,"

(Non-Proprietary)

3. Westinghouse Electric Company CAW-I 1-3130, Application For Withholding Proprietary Information From Public Disclosure, WBT-D-2995 P, "Watts Bar Unit 2 (WBT) Responses to Request for Additional Information (RAI) - Plant Data for Transmittal to NRC," (Proprietary),

dated March 11,2011

4. Additional Information on Watts Bar Unit 2 Boric Acid Precipitation Analysis 1

Tennessee Valley Authority - Watts Bar Nuclear Plant - Unit 2, Docket No. 50-391 Attachment 2 Westinghouse Electric Company WBT-D-2995 NP, "Watts Bar Unit 2 (WBT) Responses to Request for Additional Information (RAI) - Plant Data for Transmittal to NRC,"

(Non-Proprietary)

Westinghouse Non-Proprietary Class 3 Page 1 of 7 WBT-D-2995 NP-Attachment Watts Bar Unit 2 (WBT) Responses to Request for Additional Information (RAI) - Plant Data for Transmittal to NRC Westinghouse Electric Company 1000 Westinghouse Drive Cranberry, Pennsylvania 16066

© 2011 Westinghouse Electric Company LLC All Rights Reserved

Page 2 of 7 WBT-D-2995 NP-Attachment Watts Bar Unit 2 (WBT) Responses to Request for Additional Information (RAI) - Plant Data for Transmittal to NRC

1. Information regarding the Watts Bar 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 (ft 3)

Lower Plenum ]a,c Core [ ]a,c Upper Plenum Below the Bottom Elevation of the Hot Leg [ aC 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 ]ajC

Page 3 of 7 WBT-D-2995 NP-Attachment

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 10%(5) SGTP Loss kin s F 2) Coefficient Coefficient 2

(dimensionless) (in (ft/gpm ) (ft/gpm 2 )

Upper Plenum to Hot Leg ]a,c [ac ]a,c Same Nozzle Hot Leg Nozzle [ ]a,c [ ]a,c [ ]a,c Same Hot Leg N/A N/A [ ]a,c Same Steam Generator Inlet N/A N/A [ a,c Same Steame Generator Gn Tubes, N/A N/A [ [ ]

Inlet to U-Bend Steam Generator U-Bend N/A N/A [ ]a,c [ a Steam Generator Tubes, N/A N/A a'C a'c U-Bend Outlet Steam Generator Outlet N/A N/A [ aC Same Pump Suction Leg N/A N/A [ ]a,c Same Cold Leg N/A N/A [ ]a,c Same Cold Leg Nozzle [ ac [ ]a,c [ ]a,c Same Intact Cold Leg to Broken ]ac ]ac ]a.c Same Cold Leg Table lb-2: Locked Rotor Reactor Coolant Pump (RCP) k-factor Flow 0% SGTP Loss 10% SGTP Loss Area Coefficient Coefficient (dimensionless) (in 2) (ft/gpm 2 ) (ft/gpm 2 )

Locked Rotor (Forward Flow) N/A N/A [ ]'C Same Locked Rotor (Reverse Flow) N/A N/A [ ],c Same

Page 4 of 7 WBT-D-2995 NP-Attachment 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 2

Rate (Ibm/hr) Flow Area (in ) 2 Flow Area (in2) k-factor (ft/gpm ) Temperature

(*F)

Upper Plenum to a~c a'c Same a'c 619.1 Hot Leg Nozzle Hot Leg Nozzle [ ac [ ]aC Same [ ac 619.1 Hot Leg [ ac [ ac Same [ ]a,c 619.1 Steam Generator a'c [ ]c Same a'c 619.1 Inlet [_]_c [_a__Se[___ 61_ . _

Steam Generator Tubes, Inlet to U- [ ]ac [ ]a.C [ ]a,c [ ]a,c 588.2 Bend Steam Generator U-Bend [ ]a.C [ ]a,c [ ]ac [ ]a,c 588.2 Steam Generator Tubes, U-Bend [ [ [ ]a,c [ ]a,c 588.2 Outlet Steam Generator [ Same [ 557.0 Outlet [_a_[___Sm__]__5.

Pump Suction Leg [ ]a,c [ ac Same [ ]a, 557.0 Cold Leg [ ]ac [ a Same [ a'C 557.3 Cold Leg Nozzle [ ]a,c [ ]a,c Same [ ]a, 557.3 Intact Cold Leg to Broken Cold Leg Not Modeled [ a, T Same [ ]aC 557.3

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 250,000 3,100 RWST, Maximum 380,000 () 3,300

( The 380,000 gal value conservatively bounds the RWST maximum capacity including tank uncertainties. Actual RWST volume delivered to the containment sump may be less.

Page 5 of 7 WBT-D-2995 NP-Attachment

d. Capacity of the condensate storage tank 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 (Ibm/see)

Flushing Flow at HLSO i)33 (1) Flushing flow is calculated as rhsl -- Thhoil.

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 1 900 3,300 (1)

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

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 Table 2-1: Elevation Data Elevation (ft)(I)

Bottom of Suction Leg Horizontal Piping [ a,c Top of Cold Leg at Reactor Coolant Pump Discharge [ ]a,c Top of the Core (also Core Height) [ ]a~c (12.000)

Bottom of the Downcomer [ ]a2C

() All elevations referenced from the bottom of the reactor vessel.

Page 6 of 7 WBT-D-2995 NP-Attachment

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

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

-16.984%. The limiting BELOCA top skewed power shape is shown in Figure 3-2 with an axial offset of 9.377%.

Bottom Skewed AVG P PWR 0 0 0 1.4" 1.2-

/

' /

/

/

/

l-C -

(.1-0 4 6 5 10 12 Elevation (ft)

Figure 3-1 Limiting Bottom Skewed Power Shape for Average Power Rod

Page 7 of 7 WBT-D-2995 NP-Attachment Top Skewed AV GP WR 0 0 0 1.4

1.2 4 4 -..- ~ 4 4 1~ 4 -*

/ 1- i- ~ 4 -~---- 4 4

/

//

C, //

/

0,6"

/

/

A-4 4- + 4 4 4

- I 4- 4 4 4 I I I I I I I I I I I I I I I I I I

- 1 I . 1 I 1I J. L L . L 0 2 4 6 1 12 Elevation (ft)

Figure 3-2 Limiting Top Skewed Power Shape for Average Power Rod

Tennessee Valley Authority - Watts Bar Nuclear Plant - Unit 2, Docket No. 50-391 Attachment 3 Westinghouse Electric Company CAW-l 1-3130, Application For Withholding Proprietary Information From Public Disclosure, WBT-D-2995 P, "Watts Bar Unit 2 (WBT) Responses to Request for Additional Information (RAI) - Plant Data for Transmittal to NRC,"

(Proprietary), dated March 11, 2011

Westinghouse Nuclear Services Westinghouse Electric Company 1000 Westinghouse Drive Cranberry Township, Pennsylvania 16066 USA U.S. Nuclear Regulatory Commission Direct tel: (412) 374-4643 Document Control Desk Direct fax: (724) 720-0754 11555 Rockville Pike e-mail: greshaja@westinghouse.com Rockville, MD 20852 Proj letter: WBT-D-2995 CAW-1 1-3130 March 11, 2011 APPLICATION FOR WITHHOLDING PROPRIETARY INFORMATION FROM PUBLIC DISCLOSURE

Subject:

"Watts Bar Unit 2 (WBT) Responses to Request for Additional Information (RAI) - Plant Data for Transmittal to NRC" (Proprietary)

The proprietary information for which withholding is being requested in the above-referenced report is further identified in Affidavit CAW- 11-3130 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 2.3 90 of the Commission's regulations.

Accordingly, this letter authorizes the utilization of the accompanying affidavit by Tennessee Valley Authority.

Correspondence with respect to the proprietary aspects of the application for withholding or the Westinghouse affidavit should reference this letter, CAW- 11-3130, and should be addressed to J. A. Gresham, Manager, Regulatory Compliance, Westinghouse Electric Company LLC, Suite 428, 1000 Westinghouse Drive, Cranberry Township, Pennsylvania 16066.

Very truly yours, JA. Gresham, Manager Regulatory Compliance Enclosures

CAW-1 1-3130 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:

A. Gresham, Manager Regulatory Compliance Sworn to and subscribed before me Iday of March 2011 this I1t NotaryPubl COMMONWEALTH OF PENNSYLVANIA Notarial Seal Cynthia Olesky, Notary Public Manor Boro, Westmoreland County My Commission Expires July 16, 2014 Member. Pennsylvania A ation of Notaries

2 CAW-11-3130 (1) 1 am Manager, Regulatory Compliance, 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-11-3130 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-11-3130 (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 "Watts Bar Unit 2 (WBT) Responses to Request for Additional Information (RAI) - Plant Data for Transmittal to NRC" (Proprietary), for submittal to the Commission, being transmitted by Tennessee Valley Authority 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 Watts Bar Unit 2 license application.

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

(a) Assist the customer in obtaining NRC review of the Watts Bar Unit 2 license.

5 CAW-l 1-3130 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 Post-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 2.3 90(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 noticeif the original was identified as proprietary.

Tennessee Valley Authority Letter for Transmittal to the NRC The following paragraphs should be included in your letter to the NRC:

Enclosed are:

1. _ copies of WBT-D-2995 P-Attachment, "Watts Bar Unit 2 (WBT) Responses to Request for Additional Information (RAI) - Plant Data for Transmittal to NRC" (Proprietary)
2. _ copies of WBT-D-2995 NP-Attachment, "Watts Bar Unit 2 (WBT) Responses to Request for Additional Information (RAI) - Plant Data for Transmittal to NRC" (Non-Proprietary)

Also enclosed is the Westinghouse Application for Withholding Proprietary Information from Public Disclosure CAW-1 1-3130, accompanying Affidavit, Proprietary Information Notice, and Copyright Notice.

As Item I contains information proprietary to Westinghouse Electric Company LLC, it is supported by an affidavit signed by Westinghouse, the owner of the information. The affidavit 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 Section 2.390 of the Commission's regulations.

Accordingly, it is respectfully requested that the information which is proprietary to Westinghouse be withheld from public disclosure in accordance with 10 CFR Section 2.390 of the Commission's regulations.

Correspondence with respect to the copyright or proprietary aspects of the items listed above or the supporting Westinghouse affidavit should reference CAW-I 1-3130 and should be addressed to J. A. Gresham, Manager, Regulatory Compliance, Westinghouse Electric Company LLC, Suite 428, 1000 Westinghouse Drive, Cranberry Township, Pennsylvania 16066.

Tennessee Valley Authority - Watts Bar Nuclear Plant - Unit 2, Docket No. 50-391 Attachment 4 Additional Information on Watts Bar Unit 2 Boric Acid Precipitation Analysis

Page 1 of 8 Additional Information on Watts Bar Unit 2 Boric Acid Precipitation Analysis Figure 1 shows the time-based liquid mass contributors to the containment sump for a Large Break LOCA (LBLOCA) scenario. Two separate conditions are shown for RWST draindown. The maximum RWST draindown rate assumes 2 functioning trains of ECCS pumps. The minimum RWST draindown rate case assumes a single functioning train of ECCS pumps. Also indicated is sump mass at the maximum active containment sump capacity (floodup to the 716 foot level). Containment floodup above this level results in spill into the reactor cavity, then spill into an inactive sump region of containment outside the crane wall.

Figure 2 shows the time-based calculated sump boron concentration using the assumed boron concentrations of the sump contributors and the sump flood-up behavior shown in Figure 1. As in Figure 1, both a maximum RWST draindown rate case and a minimum RWST draindown rate case are shown.

Figure 3 shows the time-based boron concentration of the core boil-off makeup flow. Prior to sump recirculation the boron concentration of the core boiloff makeup is assumed to be the RWST Tech Spec maximum boron concentration. After the switchover to sump recirculation is complete, the boron concentration of the core boiloff makeup is the sump concentration. For the period in-between the start of switchover to sump recirculation and the completion of the switchover, the boron concentration of the core boiloff makeup is calculated to be a mix of RWST and sump boron concentration. As in Figures 1 and 2, both a maximum RWST draindown rate case and a minimum RWST draindown rate case are shown. A calculated decay-heat-weighted average boron concentration for 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> after the LOCA is indicated for each case. This decay-heat-weighted average boron concentration is used as input to the core region boric acid buildup calculations. The average is weighted for decay heat to capture the effect of higher boiloff early in the post-LOCA period.

Table 1 contains tabulated data for the limiting case of minimum RWST draindown rate core boiloff make-up boron concentration plot in Figure 3 and core average and upper plenum void fractions.

7,000,000.00 4,000,000.00 3,000,000.00 2,000,000.00 .i, 1,000,000.00 0.00 0.00 5,00000 10,00000 15,00000 20,000.00 25,000.00 Thn (SoC)

- Max Ice Men Mass RWST Mass - Max Dranidom Raie ....... Total Mass (WiM RWST Dramkdow Rate)

Total Mass (Max RWST DralKdoon Rate)

. --- Bodon Mass - RWST Mass - Min Drando

- Sump* Oefs 0

(0 Figure 1 - Mass in Sump vs. Time OD

3,00000 2,80000 z2,6.000 C

c.2,400.00 0

0 I

z 8 2,200.00 2

0 2,000.00 ---------

1,800.00 ! I 0o00 5,000.00 10,000.00 15,000-00 20,00&00 25,000-00 Time (s)

. M RWST DramdownW Overfw W-- RWST Dram-own wl Overfo -- 3 Hour TIne Figure 2 - Boron Concentration of Sump Mass vs. Time

3,400.00 3,300.00 3,200.00 3,100.00 93,000.00

2,90000 2 280000o -.

2,70000 2,600.00 2,600.0 -

000 2,000-00 4,000-00 6,000.00 8,000.00 10,000.00 1ZOOO.00 Time (s)

Max RWST DrAtdcwn Weiohed Average - Max RWST Draow Rate Win RWST D* a Rate

.. Mi RWST DrkDo

Wegted Average -U CD 0

Co Figure 3 - Boron Concentration of Injected ECCS Flow

Page 5 of 8 Table 1 - Core Boiloff Make-up Boron Concentration and Vessel Void Fractions Core SI Boron Upper Average Concentration Plenum Void Void Time (s) (ppm) Fraction Fraction 2 3300 -

10 3300 -

28 3300 -

56 3300 -

89 3300 -

117 3300 1.000 0.764 151 3300 1.000 0.750 184 3300 1.000 0.737 217 3300 1.000 0.727 278 3300 1.000 0.712 344 3300 1.000 0.697 449 3300 1.000 0.677 543 3300 1.000 0.663 566 3300 1.000 0.659 599 3300 1.000 0.654 612 3300 0.988 0.653 645 3300 0.954 0.649 665 3300 0.933 0.646 699 3300 0.898 0.642 757 3300 0.890 0.637 797 3300 0.885 0.633 863 3300 0.879 0.629 900 3300 0.875 0.626 1000 3300 0.866 0.620 1100 3300 0.859 0.614 1126 3300 0.857 0.613 1224 3300 0.850 0.608 1289 3300 0.846 0.605 1300 2794 0.845 0.604 1400 2801 0.839 0.600 1495 2806 0.833 0.596 1500 2807 0.833 0.596 1559 2810 0.830 0.594 1625 2814 0.827 0.591 1723 2820 0.822 0.588 1800 2823 0.818 0.585 1900 2828 0.814 0.582 2039 2833 0.808 0.578

Page 6 of 8 Core SI Boron Upper Average Concentration Plenum Void Void Tim~e (s) (ppm) Fraction Fraction 2088 2837 0.806 0.576 2129 2840 0.804 0.575 2212 2847 0.801 0.573 2251 2850 0.799 0.571 2378 2860 0.794 0.568 2500 2869 0.790 0.565 2600 2876 0.786 0.562 2700 2883 0.783 0.560 2800 2890 0.780 0.557 2900 2897 0.776 0.555 2990 2903 0.773 0.553 3000 2813 0.773 0.553 3100 2808 0.771 0.551 3200 2803 0.768 0.549 3300 2798 0.765 0.547 3330 2796 0.764 0.546 3413 2792 0.763 0.545 3446 2791 0.762 0.544 3462 2790 0.761 0.544 3471 2790 0.761 0.544 3487 2789 0.760 0.543 3520 2788 0.760 0.543 3603 2785 0.758 0.541 3611 2785 0.758 0.541 3620 2785 0.757 0.541 3628 2784 0.757 0.541 3728 2780 0.754 0.539 3800 2778 0.753 0.538 3900 2774 0.751 0.537 4000 2770 0.749 0.535 4100 2767 0.746 0.533 4200 2764 0.744 0.532 4300 2760 0.742 0.530 4400 2757 0.740 0.529 4500 2754 0.738 0.527 4600 2751 0.736 0.526 4700 2748 0.734 0.525 4800 2745 0.733 0.523 4900 2743 0.731 0.522 5000 2740 0.729 0.521

Page 7 of 8 Core SI Boron Upper Average Concentration Plenum Void Void Time (s) * (ppm) Fraction Fraction 5100 2737 0.727 0.520 5200 2735 0.726 0.519 5300 2732 0.724 0.517 5400 2730 0.723 0.516 5500 2727 0.721 0.515 5600 2725 0.720 0.514 5700 2723 0.718 0.513 5800 2720 0.717 0.512 5900 2718 0.715 0.511 6000 2716 0.714 0.510 6100 2714 0.713 0.509 6200 2712 0.711 0.508 6300 2710 0.710 0.507 6400 2708 0.709 0.506 6500 2706 0.707 0.505 6600 2704 0.706 0.504 6700 2702 0.705 0.503 6800 2700 0.704 0.503 6900 2698 0.703 0.502 7000 2696 0.701 0.501 7100 2694 0.700 0.500 7141 2694 0.700 0.500 7200 2694 0.699 0.499 7300 2694 0.698 0.498 7400 2694 0.697 0.498 7500 2694 0.696 0.497 7600 2694 0.695 0.496 7700 2694 0.694 0.495 7800 2694 0.693 0.495 7900 2694 0.692 0.494 8000 2694 0.691 0.493 8100 2694 0.690 0.493 8200 2694 0.689 0.492 8300 2694 0.688 0.491 8400 2694 0.687 0.491 8500 2694 0.686 0.490 8600 2694 0.685 0.489 8700 2694 0.685 0.489 8800 2694 0.684 0.488 8900 2694 0.683 0.487

Page 8 of 8 Core SI Boron Upper Average Concentration Plenum Void Void Time (s) (ppm) Fraction Fraction 9000 2694 0.682 0.487 9100 2694 0.681 0.486 9200 2694 0.680 0.486 9300 2694 0.680 0.485 9400 2694 0.679 0.484 9500 2694 0.678 0.484 9600 2694 0.677 0.483 9700 2694 0.676 0.483 9800 2694 0.676 0.482 9900 2694 0.675 0.482 10000 2694 0.674 0.481 10100 2694 0.673 0.481 10200 2694 0.673 0.480 10300 2694 0.672 0.479 10400 2694 0.671 0.479 10500 2694 0.670 0.478 10600 2694 0.670 0.478 10700 2694 0.669 0.477 10800 2694 0.668 0.477

  • The as analyzed weighted average is 2881.74 ppm.
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