ML20118C429

Issuance of Amendments Revision of Technical Specifications for the Ultimate Heat Sink

ML20118C429
Person / Time
Site:	Braidwood
Issue date:	06/09/2020
From:	Joel Wiebe Plant Licensing Branch III
To:	Bryan Hanson Exelon Generation Co, Exelon Nuclear
Wiebe J
References
EPID L-2019-LLA-0201
Download: ML20118C429 (22)

Text

June 9, 2020 Mr. Bryan C. Hanson Senior Vice President Exelon Generation Company, LLC President and Chief Nuclear Officer (CNO)

Exelon Nuclear 4300 Winfield Road Warrenville, IL 60555

SUBJECT:

BRAIDWOOD STATION, UNITS 1 AND 2, - ISSUANCE OF AMENDMENTS NOS. 210 RE: REVISION OF TECHNICAL SPECIFICATIONS FOR THE ULTIMATE HEAT SINK (EPID L-2019-LLA-0201)

Dear Mr. Hanson:

The U.S. Nuclear Regulatory Commission (the Commission) has issued the enclosed Amendment No. 210 (No. 209 will not be used) to Renewed Facility Operating License No. NPF-72 and Amendment No. 210 to Renewed Facility Operating License No. NPF-77 for the Braidwood Station, Units 1 and 2. The amendments are in response to your application dated September 11, 2019 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML19254D105), as supplemented by letter dated March 9, 2020 (ADAMS Accession No. ML20071E921).

The amendments revise Technical Specification 3.7.9, Ultimate Heat Sink inventory verification from a level-based verification to a volume-based verification.

A copy of the Safety Evaluation is also enclosed. A Notice of Issuance will be included in the Commissions biweekly Federal Register notice.

Sincerely,

/RA/

Joel S. Wiebe, Senior Project Manager Plant Licensing Branch III Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. STN 50-456, STN 50-457,

Enclosures:

1. Amendment No. 210 to NPF-72

2. Amendment No. 210 to NPF-77

3. Safety Evaluation cc: Listserv EXELON GENERATION COMPANY, LLC DOCKET NO. STN 50-456 BRAIDWOOD STATION, UNIT 1 AMENDMENT TO RENEWED FACILITY OPERATING LICENSE Amendment No. 210 Renewed License No. NPF-72

1.

The U.S. Nuclear Regulatory Commission (the Commission) has found that:

A.

The application for amendment by Exelon Generation Company, LLC (the licensee) dated September 11, 2019, as supplemented by letter dated March 9, 2020, complies with the standards and requirements of the Atomic Energy Act of 1954, as amended (the Act), and the Commissions rules and regulations set forth in 10 CFR Chapter I; B.

The facility will operate in conformity with the application, the provisions of the Act, and the rules and regulations of the Commission; C.

There is reasonable assurance: (i) that the activities authorized by this amendment can be conducted without endangering the health and safety of the public, and (ii) that such activities will be conducted in compliance with the Commissions regulations; D.

The issuance of this amendment will not be inimical to the common defense and security or to the health and safety of the public; and E.

The issuance of this amendment is in accordance with 10 CFR Part 51 of the Commissions regulations and all applicable requirements have been satisfied.

2.

Accordingly, the renewed operating license is amended by changes to the Technical Specifications as indicated in the attachment to this license amendment, and paragraph 2.C.(2) of Renewed Facility Operating License No. NPF-72 is hereby amended to read as follows:

(2)

Technical Specifications The Technical Specifications contained in Appendix A as revised through Amendment No. 210 and the Environmental Protection Plan contained in Appendix B, both of which are attached hereto, are hereby incorporated into the renewed license. The licensee shall operate the facility in accordance with the Technical Specifications and the Environmental Protection Plan.

3.

This license amendment is effective as of the date of its issuance and shall be implemented within 60 days of the date of issuance.

FOR THE NUCLEAR REGULATORY COMMISSION Nancy L. Salgado, Chief Plant Licensing Branch III Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation

Attachment:

Changes to the Technical Specifications and Renewed Facility Operating License Date of Issuance: June 9, 2020 Nancy L.

Salgado Digitally signed by Nancy L. Salgado Date: 2020.06.09 15:47:58 -04'00'

EXELON GENERATION COMPANY, LLC DOCKET NO. STN 50-457 BRAIDWOOD STATION, UNIT 2 AMENDMENT TO RENEWED FACILITY OPERATING LICENSE Amendment No. 210 Renewed License No. NPF-77

1.

The U.S. Nuclear Regulatory Commission (the Commission) has found that:

A.

The application for amendment by Exelon Generation Company, LLC (the licensee) dated September 11, 2019, as supplemented by letter dated March 9, 2020, complies with the standards and requirements of the Atomic Energy Act of 1954, as amended (the Act), and the Commissions rules and regulations set forth in 10 CFR Chapter I; B.

The facility will operate in conformity with the application, the provisions of the Act, and the rules and regulations of the Commission; C.

There is reasonable assurance: (i) that the activities authorized by this amendment can be conducted without endangering the health and safety of the public, and (ii) that such activities will be conducted in compliance with the Commissions regulations; D.

The issuance of this amendment will not be inimical to the common defense and security or to the health and safety of the public; and E.

The issuance of this amendment is in accordance with 10 CFR Part 51 of the Commissions regulations and all applicable requirements have been satisfied.

2.

Accordingly, the renewed operating license is amended by changes to the Technical Specifications as indicated in the attachment to this license amendment, and paragraph 2.C.(2) of Renewed Facility Operating License No. NPF-77 is hereby amended to read as follows:

(2)

Technical Specifications The Technical Specifications contained in Appendix A as revised through Amendment No. 210 and the Environmental Protection Plan contained in Appendix B, both of which are attached to Renewed License No. NPF-72, dated January 27, 2016, are hereby incorporated into the renewed license. The licensee shall operate the facility in accordance with the Technical Specifications and the Environmental Protection Plan.

3.

This license amendment is effective as of the date of its issuance and shall be implemented within 60 days of the date of issuance.

FOR THE NUCLEAR REGULATORY COMMISSION Nancy L. Salgado, Chief Plant Licensing Branch III Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation

Attachment:

Changes to the Technical Specifications and Renewed Facility Operating License Date of Issuance: June 9, 2020 Nancy L.

Salgado Digitally signed by Nancy L. Salgado Date: 2020.06.09 15:48:31 -04'00'

ATTACHMENT TO LICENSE AMENDMENT NOS. 210 AND 210 RENEWED FACILITY OPERATING LICENSE NOS. NPF-72 AND NPF-77 BRAIDWOOD STATION, UNITS 1 AND 2 DOCKET NOS. STN 50-456 AND STN 50-457 Replace the following pages of the Renewed Facility Operating Licenses and Appendix A, Technical Specifications, with the attached revised pages. The revised pages are identified by amendment number and contain marginal lines indicating the areas of change.

REMOVE INSERT License No. NPF-72 License No. NPF-72 Page 3 Page 3 License No. NPF-77 License No. NPF-77 Page 3 Page 3 TSs TSs Page 3.7.9 - 1 Page 3.7.9 - 1

(2)

Exelon Generation Company, pursuant to the Act and 10 CFR Part 70, to receive, possess and use at any time special nuclear material as reactor fuel, in accordance with the limitations for storage and amounts required for reactor operation, as described in the Final Safety Analysis Report, as supplemented and amended; (3)

Exelon Generation Company, pursuant to the Act and 10 CFR Parts 30, 40 and 70, to receive, possess, and use at any time any byproduct, source and special nuclear material as sealed neutron sources for reactor startup, sealed sources for reactor instrumentation and radiation monitoring equipment calibration, and as fission detectors in amounts as required; (4)

Exelon Generation Company, pursuant to the Act and 10 CFR Parts 30, 40 and 70, to receive, possess, and use in amounts as required any byproduct, source or special nuclear material without restriction to chemical or physical form, for sample analysis or instrument calibration or associated with radioactive apparatus or components; and (5)

Exelon Generation Company, pursuant to the Act and 10 CFR Parts 30, 40 and 70, to possess, but not separate, such byproduct and special nuclear materials as may be produced by the operation of the facility.

C.

This renewed license shall be deemed to contain and is subject to the conditions specified in the Commissions regulations set forth in 10 CFR Chapter I and is subject to all applicable provisions of the Act and to the rules, regulations, and orders of the Commission now or hereafter in effect; and is subject to the additional conditions specified or incorporated below:

(1)

Maximum Power Level The licensee is authorized to operate the facility at reactor core power levels not in excess of 3645 megawatts thermal (100 percent rated power) in accordance with the conditions specified herein.

(2)

Technical Specifications The Technical Specifications contained in Appendix A as revised through Amendment No. 210 and the Environmental Protection Plan contained in Appendix B, both of which are attached hereto, are hereby incorporated into the renewed license. The licensee shall operate the facility in accordance with the Technical Specifications and the Environmental Protection Plan.

Renewed License No. NPF-72 Amendment No. 210

(2)

Exelon Generation Company, LLC, pursuant to the Act and 10 CFR Part 70, to receive, possess and use at any time special nuclear material as reactor fuel, in accordance with the limitations for storage and amounts required for reactor operation, as described in the Final Safety Analysis Report, as supplemented and amended; (3)

Exelon Generation Company, LLC, pursuant to the Act and 10 CFR Parts 30, 40 and 70, to receive, possess, and use at any time any byproduct, source and special nuclear material as sealed neutron sources for reactor startup, sealed sources for reactor instrumentation and radiation monitoring equipment calibration, and as fission detectors in amounts as required; (4)

Exelon Generation Company, LLC, pursuant to the Act and 10 CFR Parts 30, 40 and 70, to receive, possess, and use in amounts as required any byproduct, source or special nuclear material without restriction to chemical or physical form, for sample analysis or instrument calibration or associated with radioactive apparatus or components; and (5)

Exelon Generation Company, LLC, pursuant to the Act and 10 CFR Parts 30, 40 and 70, to possess, but not separate, such byproduct and special nuclear materials as may be produced by the operation of the facility.

C.

This renewed license shall be deemed to contain and is subject to the conditions specified in the Commissions regulations set forth in 10 CFR Chapter I and is subject to all applicable provisions of the Act and to the rules, regulations, and orders of the Commission now or hereafter in effect; and is subject to the additional conditions specified or incorporated below:

(1)

Maximum Power Level The licensee is authorized to operate the facility at reactor core power levels not in excess of 3645 megawatts thermal (100 percent rated power) in accordance with the conditions specified herein.

(2)

Technical Specifications The Technical Specifications contained in Appendix A as revised through Amendment No. 210 and the Environmental Protection Plan contained in Appendix B, both of which are attached to Renewed License No. NPF-72, dated January 27, 2016, are hereby incorporated into the renewed license. The licensee shall operate the facility in accordance with the Technical Specifications and the Environmental Protection Plan.

Renewed License No. NPF-77 Amendment No. 210

UHS 3.7.9 BRAIDWOOD UNITS 1 & 2 3.7.9 1 Amendment 210XXXXXXX 3.7 PLANT SYSTEMS 3.7.9 Ultimate Heat Sink (UHS)

LCO 3.7.9 The UHS shall be OPERABLE.

APPLICABILITY:

MODES 1, 2, 3, and 4.

ACTIONS CONDITION REQUIRED ACTION COMPLETION TIME A.

UHS inoperable.

A.1 Be in MODE 3.

AND A.2 Be in MODE 5.

6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> 36 hours SURVEILLANCE REQUIREMENTS SURVEILLANCE FREQUENCY SR 3.7.9.1 Verify water level of UHS is 590 ft Mean Sea Level (MSL).

In accordance with the Surveillance Frequency Control Program SR 3.7.9.2 Verify average water temperature of UHS is 102F.

In accordance with the Surveillance Frequency Control Program SR 3.7.9.3 Verify UHS contains a water volume of 555.8 acre-feet.

In accordance with the Surveillance Frequency Control Program

SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO. 210 TO RENEWED FACILITY OPERATING LICENSE NO. NPF-72 AND AMENDMENT NO. 210 TO RENEWED FACILITY OPERATING LICENSE NO. NPF-77 EXELON GENERATION COMPANY, LLC BRAIDWOOD STATION, UNITS 1 AND 2 DOCKET NOS. STN 50-456, STN 50-457

1.0 INTRODUCTION

By letter dated September 11, 2019 [Reference 1], as supplemented by letter dated March 9, 2020 [Reference 2], Exelon Generation Company, LLC, (EGC, the licensee), requested amendments to Renewed Facility Operating License Nos. NPF-72 and NPF-77 for Braidwood Station, Units 1 and 2 (BRW), respectively. The amendments proposed changes for BRW technical specification (TS) 3.7.9, "Ultimate Heat Sink (UHS)." Specifically, the licensee proposed to change the verification of the UHS inventory, from a level-based verification to a volume-based verification. The proposed TS change more accurately reflects the volume requirement of the design bases by requiring a volume-based inventory validation because the design basis identifies the volume of the UHS needed to support the BRW accident analysis.

Additionally, a volume-based acceptance criterion eliminates impact from variations in bottom elevation measurement.

The supplemental letter dated March 9, 2020, provided additional information that clarified the application, did not expand the scope of the application as originally noticed, and did not change the U.S. Nuclear Regulatory Commission (Commission or NRC) staffs original proposed no significant hazards consideration determination as published in the Federal Register on December 17, 2019 (84 FR 68952).

2.0 REGULATORY EVALUATION

2.1 UHS Description The BRW UHS consists of an excavated essential service cooling pond (ESCP) integral with the main BRW cooling pond. The UHS is designed to withstand the separate occurrence of either the safe shutdown earthquake or the probable maximum flood of the cooling pond from Crane Creek, Granary Creek, the Mazon River, and the Kankakee River. The makeup and blowdown lines from the Kankakee River serving the cooling pond are Seismic Category II and may not be available following a design-basis seismic event.

The main cooling pond is surrounded by a system of dikes and is excavated to elevation 590 feet. The ESCP is a Seismic Category I 6-feet-deep pond excavated to a bottom elevation of 584 feet within the main cooling pond. The excavation is made such that the ESCP remains intact in the event of failure of the Seismic Category II retaining dikes impounding the main cooling pond. The ESCP is designed to provide sufficient water volume to both units for a minimum 30-day period with one unit post-accident and the other unit in an orderly shutdown without requiring makeup water from the Kankakee River in accordance with Regulatory Guide (RG) 1.27, Ultimate Heat Sink for Nuclear Power Plants, Revision 2 [Reference 3].

The ESCP is approximately rectangular, with a gross design surface area of approximately 96 acres and a gross design capacity of 555.8 acre-feet [References 4 and 5] with water level at elevation 590 feet. Under normal conditions, the ESCP is indistinguishable from the remainder of the main cooling pond. The ESCP cooling water intake structure is located at the northwest corner of the ESCP, and the discharge structure for essential service water is at the southern end. The floor of the intake structure is at 570 feet 2 inches elevation, about 14 feet below the bottom of the UHS. An engineered slope of 1(Vertical):10(Horizontal) leads from the UHS to the intake structure. A modification was made to the UHS during 2014-2015 [Reference 6] and consists a sheet pile wall spanning the north-south limits on the eastern side of the ESCP. The wall has been installed approximately 300 ft east of the eastern edge of the ESCP to ensure that its installation does not adversely affect the eastern slope of the ESCP. The wall was constructed using hot-rolled sheet pile sections. The upper portions of the wall joints are sealed with a hydrophilic sealer. The top of the sheet pile wall is installed to a design elevation of 591.0 feet. Unsealed handling holes on each sheet pile make elevation 590.95 feet the lowest elevation of unsealed areas of the sheet pile wall.

The essential service water system (SX) takes suction from the UHS at the Lake Screen House Intake Structure and supplies the SX pumps at the Auxiliary Building elevation 530 feet above mean sea level where the SX pumps supply the safety-related loads and components required for safe shutdown.

2.2 Licensees Proposed Changes 2.2.1 TS 3.7.9 UHS Both BRW Units 1 and 2 TS 3.7.9 Ultimate Heat Sink (UHS) are being revised as represented below by the double strike through deletion and underlined replacement text.

3.7 Plant systems 3.7.9 UHS LCO The UHS shall be operable.

APPLICABILITY: MODES 1, 2, 3, and 4.

ACTIONS CONDITION REQUIRED ACTION COMPLETION TIME A. UHS inoperable.

A.1 Be in MODE 3.

AND A.2 Be in MODE 5.

6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> 36 hours SURVEILLANCE REQUIREMENTS (SRs)

SURVEILLANCE FREQUENCY SR 3.7.9.1 Verify water level of the UHS is 590 ft Mean Sea Level (MSL).

In accordance with the Surveillance Frequency Program SR 3.7.9.2 Verify average water temperature of UHS is 102°F.

In accordance with the Surveillance Frequency Program SR 3.7.9.3 Verify bottom level of UHS is 584 ft MSL.

Verify UHS contains a water volume of 555.8 acre-feet.

In accordance with the Surveillance Frequency Program 2.3 Regulatory Requirements Licensing Basis Requirements Title 10 of the Code of Federal Regulations (10 CFR) 50.36(c) requires that the TSs include items in five specific categories. These categories include: (1) safety limits, limiting safety system settings and limiting control settings; (2) limiting conditions for operation (LCOs); (3) surveillance requirements (SR); (4) design features; and (5) administrative controls. However, the regulation does not specify the particular TSs to be included in a plants license.

The regulation at 10 CFR 50.36(c)(3) requires TS to include items in the category of SRs, which are requirements relating to test, calibration, or inspection, to assure that the necessary quality of systems and components is maintained, that facility operation will be within safety limits, and that the LCOs will be met.

The BRW Updated Final Safety Analysis Report, Section 3.1.1 (ADAMS Accession No. ML19170A316) states that BRW complies with the General Design Criteria (GDC). The following GDC in Appendix A to 10 CFR Part 50 are relevant to the design of the UHS:

GDC 2 - Design bases for protection against natural phenomena; GDC 5 - Sharing of structures, system, and components; GDC 44 - Cooling water; GDC 45 - Inspection of cooling water system; and GDC 46 - Testing of cooling water system.

Regulatory Guidance NUREG-0800 Standard Review Plan (SRP) 2.4.8, Cooling Water Canals and Reservoirs, Review Procedures [Reference 7] reads, in part:

2. Hydraulic Design Bases of Canals: The criteria of Regulatory Guide 1.27 should be used if the canals are a part of the ultimate heat sink. Erosion and sedimentation during floods that may lead to loss of functionality of the canals, if it is part of the ultimate heat sink, are also reviewed as required by GDC 1 and GDC

2.

3. Hydraulic Design Bases of Reservoirs: If reservoirs comprise a part of the ultimate heat sink, the staff reviews the design bases of these reservoirs, as recommended by Regulatory Guide 1.27. The volume of liquid water stored in a reservoir that comprises part of the ultimate heat sink should be sufficient to meet all safety-related water-supply requirements after accounting for loss in storage capacity due to seepage, sedimentation, evaporation, ice-sheet formation, and other causes.

NUREG-0800 SRP 9.2.5, Ultimate Heat Sink, Evaluation Findings [Reference 8] reads in part:

a. The applicant meets GDC 2 requirements for capability to withstand the effects of natural phenomena like earthquakes, tornadoes, tornado missiles, hurricanes, and floods. Acceptance is based on RG 1.27, Positions C.2 and C.3.

b. The applicant meets GDC 5 requirements for sharing of SSCs by demonstrating that such sharing does not affect the safe shutdown of any unit in an active or passive failure.

c. The applicant meets GDC 44 UHS requirements. Acceptance is based on RG 1.27, Positions C.2 and C.3; RG 1.72, Positions C.1, C.4, C.5, C.6, and C.7; and ANSI/ANS

[American National Standards Institute/American Nuclear Society] 5.1, Decay Heat Power for Light Water Reactors, October 19791.

d. The applicant meets GDC 45 requirements for inservice inspection of the safety-related components and equipment by demonstrating the accessibility of the UHS system for periodic inspections.

e. The applicant meets GDC 46 requirements for periodic pressure and functional testing to ensure structural and leak tight integrity, operability, and performance of its active components, and operability of the system as a whole by demonstrating the capability to operate the system at full capacity during normal startup or shutdown procedures or during normal operation without degrading the system to provide for a safe shutdown or to mitigate the consequences of an accident.

1 Available from American National Standards Institute (ANSI) at https://webstore.ansi.org Regulatory Guide,1.27 Revision 2, Discussion Background reads in part:

To ensure that the UHS has sufficient water available for its safety functions if a dam or other water-controlling structure is required, the dam or other water-controlling structure, within the jurisdiction of the licensee/applicant, and connecting piping systems should be included in the Structures Monitoring Program in accordance with Regulatory Guide 1.160 [ADAMS Accession No. ML18220B281] and the Maintenance Rule at 10 CFR 50.65. Inspection and monitoring of dams or other water control structures should be conducted to ensure that changes in structural, hydraulic and foundation conditions can be detected.

NUREG-1431 Volume 1, Revision 4.0, Specifications - Standard Technical Specifications (STS); Westinghouse Plants [Reference 9], provides standard technical specifications and surveillances for the UHS in section 3.7.9.

NUREG-1431 Volume 2, Revision 4.0 Bases - STS; Westinghouse Plants [Reference 10],

provides standard bases for the UHS TS in section B 3.7.9.

Precedents Reviewed Arkansas Nuclear One (ANO) Units 1 and 2 - The NRC staff issued Amendments 170 and 153 to Facility Operating License Nos. DPR-51 and NPF-6 respectively to change the SR to read in part: At least once per 12 months by making soundings of the pond (i.e., Emergency Cooling Pond) and verifying an average depth of 5 feet and that the contained water volume of the pond is within its limit. [Reference 11]

3.0 TECHNICAL EVALUATION

3.1 Proposed Change to SR 3.7.9.3 In its letter dated September 11, 2019, the licensee stated that the volume of cooling water in the UHS is the critical parameter for the UHS post-accident temperature analysis.

Furthermore, the licensee stated that changing the acceptance criteria for SR 3.7.9.3 to a volume-based value of 555.8 acre-feet or greater will continue to support the cooling water volume assumption in the design analysis. Over the life of the plant there is a potential for loss of storage capacity due to sedimentation in the ESCP. Continued periodic survey of the bottom elevation as part of the ESCP surveillance will detect changes in bottom elevations.

The proposed change does not impact the top elevation of 590 feet for the ESCP and retains SR 3.7.9.1 for verifying the top level of the UHS. Therefore, the proposed change does not impact the Net Positive Suction Head analysis for the SX pumps.

Currently, SRs 3.7.9.1 and 3.7.9.3 when performed together validate the design values for the top and bottom levels respectively of the UHS pond. If the bottom elevation is determined to be above elevation 584 feet, the UHS is considered inoperable even if the volume meets the minimum value assumed in the design basis analysis. Validation of the top and bottom elevations of the UHS support the derivation of a gross calculated volume of the UHS that is compared to the UHS volume required to satisfy the design basis analysis.

The NRC staff notes that the frequency of performance of SR 3.7.9.3 after the BRWs full conversion to improved TS per NUREG-1431 via Amendment 98 in December 1998 was 18 months [Reference 12].

Regulatory Position C.4 for RG 1.27, Revision 2, reads:

4. The technical specifications for the plant should include provisions for actions to be taken in the event that conditions threaten partial loss of the capability of the ultimate heat sink or the plant temporarily does not satisfy regulatory positions 1 and 3 during operation.

With the proposed amendment to TS 3.7.9, BRW UHS would be declared inoperable if the SR are not satisfied for either: 3.7.9.1 pertaining to water level; 3.7.9.2 pertaining to water temperature; or 3.7.9.3 pertaining to water volume.

Appendix A to the BRW Updated Final Safety Analysis Report (UFSAR) (ADAMS Accession No. ML18355A440) indicates that the licensee meets all objectives set forth in Regulatory Guide (RG) 1.27, Revision 2. No exceptions to RG 1.27, Revision 2, were noted. UFSAR Section 2.4.11.6 Heat Sink Dependability Requirements (ADAMS Accession No. ML19169A114) reads, in part:

Statistical analysis of 5 years of data (1957-1961) on the Kankakee River at the Wilmington gauge indicates that 50% of the time the turbidity would be lower than 15 Jackson Turbidity Units (JTU). Assuming that the sediment load can be estimated from the turbidity, a sedimentation rate of 0.38 acre-feet per year could theoretically deposit in the ESCP. The total sediment deposition for a 40-year period would be 15.3 acre-feet, or 2.7% of the capacity of the ESCP. This could raise the bottom elevation to 584.17 feet. It is unlikely that all the sediment would accumulate in the ESCP, however, a periodic survey of the pond will be made to detect any change in bottom elevation.

In its letter dated September 11, 2019, the licensee acknowledged that over the life of the plant, there is a potential for loss of storage capacity in the UHS due to sedimentation in the ESCP. The licensee stated that the design basis analysis for the UHS temperature calculated the needed volume of cooling water in the UHS.

To gain a better understanding of the UHS design, the NRC staff reviewed BRW Calculation ATD-0109, "Thermal Performance of Ultimate Heat Sink During Postulated Loss of Coolant Accident," Revision 4. This calculation was submitted to the NRC as Attachment A to EGCs letter dated August 19, 2014. [Reference 4]. The August 19, 2014, letter requested that the average UHS water temperature per SR 3.7.9.2 be raised to 102 degrees Fahrenheit (°F). This analysis accounts for the design slope of the side of the ESCP and includes a 3-inch sedimentation sensitivity case analysis.

The design volume capacity for the UHS with the water level at elevation 590 feet is 555.8 acre-feet. The analysis adjusts this value using the UHS effectiveness value of 82.3 percent. The effectiveness value is derived through the calculation of the nonparticipating part of the UHS which is defined as the part of the UHS effectiveness percentage that does not see the plant heat load. In the case of the BRW UHS, this constitutes 17.7 percent of the UHS. It is noted that the proposed change to SR 3.7.9.3 specifies a UHS water volume of 555.8 acre-feet. It is also noted that this value is the UHS gross water volume. That is, the value is neither adjusted for the UHS effectiveness value of 82.3 percent nor for any amount of sedimentation.

Based on the information contained in BRW Calculation ATD-0109, the NRC staff issued Amendment 189 for BRW on July 26, 2016, that authorized an average UHS water temperature of 102 °F for SR 3.7.9.2. [Reference 13].

The licensee stated that continued periodic survey of the bottom elevation as part of the ESCP surveillance will detect changes in bottom elevation of the UHS. More specifically, to satisfy the current requirements of SR 3.7.9.3 a survey of the ESCP is performed on a frequency in accordance with the surveillance frequency control program to verify the bottom elevation of the ESCP is 584 feet or less. The licensee also validates that the water level of the UHS is higher than or equal to 590 feet and determines the water volume of the ESCP below elevation 590 feet.

The licensee provided the following from the most recent survey of the BRW UHS:

The most recent surveillance was performed in March 2019 and shows an average UHS depth elevation of 583.7 feet which is below the 584 feet elevation. The actual gross water volume below elevation 590 feet has been determined to be 597.9 acre-feet. The measured volume of 597.9 acre-feet is larger than the design value of 555.8 acre-feet. The greater measured volume value is largely due to the water volume below elevation 584 feet and the modification that restored the surface area and expanded the 590 feet elevation boundary on the eastside of the UHS [References 2 and 5].

In an email dated January 23, 2020, the NRC staff requested additional information about the proposed change to SR 3.7.9.3 [Reference 14]. It was noted that Appendix A to the BRW UFSAR indicates that the licensee meets all objectives set forth in RG 1.27, Revision 2, "Ultimate Heat Sink For Nuclear Power Plants," without exceptions. In particular, the NRC staff cited RG 1.27 Discussion background which reads in part:

To ensure that the UHS has sufficient water available for its safety functions if a dam or other water-controlling structure is required, the dam or other water controlling structure, within the jurisdiction of the licensee/applicant, and connecting piping systems should be included in the Structures Monitoring Program in accordance with Regulatory Guide 1.160 and the Maintenance Rule at 10 CFR 50.65. Inspection and monitoring of dams or other water control structures should be conducted to ensure that changes in structural, hydraulic and foundation conditions can be detected.

The NRC staff also evaluated the proposed TS change with respect to Regulatory Position C.4 (i.e., as cited above) for RG 1.27, Revision 2, and Review Procedures No. 2 Hydraulic Design Bases of Canals and No. 3 Hydraulic Design Bases of Reservoirs of NUREG-0800 SRP 2.4.8, Cooling Water Canals and Reservoirs, including:

Erosion and sedimentation during floods may lead to loss of functionality of the UHS canals and the UHS in general; and The volume of liquid water stored in a reservoir that comprises part of the ultimate heat sink should be sufficient to meet all safety-related water-supply requirements after accounting for loss in storage capacity due to seepage, sedimentation, evaporation, ice-sheet formation, and other causes.

It was noted that the review of the history associated with the BRW UHS, suggested that the nonconforming conditions of the UHS as reflected in the licensees letter dated August 24, 2015 [Reference 15], would have been identified through the current requirement for soundings of the UHS via SR 3.7.9.3.

The NRC staff requested that the licensee provide a description of how its implementation of the TS satisfies the guidance in the above cited excerpts of RG 1.27 and NUREG-0800 SRP 2.4.8.

In its letter dated March 9, 2020, the licensee responded in part:

The Essential Service Cooling Pond (ESCP) is a Category I, safety-related structure required to retain structural integrity to support an adequate volume of cooling water for safety related systems during design basis events. As such, the ESCP is included in the Braidwood Structures Monitoring Program.

The Structures Monitoring Program credits the work done in Surveillance procedure BwVSR 3.7.9.3. This procedure is performed on an 18-month frequency. The procedure verifies the bottom elevation of the ESCP is 584 ft or below in support of Technical Specifications Surveillance Requirement SR 3.7.9.3 (verify the bottom elevation of the Ultimate Heat Sink (UHS)).

Procedure BwVSR 3.7.9.3 performs a hydrographic survey of the ESCP. The physical contours and elevations of the cooling pond excavation under water (bottom surface, top banks and slopes) are surveyed using sonar technology.

The resulting pond volume, based on the surveyed data (Depth and Surface areas), is also determined. Changes in the hydrography would impact the volume of the pond which is proposed as the acceptance criteria for the Technical Specification Surveillance. This procedure is used to validate the ESCP contains the water volume that supports the Design Basis Analysis and meets regulatory requirements (30 days supply in accordance with Regulatory Guide 1.27).

The current surveillance procedure includes acceptance criteria for the elevation of the bottom of the ESCP (584 ft or below), the elevation of the top banks of the ESCP (590 ft or above) and the storage capacity of the ESCP (555.8 acre-ft or greater). This procedure will continue to be used in support of Surveillance Requirement 3.7.9.3 and in support of Structures Monitoring requirements. The elevation of the bottom surface of the ESCP will continue to be verified in the procedure; it will no longer be acceptance criteria. It will be noted in the procedure that any adverse trends in the bottom elevation shall be entered in the Corrective Action Program and addressed accordingly.

The current surveillance procedure has been effective in the identification of adverse conditions in the physical characteristics of the ESCP. In 2014, the elevation on a section of the ESCP East banks was found to be below 590 ft (ADAMS document ML14231A902) [Reference 4]. This condition has been corrected.

The method that is used to determine the elevation of the bottom of the ESCP has an uncertainty value of 0.17 ft. This uncertainty is added to the measured bottom elevation. The ESCP volume is calculated using the adjusted bottom elevation.

The design basis analysis ATD-0109, "Thermal Performance of Ultimate Heat Sink During Postulated Loss of Coolant Accident," (Attachment 5 of ML14231A902) for the UHS maximum post-accident temperature establishes the current licensing basis for the UHS contained gross and effective water volume.

The required ESCP contained gross volume is 555.8 acre-ft with the water level at the 590 ft elevation and the bottom elevation at 584 ft. This volume is adjusted in ATD-0109 using the ESCP effectiveness to calculate the effective water volume of 457.4 acre-ft that is used for the temperature analysis. The ESCP gross values from the design basis analysis is shown in UFSAR Figure 2.4-46A.

UFSAR Figure 9.2.8, which is referenced in Braidwood UFSAR Section 9.2.5, shows UHS volume and area based on the original design of the UHS.

Therefore, Braidwood's ESCP meets the requirement of Regulatory Guide 1.27 and NUREG0800 Standard Review Plan 2.4.8.

As part of the implementation actions for this License Amendment Request, the information shown in the UFSAR figures 2.4-46A will be enhanced by adding a table with specific values as given in design analysis ATD-0109. UFSAR Section 9.2-5 will also be revised to reference UFSAR Section 2.4 for information on the design basis of the ESCP.

The Surveillance for the volume of the ESCP will continue to be performed on a frequency of 18 months. This is the current frequency for Surveillance Requirement 3.7.9.3. This frequency is based on Engineering Judgement and the likelihood that any geologic or natural event that significantly altered the topography of the UHS as to affect the contained volume in a shorter period would be identified by other means. This frequency has been in effect since original plant licensing. This frequency is supported by the as-found ESCP survey results that are reviewed to ensure the 18-month frequency is still appropriate.

The NRC staff noted the initial frequency of the proposed SR and determined the SR will continue to provide assurance that the necessary quality of UHS is maintained, that facility operation will be within safety limits, and that the LCO will be met.

Based on the foregoing analysis and the supplemental information provided in the licensees letter dated March 9, 2020, the NRC staff concludes that SR 3.7.9.3, as amended by the proposed change, will continue to satisfy the requirements of 10 CFR 50.36(c)(3) and GDC 2, GDC 5, GDC 44, GDC 45, and GDC 46, and is, therefore, acceptable.

3.2 Summary The current SR 3.7.9.3 criteria would identify that, if the bottom elevation is determined to be above elevation 584 feet, the UHS is inoperable even if the volume meets the minimum value assumed in the design basis analysis.

Current TS SR 3.7.9.3 Verify bottom level of UHS is 584 ft MSL.

Revised TS Surveillance 3.7.9.3 Verify UHS contains a water volume of 555.8 acre-feet.

The Frequency for this SR will remain unchanged and reads In accordance with the Surveillance Frequency Control Program.

Based on its technical review discussed in Section 3.1 above, the NRC staff finds that the proposed TS change more accurately reflects the requirements of the design bases by requiring a volume-based inventory validation. Additionally, a volume-based acceptance criterion eliminates impact from variations in bottom elevation measurement. The proposed change has no impact on plant operation, nuclear safety, or the health and safety of the public because it does not change the required basis (minimum inventory). The NRC staff also finds that 10 CFR 50.36(c)(2) and 10 CFR 50.36(c)(3) are met because the UHS will be operable with a UHS gross water volume of 555.8 acre-feet. Based on the above, the NRC staff determined that GDC 2, GDC 5, GDC 44, GDC 45, and GDC 46, are met. The NRC staff, therefore, concludes that the revised TS SR is acceptable.

4.0 STATE CONSULTATION

In accordance with the Commissions regulations, the Illinois State official was notified of the proposed issuance of the amendment on April 14, 2020. The State official had no comments.

5.0 ENVIRONMENTAL CONSIDERATION

The amendments change a requirement with respect to installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20 and change surveillance requirements. The NRC staff has determined that the amendments involve no significant increase in the amounts, and no significant change in the types, of any effluents that may be released offsite, and that there is no significant increase in individual or cumulative occupational radiation exposure. The Commission has previously issued a proposed finding that the amendments involve no significant hazards consideration (84 FR 68952, December 17, 2019), and there has been no public comment on such finding. Accordingly, the amendment meets the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9). Pursuant to 10 CFR 51.22(b), no environmental impact statement or environmental assessment need be prepared in connection with the issuance of the amendment.

6.0 CONCLUSION

The Commission has concluded, based on the considerations discussed above, that: (1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, (2) there is reasonable assurance that such activities will be conducted in compliance with the Commission's regulations, and (3) the issuance of the amendment will not be inimical to the common defense and security or to the health and safety of the public.

7.0 REFERENCES

1.

Exelon Generation Company, LLC, (EGC) Letter (Serial No. RS-19-082) to NRC dated September 11, 2019; License Amendment Request to Revise Technical Specifications 3.7.9, Ultimate Heat Sink (UHS); Braidwood Station, Units 1 and 2; NRC Docket Nos.

STN 50-456 and STN 50-457; Renewed Facility Operating License Nos. NPF-72 and NPF-77; (EPID: L-2019-LLA-0210) [ADAMS Accession No. ML19254D105].

2.

Exelon Generation Company, LLC, (EGC) Letter (Serial No. RS-20-022) to NRC dated March 9, 2020; Response to Request for Additional Information Regarding License Amendment Request to Revise Braidwood Station Technical Specifications 3.7.9, "Ultimate Heat Sink (UHS)"; Braidwood Station, Units 1 and 2; NRC Docket Nos. STN 50-456 and STN 50-457; Renewed Facility Operating License Nos. NPF-72 and NPF-77; (EPID: L-2019-LLA-0210) [ADAMS Accession No. ML20071E921].

3.

US NRC Regulatory Guide 1.27 Revision 2; Ultimate Heat Sink For Nuclear Power Plants, January 1976 [ADAMS Accession No. ML003739969].

4.

Exelon Generation Company, LLC, (EGC) Letter (Serial No. RS-14-193) to NRC dated August 19, 2014; Request for a License Amendment to Braidwood Station, Units 1 and 2, Technical Specification 3.7.9, "Ultimate Heat Sink"; Braidwood Station, Units 1 and 2; Facility Operating License Nos. NPF-72 and NPF-77; NRC Docket Nos. STN 50-456 and STN 50-457; [ADAMS Accession No. ML14231A902].

5.

Exelon Generation Company, LLC, (EGC) Letter (Serial No. RS-15-129) to NRC dated April 30, 2015; Response to Request for Additional Information Regarding Request for a License Amendment to Braidwood Station, Units 1 and 2, Technical Specification 3.7.9, "Ultimate Heat Sink"; Braidwood Station, Units 1 and 2; Facility Operating License Nos.

NPF-72 and NPF-77; NRC Docket Nos. 50-456 and 50-457; [ADAMS Accession No. ML15120A396].

6.

Exelon Generation Company, LLC, (EGC) Letter (Serial No. RS-15-231) to NRC dated August 24, 2015; Supplemental Information in Support of Request for a License Amendment to Braidwood Station, Units 1 and 2, Technical Specification 3.7.9, "Ultimate Heat Sink"; Braidwood Station, Units 1 and 2; Facility Operating License Nos. NPF-72 and NPF-77; NRC Docket Nos. 50-456 and 50-457 [ADAMS Accession No. ML15236A144].

7.

NUREG-800 U.S. Nuclear Regulatory Commission Standard Review Plan 2.4.8 Cooling Water Canals and Reservoirs. [ADAMS Accession No. ML070730431].

8.

NUREG-800 U.S. Nuclear Regulatory Commission Standard Review Plan 9.2.5 Ultimate Heat Sink; Revision 3-March 2007 [ADAMS Accession No. ML070550048].

9.

NUREG-1431 Revision 4, Volume 1; Standard Technical Specifications - Westinghouse Plants: Specifications Published April 2012 [ADAMS Accession No. ML12100A222].

10.

NUREG-1431 Revision 4, Volume 2; Standard Technical Specifications - Westinghouse Plants: Bases; Published April 2012 [ADAMS Accession No. ML12100A228].

11.

NRC Letter to Entergy Operations, Inc; Arkansas Nuclear One, Units 1 And 2 -

Issuance of Amendment Nos. 170 And 153 To Facility Operating License Nos. DPR-51 and NPF Arkansas Nuclear One, Units 1 and 2 (TAC Nos. M87145 and M87146);

November 2, 1993 [ADAMS Accession No. ML021260265].

12.

Braidwood Full Conversion to ITS and ITS Bases, Attachment C-2; Dated December 22, 1998; [ADAMS Accession No. ML11223A306].

13.

NRC Letter to Exelon Generation Company, LLC dated July 26, 2016; Braidwood Station, Units 1 And 2 - Issuance of Amendments Re: Ultimate Heat Sink Temperature Increase (CAC Nos. MF4671 and MF4672); Docket Nos. STN 50-456 and STN 50-457

[ADAMS Accession No. ML16133A438].

14.

Email from J. Wiebe (U.S. Nuclear Regulatory Commission) to L. Zurawski; (Exelon Generation Company, LLC), RAls for L-2019-LLA-0201 - Braidwood, Units 1 and 2, LAR to Revise TS 3.7.9, Ultimate Heat Sink," dated January 23, 2020 [ADAMS Accession No. ML20023A081].

15.

Exelon Generation Company, LLC, (EGC) Letter (Serial No. RS-15-231) to NRC dated August 24, 2015; Supplemental Information in Support of Request for a License Amendment to Braidwood Station, Units 1 and 2, Technical Specification 3.7.9, "Ultimate Heat Sink"; NRC Docket Nos. STN 50-456 and STN 50-457; Renewed Facility Operating License Nos. NPF-72 and NPF-77 [ADAMS Accession No. ML15236A144].

Principal Contributor: D. Nold Date of Issuance: June 9, 2020

SUBJECT:

BRAIDWOOD STATION, UNITS 1 AND 2, - ISSUANCE OF AMENDMENTS NOS. 210 RE: REVISION OF TECHNICAL SPECIFICATIONS FOR THE ULTIMATE HEAT SINK (EPID L-2019-LLA-0201) DATED JUNE 9, 2020 DISTRIBUTION:

PUBLIC PM File Copy RidsNrrDssStsb Resource RidsRgn3MailCenter Resource RidsNrrDorlLpl3 Resource RidsNrrLASRohrer Resource RidsNrrPMBraidwood Resource RidsACRS_MailCTR Resource RidsNrrDssScpb Resource ADAMS Accession No.: ML20118C429

• via e-mail OFFICE NRR/DORL/LPL3/PM NRR/DORL/LPL3/LA NRR/DSS/STSB/BC NRR/DSS/SCPB/BC NAME JWiebe SRohrer VCusumano*

BWittick*

DATE 04/22/2020 04/28/2020 04/21/2020 04/02/2020 OFFICE NRR/DEX/EMIB/BC(A) OGC NRR/DORL/LPL3/BC NRR/DORL/LPL3/PM NAME DScarbrough*

STurk* NLO w/rev NSalgado*

JWiebe DATE 06/01/2020 05/29/2020 06/09/2020 06/09/2020