RS-20-022, Response to Request for Additional Information Regarding License Amendment Request to Revise Braidwood Station Technical Specifications 3.7.9, Ultimate Heat Sink (Uhs)

Response to Request for Additional Information Regarding License Amendment Request to Revise Braidwood Station Technical Specifications 3.7.9, Ultimate Heat Sink (Uhs)

ML20071E912
Person / Time
Site:	Braidwood
Issue date:	03/09/2020
From:	Demetrius Murray Exelon Generation Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
Shared Package
ML20071e921	List: RS-20-022, Response to Request for Additional Information Regarding License Amendment Request to Revise Braidwood Station Technical Specifications 3.7.9, Ultimate Heat Sink (Uhs)
References
RS-20-022
Download: ML20071E912 (11)

Text

PROPRIETARY INFORMATION -WITHHOLD UNDER 10 CFR 2.390

. **r RS-20-022 March 9, 2020 4300 Winfield Road Warrenville, IL 60555 630 657 2000 Office 10 CFR 50.90 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Braidwood Station, Units 1 and 2 Renewed Facility Operating License Nos. NPF-72 and NPF-77 NRC Docket Nos. STN 50-456 and STN 50-457

Subject:

Response to Request for Additional Information Regarding License Amendment Request to Revise Braidwood Station Technical Specifications 3. 7.9, "Ultimate Heat Sink (UHS)"

References:

1) Letter from D. Murray (Exelon Generation Company, LLC) to U.S. Nuclear Regulatory Commission, "License Amendment Request to Revise Technical Specifications 3.7.9, 'Ultimate Heat Sink (UHS),"' dated September 11, 2019 (ADAMS Accession No. ML19254D105)

2) 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)

In Exelon Generation Company, LLC (EGC) letter dated September 11, 2019 (Reference 1 ), EGC requested an amendment to the Renewed Facility Operating License Nos. NPF-72 and NPF-77 for Braidwood Station, Units 1 and 2 (Braidwood). The proposed amendment would revise the ultimate heat sink inventory verification from a level-based verification to a volume-based verification.

In NRC email dated January 23, 2020 (Reference 2), the NRC determined that additional information is needed to complete its review. As discussed during the clarification call held with the NRC on January 30, 2020, the response to the request for additional information (RAI) is requested within 45 days of the clarification call (i.e., by March 14, 2020). Additionally, Question 3 does not require a response as discussed during the clarification call. The attachments to this letter provide the requested information.

EGC has reviewed the information supporting the no significant hazards consideration and the environmental consideration that was previously provided to the NRC in Attachment 1 of the Reference 1 letter. The additional information provided in this submittal does not affect the conclusion that the proposed license amendment does not involve a significant hazards Attachments 3 and 4 contain Proprietary Information.

When separated from Attachments 3 and 4, this document is decontrolled.

U.S. Nuclear Regulatory Commission March 9, 2020 Page 2 consideration. This additional information also does not affect the conclusion that there is no need for an environmental assessment to be prepared in support of the proposed amendment.

Attachments 3 and 4 are proprietary versions of surveillance procedure BwVSR 3.7.9.3, "Braidwood Cooling Lake Hydrographic Survey," and Work Order (WO) 4720132 - Braidwood Cooling Lake Hydrographic Survey. Attachments 3 and 4 contain information proprietary to EGC. EGC requests that the contents of Attachments 3 and 4 be withheld from public disclosure in accordance with 10 CFR 2.390(a)(4).

This letter contains no regulatory commitments. Should you have any questions concerning this submittal, please contact Ms. Lisa Zurawski at (630) 657-2816.

I declare under penalty of perjury that the foregoing is true and correct. Executed on the 9th day of March 2020.

Dwi Murray Sr. Manager - Licensing Exelon Generation Company, LLC Attachments:

1) Response to Request for Additional Information

2) Affidavit of Withholding

3) Proprietary BwVSR 3.7.9.3, "Braidwood Cooling Lake Hydrographic Survey"

4) Proprietary WO 4720132 - Braidwood Cooling Lake Hydrographic Survey cc:

NRC Regional Administrator - Region Ill NRC Senior Resident Inspector - Braidwood Station NRC Project Manager, NRR - Braidwood Station

ATTACHMENT 1 Response to Request for Additional Information

ATTACHMENT 1 Response to Request for Additional Information By letter dated September 11, 2019, (Reference 1) Exelon Generation Company, LLC (EGC) requested an amendment to the Renewed Facility Operating License Nos. NPF-72 and NPF-77 for Braidwood Station, Units 1 and 2. The proposed amendment would revise the ultimate heat sink inventory verification from a level-based verification to a volume-based verification.

By email dated January 23, 2020 (Reference 2), the NRC determined that additional information is needed to complete its review. This attachment provides the response to the requested information.

References:

1)

Letter from D. Murray (Exelon Generation Company, LLC) to U.S. Nuclear Regulatory Commission, "License Amendment Request to Revise Technical Specifications 3.7.9,

'Ultimate Heat Sink (UHS),"' dated September 11, 2019 (ADAMS Accession No. ML192540105)

2)

Email from J. Wiebe (U.S. Nuclear Regulatory Commission) to L. M. 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)

Regulatory Requirement:

10 CFR 50.36(c)(3) requires TS to include items in the category of surveillance requirements (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 LCO will be met.

Discussion:

Appendix A to the Braidwood Station Unit 1 and Unit 2 UFSAR indicates that the licensee meets all objectives set forth in Regulatory Guide 1.27 Revision 2, "Ultimate Heat Sink For Nuclear Power Plants." No exceptions to RG 1.27, Revision 2 were noted.

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 (Ref. 6) 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.

Regulatory Position C.4 for Regulatory Guide 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 Page 1 of 5

ATTACHMENT 1 Response to Request for Additional Information of the ultimate heat sink or the plant temporarily does not satisfy regulatory positions 1 and 3 during operation.

NUREG-0800 Standard Review Plan, Revision 2, dated July 1981, 2.4.8 Cooling Water Canals and Reservoirs excerpts from "Acceptance Criteria" read:

To meet the requirements of 10 CFR Part 50, §50.55a, GDC 2, GDC 44, and 10 CFR Part 100 as they relate to cooling water canals and reservoirs, the following specific criteria are used:

1.

Where canals comprise a part of the ultimate heat sink, Regulatory Guide 1.27 is used as a basis for the adequacy of design criteria and provisions.

2.g.

If reservoirs comprise a part of the ultimate heat sink, Regulatory Guide 1.27 is used as a basis for judging the adequacy of the design criteria and provisions.

The licensee stated that to satisfy the current requirements of Braidwood Station Unit 1 and Unit 2, SR 3.7.9.3 a survey of the essential service cooling pond (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 utilizing ProcedLJre BwVSR 3.7.9.3, "Braidwood Cooling Lake Hydrographic Survey." This procedure also validates 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 staff review of the history associated with the Braidwood Station UHS, suggests that the non-conforming conditions of the UHS as reflected in Exelon Generation Company, LLC, (EGC) Letter (Serial No. RS-15-231) dated August 24, 2015 (ADAMS Accession No. ML15236A144) would have been identified through the current requirement for soundings of the UHS via SR 3.7.9.3.

The staff notes that the frequency of performance was 18 months for SR 3. 7.9.3 after the Braidwood Stations full conversion to improved Technical Specifications per NUREG-1431 per Amendment 98 in December 1998 (ADAMS Accession No. ML11223A306).

The staff also notes that its review of the docketed information associated with the review and approval of Amendment Number 189 for Braidwood Station Units 1 & 2 indicates that there is both a gross and effective value for the required water volume contained in the UHS. EGC's response to NRC RAl-5 related to Amendment Number 189 (Attachment 1 to ADAMS Accession No. ML15120A396) identifies the value of 555.8 acre-feet that is proposed in EGC's letter dated September 11, 2019, for inclusion within SR 3. 7.9.3 as the gross value.

The effective area and volume were calculated to be 82.3% of the gross value per Table 1 of. The Braidwood Updated Final Safety Analysis Report (UFSAR), Revision 17, Section 9.2.5, "Ultimate Heat Sink," Page 9.2-43 (ADAMS Accession No. ML19170A384),

provides insufficient information with respect to interpretation of the value proposed for inclusion in SR 3. 7.9.3. The marked-up TS Bases page B 3. 7.9-4 as provided with the LAR does not provide information to clarify the proposed SR 3. 7.9.3.

Page 2 of 5

ATTACHMENT 1 Response to Request for Additional Information Request for Additional Information:

Question 1:

Describe how the attributes of Reference 5 to EGC's letter dated September 11, 2019 (BwVSR 3.7.9.3, "Braidwood Cooling Lake Hydrographic Survey," Revision 7) satisfy the guidance in the above cited excerpts of Regulatory Guide 1.27 and NUREG-0800 Standard Review Plan 2.4.8.

Alternatively, describe how Reference 5 provides appropriate alternatives and assures the minimum required water volume and monitoring of water controlling structures are met. Include a discussion of how the uncertainty of the survey measurement and related calculations is accounted for.

Response to Question 1 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 (Attachment 4). 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). This condition has been corrected. As documented in Section 9.2.5.1 of the Braidwood Updated Final Safety Analysis Report (UFSAR), a sheet pile wall has been added to the East Side of the pond to restore the upper elevation to the required 590 ft (ADAMS document ML 1523336A144); the top of the sheet wall extends about one (1) ft above the 590 ft elevation. The bottom of the handling Page 3 of 5

ATTACHMENT 1 Response to Request for Additional Information holes on each sheet pile section represents the lowest elevation of unsealed areas of the sheet pile wall. The added wall effectively raises the operating level of the ESCP to the elevation of the bottom of the handling holes.

The method that is used to determine the elevation of the bottom of the ESCP has an uncertainty value of 0.17 ft (Reference Vendor Report in Attachment 4). 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 NUREG-0800 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.

Question 2:

Provide the initial frequency of performance for the proposed SR 3. 7.9.3 and its basis.

Response to Question 2:

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.

Page 4 of 5

ATTACHMENT 1 Response to Request for Additional Information Question 3:

Proposed SR 3.7.9.3 reads "Verify UHS contains a water volume of?:. 555.8 acre-feet."

This is a gross value as identified above. Clarify the current licensing basis (CLB) requirements for Braidwood Station gross and effective water volume of the UHS.

Response to Question 3:

As discussed during the clarification call held on January 30, 2020, Question 3 no longer requires a response.

Page 5 of 5

ATTACHMENT 2 Affidavit of Withholding Affidavit of Withholding I, Dwi Murray, Sr. Manager - Licensing, Exelon Generation Company, LLC (EGC), do hereby affirm and state:

1. I am Sr. Manager - Licensing for EGC and I am authorized to execute this affidavit on behalf of EGC.

2. I am further authorized to review the documents sought to be withheld from public disclosure in connection with submittals to the Nuclear Regulatory Commission (NRC).

3. I am also authorized to apply to the NRC for the withholding of the aforementioned documents from public disclosure under 10 CFR 2.390(a)(4) and 9.17(a)(4) on the grounds that the documents contain privileged or confidential or proprietary commercial information. The documents EGC seeks to withhold from public disclosure have been marked "Proprietary."

4. On behalf of EGC, I request that the following document marked by EGC as "Proprietary" be withheld, in its entirety, by the NRC from public disclosure:

Attachments 3 and 4 of letter from EGC to NRC, Response to Request for Additional Information Regarding License Amendment Request to Revise Braidwood Station Technical Specifications 3.7.9, "Ultimate Heat Sink (UHS)."

5. In making this application for withholding of proprietary and confidential information of which EGC is the owner, EGC relies on 10 CFR 2.390(a)(4) and 10 CFR 9.17(a)(4). The proprietary documents contain privileged or confidential or proprietary commercial information.

6. The proprietary information should be withheld from disclosure by the NRC pursuant to the policy reflected in 10 CFR 2.390(a)(4), and for the following reasons to be considered pursuant to 10 CFR 2.390(b)(4):

i.

The documents are each either a policy, procedure, process, technical requirements document, or other document that forms part of the Exelon Nuclear Management Model (ENMM).

ii. The ENMM is a set of confidential policies and procedures that enable EGC to consistently achieve excellence in all key dimensions of its business. It documents proven ways of achieving excellence and defines how EGC executes and manages performance and assesses results. EGC expended significant resources, in terms of time and money, to develop, implement, and update the ENMM. EGC derives economic benefit from the ENMM in terms of increased efficiency and improved results as well as revenue generated from EGC's sale or licensing of the ENMM.

iii. EGC is providing the NRC with the documents and information in confidence.

iv. The documents are now, and have been, held in confidence by EGC. EGC does not customarily make these documents available to the public. EGC has not authorized making the documents available through public sources.

v. Economic harm would come to EGC with the publication of the individual documents that form the ENMM, as it would reduce or eliminate the need for any third party to purchase or license the ENMM from EGC, and would reduce the competitive position of EGC based on the benefits that the ENMM provides to EGC in the management of its own nuclear plants. The ENMM is considered by EGC to be a very valuable part of our intellectual property and it would be very difficult, costly and time-consuming for another to duplicate it without access to these documents.

7. EGC requests that each of the documents listed above in paragraph 4 be withheld from public disclosure based on the reasons stated above in paragraph 6.i. through 6.v.

Page 1 of 2 Affidavit of Withholding I declare under penalty of perjury that the foregoing affidavit and statements therein are true and correct to the best of my knowledge, information, and belief.

Dwi Murray Sr. Manager - Licensing Exelon Generation Company, LLC Date: March 9, 2020 Page 2 of 2