|
|
Line 52: |
Line 52: |
| : 1. For the analyses completed pertaining to the Emergency Core Cooling System (ECCS) bypass error for the lowered loop design, a 2.506-ft peak power location was used, and the analyses for the ECCS bypass error for the raised loop design used a 9.536-ft peak power location. In the December 6, 2012, supplemental letter, the effects of the end-of-bypass timing error are expressed in terms of liquid inventory available to reach the lower plenum and initiate a bottom-up core reflood. The effects of an adiabatic heatup, which is terminated by the core reflood, are also discussed. In consideration of these phenomena, it would appear that a higher elevation in the core would be a more limiting location to evaluate the effects of an error associated with end-of-bypass timing. | | : 1. For the analyses completed pertaining to the Emergency Core Cooling System (ECCS) bypass error for the lowered loop design, a 2.506-ft peak power location was used, and the analyses for the ECCS bypass error for the raised loop design used a 9.536-ft peak power location. In the December 6, 2012, supplemental letter, the effects of the end-of-bypass timing error are expressed in terms of liquid inventory available to reach the lower plenum and initiate a bottom-up core reflood. The effects of an adiabatic heatup, which is terminated by the core reflood, are also discussed. In consideration of these phenomena, it would appear that a higher elevation in the core would be a more limiting location to evaluate the effects of an error associated with end-of-bypass timing. |
|
| |
|
| Provide information to demonstrate that the bottom-peaked power shape being used for the lowered loop design is conservative and/or appropriate. | | Provide information to demonstrate that the bottom-peaked power shape being used for the lowered loop design is conservative and/or appropriate. |
| : 2. After evaluating a 177 fuel assembly (FA) lowered loop plant with column weldments modeled for a 205 FA plant, details of the column weldments for a 177 FA plant were developed. The model for column weldments of a 177 FA plant were then used for the analyses of a raised loop plant. Two 177 FA raised loop cases showed that the newly developed column weldments increased PCT by 3 degrees Fahrenheit. | | : 2. After evaluating a 177 fuel assembly (FA) lowered loop plant with column weldments modeled for a 205 FA plant, details of the column weldments for a 177 FA plant were developed. The model for column weldments of a 177 FA plant were then used for the analyses of a raised loop plant. Two 177 FA raised loop cases showed that the newly developed column weldments increased PCT by 3 degrees Fahrenheit. |
|
| |
|
| DRAFT It was also reported that the column weldments in a lowered loop plant increased PCT by 35.6 degrees Fahrenheit for an unruptured fuel segment. To determine the effect of column weldments on a ruptured fuel segment, the result is doubled. This resulted in a PCT increase of 71.2 degrees Fahrenheit for a ruptured fuel segment. This was bounded by generically estimating the effect of column weldments to be an increase in PCT of 80 degrees Fahrenheit. | | DRAFT It was also reported that the column weldments in a lowered loop plant increased PCT by 35.6 degrees Fahrenheit for an unruptured fuel segment. To determine the effect of column weldments on a ruptured fuel segment, the result is doubled. This resulted in a PCT increase of 71.2 degrees Fahrenheit for a ruptured fuel segment. This was bounded by generically estimating the effect of column weldments to be an increase in PCT of 80 degrees Fahrenheit. |
|
| |
|
| Column weldments in a raised loop plant increased PCT by 8.9 degrees Fahrenheit for an unruptured segment, which is one fourth of the effect seen in the lowered loop design. | | Column weldments in a raised loop plant increased PCT by 8.9 degrees Fahrenheit for an unruptured segment, which is one fourth of the effect seen in the lowered loop design. |
| : a. Provide justification to show that analyzing column weldments modeled for a 177 FA plant has an effect on PCT of the same magnitude in a lowered loop plant as in a raised loop plant. | | : a. Provide justification to show that analyzing column weldments modeled for a 177 FA plant has an effect on PCT of the same magnitude in a lowered loop plant as in a raised loop plant. |
| : b. Provide justification to show that the generic 80 degree increase in PCT is bounding for a ruptured fuel segment in a lowered loop plant using the 177 FA column weldment model. | | : b. Provide justification to show that the generic 80 degree increase in PCT is bounding for a ruptured fuel segment in a lowered loop plant using the 177 FA column weldment model. |
| : c. Describe the nodalization for the column weldments used in RELAP5 analyses. | | : c. Describe the nodalization for the column weldments used in RELAP5 analyses. |
| : 3. Provide drawings to compare the column weldment design for a 205 FA plant to the column weldments for the 177 FA plant.}} | | : 3. Provide drawings to compare the column weldment design for a 205 FA plant to the column weldments for the 177 FA plant.}} |
Letter Sequence Draft RAI |
---|
|
|
|
|
---|
Category:Memoranda
MONTHYEARML23102A0382023-04-10010 April 2023 Occupational Radiation Exposure Annual Report ML22073A2442022-03-16016 March 2022 TMI NMSS Memo for ISFSI PSP Review Completion, Staff Review of the Three Mile Island Independent Spent Fuel Storage Installation Physical Security Plan (Rev.0) and License Amendment Request (Cac/Epid No: 000078/05000289/L-2021-SPR-0004) ML22074A0922022-03-15015 March 2022 TMI: 1 ISFSI Only PSP Rev. 0 Notice of Safeguards Memo ML21277A2472021-11-0505 November 2021 Notification of Significant Licensing Action - Proposed Issuance of Order Approving the Transfer of Licenses for Which a Hearing Has Been Requested - Exelon Generation Company, LLC; Et. Al ML21218A0082021-08-10010 August 2021 NSIR Review of the Three Mile Island Physical Security Plan Revision 24 for the Verification of ASM 20-103 Incorporation ML21166A1182021-06-15015 June 2021 Technical Assistance Request - Review of Physical Security Plan for the Three Mile Island Unit 1 Power Station Independent Spent Fuel Storage Installation ML19182A3562019-07-23023 July 2019 Quarterly Report on the Status of Public Petitions Under Title 10 of the Code of Federal Regulations, Section 2.206 - April 1 to June 30, 2019 ML19044A3842019-02-0606 February 2019 Notification of the Facility Director Change for the Nuclear Regulatory Commission Regulated Independent Spent Fuel Storage Installations (CLNl90659) ML18093B1022018-04-0303 April 2018 Notice of Public Meeting with Exelon Generation Company, LLC, to Discuss the NRCs Assessment of Safety Performance at Three Mile Island Nuclear Station, Unit 1 for 2017, as Described in the Annual Assessment Letter Dated February 28, 2018 ML17271A0532017-09-29029 September 2017 2017 Summary of Annual Decommissioning Funding Status Reports for Reactors in Decommissioning ML17142A2382017-05-25025 May 2017 OEDO-17-00280 - Briefing Package for Drop-In Visit on June 9, 2017, by Senior Management of Exelon Generation Company, LLC with Chairman Svinicki, Commissioner Baran, and Commissioner Burns ML16252A2732016-08-26026 August 2016 Notification of the Facility Director Change Update for the NRC Independent Spent Fuel Storage Installations (EM-NRC-16-020) ML16075A3292016-03-16016 March 2016 OEDO-16-00165 - Briefing Package for Drop-In Visit on March 23, 2016, by Senior Management of Exelon Generation Company, LLC with the NRC Executive Director for Operations ML15230A5332015-08-18018 August 2015 Draft Request for Additional Information ML15175A3002015-08-0606 August 2015 Final Response to Task Interface Agreement 2015-01, Assessment of Three Mile Island Nuclear Station'S Use of a Non-Seismic Qualified Cleanup Path for the Borated Water Storage Tank ML15089A1642015-04-27027 April 2015 Summary of February 25, 2015, Partially Closed Meeting with Industry Stakeholders Regarding the Babcock and Wilcox Loss of Coolant Accident Evaluation Model Analysis ML14133A0592014-07-0101 July 2014 Summary of Closed Meeting Between Representatives of the Army Corps of Engineers, Nuclear Regulatory Commission, Federal Energy Regulatory Commission, Exelon Generation Co, LLC, and PPL Susquehanna, LLC, to Discuss Dam Failure Analysis.. ML14112A2392014-04-22022 April 2014 Notice of Forthcoming Closed Meeting to Discuss Dam Failure Analysis for Peach Bottom Atomic Power Station Units 2 and 3, Susquehanna Steam Electric Station Units 1 and 2, and Three Mile Island Nuclear Station Unit 1 ML14106A3742014-03-31031 March 2014 Notification of Facility Director Change for the Nuclear Regulatory Commission Regulated Fort St Vrain, Three Mile Island and Idaho Spent Fuel Facility Independent Spent Fuel Storage Installations (EM-FMDP-14-018) ML13269A1792013-09-25025 September 2013 Draft Request for Additional Information ML13262A1632013-09-23023 September 2013 Meeting Report - Three Mile Island, Unit 2, Post-Shutdown Decommissioning Activities Report Public Meeting ML13253A2252013-09-10010 September 2013 Draft Request for Additional Information ML13249A2072013-09-0505 September 2013 Draft Request for Additional Information ML13221A4462013-08-12012 August 2013 Meeting Notice: to Discuss the Three Mile Island, Unit 2, Post-Shutdown Decommissioning Activities Report Submittal and Obtain Public Comments ML13190A1992013-08-0606 August 2013 FRN - Memo to Cindy Bladey Transmitting Federal Register Notice on Receipt of Three Mile Island - Unit 2 Post-Shutdown Decommissioning Activities Report ML13193A1452013-07-12012 July 2013 Electronic Transmission, Draft Request for Additional Information Regarding Proposed Revision to Pressure and Temperature Limit Curves and Exemption Request for Initial Reference Temperature Values (TAC Nos. MF0425 & MF0426) ML13190A3522013-07-10010 July 2013 Notice of Forthcoming Teleconference with Exelon Generation Company, LLC ML13177A3902013-06-26026 June 2013 Electronic Transmission, Draft Request for Additional Information Regarding Overall Integrated Plan in Response to Order Number EA-12-051, Reliable Spent Fuel Pool Instrumentation ML13136A2032013-05-20020 May 2013 Meeting Notice with Exelon Generation Company, LLC, to Discuss Once Through Steam Generator Tube-to-Tube Wear at Three Mile Island, Unit 1 ML13066A1262013-03-0707 March 2013 Electronic Transmission, Draft Request for Additional Information Regarding Fifth Inservice Test Interval Relief Request PR-01 Nuclear Services Closed Cooling Water Flow Measurement ML13050A6362013-02-20020 February 2013 Draft RAI Memo ML13044A6652013-02-13013 February 2013 Electronic Transmission, Draft Request for Additional Information Regarding Relief Request VR-01, Associated with the Fifth Inservice Testing Interval ML13044A3122013-02-13013 February 2013 Electronic Transmission, Draft Request for Additional Information Regarding 30-Day Report for Emergency Core Cooling System Model Changes Pursuant to the Requirements of 10 CFR 50.46 ML12348A6962012-12-17017 December 2012 1/3/2013 - Notice of Forthcoming Meeting with Exelon Generation Company, LLC, to Discuss Requests for Additional Information Regarding Exelon Physical Security Plans ML12310A2022012-11-0606 November 2012 Electronic Transmission, Draft Request for Additional Information Regarding 30-Day Report for Emergency Core Cooling System Model Changes Pursuant to the Requirements of 10 CFR 50.46 ML12306A4542012-11-0101 November 2012 Electronic Transmission, Draft Request for Additional Information Regarding 2011 Steam Generator Tube Inspection Report ML1208701692012-03-28028 March 2012 Electronic Transmission, Draft Request for Additional Information Regarding Fourth Interval Inservice Testing Relief Request PR-05 ML1208602902012-03-26026 March 2012 Notice of Forthcoming Public Meeting with Exelon Generation to Discuss Future Fleet Submittal Regarding Licensed Operator Eligibility Requirements ML1134801002011-12-19019 December 2011 Notice of Forthcoming Meeting with Exelon Generation Company, LLC, and Entergy Operations, Inc., to Discuss Steam Generator Inspection Results at Three Mile Island, Unit 1, and Arkansas Nuclear One, Unit 1 ML1133605762011-12-0505 December 2011 Electronic Transmission, Draft Request for Additional Information Regarding Proposed License Amendment Revising Technical Specifications to Incorporate Administrative Changes ML1119900962011-07-20020 July 2011 Electronic Transmission, Draft Request for Additional Information Regarding Third Inservice Inspection Interval Relief Requests RR-11-01 and RR11-02 ML1113802512011-06-0303 June 2011 Memo to Cindy Bladey Federal Register Notice Providing Notice of Issuance of Director'S Decision Under 10 CFR 2.206 ML1111804942011-04-28028 April 2011 Electronic Transmission, Draft Request for Additional Information Regarding Fourth Interval Inservice Inspection Relief Request I4R-04 ML1107305692011-03-14014 March 2011 Electronic Transmission, Draft Request for Additional Information Regarding Relief Request RR-10-01, Control Rod Drive Housing Examinations Associated with the Third Inservice Inspection Interval ML1106200272011-03-0303 March 2011 Electronic Transmission, Draft Request for Additional Information Proposed Technical Specification Changes Regarding Number of Required Operable Main Steam Safety Valves ML1105509182011-02-25025 February 2011 Notice of Meeting with Exelon Generation Company, LLC, to Discuss Three Mile Island, Unit 1, Main Steam Safety Valve License Amendment Request ML1105403472011-02-23023 February 2011 Electronic Transmission, Draft Request for Additional Information, Proposed Technical Specification Changes Regarding Relocation of Equipment Load List from Technical Specifications to a Licensee Controlled Document ML1103416642011-02-0404 February 2011 Electronic Transmission, Draft Request for Additional Information, Proposed Technical Specification Changes Regarding Number of Required Operable Main Steam Safety Valves ML1103402022011-02-0303 February 2011 Electronic Transmission, Draft Request for Additional Information Regarding Relief Request RR-10-02, Weld Overlay of the Pressurizer Spray Nozzle to Safe-End and Safe-End to Elbow Dissimilar Metal Welds ML1034405552010-12-10010 December 2010 Electronic Transmission, Draft Request for Additional Information Regarding Relief Request 14R-02 2023-04-10
[Table view] Category:Request for Additional Information (RAI)
MONTHYEARML24157A3672024-06-13013 June 2024 Updated Post-Shutdown Decommissioning Activities Report Request for Additional Information Transmittal Letter ML24011A2352024-01-11011 January 2024 Eco Request for Additional Information for 2023 License Amendment Request 1-11-24 ML23187A0202023-06-29029 June 2023 TMI Unit 2 RAI Related to the Amended Post-Shutdown Decommissioning Activities Report ML23187A0332023-06-29029 June 2023 TMI Unit 2, PSDAR Rev. 5 RAIs ML23082A3432023-03-31031 March 2023 Enclosure - RAI - Three Mile Island, Unit 2 - Acceptance Review and Request for Additional Information for the Historic and Cultural Resources License Amendment Request - EPID: 2023-LLA-0026 ML22357A0142022-12-22022 December 2022 NRC Request for Additional Information Related to the TMI-2 Pdms Transition License Amendment Request ML22210A0882022-07-29029 July 2022 Enclosure - Three Mile Island, Unit No. 2 - Request for Additional Information for Requested Licensing Action Regarding Decommissioning Technical Specifications ML22143A8902022-05-23023 May 2022 Request for Additional information- TMI-1 ISFSI Only Physical Security License Amendment Request ML22125A0122022-04-28028 April 2022 Clarification RAI Partial Response Email from C Smith to a Snyder ML22110A0202022-04-19019 April 2022 Unit 1 Request for Additional Information ML22038A9362022-02-0707 February 2022 TMI2 Accident Analyses Questions ML21256A1902021-09-10010 September 2021 NRR E-mail Capture - Exelon Generation Company, LLC - Request for Additional Information Regarding License Transfer Application ML21144A2132021-05-24024 May 2021 NRR E-mail Capture - Exelon Generation Company, LLC - Request for Additional Information Regarding License Transfer Application ML20164A0902020-06-10010 June 2020 Request for Additional Information Related to TMI-1 License Amendment Request to Delete Permanently Defueled Technical Specification 3/4.1.4 (L-2019-LLA-0250) ML19319B2082019-11-15015 November 2019 NRR E-mail Capture - Request for Additional Information Related to TMI-1 Request for Exemption from Portions of 10 CFR 50.47 and Part 50 Appendix E (L-2019-LLA-0216) ML19179A0612019-07-19019 July 2019 Three Mile Point 1 - Supplemental Information Needed to Proposed Alternative to Use ASME Code Case N-879 ML18220A7832018-08-0707 August 2018 NRR E-mail Capture - Request for Additional Information Related to TMI Fall 2017 Steam Generator Tube Inspection Report ML18212A2712018-07-31031 July 2018 NRR E-mail Capture - Request for Additional Information Related to Amendment Regarding Decommissioning ERO Staffing Changes ML17285B1962017-10-27027 October 2017 Request for Additional Information Regarding Generic Letter 2016-01, Monitoring of Neutron-Absorbing Materials in Spent Fuel Pools. ML17062A4912017-03-0303 March 2017 NRR E-mail Capture - Exelon Generation Company, LLC - Request for Additional Information Regarding Fleet Alternative to RPV Threads in Flange Examination (CAC Nos. MF8712-MF8729) ML16356A4802016-12-21021 December 2016 NRR E-mail Capture - RAIs on TMI License Amendment Request for Approval of Changes to the Three Mile Island Nuclear Station Emergency Plan Related to Staffing ML16337A0072016-12-0101 December 2016 NRR E-mail Capture - Draft RAIs Three Mile Island Nuclear Station, Units 1 and 2, License Amendment Request for Approval of Changes to the Three Mile Island Nuclear Station Emergency Plan Related to Staffing ML16287A4042016-10-11011 October 2016 Notification of Conduct of a Triennial Fire Protection Baseline Inspection ML15230A5332015-08-18018 August 2015 Draft Request for Additional Information ML15020A7372015-03-0808 March 2015 Request for Additional Information Regarding Related to December 22, 2014, Report Submitted Pursuant to 10 CFR 50.46 ML14307A1172014-11-14014 November 2014 Request for Additional Information Regarding Relief Request RR-14-01 Concerning Alternative Root Mean Square Depth Sizing Requirements ML14240A4122014-09-0404 September 2014 Request for Additional Information Regarding License Amendment Request to Eliminate Certain Technical Specification Reporting Requirements (Tac MF0628) ML14134A3222014-05-22022 May 2014 Request for Additional Information Regarding Review of Three Mile Island Nuclear Station Unit 1 Cycle 20 Core Operating Limits Report ML14134A1722014-05-14014 May 2014 Draft RAIs in Support of NRC Staff Review of TMI Cycle 20 COLR ML14052A2592014-02-27027 February 2014 Request for Additional Information Regarding Proposed License Amendment Request to Revise Technical Specification Reporting Requirements ML14030A5832014-01-29029 January 2014 Draft Request for Additional Information Proposed Revision to Technical Specifications Reporting Requirements Exelon Generation Company, LLC Three Mile Island Nuclear Station, Unit 1 ML13266A2852013-10-21021 October 2013 Request for Additional Information on Three Mile Island Nuclear Station Unit 2 - post-shutdown Decommissioning Activities Report ML13276A6492013-10-0303 October 2013 Notification of Conduct of a Triennial Fire Protection Baseline Inspection ML13269A1792013-09-25025 September 2013 Draft Request for Additional Information ML13253A2252013-09-10010 September 2013 Draft Request for Additional Information ML13249A2072013-09-0505 September 2013 Draft Request for Additional Information ML13193A1752013-07-22022 July 2013 Request for Additional Information Regarding Revision to Pressure and Temperature Limit Curves and Exemption Request for Initial Reference Temperature Values ML13196A3382013-07-15015 July 2013 2013 Decommissioning Fund Report RAI ML13193A1452013-07-12012 July 2013 Electronic Transmission, Draft Request for Additional Information Regarding Proposed Revision to Pressure and Temperature Limit Curves and Exemption Request for Initial Reference Temperature Values (TAC Nos. MF0425 & MF0426) ML13176A4702013-06-26026 June 2013 Request for Additional Information Regarding Overall Integrated Plan in Response to Order Number EA-12-051, Reliable Spent Fuel Pool Instrumentation ML13177A3902013-06-26026 June 2013 Electronic Transmission, Draft Request for Additional Information Regarding Overall Integrated Plan in Response to Order Number EA-12-051, Reliable Spent Fuel Pool Instrumentation ML13066A2442013-03-19019 March 2013 Request for Additional Information Regarding Fifth Inservice Test Interval Relief Request PR-01 Nuclear Services Closed Cooling Water Flow Measurement ML13066A1262013-03-0707 March 2013 Electronic Transmission, Draft Request for Additional Information Regarding Fifth Inservice Test Interval Relief Request PR-01 Nuclear Services Closed Cooling Water Flow Measurement ML13044A3212013-03-0505 March 2013 Request for Additional Information Regarding 30-Day Report for Emergency Core Cooling System Model Changes Pursuant to the Requirements of 10 CFR 50.46 ML13045A6432013-02-25025 February 2013 Request for Additional Information Regarding Relief Request VR-01, Associated with the Fifth Inservice Testing Interval ML13051A3852013-02-25025 February 2013 Request for Additional Information Regarding End-of-Interval Relief Request RR-12-01, Pressure Nozzle-to-Head Weld Exams ML13050A6362013-02-20020 February 2013 Draft RAI Memo ML13044A3122013-02-13013 February 2013 Electronic Transmission, Draft Request for Additional Information Regarding 30-Day Report for Emergency Core Cooling System Model Changes Pursuant to the Requirements of 10 CFR 50.46 ML13044A6652013-02-13013 February 2013 Electronic Transmission, Draft Request for Additional Information Regarding Relief Request VR-01, Associated with the Fifth Inservice Testing Interval ML12306A4812012-11-19019 November 2012 Request for Additional Information Regarding 2011 Steam Generator Tube Inspection Report 2024-06-13
[Table view] |
Text
February 13, 2013 MEMORANDUM TO: Meena Khanna, Chief Plant Licensing Branch I-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation
FROM: Peter Bamford, Project Manager Plant Licensing Branch I-2
/ra/ Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation
SUBJECT:
THREE MILE ISLAND, UNIT NO. 1 - ELECTRONIC TRANSMISSION, DRAFT REQUEST FOR ADDITIONAL INFORMATION REGARDING 30-DAY REPORT FOR EMERGENCY CORE COOLING SYSTEM MODEL CHANGES PURSUANT TO THE REQUIREMENTS OF 10 CFR 50.46 (TAC NO. ME8237)
The attached draft request for additional information (RAI) was transmitted by electronic transmission on February 12, 2012, to Mr. Thomas Loomis, at Exelon Generation Company, LLC (Exelon, the licensee). This draft RAI was transmitted to facilitate the technical review
being conducted by the Nuclear Regulatory Commission (NRC) staff and to support a conference call (if needed) with Exelon in order to clarify the licensee's submittal reporting a change or error discovered in an Emergency Core Cooling System evaluation model or in the application of such a model that affects the peak cladding temperature (PCT) calculation at Three Mile Island Nuclear Station, Unit 1 (TMI-1). The draft RAI is related to the licensee's submittal dated March 21, 2012. The draft questions were sent to ensure that they were understandable, the regulatory basis was clear, and to determine if the information was previously docketed. Additionally, review of the draft RAI would allow Exelon to evaluate and agree upon a schedule to respond to the RAI. This memorandum and the attachment do not represent an NRC staff position. Docket Nos. 50-289
Enclosure:
As stated February 13, 2013 MEMORANDUM TO: Meena Khanna, Chief Plant Licensing Branch I-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation
FROM: Peter Bamford, Project Manager /ra/ Plant Licensing Branch I-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation
SUBJECT:
THREE MILE ISLAND, UNIT NO. 1 - ELECTRONIC TRANSMISSION, DRAFT REQUEST FOR ADDITIONAL INFORMATION REGARDING 30-DAY REPORT FOR EMERGENCY CORE COOLING SYSTEM MODEL CHANGES PURSUANT TO THE REQUIREMENTS OF 10 CFR 50.46 (TAC NO. ME8237)
The attached draft request for additional information (RAI) was transmitted by electronic transmission on February 12, 2012, to Mr. Thomas Loomis, at Exelon Generation Company, LLC (Exelon, the licensee). This draft RAI was transmitted to facilitate the technical review
being conducted by the Nuclear Regulatory Commission (NRC) staff and to support a conference call (if needed) with Exelon in order to clarify the licensee's submittal reporting a change or error discovered in an Emergency Core Cooling System evaluation model or in the application of such a model that affects the peak cladding temperature (PCT) calculation at Three Mile Island Nuclear Station, Unit 1 (TMI-1). The draft RAI is related to the licensee's submittal dated March 21, 2012. The draft questions were sent to ensure that they were understandable, the regulatory basis was clear, and to determine if the information was previously docketed. Additionally, review of the draft RAI would allow Exelon to evaluate and agree upon a schedule to respond to the RAI. This memorandum and the attachment do not represent an NRC staff position. Docket Nos. 50-289
Enclosure:
As stated DISTRIBUTION
- Public RidsNrrPMPBamford LPL1-2 R/F Accession No.: ML13044A312
- via email OFFICE LPL1-2/PM SRXB/BC NAME PBamford CJackson*DATE 02/13/13 02/11/2013 OFFICIAL RECORD COPY DRAFT Enclosure REQUEST FOR ADDITIONAL INFORMATION REGARDING THREE MILE ISLAND NUCLEAR STATION, UNIT 1 30-DAY REPORT FOR EMERGENCY CORE COOLING SYSTEM MODEL CHANGES PURSUANT TO THE REQUIREMENTS OF 10 CFR 50.46 DOCKET NO. 50-289
By letter dated March 21, 2012 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML12081A083), Exelon Generation Company, LLC (Exelon, the licensee), sent a notice reporting a change or error discovered in an evaluation model or in the application of such a model that affects the peak cladding temperature (PCT) calculation for Three Mile Island Nuclear Station, Unit 1 (TMI-1). This report was submitted pursuant to the requirements of Title 10 of the Code of Federal Regulations (10 CFR) Section 50.46, which requires, in part, that licensees report a change in the evaluation model used resulting in a significant change in PCT (greater than 50 degrees Fahrenheit). As described in the statements of consideration published in the Federal Register (FR), the intent of this requirement is to enable the Nuclear Regulatory commission (NRC) staff to establish the safety significance of this change (53 FR 35996-36005).
The submittal dated March 21, 2012, was supplemented by letter dated December 12, 2012 (ADAMS Accession No. ML12349A175). The December 12, 2012, letter referenced an additional letter from AREVA NP Inc. (AREVA), which was submitted to the NRC on December 6, 2012 (ADAMS Accession No. ML12342A381). The following questions pertain to the AREVA submittal, insofar as it applies to the TMI-1 report.
- 1. For the analyses completed pertaining to the Emergency Core Cooling System (ECCS) bypass error for the lowered loop design, a 2.506-ft peak power location was used, and the analyses for the ECCS bypass error for the raised loop design used a 9.536-ft peak power location. In the December 6, 2012, supplemental letter, the effects of the end-of-bypass timing error are expressed in terms of liquid inventory available to reach the lower plenum and initiate a bottom-up core reflood. The effects of an adiabatic heatup, which is terminated by the core reflood, are also discussed. In consideration of these phenomena, it would appear that a higher elevation in the core would be a more limiting location to evaluate the effects of an error associated with end-of-bypass timing.
Provide information to demonstrate that the bottom-peaked power shape being used for the lowered loop design is conservative and/or appropriate.
- 2. After evaluating a 177 fuel assembly (FA) lowered loop plant with column weldments modeled for a 205 FA plant, details of the column weldments for a 177 FA plant were developed. The model for column weldments of a 177 FA plant were then used for the analyses of a raised loop plant. Two 177 FA raised loop cases showed that the newly developed column weldments increased PCT by 3 degrees Fahrenheit.
DRAFT It was also reported that the column weldments in a lowered loop plant increased PCT by 35.6 degrees Fahrenheit for an unruptured fuel segment. To determine the effect of column weldments on a ruptured fuel segment, the result is doubled. This resulted in a PCT increase of 71.2 degrees Fahrenheit for a ruptured fuel segment. This was bounded by generically estimating the effect of column weldments to be an increase in PCT of 80 degrees Fahrenheit.
Column weldments in a raised loop plant increased PCT by 8.9 degrees Fahrenheit for an unruptured segment, which is one fourth of the effect seen in the lowered loop design.
- a. Provide justification to show that analyzing column weldments modeled for a 177 FA plant has an effect on PCT of the same magnitude in a lowered loop plant as in a raised loop plant.
- b. Provide justification to show that the generic 80 degree increase in PCT is bounding for a ruptured fuel segment in a lowered loop plant using the 177 FA column weldment model.
- c. Describe the nodalization for the column weldments used in RELAP5 analyses.
- 3. Provide drawings to compare the column weldment design for a 205 FA plant to the column weldments for the 177 FA plant.