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MONTHYEARTMI-10-035, Technical Specification Change Request No. 351: Maximum Allowable Power with Inoperable Main Steam Safety Valves2010-09-24024 September 2010 Technical Specification Change Request No. 351: Maximum Allowable Power with Inoperable Main Steam Safety Valves Project stage: Other ML1030500282010-11-0101 November 2010 Acceptance Review of TMI-1 LAR Regarding Maximum Allowable Power Level with Inoperable Mssvs, TAC ME4808 Project stage: Acceptance Review 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 Project stage: Draft RAI ML1103503792011-02-14014 February 2011 Request for Additional Information Regarding License Amendment Request Proposing Changes to the Number of Required Operable Main Steam Safety Valves Project stage: RAI 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 Project stage: Meeting 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 Project stage: Draft RAI ML1107702962011-03-18018 March 2011 Response to Request for Additional Information Related to Technical Specification Change Request No. 351: Maximum Allowable Power with Inoperable Main Steam Safety Valves Project stage: Response to RAI ML1108109722011-03-25025 March 2011 Summary of March 14, 2011, Meeting with Exelon to Discuss Proposed Main Steam Safety Valve License Amendment Request Project stage: Meeting ML1106201672011-03-25025 March 2011 Request for Additional Information Regarding License Amendment Request Proposing Changes to the Number of Required Operable Main Steam Safety Valves Project stage: RAI TMI-11-075, Response to Request for Additional Information Related to Technical Specification Change Request No. 351 Maximum Allowable Power with Inoperable Main Steam Safety Valves2011-04-21021 April 2011 Response to Request for Additional Information Related to Technical Specification Change Request No. 351 Maximum Allowable Power with Inoperable Main Steam Safety Valves Project stage: Response to RAI TMI-11-077, Supplemental Response to Request for Additional Information Related to Technical Specification Change Request No. 351: Maximum Allowable Power with Inoperable Main Steam Safety Valves.2011-05-27027 May 2011 Supplemental Response to Request for Additional Information Related to Technical Specification Change Request No. 351: Maximum Allowable Power with Inoperable Main Steam Safety Valves. Project stage: Supplement ML1123605812011-09-14014 September 2011 Issuance of Amendment Maximum Allowable Power with Inoperable Main Steam Safety Valves Project stage: Approval 2011-03-18
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Category:Letter
MONTHYEARML24038A0222024-02-0505 February 2024 Achp Letter on Section 106 Programmatic Agreement Participation IR 05000289/20230062024-01-29029 January 2024 Constellation Energy Generation, LLC, Three Mile Island Nuclear Station, Unit 1 - NRC Inspection Report No. 05000289/2023006 ML23342A1242024-01-0909 January 2024 Independent Spent Fuel Storage Installation Security Inspection Plan ML23325A1092024-01-0505 January 2024 Review of the Management Plan for Three Mile Island Station, Unit No. 2, Debris Material ML23354A2062023-12-20020 December 2023 (TMI-2), Request for Exemption from Enhanced Weapons, Firearms Background Checks, and Security Event Notifications Implementation ML23354A2112023-12-20020 December 2023 Response to Request for Additional Information for the TMI-2 Post-Shutdown Decommissioning Activities Report, Rev. 5 IR 05000320/20230032023-11-28028 November 2023 TMI-2 Solutions, LLC, Three Mile Island Nuclear Station, Unit 2, NRC Inspection Report No. 05000320/2023003 ML23243A9082023-08-29029 August 2023 Shpo Letter to TMI-2 Regarding Section 106 Activities IR 05000320/20230022023-08-17017 August 2023 TMI-2 Solutions, LLC, Three Mile Island Nuclear Station, Unit 2 - NRC Inspection Report 05000320/2023002 ML23216A1742023-08-14014 August 2023 Consultation Letter to David Morrison for TMI-2 ML23216A1772023-08-14014 August 2023 Consultation Letter to Rebecca Countess for TMI-2 ML23216A1752023-08-14014 August 2023 Consultation Letter to Joanna Cain for TMI-2 ML23216A1732023-08-14014 August 2023 Consultation Letter to Christine Turner for TMI-2 IR 05000289/20230052023-08-14014 August 2023 Constellation Energy Generation, LLC, Three Mile Island Nuclear Station, Unit 1 - NRC Inspection Report 05000289/2023005 ML23216A1782023-08-14014 August 2023 Consultation Letter to Steve Letavic for TMI-2 ML23221A1402023-08-0808 August 2023 (TMI-2), Response to Requests for Additional Information for the TMI-2 Post-Shutdown Decommissioning Activities Report, Rev. 5 ML23200A1882023-07-31031 July 2023 TMI-2 Correction Letter Amendment 67 ML23209A7632023-07-28028 July 2023 Letter from PA Shpo to TMI-2 Solutions on Cultural and Historic Impacts of Decommissioning ML23192A8272023-07-10010 July 2023 TMI-2 Solutions, LLC - Response to Shpo Request for Additional Information for Er Project 2021PR03278.006, TMI-2 Decommissioning Project ML23167A4642023-07-0505 July 2023 Letter - TMI-2- Exemption 10 CFR Part 20 Append G Issuance ML23167A0312023-06-28028 June 2023 Acceptance Review and Schedule for the Request for Exemption from a Requirement from 10 CFR 20, Appendix G, Section Iii.E, EPID L-2023-LLE-0016 ML23171B0222023-06-19019 June 2023 (TMI-2) - Notification Pursuant to 10 CFR 72.140(d) Regarding Application of Previously Approved TMI-2 Quality Assurance Program to Independent Spent Fuel Storage Installation Activities ML23137A2822023-05-17017 May 2023 (TMI-2), Request for Exemption from 10 CFR 20, Appendix G, Section Iii.E ML23138A0662023-05-17017 May 2023 TMI-2 NHPA Section 106 Shpo Letter to NRC 5-17-23 ML23026A3132023-05-0202 May 2023 Issuance of Exemption from 10 CFR 70.24 (EPID-L-2023-LLE-0003) ML23122A1842023-05-0101 May 2023 Shpo_Er_Summary_Letter ML23121A2492023-05-0101 May 2023 License Amendment Request, Historic and Cultural Resources Review, Response to Request for Additional Information ML23117A0012023-04-26026 April 2023 Commitment Revision Summary Report ML23027A0832023-04-24024 April 2023 Environmental Assessment/Finding of No Significant Impact - Request for Exemption from 10 CFR 70.24 ML23108A0802023-04-18018 April 2023 Annual Radiological Effluent Release Report ML23108A0822023-04-18018 April 2023 Annual Radiological Environmental Operating Report IR 05000320/20230012023-04-12012 April 2023 TMI-2 Solutions, LLC, Three Mile Island Nuclear Station, Unit 2 - NRC Inspection Report No. 05000320/2023001 ML23102A0382023-04-10010 April 2023 Occupational Radiation Exposure Annual Report ML23108A2002023-04-10010 April 2023 CFR 20.2206(b) Personnel Radiation Exposure Report for 2022 ML23094A2582023-04-0606 April 2023 Letter to Sidney Hill, Chief, Onondaga Nation, Re., Initiation of Consultation Under Section 106 of the NHPA for the Proposed License Amendment Request for TMI 2 ML23093A0572023-04-0606 April 2023 Letter to Joanna Cain, President, Re., Ongoing Activities Related to the Proposed License Amendment Request for Three Mile Island Nuclear Station, Unit 2 ML23094A2362023-04-0606 April 2023 Letter to Carissa Speck, Re., Initiation of Consultation Under Section 106 of the NHPA for the Proposed License Amendment Request for Three Mile Island Nuclear Station, Unit 2 ML23094A2542023-04-0606 April 2023 Ltr J Bendremer Thpo Stockbridge-Munsee Community Band of Mohican Indians Re Initiation of Consultation Under Section 106 of the NHPA for Proposed License Amendment Request for TMI 2 ML23086C0652023-04-0606 April 2023 Ltr Larry Heady, Thpo, De. Tribe of Indian; Re., Initiation of Consultation Under Section 106 of the NHPA for the Proposed License Amendment Request for TMI Nuclear Station, Unit 2 ML23093A0562023-04-0606 April 2023 Letter to Steve Minnick, Site Decommissioning Director, Re., Ongoing Activities Related to the Proposed License Amendment Request for Three Mile Island Nuclear Station, Unit 2 ML23094A2602023-04-0606 April 2023 Letter to William Tarrant, Seneca-Cayuga Nation, Re., Initiation of Consultation Under Section 106 of the NHPA for the Proposed License Amendment Request for TMI 2 ML23094A2392023-04-0606 April 2023 Letter to Courtney Gerzetich, Thpo, Onedia Nation of Wisconsin, Re., Initiation of Consultation Under Section 106 of the NHPA for the Proposed License Amendment Request for TMI 2 ML23093A0592023-04-0606 April 2023 Letter to Rebecca Countess, Chair, Re., Ongoing Activities Related to the Proposed License Amendment Request for Three Mile Island Nuclear Station, Unit 2 2024-02-05
[Table view] Category:Request for Additional Information (RAI)
MONTHYEARML24011A2352024-01-11011 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 ML12310A1752012-11-13013 November 2012 Request for Additional Information Regarding 30-Day Report for Emergency Core Cooling System Model Changes Pursuant to the Requirements of 10 CFR 50.46 2024-01-11
[Table view] |
Text
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- 1' Mr. Michael J. Pacilio President and Chief Nuclear Officer Exelon Nuclear 4300 Winfield Road Warrenville, IL 60555
SUBJECT:
THREE MILE ISLAND NUCLEAR STATION, UNIT 1 - REQUEST FOR ADDITIONAL INFORMATION REGARDING LICENSE AMENDMENT REQUEST PROPOSING CHANGES TO THE NUMBER OF REQUIRED OPERABLE MAIN STEAM SAFETY VALVES (TAC NO. ME4808)
Dear Mr. Pacilio:
By letter dated September 24, 2010 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML102780570), Exelon Generation Company, LLC (Exelon, the licensee) submitted a license amendment request proposing to revise the Technical Specifications (TSs) for Three Mile Island Nuclear Station, Unit 1. The proposed changes would modify TS 3.4.1.2.3 regarding the number of main steam safety valves required to be operable as a function of power level.
The Nuclear Regulatory Commission staff has been reviewing the response and has determined that additional information is needed to complete its review. The speci"fic questions are found in the enclosed request for additional information (RAI). The questions were sent via electronic transmission on March 2, 2011, to Ms. Wendi Croft, of your staff. The draft questions were sent to ensure that the questions were understandable, the regulatory basis for the questions was clear, and to determine if the information was previously docketed. The draft questions were discussed in a meeting with your staff on March 14, 2011. Based on the outcome of the meeting, questions 2, 3, and 4 were slightly modified. It was agreed that a response to this RAI would be submitted by April 22, 2011.
Please contact me at 301-415-2833, if you have any questions.
Peter Bamford, Project Manager Plant Licensing Branch 1-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-289
Enclosure:
As stated cc w/encl: Distribution via Listserv
REQUEST FOR ADDITIONAL INFORMATION THREE MILE ISLAND NUCLEAR STATION, UNIT 1 PROPOSED TECHNICAL SPECIFICATION CHANGES REGARDING MAIN STEAM SAFETY VALVES DOCKET NO. 50-289 By letter dated September 24, 2010 (Agencywide Documents Access and Management System Accession No. ML102780570), Exelon Generation Company, LLC (the licensee), submitted a license amendment request (LAR) for Three Mile Island Nuclear Station, Unit 1 (TMI-1). The licensee proposes to revise Technical Specification (TS) 3.4.1.2.3 to allow up to two Main Steam Safety Valves (MSSVs) per steam generator to be inoperable with no required reduction in power level. The LAR would also revise the required maximum overpower trip setpoints for any additional inoperable MSSVs. In order for the Nuclear Regulatory Commission (NRC) staff to complete its review of the LAR, a response to the following request for additional information is requested.
- 1. In the LAR the licensee states, "The design capacity of the MSSVs is based on the ASME [American Society of Mechanical Engineers Boiler and Pressure Vessel] Code, Section 111." Section 10.3.1.1 of the TMI-1 Updated Final Safety Analysis Report (UFSAR), states, "Safety valves on the main steam lines and branches to the emergency feedwater turbine are designed in accordance with ASME Code Section III, Class A requirements." Further, UFSAR Section 10.7.4, "Overpressure Protection," refers to ASME Section III, 1989 edition for the determination of MSSV set pressures. The ASME Code,Section III, Paragraph NC-7410, "Set Pressure Limitations for Upset Conditions,"
states, "the stamped set pressure of at least one of the pressure relief devices [MSSVs]
connected to the system shall not be greater than the design pressure of any component within the pressure retaining boundary of the protected system."
In the LAR, the licensee is requesting to revise TMI-1 TS 3.4.1.2.3 to allow TMI-1 to operate at full power with seven of the nine MSSVs operable per steam generator and at reduced power level with up to five MSSVs inoperable per steam generator. In Attachment 3 of the LAR, Section 7.0, the licensee provides suggested changes to TS 3.4.1.2.3, as determined by the AREVA analyses which is included in the LAR, based on the number of inoperable MSSVs. The AREVA analysis includes a proposed conditional statement to ensure that the TS revision for TMI-1 would continue to meet the requirements of ASME Section III, NC-7410.
The proposed TS revision in the LAR does not include this conditional statement. The licensee states, "TMI has not adopted the suggested change in 86-9054640-002 Section 7.0, which states, "At leas[t] one (1) OPERABLE MSSV on each steam generator must have a nominal lift setpoint ~ 1050 [pounds per square inch gauge or psig]." The reason provided in the application is, in part, that the main steam piping is designed to [United States of America Standard or USAS] B31.1 and that there is no requirement for B31.1 piping to have at least one safety valve set at, or below, the piping design pressure.
Enclosure
- 2 The NRC staff requests that the licensee explain in more detail why the AREVA recommendation was not included in the application. This explanation should specifically address the requirements for the ASME Section III designed branches to the emergency feedwater pump turbine, as well as the ASME Section III design code for the MSSVs themselves, as described in the UFSAR. Also, the staff requests that the licensee provide a basis for the acceptance criteria that peak steam line pressure remains below 110 percent (%) of 1050 psig.
- 2. Attachment 3 of the LAR provides the AREVA analyses for all of the scenarios involving certain MSSVs inoperable at various power levels. The NRC staff requests that the licensee identify the basis for, and assumptions used, in the analysis for drift tolerance for each of the MSSV pressure setpoints. Also, the staff requests a description of the valves' accumulation behavior as illustrated in Figures 4-16 through 4-19, and clarify whether valve lift setpoint uncertainty and valve accumulation uncertainty are considered independently.
- 3. In Section 4.1 of Attachment 3 in the LAR, AREVA provides an analysis of allowing TMI 1 upset condition (turbine trip) at full power (100% with a 2% uncertainty, hence 102%)
with two MSSVs out of service. The licensee indicates that the most limiting condition occurs on steam generator 'B' steam line 4, with the following two MSSVs out of service:
MS-V17D and MS-V20D, each with lift setpoint pressures of 1050 psig. On Figure 4-13, AREVA shows the maximum pressures reached in the main steam lines were 1159.06 psia [pounds per square inch absolute] (1144.36 psig), in steam lines 3 and 4, and approximately 1140 psia (1125.3 psig), in steam lines 1 and 2. Also, in Figure 4-13, the maximum steam line pressure for all four steam lines appear to exceed 1115 psia (1100 psig) prior to 3 seconds during the turbine trip transient.
Regarding Figures 4-16,4-17, and 4-1B, MS-V19A with a setpoint of 10BO psig on steam line 1; MS-V20B with a setpoint of 1092.5 psig on steam line 2; and MS-V20C with a setpoint of 1092.5 psig on steam line 3, respectively, are depicted as not lifting in response to the turbine trip transient when the maximum pressures for steam lines 1, 2 and 3 are reached. Additionally on Figures 4-16 through 4-19, the following MSSVs are depicted as lifting wen after 3 seconds into the transient:
- MS-V1BA with a setpoint of 1060 psig on steam line 1
- MS-V1BB with a setpoint of 1060 psig and MS-V19B with a setpoint of 10BO psig on steam line 2
- MS-V1BC with a setpoint of 1060 psig and MS-V19C with a setpoint of 10BO psig on steam line 3
- MS-V1BD with a setpoint of 1060 psig on steam line 4 Figure 4-13 appears to contradict Figures 4-16 through 4-19 in regards to the time in which the MSSVs actuate during the transient.
The NRC staff requests that:
- a. The licensee clarify whether MSSVs MS-V19A, MS-V20B, and MS-V20C open in response to the maximum steam line pressures exceeding the
- 3 safety valves' setpoints during a turbine trip transient.
- b. The licensee clarify the times in which the other MSSVs, as described above, lift open in comparison to the pressure in each steam line during the turbine trip transient.
- c. For the limiting case, steam generator exit pressure is provided in Figure 4-13. The NRC staff requests a plot showing the pressure in the control volume for each steam line representing the pressure at the safety valves, and the parameters used to derive these values.
- d. Please provide a nodalization diagram of the main steam system, indicating the location of each safety valve.
- 4. Section NC-7511 of the ASME Section III Code states that the total rated relieving capacity shall be sufficient to prevent a rise in pressure of more than 10% above the design pressure of any component with the pressure retaining boundary of the protected system under any system upset conditions. In the TMI-'I LAR, the licensee states that the design capacity for the MSSVs is sufficient to limit secondary system pressure to less than or equal to 110% of design pressure when passing 100% of design steam flow.
The main steam line design pressure for TMI-1 is 1050 psig (1064.7 psia); hence 110%
of design pressure is 1155 psig (1169.7 psia).
In Section 4.1 of Attachment 3 in the LAR, AREVA provides an analysis of allowing TMI 1 upset condition (turbine trip) at full power with two MSSVs out of service. The licensee indicates that the most limiting condition occurs on steam generator 'B' steam line 4, where the MS-V17D and MS-V20D MSSVs are located, each with lift setpoint pressures of 1050 psig (1064.7 psia). The analysis shows the maximum steam line pressure does not exceed the limit of 1169.7 psia.
The AREVA analysis in Section 4.2 of Attachment 3 provides the results of three MSSVs (MS-V17D, MS-V1BD, and MS-V20D) being inoperable in steam line 4 at full power. The analysis determines that this condition would exceed the maximum allowable steam line pressure limit of 1169.7 psia.
However, the NRC staff postulates that a more limiting condition could possibly exist with MS-V17B and MS-V1BB MSSVs inoperable on steam line 2. Figure 4-17 in Attachment 3 depicts MSSV MS-V20B (setpoint of 1092.5 psig) not lifting during the transient. Based on AREVA's method of making the two lowest MSSVs in the steam line inoperable, the remaining relief capability on steam line 2 may be less than that of steam line 4 determined by AREVA as the most limiting case. Therefore, in comparison to the analysis in Section 4.2 showing only one MSSV lifting (MS-V19B lifts with a setpoint of 10BO psig) on steam line 2, the maximum pressure reached could exceed the allowable steam line pressure limit at full power.
Therefore, the NRC staff requests that the licensee provide the results of the sensitivity study, as well as the inputs and assumptions, used to determine how the MS-V17D and MS-V20D MSSVs were selected as the most limiting case for the turbine trip transient.
-4
- 5. In Attachment 3 of the LAR, Section 5.3 evaluated a plant condition with four MSSVs inoperable at 62% power level. However, Table 4 in the proposed LAR shows in the "Analyzed Power Level (% of 2772 MWt)" column that TMI-1 can operate at a power level of 77% with four MSSVs per steam generator inoperable. In Section 5.5 of the AREVA report included with the application, the 77% case is discussed, referring to a separate AREVA analysis, which is not included in the application. The NRC staff requests that the licensee provide the analysis of four MSSVs inoperable per steam generator at 77% power for confirmation that the analysis supports the requested TS changes.
March 25, 2011 Mr. Michael J. Pacilio President and Chief Nuclear Officer Exelon Nuclear 4300 Winfield Road Warrenville, IL 60555
SUBJECT:
THREE MILE ISLAND NUCLEAR STATION, UNIT 1 - REQUEST FOR ADDITIONAL INFORMATION REGARDING LICENSE AMENDMENT REQUEST PROPOSING CHANGES TO THE NUMBER OF REQUIRED OPERABLE MAIN STEAM SAFETY VALVES (TAC NO. ME4808)
Dear Mr. Pacilio:
By letter dated September 24, 2010 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML102780570), Exelon Generation Company, LLC (Exelon, the licensee) submitted a license amendment request proposing to revise the Technical Specifications (TSs) for Three Mile Island Nuclear Station, Unit 1. The proposed changes would modify TS 3.4.1.2.3 regarding the number of main steam safety valves required to be operable as a function of power level.
The Nuclear Regulatory Commission staff has been reviewing the response and has determined that additional information is needed to complete its review. The specific questions are found in the enclosed request for additional information (RAI). The questions were sent via electronic transmission on March 2, 2011, to Ms. Wendi Croft, of your staff. The draft questions were sent to ensure that the questions were understandable, the regulatory basis for the questions was clear, and to determine if the information was previously docketed. The draft questions were discussed in a meeting with your staff on March 14, 2011. Based on the outcome of the meeting, questions 2,3, and 4 were slightly modified. It was agreed that a response to this RAI would be submitted by April 22, 2011.
Please contact me at 301-415-2833, if you have any questions.
Sincerely, Ira!
Peter Bamford, Project Manager Plant Licensing Branch 1-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-289
Enclosure:
As stated cc w/encl: Distribution via Listserv DISTRIBUTION:
RidsNrrPMThreeMilelsland Resource PUBLIC LPLI-2 RtF RidsAcrsAcnw_MailCTR Resource RidsNrrLAABaxter Resource RidsOgcRp Resource RidsRgn1 MailCenter Resource RidsNrrDorlDpr Resource RidsNrrDorlLpl1-2 Resouce GArmstrong, NRR RidsNrrDssSbpb Resource SGardocki, NRR AGuzzetta, NRR BParks, NRR
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ADAMS Accession No . ML110620167
- via email II OFFICE LPL 1-2/PM LPL1*2/LA LPl1*2/LA LPLI-2IBC=
i NAME PBamford ABaxter
- GPurciarelio HChernoff for GCasto*
i DATE 03/18/2011 03/23/2011 03116/2011 03/25/2011 OFFICIAL RECORD COpy