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| | number = ML17163A422 | | | number = ML17163A422 |
| | issue date = 06/14/2017 | | | issue date = 06/14/2017 |
| | title = LaSalle County Station, Units 1 and 2, Request for Additional Information Regarding License Amendment Request to Revise Suppression Pool Swell Design Analysis (CAC Nos. MF8702 and MF8703) | | | title = Request for Additional Information Regarding License Amendment Request to Revise Suppression Pool Swell Design Analysis |
| | author name = Vaidya B K | | | author name = Vaidya B |
| | author affiliation = NRC/NRR/DORL/LPLIII | | | author affiliation = NRC/NRR/DORL/LPLIII |
| | addressee name = Hanson B C | | | addressee name = Hanson B |
| | addressee affiliation = Exelon Generation Co, LLC | | | addressee affiliation = Exelon Generation Co, LLC |
| | docket = 05000373, 05000374 | | | docket = 05000373, 05000374 |
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| =Text= | | =Text= |
| {{#Wiki_filter:UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 June 14, 2017 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 | | {{#Wiki_filter:UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 June 14, 2017 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 |
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| ==SUBJECT:== | | ==SUBJECT:== |
| LASALLE COUNTY STATION, UNITS 1 AND 2, REQUEST FOR ADDITIONAL INFORMATION REGARDING LICENSE AMENDMENT REQUEST TO REVISE SUPPRESSION POOL SWELL DESIGN ANALYSIS (GAG NOS, MF8702 AND MF8703) | | LASALLE COUNTY STATION, UNITS 1 AND 2, REQUEST FOR ADDITIONAL INFORMATION REGARDING LICENSE AMENDMENT REQUEST TO REVISE SUPPRESSION POOL SWELL DESIGN ANALYSIS (GAG NOS, MF8702 AND MF8703) |
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| ==Dear Mr. Hanson:== | | ==Dear Mr. Hanson:== |
| By letter dated October 27, 2016, Exelon Generation Company, LLC (the licensee) submitted an amendment request for the LaSalle County Station, Units 1 and 2. The proposed amendment would revise the suppression pool swell analysis for a design basis loss-of-coolant accident (LOCA). The licensee stated that the changes are necessary because the current analysis determining the suppression pool swell response to a LOCA was determined to be conservative. The U.S. Nuclear Regulatory Commission (NRG) staff reviewed your application and has determined that additional information is required to complete the review. The specific information requested is addressed in the enclosure to this letter. During the telephone call on June 13, 2017, between the NRG staff and the licensee for clarification of these requests for additional information, it was agreed that the licensee will provide the responses no later than July 31, 2017. The NRG staff considers that timely responses to requests for additional information help ensure sufficient time is available for staff review and contribute toward the NRC's goal of efficient and effective use of staff resources. If you have any questions, please call me at 301-415-3308. Docket Nos. 50-373 and 50-374 | | |
| | By letter dated October 27, 2016, Exelon Generation Company, LLC (the licensee) submitted an amendment request for the LaSalle County Station, Units 1 and 2. The proposed amendment would revise the suppression pool swell analysis for a design basis loss-of-coolant accident (LOCA). The licensee stated that the changes are necessary because the current analysis determining the suppression pool swell response to a LOCA was determined to be non-conservative. |
| | The U.S. Nuclear Regulatory Commission (NRG) staff reviewed your application and has determined that additional information is required to complete the review. The specific information requested is addressed in the enclosure to this letter. During the telephone call on June 13, 2017, between the NRG staff and the licensee for clarification of these requests for additional information, it was agreed that the licensee will provide the responses no later than July 31, 2017. |
| | The NRG staff considers that timely responses to requests for additional information help ensure sufficient time is available for staff review and contribute toward the NRC's goal of efficient and effective use of staff resources. |
| | If you have any questions, please call me at 301-415-3308. |
| | Sincerely, , |
| | RM:~.J1(' |
| | ,}1,' 2---- |
| | ~ ** |
| | Bhalchandra Vaidya, Project Manager Plant Licensing Branch Ill Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-373 and 50-374 |
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| ==Enclosure:== | | ==Enclosure:== |
| As stated Sincerely, , ,}1,' 2----** Bhalchandra Vaidya, Project Manager Plant Licensing Branch Ill Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation | | As stated |
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| | ML17163A422 *no substantial chanaes from email OFFICE LPL3/PM LPL3/LA SRXB/BC LPL3/BC LPL3/PM NAME BVaidya SRohrer EOesterle* DWrona BVaidya DATE 06/14/17 06/14/17 05/31/17 06/14/17 06/14/17 REQUEST FOR ADDITIONAL INFORMATION REGARDING LICENSE AMENDMENT REQUEST FOR REVISIONS TO SUPPRESSION POOL SWELL DESIGN ANALYSIS - |
| | LA SALLE COUNTY STATION (LSCS), UNITS 1AND2 DOCKET NOS. 50-373 AND 50-374 (CAC NOS. MF8702 AND MF8703) |
| | The U.S. Nuclear Regulatory Commission (NRG) staff has reviewed the information provided in the license amendment request and determined that additional information is required in order to complete its review. The NRC staff requests responses to the request for additional information (RAI) to evaluate compliance with the applicable regulatory requirements and criteria in Title 10 of the Code of Federal Regulations (10 CFR) Part 50, Appendix A, General Design Criteria (GDC) 4 and GDC 50, Standard Review Plan, 6.2.1.1.C, NUREG-0487, Supplement 2, "MARK ll Containment Lead Plant Program Load Evaluation and Acceptance Criteria," published February 1981, and NUREG-0808, "MARK II Containment Program Load Evaluation and Acceptance Criteria," Appendix A, published August 1981. The RAls are provided below. |
| | SRXB- RAI 1 Reference 1, Table 5, Attachment 1, second column of item 4 states: |
| | TRACG represents a change in methodology, it does not change conseNatisms. |
| | Please provide reasons why the conservatism is not changed in using TRACG [GEH Proprietary Version of the Transient Reactor Analysis Code (TRAC), GEH Computer Code for Best Estimate BWR Transient and Accident Analysis Calculations] which is the best-estimate methodology compared to using the current conservative M3CPT [Mark Ill Containment Pressure and Temperature; GEH Computer Code M3CPT for Short-term DBA-LOCA {loss-of-coolant accident} Containment Response Analysis] methodology for mass and energy release analysis for a design basis accident (DBA) LOCA. |
| | SXRB -RAI 2 Reference 1, Section 4.4, Attachment 1, stated all systems, structures, and components (SSCs) affected were not assessed, instead a representative sample of low margin SSC were selected. Provide the following information: |
| | (a) Further explanation on the basis of selection of the SSCs (i.e., low margin of which parameter) for analyzing structural impacts, Enclosure |
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| | (b) Specify the systems to which the piping, associated supports and penetrations that are analyzed belong to, and any special reasons for selecting these systems. |
| | (c) \What is total number of SSCs that are affected and how many were selected for structural re-analysis, (d) Maximum and minimum value of percentage in stress margins in the SSCs selected for structural analysis, (e) Revised (new) maximum and minimum percentage in the stress margin in the SSCs structurally analyzed, |
| | {f) Justification as to why the SSCs not structurally analyzed will have adequate stress margin. |
| | SXRB-RAI 3 Reference 1, item 2 of Table 6 in Attachment 1, Section 6.2.2, and Tables 6-1 through 6-4 in Attachment (a) Explain how the 0.7 ft [toot] adder to the PICSM [General Electric-Hitachi pool swell response code] predicted pool swell height which accounts tor the difference between initial pre-LOCA elevation and initial PICSM elevation which corresponds to the elevation after vent clearing was determined. |
| | (b) ln Tables 6-1 through 6-4, explain if the 0.7 ft adder is included in the data for pool swell elevation above initial elevation. |
| | SXRB- RAI 4 Reference 1, Note 3 in Table 4-1, Attachment 2. Explain the basis for selecting feedwater temperature reduction of 100 °F (degree Fahrenheit) from its normal operating temperature 428.5 °F at the current licensed thermal power. Provide justification that the 100 °F reduction is conservative. |
| | SXRB- RAI 5 Reference 1, Section 4.3.1, Attachment 2, states: |
| | Other plant performance improvement and equipment out of service options identified in Reference 1 [GE Hitachi Nuclear Energy, "Safety Analysis Report for LaSalle County Station Units 1 and 2 Thermal Power Optimization," NEDC-33485P, Revision 0, January 2010, ADAMS Accession No. ML100321327] have no effect on the RSLB |
| | [Recirculation Suction Line Break] mass and energy release analyses. The current analysis, therefore, continues to support all flexibility and equipment out of service options. |
| | Table in Section 1.3.2 of NEDC-33485P, Revision 0, shows several performance improvement and equipment out-of-service (OOS) features currently licensed at LSCS are acceptable at the thermal power optimization (TPO) reactor thermal power (RTP) level. Explain how it is |
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| | determined that these features have no effect on the RSLB Mass and Energy (M&E) release analysis. |
| | SXRB |
| | * RAI 6 Reference 1, assumption (ii), Section 6.1.1 in Attachment 2. The PICSM analysis for cases 3 and 4, assumes a constant value of steam/air ratio (air fraction = 0.61 as per Figure 7-1 in ) after the initial air in the downcomer vent is purged. The value assumed is at the time (0.87 seconds as per Figure 7-1 in Attachment 2) when all air in the downcomer vent is purged. Describe the analysis that resulted in the graph shown in Figure 7-1, uDrywell Air Fraction (Air Mass/(Air Mass+ Steam Mass))." |
| | SXRB-RAI 7 Reference 1, Section 6.1.1, Attachment 2, assumption 3, states: |
| | The mass flow rate of non-condensables into the bubble is calculated assuming adiabatic flow through a duct with friction. |
| | (a) Clarify which duct (i.e., downcomer vent or other) is meant to be feeding the non-condensables into the bubble. |
| | (b) What is the assumed value of frictional loss coefficient and how is it determined? |
| | (c) Justify the assumption of adiabatic flow with friction is conservative. |
| | SXRB-RAI 8 Reference 1, Section 6.1.1, Attachment 2, assumption 6, states: |
| | Following vent clearing, the water above the exit of the vent (equal to the initial vent submergence plus the pool displacement due to vent clearing) accelerates as a slug of constant thickness. |
| | The water column in the downcomer vent cleared during a LOCA is cylindrical in shape having its diameter same as the vent diameter and length equal to the length of the water column. Describe the geometric shape of the slug assumed in the above assumption and how its dimensions are determined from the dimensions of the initial water column in the vent. Provide the basis for assuming a constant thickness of the slug. |
| | SXRB -RAI 9 Reference 1, Section 6.1.1, Attachment 2, assumption 7, states: |
| | Frictional losses between the water and the confining walls are negligible. |
| | Describe which confining walls are referred to in the above assumption. |
| | SXRB - RAI 10 Reference 1, Section 6.1.1, Attachment 2, assumption 10, states: |
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| ML 17163A422 OFFICE LPL3/PM LPL3/LA NAME BVaidya SRohrer DATE 06/14/17 06/14/17 *no substantial chanaes from email SRXB/BC LPL3/BC LPL3/PM EOesterle* DWrona BVaidya 05/31/17 06/14/17 06/14/17 REQUEST FOR ADDITIONAL INFORMATION REGARDING LICENSE AMENDMENT REQUEST FOR REVISIONS TO SUPPRESSION POOL SWELL DESIGN ANALYSIS -LA SALLE COUNTY STATION (LSCS), UNITS 1AND2 DOCKET NOS. 50-373 AND 50-374 (CAC NOS. MF8702 AND MF8703) The U.S. Nuclear Regulatory Commission (NRG) staff has reviewed the information provided in the license amendment request and determined that additional information is required in order to complete its review. The NRC staff requests responses to the request for additional information (RAI) to evaluate compliance with the applicable regulatory requirements and criteria in Title 10 of the Code of Federal Regulations (10 CFR) Part 50, Appendix A, General Design Criteria (GDC) 4 and GDC 50, Standard Review Plan, 6.2.1.1.C, NUREG-0487, Supplement 2, "MARK ll Containment Lead Plant Program Load Evaluation and Acceptance Criteria," published February 1981, and NUREG-0808, "MARK II Containment Program Load Evaluation and Acceptance Criteria," Appendix A, published August 1981. The RAls are provided below. SRXB-RAI 1 Reference 1, Table 5, Attachment 1, second column of item 4 states: TRACG represents a change in methodology, it does not change conseNatisms. Please provide reasons why the conservatism is not changed in using TRACG [GEH Proprietary Version of the Transient Reactor Analysis Code (TRAC), GEH Computer Code for Best Estimate BWR Transient and Accident Analysis Calculations] which is the best-estimate methodology compared to using the current conservative M3CPT [Mark Ill Containment Pressure and Temperature; GEH Computer Code M3CPT for Short-term DBA-LOCA coolant accident} Containment Response Analysis] methodology for mass and energy release analysis for a design basis accident (DBA) LOCA. SXRB -RAI 2 Reference 1, Section 4.4, Attachment 1, stated all systems, structures, and components (SSCs) affected were not assessed, instead a representative sample of low margin SSC were selected. Provide the following information: (a) Further explanation on the basis of selection of the SSCs (i.e., low margin of which parameter) for analyzing structural impacts, Enclosure (b) Specify the systems to which the piping, associated supports and penetrations that are analyzed belong to, and any special reasons for selecting these systems. (c) \What is total number of SSCs that are affected and how many were selected for structural re-analysis, (d) Maximum and minimum value of percentage in stress margins in the SSCs selected for structural analysis, (e) Revised (new) maximum and minimum percentage in the stress margin in the SSCs structurally analyzed, {f) Justification as to why the SSCs not structurally analyzed will have adequate stress margin. SXRB-RAI 3 Reference 1, item 2 of Table 6 in Attachment 1, Section 6.2.2, and Tables 6-1 through 6-4 in Attachment (a) Explain how the 0.7 ft [toot] adder to the PICSM [General Electric-Hitachi pool swell response code] predicted pool swell height which accounts tor the difference between initial pre-LOCA elevation and initial PICSM elevation which corresponds to the elevation after vent clearing was determined. (b) ln Tables 6-1 through 6-4, explain if the 0.7 ft adder is included in the data for pool swell elevation above initial elevation. SXRB-RAI 4 Reference 1, Note 3 in Table 4-1, Attachment 2. Explain the basis for selecting feedwater temperature reduction of 100 °F (degree Fahrenheit) from its normal operating temperature 428.5 °F at the current licensed thermal power. Provide justification that the 100 °F reduction is conservative. SXRB-RAI 5 Reference 1, Section 4.3.1, Attachment 2, states: Other plant performance improvement and equipment out of service options identified in Reference 1 [GE Hitachi Nuclear Energy, "Safety Analysis Report for LaSalle County Station Units 1 and 2 Thermal Power Optimization," NEDC-33485P, Revision 0, January 2010, ADAMS Accession No. ML 100321327] have no effect on the RSLB [Recirculation Suction Line Break] mass and energy release analyses. The current analysis, therefore, continues to support all flexibility and equipment out of service options. Table in Section 1.3.2 of NEDC-33485P, Revision 0, shows several performance improvement and equipment out-of-service (OOS) features currently licensed at LSCS are acceptable at the thermal power optimization (TPO) reactor thermal power (RTP) level. Explain how it is determined that these features have no effect on the RSLB Mass and Energy (M&E) release analysis. SXRB
| | The air velocity in the OW [drywell} is sufficiently small so that static and stagnation conditions are equivalent. |
| * RAI 6 Reference 1, assumption (ii), Section 6.1.1 in Attachment 2. The PICSM analysis for cases 3 and 4, assumes a constant value of steam/air ratio (air fraction = 0.61 as per Figure 7 -1 in Attachment 2) after the initial air in the downcomer vent is purged. The value assumed is at the time (0.87 seconds as per Figure 7-1 in Attachment 2) when all air in the downcomer vent is purged. Describe the analysis that resulted in the graph shown in Figure 7-1, uDrywell Air Fraction (Air Mass/(Air Mass+ Steam Mass))." SXRB-RAI 7 Reference 1, Section 6.1.1, Attachment 2, assumption 3, states: The mass flow rate of non-condensables into the bubble is calculated assuming adiabatic flow through a duct with friction. (a) Clarify which duct (i.e., downcomer vent or other) is meant to be feeding the condensables into the bubble. (b) What is the assumed value of frictional loss coefficient and how is it determined? (c) Justify the assumption of adiabatic flow with friction is conservative. SXRB-RAI 8 Reference 1, Section 6.1.1, Attachment 2, assumption 6, states: Following vent clearing, the water above the exit of the vent (equal to the initial vent submergence plus the pool displacement due to vent clearing) accelerates as a slug of constant thickness. The water column in the downcomer vent cleared during a LOCA is cylindrical in shape having its diameter same as the vent diameter and length equal to the length of the water column. Describe the geometric shape of the slug assumed in the above assumption and how its dimensions are determined from the dimensions of the initial water column in the vent. Provide the basis for assuming a constant thickness of the slug. SXRB -RAI 9 Reference 1, Section 6.1.1, Attachment 2, assumption 7, states: Frictional losses between the water and the confining walls are negligible. Describe which confining walls are referred to in the above assumption. SXRB -RAI 10 Reference 1, Section 6.1.1, Attachment 2, assumption 10, states: The air velocity in the OW [drywell} is sufficiently small so that static and stagnation conditions are equivalent. Specify with justification at what time during the transient, the air velocity in the drywell is assumed sufficiently small so that its velocity head is negligible. SXRB -RAI 11 The drywell pressure response described in Reference 1, Section 5.0, Attachment 2, used TRACG for M&E analysis, and M3CPT code for drywell pressure analysis and the assumption and inputs listed in Section 5.1.1 and Appendix A, respectively. Provide the following information: (a) Computer codes used in the analysis of record (AOR) for calculation of "Pa (pressure absolute." (b) Differences in the inputs and assumptions for M&E and drywall pressure response between the AOR and the proposed analysis with justification in the inputs and assumptions for which the conservatism in the proposed analysis is reduced. (c) In case the peak drywell pressure calculated using the assumptions and inputs in the proposed analysis results in a greater value than its current Pa, please explain and justify why Pa is not being revised. SXRB -RAI 12 In Reference 1, Attachment 2, refer to Figures 5-1, 6-3, and 6-3A, (a) Figure 5-1; describe the analysis to which the graphs labelled "LSCS Design Calculation 3C7-1075-001" and "LAMB CLTP 100P 100F" belong. (b) Figures 6-3 and 6-3A; describe the analysis to which the graphs labelled "LSCS Design Calculation 3C7-1075-001 R6" belong. SXRB -RAI 13 In Reference 1, Attachment 2, refer to Figure 5-1. Provide reasons for the discontinuity (drastic reversal of slope) in the graph labelled "LSCS Design Calculation 3C7-1075-001," and why does it differ from other graphs shown in this figure, with respect to its reversal of slope after vent clearing. REFERENCES 1. Letter from Exelon Generation Company, LLC to NRC dated October 27, 2016, "License Amendment Request to Revise Suppression Pool Swell Design Analysis," (Agencywide Documents Access and Management System (ADAMS) Package Accession No. ML 16305A295).}}
| | Specify with justification at what time during the transient, the air velocity in the drywell is assumed sufficiently small so that its velocity head is negligible. |
| | SXRB - RAI 11 The drywell pressure response described in Reference 1, Section 5.0, Attachment 2, used TRACG for M&E analysis, and M3CPT code for drywell pressure analysis and the assumption and inputs listed in Section 5.1.1 and Appendix A, respectively. Provide the following information: |
| | (a) Computer codes used in the analysis of record (AOR) for calculation of "Pa (pressure absolute." |
| | (b) Differences in the inputs and assumptions for M&E and drywall pressure response between the AOR and the proposed analysis with justification in the inputs and assumptions for which the conservatism in the proposed analysis is reduced. |
| | (c) In case the peak drywell pressure calculated using the assumptions and inputs in the proposed analysis results in a greater value than its current Pa, please explain and justify why Pa is not being revised. |
| | SXRB - RAI 12 In Reference 1, Attachment 2, refer to Figures 5-1, 6-3, and 6-3A, (a) Figure 5-1; describe the analysis to which the graphs labelled "LSCS Design Calculation 3C7-1075-001" and "LAMB CLTP 100P 100F" belong. |
| | (b) Figures 6-3 and 6-3A; describe the analysis to which the graphs labelled "LSCS Design Calculation 3C7-1075-001 R6" belong. |
| | SXRB - RAI 13 In Reference 1, Attachment 2, refer to Figure 5-1. Provide reasons for the discontinuity (drastic reversal of slope) in the graph labelled "LSCS Design Calculation 3C7-1075-001," and why does it differ from other graphs shown in this figure, with respect to its reversal of slope after vent clearing. |
| | REFERENCES |
| | : 1. Letter from Exelon Generation Company, LLC to NRC dated October 27, 2016, "License Amendment Request to Revise Suppression Pool Swell Design Analysis," (Agencywide Documents Access and Management System (ADAMS) Package Accession No. ML16305A295).}} |
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Category:Letter
MONTHYEARIR 05000373/20240022024-08-13013 August 2024 County Station - Integrated Inspection Report 05000373/2024002 and 05000374/2024002 ML24222A6772024-08-0909 August 2024 Response to Request for Additional Information for Application to Revise Technical Specifications to Adopt TSTF-591-A, “Revise Risk Informed Completion Time (RICT) Program” Revision 0 and Revise 10 CFR 50.69 License Condition IR 05000373/20244202024-08-0505 August 2024 County Station - Security Baseline Inspection Report 05000373 2024420 and 05000374 2024420 ML24208A0962024-07-25025 July 2024 57243-EN 57243 - Rssc Wire & Cable LLC, Dba Marmon - Part 21 Notification RS-24-064, Nuclear Radiological Emergency Plan Document Revisions2024-06-28028 June 2024 Nuclear Radiological Emergency Plan Document Revisions ML24178A2522024-06-27027 June 2024 County Station – Acknowledgement of Response to NRC Inspection Report 05000373/2024001 and 05000374/2024001 and Disputed Non-Cited Violation RS-24-061, Constellation Energy Generation, LLC, Response to NRC Regulatory Issue Summary 2024-01, Preparation and Scheduling of Operator Licensing Examinations2024-06-14014 June 2024 Constellation Energy Generation, LLC, Response to NRC Regulatory Issue Summary 2024-01, Preparation and Scheduling of Operator Licensing Examinations IR 05000373/20240102024-05-29029 May 2024 County Station - Commercial Grade Dedication Inspection Report 05000373/2024010 and 05000374/2024010 ML24142A3352024-05-21021 May 2024 Quad Cities—Information Request to Support the NRC Annual Baseline Emergency Action Level and Emergency Plan Changes RS-24-055, 2023 Corporate Regulatory Commitment Change Summary Report2024-05-17017 May 2024 2023 Corporate Regulatory Commitment Change Summary Report IR 05000373/20240012024-05-13013 May 2024 County Station - Integrated Report 05000373/2024001 and 05000374/2024001 RS-24-038, Relief Request Concerning Extension of Permanent Relief from Ultrasonic Examination of Reactor Pressure Vessel Circumferential Shell Welds2024-05-0202 May 2024 Relief Request Concerning Extension of Permanent Relief from Ultrasonic Examination of Reactor Pressure Vessel Circumferential Shell Welds RS-24-041, Alternative Request to Utilize Code Case OMN-32, Alternative Requirements for Range and Accuracy of Pressure, Flow, and Differential Pressure Instruments Used in Pump Tests2024-04-30030 April 2024 Alternative Request to Utilize Code Case OMN-32, Alternative Requirements for Range and Accuracy of Pressure, Flow, and Differential Pressure Instruments Used in Pump Tests ML24108A1562024-04-15015 April 2024 Updated Final Safety Analysis Report (Ufsar), Revision 26 and Fire Protection Report (Fpr), Revision 11 IR 05000373/20230042024-01-24024 January 2024 County Station - Integrated Inspection Report 05000373/2023004 and 05000374/2023004 ML24024A1332024-01-24024 January 2024 Confirmation of Initial License Examination IR 05000373/20230122024-01-18018 January 2024 County Station - Biennial Problem Identification and Resolution Inspection Report 05000373/2023012 and 05000374/2023012 ML23354A2902024-01-0505 January 2024 Exemption from Select Requirements of 10 CFR Part 73 (EPID L-2023-LLE-0028 (Security Notifications, Reports, and Recordkeeping and Suspicious Activity Reporting)) ML23360A6082023-12-27027 December 2023 County Station Request for Information for NRC Commercial Grade Dedication Inspection: Inspection Report 05000373/2024010 and 05000374/2024010 ML23278A1292023-12-14014 December 2023 Units 1 & 2; Limerick, Units 1 & 2; Nine Mile Point, Units 1 & 2; and Peach Bottom, Units 2 & 3 -Revision to Approved Alternatives to Use Boiling Water Reactor Vessel and Internals Project Guidelines ML23305A1402023-12-13013 December 2023 Units 1 & 2; Nine Mile Point, Unit 2; Peach Bottom, Units 2 & 3; and Quad Cities, Units 1 and 2 - Issuance of Amendments to Adopt Traveler TSTF-580 RS-23-120, Supplemental Information Letter for Part 73 Exemption Request - Responses to Request for Confirmatory Information2023-11-10010 November 2023 Supplemental Information Letter for Part 73 Exemption Request - Responses to Request for Confirmatory Information ML23317A1192023-11-10010 November 2023 Constellation Energy Generation, LLC - 2023 Annual Report - Guarantees of Payment of Deferred Premiums IR 05000373/20230032023-11-0909 November 2023 County Station Integrated Inspection Report 05000373/2023003, 05000374/2023003, and 07200070/2023001 ML23286A2602023-11-0808 November 2023 Issuance of Amendment Nos. 260 and 245 to Renewed Facility Operating Licenses Relocation of Pressure and Temperature Limit Curves to the Pressure Temperature Report IR 05000373/20234012023-11-0707 November 2023 County Station Security Baseline Inspection Report 05000373/2023401 and 05000374/2023401 RS-23-103, Request for Exemption from Enhanced Weapons, Firearms Background Checks, and Security Event Notifications Implementation2023-10-13013 October 2023 Request for Exemption from Enhanced Weapons, Firearms Background Checks, and Security Event Notifications Implementation RS-23-097, Constellation Energy Generation, LLC, Advisement of Leadership Changes and Submittal of Updated Standard Practice Procedures Plans2023-10-12012 October 2023 Constellation Energy Generation, LLC, Advisement of Leadership Changes and Submittal of Updated Standard Practice Procedures Plans IR 05000374/20230102023-10-11011 October 2023 NRC Inspection Report 05000374/2023010 IR 05000373/20233012023-09-15015 September 2023 Errata to NRC Initial License Examination Report 05000373/2023301; 05000374/2023301 RS-23-080, Constellation Energy Generation, LLC, Application to Revise Technical Specifications to Adopt TSTF-264-A, Revision 0, 3.3.9 and 3.3.10 - Delete Flux Monitors Specific Overlap Requirement SRs2023-08-30030 August 2023 Constellation Energy Generation, LLC, Application to Revise Technical Specifications to Adopt TSTF-264-A, Revision 0, 3.3.9 and 3.3.10 - Delete Flux Monitors Specific Overlap Requirement SRs RS-23-087, Revision to Approved Alternatives Associated with the Use of the BWRVIP Guidelines in Lieu of Specific ASME Code Requirements on Reactor2023-08-0404 August 2023 Revision to Approved Alternatives Associated with the Use of the BWRVIP Guidelines in Lieu of Specific ASME Code Requirements on Reactor ML23212A9012023-08-0303 August 2023 Regulatory Audit Report to Support the Review of the Amendments to Relocation of the Pressure Temperature Limit Curves to the Pressure and Temperature Limits Report IR 05000373/20230022023-08-0101 August 2023 County Station - Integrated Inspection Report 05000373/2023002 and 05000374/2023002 ML23208A3182023-07-27027 July 2023 Notification of an NRC Biennial Licensed Operator Requalification Program Inspection and RFI RS-23-084, Response to Request for Additional Information Regarding the Application to Revise Design Basis to Allow Use of Plastic Section Properties in Lower Downcomer Braces Analysis2023-07-24024 July 2023 Response to Request for Additional Information Regarding the Application to Revise Design Basis to Allow Use of Plastic Section Properties in Lower Downcomer Braces Analysis ML23192A5272023-07-12012 July 2023 NRC Initial License Examination Report 05000373/2023301; 05000374/2023301 ML23186A2062023-07-0606 July 2023 Information Request for a NRC Post-Approval Site Inspection for License Renewal 05000374/2023010 ML23181A1502023-06-30030 June 2023 Combined Response to Request for Additional Information and Supplemental Information in Support of LAR to Relocate Pressure and Temperature Limit Curves to the Pressure and Temperature Limits Report ML23178A2422023-06-28028 June 2023 Reassignment of the U.S. Nuclear Regulatory Commission Branch Chief in the Division of Operating Reactor Licensing for Plant Licensing Branch III IR 05000373/20230112023-06-26026 June 2023 County Station - Quadrennial Fire Protection Team Inspection Report 05000373/2023011 and 05000374/2023011 RS-23-077, Response to NRC Regulatory Issue Summary 2023-01, Preparation and Scheduling of Operator Licensing Examinations2023-06-16016 June 2023 Response to NRC Regulatory Issue Summary 2023-01, Preparation and Scheduling of Operator Licensing Examinations ML23167A0352023-06-16016 June 2023 Registration of Use of Cask to Store Spent Fuel ML23171A9562023-06-12012 June 2023 Post Exam Ltr RS-23-042, Application to Revise Technical Specifications to Adopt TSTF-580, Provide Exception from Entering Mode 4 with No Operable RHR Shutdown Cooling2023-05-25025 May 2023 Application to Revise Technical Specifications to Adopt TSTF-580, Provide Exception from Entering Mode 4 with No Operable RHR Shutdown Cooling IR 05000373/20230012023-05-10010 May 2023 County Station - Integrated Inspection Report 05000373/2023001 and 05000374/2023001 ML23123A2202023-05-0303 May 2023 Relief Request I4R-14 for Alternative Frequency to Containment Unbonded Post-Tensioning System Inservice Inspection ML23118A3472023-05-0101 May 2023 County, 1 & 2; Nine Mile Point, 2; and Quad Cities, 1 & 2 - Correction of Amendment No. 193 Adoption of TSTF-306, Revision 2, Add Action to LCO 3.3.6.1 to Give Option to Isolate the Penetration EPID L-2022-LLA-0143 ML23121A1612023-05-0101 May 2023 Information Meeting (Open House) with a Question-and-Answer Session to Discuss NRC 2022 End-of-Cycle Plant Performance Assessment of LaSalle County Station, Units 1 and 2 ML23114A2522023-04-28028 April 2023 Request to Use a Provision of a Later Edition of the ASME Boiler & Pressure Vessel Code, Section XI 2024-08-09
[Table view] Category:Request for Additional Information (RAI)
MONTHYEARML24197A0162024-07-12012 July 2024 NRR E-mail Capture - Final RAI - Constellation Energy Generation, LLC - Fleet Request - License Amendment Request to Adopt TSTF-591 ML24142A3352024-05-21021 May 2024 Quad Cities—Information Request to Support the NRC Annual Baseline Emergency Action Level and Emergency Plan Changes ML23360A6082023-12-27027 December 2023 County Station Request for Information for NRC Commercial Grade Dedication Inspection: Inspection Report 05000373/2024010 and 05000374/2024010 ML23264A7992023-09-21021 September 2023 NRR E-mail Capture - Final RAI - Constellation Energy Generation, LLC Fleet Request License Amendment Request to Adopt TSTF-580, Revision 1 ML23208A3182023-07-27027 July 2023 Notification of an NRC Biennial Licensed Operator Requalification Program Inspection and RFI ML23153A1562023-06-0202 June 2023 NRR E-mail Capture - RAI LaSalle pressure-temperature Limits Report (PTLR) Amendment Request ML23150A2482023-05-25025 May 2023 NRR E-mail Capture - RAI Re LaSalle Downcomer Analysis Amendment Request ML23110A3202023-04-21021 April 2023 Information Request to Support the NRC Annual Baseline Emergency Action Level and Emergency Plan Changes Inspection ML22361A0792022-12-27027 December 2022 Notification of NRC Baseline Inspection and Request for Information (05000374/2023001) ML22256A0112022-09-12012 September 2022 NRR E-mail Capture - Request for Additional Information LaSalle County Station, Units 1 and 2 and Quad Cities Nuclear Power Station, Units 1 and 2 License Amendments Related to Fuel Storage ML22138A4112022-05-18018 May 2022 NRR E-mail Capture - Lasalle 1 and 2 - (RAI) License Amendment Request Regarding New Fuel Storage Vault and Spent Fuel Storage Pool Criticality Methodologies, with Changes to TS Sections 4.3.1 and 5.6.5 (EPID-L-2021-LLA-0124) ML22126A0392022-05-0606 May 2022 NRR E-mail Capture - Lasalle 1 and 2 Draft (RAI) License Amendment Request Regarding New Fuel Storage Vault and Spent Fuel Storage Pool Criticality Methodologies, with Proposed Changes to TS Sections 4.3.1 and 5.6.5 ML22097A0832022-04-0707 April 2022 County Station Information Request for the Cyber-Security Baseline Inspection, Notification to Perform Inspection 05000373/2022403 and 05000374/2022403 ML22062B0232022-03-0303 March 2022 NRR E-mail Capture - EPID-L-2022-LLR-0028, LaSalle Unit 1, Request for Additional Information (Rai), LaSalle Unit 1, Relief Request I4R-13 Relief from Code Examinations for 1B33-F060A and 1B33-F060B Repairs ML22041B5362022-02-10010 February 2022 NRR E-mail Capture - Constellation Energy Generation, LLC - Request for Additional Information Regarding Fleet License Amendment Request to Adopt TSTF-541 ML22020A0642022-01-13013 January 2022 NRR E-mail Capture - Exelon Generation Company, LLC - Request for Additional Information Regarding Proposed Fleet Alternative for Repair of Water Level Instrumentation Partial Penetration Nozzles ML21292A1782021-10-19019 October 2021 Information Request for a NRC Post-Approval Site Inspection for License Renewal 05000373/2022010 ML21256A1902021-09-10010 September 2021 NRR E-mail Capture - Exelon Generation Company, LLC - Request for Additional Information Regarding License Transfer Application ML21207A0072021-07-26026 July 2021 NRR E-mail Capture - La Salle Units 1 and 2 - Request for Additional Information (RAI) License Amendment Request to Incorporate Licensing Topical Report NEDE-33885P-A, Revision 1, GNF CRDA Application Methodology(EPID-L-2021-LLA-0016) ML21190A0192021-07-0808 July 2021 NRR E-mail Capture - Exelon Fleet - Request for Additional Information Regarding Adoption of TSTF-582 and TSTF-583-T ML21187A2972021-07-0707 July 2021 Information Request for an NRC Triennial 10 CFR 50.59 (Evaluation of Changes, Tests, and Experiments) Baseline Inspection ML21144A2132021-05-24024 May 2021 NRR E-mail Capture - Exelon Generation Company, LLC - Request for Additional Information Regarding License Transfer Application ML21117A0342021-05-0505 May 2021 Request for Additional Information Regarding Proposed Alternative to Use ASME Code Case N-893 ML21119A2282021-04-29029 April 2021 NRR E-mail Capture - Request for Additional Information (RAI) - LaSalle, EPID-L-2020-LLA-0018, License Amendment Request (LAR) TSTF-505 ML21077A1902021-03-18018 March 2021 NRR E-mail Capture - Lasalle Units 1 and 2 - Request for Additional Information (RAI) Request for License Amendment Regarding Ultimate Heat Sink, (EPID-L-2020-LLA-0165) ML21068A2762021-03-0909 March 2021 NRR E-mail Capture - La Salle Units 1 and 2 - Request for Additional Information (RAI) Relief Request I4R-12 Relief from Code Surface Examinations for 2B33-F060B Valve Repair (EPID-L-2020-LLA-0016) ML21067A6752021-03-0808 March 2021 NRR E-mail Capture - La Salle Units 1 and 2 - Request for Additional Information (RAI) UHS Amendment Request (EPID-L-2020-LLA-0165) ML21060B4352021-03-0101 March 2021 NRR E-mail Capture - Second Round - Request for Additional Information (Rais) EPID-L-2020-LLA-0018, LaSalle License Amendment Request to Adopt Risk Informed Completion Times TSTF-505, Revision 2 ML21062A0652021-03-0101 March 2021 NRR E-mail Capture - Exelon Generation Company, LLC - Request for Additional Information Regarding Proposed Fleet Alternative to Documentation Requirements for Pressure Retaining Bolting ML21053A0252021-02-20020 February 2021 NRR E-mail Capture - Request for Additional Information (Rais) - LaSalle Request for Exemption from Pre-Access Drug and Alcohol Testing ML21049A2572021-02-18018 February 2021 Request for Additional Information Byron/Dresden Proposed Changes to Site Emergency Plans to Support Post-Shutdown and Permanently Defueled Conditions (EPID-2020-LLA-0240 & EPID-2020-LLA-0237) ML21048A0432021-02-16016 February 2021 County Station - Notification of NRC Design Bases Assurance Inspection (Programs) and Initial Request for Information - Inspection Report 05000373/2021011 and 05000374/2021011 ML20364A2452020-12-29029 December 2020 Notification of an NRC Triennial Heat Sink Performance Inspection and Request for Information; Inspection Report 05000373/2021002; 05000374/2021002 ML20346A1042020-12-11011 December 2020 NRR E-mail Capture - LaSalle County Station, Units 1 and 2 - Request for Additional Information Regarding the License Amendment Request to Adopt 10 CFR 50.69 ML20330A1892020-11-25025 November 2020 Request for Information for an NRC Post-Approval Site Inspection for License Renewal; Inspection Report 05000374/2021010 ML20321A0852020-11-16016 November 2020 Notification of NRC Baseline Inspection and Request for Information (05000374/2021001) ML20247J4082020-09-29029 September 2020 Apla Request for Additional Information LAR 50.69 and TSTF-505 (Epids L-2020-LLA-0017) and ML20253A3422020-09-17017 September 2020 Correction to Request for Additional Information Request to Adopt 10 CFR 50.69, Risk-Informed Categorization and Treatment of Structures, Systems, and Components for Nuclear Power Reactors (EPID-2020-LLA-0017) ML20253A2272020-09-16016 September 2020 Correction to Request for Additional Information Application to Adopt Risk-Informed Completion Times TSTF-505, Revision 2, Provide Risk-Informed Extended Completion Times - RITSTF Initiative 4b ML20240A2182020-09-0303 September 2020 Request for Additional Information Regarding Amendment Request for Amendments to Renewed Facility Operating Licenses to Adopt 10 CFR 50.69, Risk-Informed Categorization and Treatment of Structures, Systems, and Co ML20239A7262020-08-27027 August 2020 Supplemental Information Needed for Acceptance of Requested Licensing Action Regarding Request for a License Amendment to Technical Specification 3.7.3, Ultimate Heat Sink ML20239A7982020-08-25025 August 2020 NRR E-mail Capture - Exelon Generation Company, LLC - Fleet License Amendment Request to Adopt TSTF-568, Revision 2 ML19275H1362019-10-0202 October 2019 NRR E-mail Capture - Exelon Generation Company, LLC - Request for Additional Information Regarding Request to Use ASME Code Case N-879 ML19179A0612019-07-19019 July 2019 Three Mile Point 1 - Supplemental Information Needed to Proposed Alternative to Use ASME Code Case N-879 ML19120A2302019-04-29029 April 2019 Ltr. 04/29/19 LaSalle County Station, Units 1 and 2 - Request for Information for an NRC Triennial Baseline Design Bases Assurance Inspection (Team); Inspection Report 05000373/2019012; 05000374/2019012 (DRS-M.Jones) ML19087A2682019-03-28028 March 2019 NRR E-mail Capture - Request for Additional Information (RAI) - LaSalle 1 and 2, EPID-L-2018-LLA-0162, LAR Removal of Operating Mode Restrictions for Performing Surveillance Testing of the Div 3 Battery and HPCS DG ML19065A0902019-03-0505 March 2019 NRR E-mail Capture - LaSalle 1 and 2, EPID-L-2018-LLR-0162, LAR Removal of Operating Mode Restrictions for Performing Surveillance Testing of the Div 3 Battery and HPCS DG, Additional Draft Request for Additional Information (RAI) ML19058A2392019-02-27027 February 2019 Information Request to Support Upcoming Problem Identification and Resolution Inspection at LaSalle County Station, Units 1 and 2 ML19036A6562019-02-0505 February 2019 NRR E-mail Capture - LaSalle 1 and 2, EPID-L-2018-LLR-0123, Relief Request I3R-15, Third Inservice Inspection Interval, Request for Additional Information (RAI) ML19022A2552019-01-22022 January 2019 NRR E-mail Capture - LaSalle Units 1 and 2, EPID-L-2018-LLA-0035, Amendment Request to Adopt TSTF-334-A, Status of Revised Draft RAIs Sent to You on December 13, 2018 2024-07-12
[Table view] |
Text
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 June 14, 2017 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:
LASALLE COUNTY STATION, UNITS 1 AND 2, REQUEST FOR ADDITIONAL INFORMATION REGARDING LICENSE AMENDMENT REQUEST TO REVISE SUPPRESSION POOL SWELL DESIGN ANALYSIS (GAG NOS, MF8702 AND MF8703)
Dear Mr. Hanson:
By letter dated October 27, 2016, Exelon Generation Company, LLC (the licensee) submitted an amendment request for the LaSalle County Station, Units 1 and 2. The proposed amendment would revise the suppression pool swell analysis for a design basis loss-of-coolant accident (LOCA). The licensee stated that the changes are necessary because the current analysis determining the suppression pool swell response to a LOCA was determined to be non-conservative.
The U.S. Nuclear Regulatory Commission (NRG) staff reviewed your application and has determined that additional information is required to complete the review. The specific information requested is addressed in the enclosure to this letter. During the telephone call on June 13, 2017, between the NRG staff and the licensee for clarification of these requests for additional information, it was agreed that the licensee will provide the responses no later than July 31, 2017.
The NRG staff considers that timely responses to requests for additional information help ensure sufficient time is available for staff review and contribute toward the NRC's goal of efficient and effective use of staff resources.
If you have any questions, please call me at 301-415-3308.
Sincerely, ,
RM:~.J1('
,}1,' 2----
~ **
Bhalchandra Vaidya, Project Manager Plant Licensing Branch Ill Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-373 and 50-374
Enclosure:
As stated
ML17163A422 *no substantial chanaes from email OFFICE LPL3/PM LPL3/LA SRXB/BC LPL3/BC LPL3/PM NAME BVaidya SRohrer EOesterle* DWrona BVaidya DATE 06/14/17 06/14/17 05/31/17 06/14/17 06/14/17 REQUEST FOR ADDITIONAL INFORMATION REGARDING LICENSE AMENDMENT REQUEST FOR REVISIONS TO SUPPRESSION POOL SWELL DESIGN ANALYSIS -
LA SALLE COUNTY STATION (LSCS), UNITS 1AND2 DOCKET NOS. 50-373 AND 50-374 (CAC NOS. MF8702 AND MF8703)
The U.S. Nuclear Regulatory Commission (NRG) staff has reviewed the information provided in the license amendment request and determined that additional information is required in order to complete its review. The NRC staff requests responses to the request for additional information (RAI) to evaluate compliance with the applicable regulatory requirements and criteria in Title 10 of the Code of Federal Regulations (10 CFR) Part 50, Appendix A, General Design Criteria (GDC) 4 and GDC 50, Standard Review Plan, 6.2.1.1.C, NUREG-0487, Supplement 2, "MARK ll Containment Lead Plant Program Load Evaluation and Acceptance Criteria," published February 1981, and NUREG-0808, "MARK II Containment Program Load Evaluation and Acceptance Criteria," Appendix A, published August 1981. The RAls are provided below.
SRXB- RAI 1 Reference 1, Table 5, Attachment 1, second column of item 4 states:
TRACG represents a change in methodology, it does not change conseNatisms.
Please provide reasons why the conservatism is not changed in using TRACG [GEH Proprietary Version of the Transient Reactor Analysis Code (TRAC), GEH Computer Code for Best Estimate BWR Transient and Accident Analysis Calculations] which is the best-estimate methodology compared to using the current conservative M3CPT [Mark Ill Containment Pressure and Temperature; GEH Computer Code M3CPT for Short-term DBA-LOCA {loss-of-coolant accident} Containment Response Analysis] methodology for mass and energy release analysis for a design basis accident (DBA) LOCA.
SXRB -RAI 2 Reference 1, Section 4.4, Attachment 1, stated all systems, structures, and components (SSCs) affected were not assessed, instead a representative sample of low margin SSC were selected. Provide the following information:
(a) Further explanation on the basis of selection of the SSCs (i.e., low margin of which parameter) for analyzing structural impacts, Enclosure
(b) Specify the systems to which the piping, associated supports and penetrations that are analyzed belong to, and any special reasons for selecting these systems.
(c) \What is total number of SSCs that are affected and how many were selected for structural re-analysis, (d) Maximum and minimum value of percentage in stress margins in the SSCs selected for structural analysis, (e) Revised (new) maximum and minimum percentage in the stress margin in the SSCs structurally analyzed,
{f) Justification as to why the SSCs not structurally analyzed will have adequate stress margin.
SXRB-RAI 3 Reference 1, item 2 of Table 6 in Attachment 1, Section 6.2.2, and Tables 6-1 through 6-4 in Attachment (a) Explain how the 0.7 ft [toot] adder to the PICSM [General Electric-Hitachi pool swell response code] predicted pool swell height which accounts tor the difference between initial pre-LOCA elevation and initial PICSM elevation which corresponds to the elevation after vent clearing was determined.
(b) ln Tables 6-1 through 6-4, explain if the 0.7 ft adder is included in the data for pool swell elevation above initial elevation.
SXRB- RAI 4 Reference 1, Note 3 in Table 4-1, Attachment 2. Explain the basis for selecting feedwater temperature reduction of 100 °F (degree Fahrenheit) from its normal operating temperature 428.5 °F at the current licensed thermal power. Provide justification that the 100 °F reduction is conservative.
SXRB- RAI 5 Reference 1, Section 4.3.1, Attachment 2, states:
Other plant performance improvement and equipment out of service options identified in Reference 1 [GE Hitachi Nuclear Energy, "Safety Analysis Report for LaSalle County Station Units 1 and 2 Thermal Power Optimization," NEDC-33485P, Revision 0, January 2010, ADAMS Accession No. ML100321327] have no effect on the RSLB
[Recirculation Suction Line Break] mass and energy release analyses. The current analysis, therefore, continues to support all flexibility and equipment out of service options.
Table in Section 1.3.2 of NEDC-33485P, Revision 0, shows several performance improvement and equipment out-of-service (OOS) features currently licensed at LSCS are acceptable at the thermal power optimization (TPO) reactor thermal power (RTP) level. Explain how it is
determined that these features have no effect on the RSLB Mass and Energy (M&E) release analysis.
SXRB
- RAI 6 Reference 1, assumption (ii), Section 6.1.1 in Attachment 2. The PICSM analysis for cases 3 and 4, assumes a constant value of steam/air ratio (air fraction = 0.61 as per Figure 7-1 in ) after the initial air in the downcomer vent is purged. The value assumed is at the time (0.87 seconds as per Figure 7-1 in Attachment 2) when all air in the downcomer vent is purged. Describe the analysis that resulted in the graph shown in Figure 7-1, uDrywell Air Fraction (Air Mass/(Air Mass+ Steam Mass))."
SXRB-RAI 7 Reference 1, Section 6.1.1, Attachment 2, assumption 3, states:
The mass flow rate of non-condensables into the bubble is calculated assuming adiabatic flow through a duct with friction.
(a) Clarify which duct (i.e., downcomer vent or other) is meant to be feeding the non-condensables into the bubble.
(b) What is the assumed value of frictional loss coefficient and how is it determined?
(c) Justify the assumption of adiabatic flow with friction is conservative.
SXRB-RAI 8 Reference 1, Section 6.1.1, Attachment 2, assumption 6, states:
Following vent clearing, the water above the exit of the vent (equal to the initial vent submergence plus the pool displacement due to vent clearing) accelerates as a slug of constant thickness.
The water column in the downcomer vent cleared during a LOCA is cylindrical in shape having its diameter same as the vent diameter and length equal to the length of the water column. Describe the geometric shape of the slug assumed in the above assumption and how its dimensions are determined from the dimensions of the initial water column in the vent. Provide the basis for assuming a constant thickness of the slug.
SXRB -RAI 9 Reference 1, Section 6.1.1, Attachment 2, assumption 7, states:
Frictional losses between the water and the confining walls are negligible.
Describe which confining walls are referred to in the above assumption.
SXRB - RAI 10 Reference 1, Section 6.1.1, Attachment 2, assumption 10, states:
The air velocity in the OW [drywell} is sufficiently small so that static and stagnation conditions are equivalent.
Specify with justification at what time during the transient, the air velocity in the drywell is assumed sufficiently small so that its velocity head is negligible.
SXRB - RAI 11 The drywell pressure response described in Reference 1, Section 5.0, Attachment 2, used TRACG for M&E analysis, and M3CPT code for drywell pressure analysis and the assumption and inputs listed in Section 5.1.1 and Appendix A, respectively. Provide the following information:
(a) Computer codes used in the analysis of record (AOR) for calculation of "Pa (pressure absolute."
(b) Differences in the inputs and assumptions for M&E and drywall pressure response between the AOR and the proposed analysis with justification in the inputs and assumptions for which the conservatism in the proposed analysis is reduced.
(c) In case the peak drywell pressure calculated using the assumptions and inputs in the proposed analysis results in a greater value than its current Pa, please explain and justify why Pa is not being revised.
SXRB - RAI 12 In Reference 1, Attachment 2, refer to Figures 5-1, 6-3, and 6-3A, (a) Figure 5-1; describe the analysis to which the graphs labelled "LSCS Design Calculation 3C7-1075-001" and "LAMB CLTP 100P 100F" belong.
(b) Figures 6-3 and 6-3A; describe the analysis to which the graphs labelled "LSCS Design Calculation 3C7-1075-001 R6" belong.
SXRB - RAI 13 In Reference 1, Attachment 2, refer to Figure 5-1. Provide reasons for the discontinuity (drastic reversal of slope) in the graph labelled "LSCS Design Calculation 3C7-1075-001," and why does it differ from other graphs shown in this figure, with respect to its reversal of slope after vent clearing.
REFERENCES
- 1. Letter from Exelon Generation Company, LLC to NRC dated October 27, 2016, "License Amendment Request to Revise Suppression Pool Swell Design Analysis," (Agencywide Documents Access and Management System (ADAMS) Package Accession No. ML16305A295).