Letter Sequence Other |
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Initiation
- Request, Request, Request, Request, Request, Request, Request, Request, Request, Request, Request, Request, Request, Request, Request, Request, Request
- Acceptance
- Supplement, Supplement, Supplement, Supplement, Supplement, Supplement, Supplement
Administration
- Withholding Request Acceptance, Withholding Request Acceptance, Withholding Request Acceptance
- Meeting, Meeting, Meeting, Meeting, Meeting, Meeting, Meeting, Meeting, Meeting, Meeting, Meeting, Meeting, Meeting, Meeting, Meeting, Meeting, Meeting, Meeting
Results
Other: ML13323A186, ML13323A189, ML13323A190, ML13323A191, ML13323B187, ML13323B191, ML13323B194, ML13323B196, ML13323B198, ML13323B199, ML13323B200, ML13323B201, ML13323B202, ML13323B204, ML13323B207, ML13323B208, ML13323B209, ML14015A045, ML14052A053, ML14072A076, ML14086A386, ML14149A089, ML14149A434, ML14149A435, ML14178A481, ML14321A438, ML14321A677, ML14344A545, ML14344A546, ML14349A790, ML15119A326, ML15175A024, ML15183A007, ML15183A009, ML15246A128, ML15246A129, ML15265A601, ML16230A232, NOC-AE-13003039, Corrections to Information Provided in Revised STP Pilot Submittal and Requests for Exemptions and License Amendment for a Risk-Informed Approach to Resolving Generic Safety Issue (GSI), NOC-AE-13003040, Attachment 1: CHLE-005, Rev. 1, Determination of the Initial Pool Chemistry for the Chle Test., NOC-AE-13003065, Response to STP-GSI-191-EMCB-RAI-1, NOC-AE-14003082, Alternate Source Term Dose Analysis: an Estimate of Risk Attributed to GSI-191, Attachment 3, NOC-AE-14003101, Enclosure 1 to Enclosure 6 Concerning Second Set of Responses to April 2014, Requests for Additional Information Regarding STP Risk-Informed GSI-191 Application, NOC-AE-14003103, University of Texas White Paper, Means of Aggregation and NUREG-1829: Geometric and Arithmetic Means, Rev. 3, Enclosure 2 to Attachment 1, NOC-AE-14003104, Revised Affidavit for Withholding for Casa Grande Analyses for Risk-Informed GSI-191 Licensing Application, NOC-AE-14003105, Third Set of Responses to April, 2014, Requests for Additional Information Regarding STP Risk-Informed GSI-191 Licensing Application, NOC-AE-14003106, Second Submittal of Casa Grande Source Code for Stp'S Risk-Informed GSI- 191 Licensing Application, NOC-AE-14003111, Submittal of Casa Grande Source Code for Stp'S Risk-Informed GSI-191 Licensing Application, NOC-AE-14003190, Attachment 2 to NOC-AE-14003190 - ALION-REP-STP-8998-14, Strainer Test Plan in Support of STP Pilot Risk-Informed GSI-191 Pilot Licensing Application, NOC-AE-15003220, Description of Revised Risk-Informed Methodology and Responses to Round 2 Requests for Additional Information Regarding STP Risk-Informed GSI-191 Licensing Application... further results
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MONTHYEARML13323B1962012-06-12012 June 2012 Attachment 4: CHLE-008, Rev. 3, Debris Bed Preparation and Formation Test Results. Project stage: Other ML13323B1942012-08-11011 August 2012 Attachment 3: CHLE-007, Rev. 3, Debris Bed Requirements and Preparation Procedures. Project stage: Other NOC-AE-13003040, Attachment 1: CHLE-005, Rev. 1, Determination of the Initial Pool Chemistry for the Chle Test.2012-08-13013 August 2012 Attachment 1: CHLE-005, Rev. 1, Determination of the Initial Pool Chemistry for the Chle Test. Project stage: Other ML13323B1912012-08-14014 August 2012 Attachment 2: CHLE-006, Rev. 1, STP Material Calculations. Project stage: Other ML13323B1982012-08-19019 August 2012 Attachment 5: CHLE-010, Rev. 2, Chle Tank Test Results for Blended and NEI Fiber Beds with Aluminum Addition. Project stage: Other ML13323B1992013-01-0909 January 2013 Attachment 6: CHLE-012, Rev. 3, T1 Mbloca Test Report, Cover Through Figure 52 Project stage: Other ML13323B2002013-01-0909 January 2013 Attachment 6: CHLE-012, Rev. 3, T1 Mbloca Test Report, Figure 53 Through End Project stage: Other ML13323B2022013-01-15015 January 2013 Attachment 8: CHLE-015, Rev. 3, Summary of Chemical Effects Testing in 2012 for STP GSI-191 License Submittal. Project stage: Other ML13323B2042013-01-22022 January 2013 Attachment 9: CHLE-016, Rev. 2, Calculated Material Release to Estimate Chemical Effects. Project stage: Other ML13323B2012013-01-22022 January 2013 Attachment 7: CHLE-014, Rev. 2, T2 LBLOCA Test Report. Project stage: Other NOC-AE-13002954, Pilot Submittal and Request for Exemption for a Risk-Informed Approach to Resolve Generic Safety Issue (GSI)-1912013-01-31031 January 2013 Pilot Submittal and Request for Exemption for a Risk-Informed Approach to Resolve Generic Safety Issue (GSI)-191 Project stage: Request ML13214A0312013-08-13013 August 2013 Acceptance Review, Exemption Requests and License Amendment Request to Revise UFSAR for Resolution of Generic Safety Issue 191, Assessment of Debris Accumulation on PWR Sump Performance (TAC MF0613-MF0614; MF2400-09) Project stage: Acceptance Review ML13323B2072013-09-16016 September 2013 Attachment 10: CHLE-018, Rev. 2, Results of Bench Tests to Assess Corrosion of Aluminum in STP Containment Conditions. Project stage: Other ML13323B2082013-09-23023 September 2013 Attachment 11: CHLE-019, Rev. 2, Test Results for Chemical Effect Tests Stimulating Corrosion and Precipitation (T3 & T4) Project stage: Other NOC-AE-13003039, Corrections to Information Provided in Revised STP Pilot Submittal and Requests for Exemptions and License Amendment for a Risk-Informed Approach to Resolving Generic Safety Issue (GSI)2013-10-0303 October 2013 Corrections to Information Provided in Revised STP Pilot Submittal and Requests for Exemptions and License Amendment for a Risk-Informed Approach to Resolving Generic Safety Issue (GSI) Project stage: Other ML13323B2092013-10-0404 October 2013 Attachment 12: CHLE-020, Rev. 2, Test Results for a 10-day Chemical Effects Test Simulating LBLOCA Conditions (T5). Project stage: Other ML13323A1892013-10-22022 October 2013 Enclosure 4-2 - Risk-Informed Closure of GSI-191, Volume 2 Probabilistic Risk Analysis Project stage: Other ML13323B1872013-10-31031 October 2013 Project, Units 1 & 2, Submittal of GSI-191 Chemical Effects Test Reports (TAC Nos. MF2400 and MF2401) Project stage: Other ML13323A1912013-11-0606 November 2013 Enclosure 4-3 Risk-Informed Closure of GSI-191, Volume 3, Engineering (Casa Grande) Analysis, Page 212 of 1-122 Project stage: Other ML13323A1902013-11-0606 November 2013 Enclosure 4-3 Risk-Informed Closure of GSI-191, Volume 3, Engineering (Casa Grande) Analysis, Cover - Page 211 of 248 Project stage: Other ML13323A1862013-11-12012 November 2013 Enclosure 4-1 - Risk-Informed Closure of GSI-191, Volume 1 Project stage: Other NOC-AE-13003043, Enclosure 5 - Response to NRC Supplemental Information Items2013-11-13013 November 2013 Enclosure 5 - Response to NRC Supplemental Information Items Project stage: Supplement ML13323A1832013-11-13013 November 2013 Project Units 1 and 2 - Supplement 1 to Revised STP Pilot Submittal and Requests for Exemptions and License Amendment for a Risk-Informed Approach to Resolving Generic Safety Issue (GSI)-191 Project stage: Supplement NOC-AE-13003054, Supplement 1 to Revised STP Pilot Submittal for a Risk-Informed Approach to Resolving Generic Safety Issue (GSI)-191 to Supersede and Replace the Revised Pilot Submittal2013-11-21021 November 2013 Supplement 1 to Revised STP Pilot Submittal for a Risk-Informed Approach to Resolving Generic Safety Issue (GSI)-191 to Supersede and Replace the Revised Pilot Submittal Project stage: Supplement ML13330B2222013-12-0505 December 2013 Notice of Meeting with STP Nuclear Operating Company to Discuss Revised Pilot Submittal and Request for Exemptions for a Risk-Informed Approach to Resolve Generic Safety Issue (GSI)-191 at South Texas Project, Units 1 and 2 (TAC MF2400-MF24 Project stage: Meeting NOC-AE-13003065, Response to STP-GSI-191-EMCB-RAI-12013-12-23023 December 2013 Response to STP-GSI-191-EMCB-RAI-1 Project stage: Other NOC-AE-13003070, Response to NRC Request for Reference Document for STP Risk-Informed GSI-191 Application2013-12-23023 December 2013 Response to NRC Request for Reference Document for STP Risk-Informed GSI-191 Application Project stage: Request ML13357A2662013-12-24024 December 2013 1/8/14 - Notice of Meeting with STP Nuclear Operating Co. to Discuss Revised Pilot Submittal and Request for Exemptions for a Risk-Informed Approach to Resolve Generic Safety Issue (GSI)-191 at South Texas Project, Units 1 and 2 Project stage: Meeting NOC-AE-13003057, Response to Request for Additional Information Re Use of RELAP5 in Analyses for Risk-Informed GSI-191 Licensing Application2014-01-0909 January 2014 Response to Request for Additional Information Re Use of RELAP5 in Analyses for Risk-Informed GSI-191 Licensing Application Project stage: Response to RAI ML14009A3072014-01-0909 January 2014 NRR E-mail Capture - Request for Additional Information - TACs MF2400 Through MF2409 Project stage: RAI ML13358A0622014-01-14014 January 2014 Summary of 12/16/13 Meeting with STP Nuclear Operating Co. to Discuss Revised Pilot Submittal and Request for Exemptions for a Risk-Informed Approach to Resolve Generic Safety Issue (GSI)-191 at South Texas Project, Units 1 and 2 Project stage: Meeting ML14015A0452014-01-14014 January 2014 NRR E-mail Capture - Rai'S Regarding South Texas Project'S Submittal for Risk-Informed Resolution of GS-191 Project stage: Other NOC-AE-14003081, STP-Specific Casa Grande Inputs CASA01 JT4, CASA09 JT4, CASA22 JT4, CASA26 JT4, & CASA43 JT42014-02-13013 February 2014 STP-Specific Casa Grande Inputs CASA01 JT4, CASA09 JT4, CASA22 JT4, CASA26 JT4, & CASA43 JT4 Project stage: Request ML14052A0532014-02-13013 February 2014 Project Units 1 & 2, Submittal of Casa Grande Code & Analyses for Risk-Informed GSI-191 Licensing Application Project stage: Other ML14149A4352014-02-14014 February 2014 Project, Units 1 and 2 - ALION-REP-STP-8998-02, Rev. 0, STP Casa Grande Analysis and LAR Enclosure 4-3 RAI Response, Enclosure 1 to Attachment 1 Project stage: Other ML14072A0842014-02-18018 February 2014 CHLE-012, T1 Mbloca Test Report, Revision 4 Project stage: Request ML14072A0792014-02-22022 February 2014 CHLE-020, Test Results for 10-Day Chemical Effects Test Simulating LBLOCA Condition (T5), Revision 3 Project stage: Request ML14072A0852014-02-22022 February 2014 CHLE-014, T2 LBLOCA Test Report, Revision 3 Project stage: Request ML14072A0822014-02-23023 February 2014 CHLE-008, Debris Bed Preparation & Formation Test Results, Revision 4 Project stage: Request ML14072A0832014-02-24024 February 2014 CHLE-010, Chle Tank Test Results for Blended and NEI Fiber Beds with Aluminum Addition, Revision 3 Project stage: Request ML14072A0762014-02-27027 February 2014 Project, Units 1 and 2, Submittal of GSI-191 Chemical Effects Test Reports (TAC Nos. MF2400 and MF2401) Project stage: Other ML14072A2112014-03-0606 March 2014 NRR E-mail Capture - STP Sensitivity Report and Presentation for Proposed Meeting Project stage: Request NOC-AE-14003082, Alternate Source Term Dose Analysis: an Estimate of Risk Attributed to GSI-191, Attachment 32014-03-11011 March 2014 Alternate Source Term Dose Analysis: an Estimate of Risk Attributed to GSI-191, Attachment 3 Project stage: Other ML14086A3862014-03-17017 March 2014 STP Risk-Informed GSI-191 Aadb RAI 3 Response, Attachment 2 Project stage: Other ML14086A3852014-03-17017 March 2014 Project, Units 1 & 2 - Response to NRC Accident Dose Branch Request for Additional Information Regarding STP Risk-Informed GSI-191 Application Project stage: Request NOC-AE-14003111, Submittal of Casa Grande Source Code for Stp'S Risk-Informed GSI-191 Licensing Application2014-03-18018 March 2014 Submittal of Casa Grande Source Code for Stp'S Risk-Informed GSI-191 Licensing Application Project stage: Other NOC-AE-14003114, Seismic Hazard and Screening Report (CEUS Sites), Response NRC Request for Information Pursuant to 10 CFR 50.54(f) Regarding Recommendation 2.1 of the Near-Term Task Force Review of Insights from the Fukushima Dai..2014-03-31031 March 2014 Seismic Hazard and Screening Report (CEUS Sites), Response NRC Request for Information Pursuant to 10 CFR 50.54(f) Regarding Recommendation 2.1 of the Near-Term Task Force Review of Insights from the Fukushima Dai.. Project stage: Request ML14091A4522014-04-0808 April 2014 Request for Withholding Information from Public Disclosure - 12/9/13 G. Powell, STPNOC Affidavit Enclosing RELAP5 Digital Media Related to GSI-191 License Amendment and Exemption Requests Project stage: Withholding Request Acceptance ML14087A0752014-04-15015 April 2014 Request for Additional Information, Request for Exemptions and Revised Pilot License Amendment Request for a Risk-Informed Approach to Resolve Generic Safety Issue (GSI)-191 Project stage: RAI NOC-AE-14003103, University of Texas White Paper, Means of Aggregation and NUREG-1829: Geometric and Arithmetic Means, Rev. 3, Enclosure 2 to Attachment 12014-04-18018 April 2014 University of Texas White Paper, Means of Aggregation and NUREG-1829: Geometric and Arithmetic Means, Rev. 3, Enclosure 2 to Attachment 1 Project stage: Other 2013-12-05
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Category:E-Mail
MONTHYEARML24086A4212024-06-26026 June 2024 Email to Chris Warren Decision on the Exemption Request for South Texas Project ML24086A4252024-06-24024 June 2024 Email to Chris Warren Availability of Environmental Assessment for the South Texas Project Exemption ML24101A0082024-04-10010 April 2024 NRR E-mail Capture - South Texas Project - Relief Request - 50.55a(z)(2) - Rvh Penetration 75 ML24052A0152024-02-20020 February 2024 NRR E-mail Capture - South Texas Project - Request for Additional Information - Request for Exemption from Enhanced Weapons, Firearms Background Checks, and Security Event Notifications (L-2023-LLE-0046) ML24052A0112024-02-16016 February 2024 NRR E-mail Capture - South Texas Project - Draft Request for Additional Information - Request for Exemption from Enhanced Weapons, Firearms Background Checks, and Security Event Notifications (L-2023-LLE-0046) ML23334A0062023-11-29029 November 2023 NRR E-mail Capture - South Texas Project - Request for Additional Information - Proposed Alternative to ASME BPV Code Requirements ML23319A4442023-11-15015 November 2023 NRR E-mail Capture - South Texas Project - Draft Request for Additional Information - Proposed Alternative to ASME BPV Code Requirements ML23278A1532023-10-0505 October 2023 NRR E-mail Capture - South Texas Project Request for Additional Information - Request for Indirect Transfer of Licenses and Conforming Amendments (L-2023-LLM-0004) ML23264A0972023-09-21021 September 2023 NRR E-mail Capture - South Texas Project - Request for Additional Information - License Amendment Request to Revise the Alternate Source Term Dose Calculation (L-2023-LLA-0047) ML23255A2862023-09-12012 September 2023 NRR E-mail Capture - South Texas Project Draft Request for Additional Information License Amendment Request to Revise the Alternate Source Term Dose Calculation (L-2023-LLA-0047) ML23191A0102023-07-0707 July 2023 NRR E-mail Capture - South Texas Project - Acceptance of Request for Indirect Transfer of Licenses and Conforming Amendments (L-2023-LLM-0004) ML23145A1872023-05-24024 May 2023 July 2023 Emergency Preparedness Program Inspection - Request for Information ML23124A3272023-05-0404 May 2023 NRR E-mail Capture - South Texas Project - Acceptance of License Amendment Request to Revise the Alternate Source Term Dose Calculation (L-2023-LLA-0047) ML23115A0702023-04-24024 April 2023 NRR E-mail Capture - South Texas Project Units 1 and 2 - Audit Plan - Proposed Alternative to ASME Code, Section XI Requirements for Containment Building Inspections ML23096A1592023-04-0606 April 2023 NRR E-mail Capture - South Texas Project - Acceptance of Requested Licensing Action - Proposed Alternative to the Requirements of the ASME Code ML23065A0912023-03-0303 March 2023 NRR E-mail Capture - South Texas Project - Draft Supplemental Information Request - Proposed Alternative to the Requirements of the ASME Code ML23003A8082022-11-28028 November 2022 NRR E-mail Capture - Texas Commission on Environmental Quality (TCEQ) Review/Comment Regarding the Draft Environmental Assessment for the South Texas Project Alternate Disposal Request (L-2021-LLL-0022)) ML22249A0692022-09-0606 September 2022 NRR E-mail Capture - South Texas Project - Acceptance of License Amendment Request Regarding Adoption of TSTF-554, Revise Reactor Coolant Leakage Requirements (L-2002-LLA-0113) ML22206A0142022-07-20020 July 2022 NRR E-mail Capture - South Texas Project - Request for Additional Information - 10 CFR 20.2002 Alternate Disposal Request ML22194A0502022-07-0707 July 2022 NRR E-mail Capture - South Texas Project - Updated Draft Request for Additional Information - 10 CFR 20.2002 Alternate Disposal Request ML22194A0492022-06-0808 June 2022 NRR E-mail Capture - South Texas Project - Draft Request for Additional Information - 10 CFR 20.2002 Alternate Disposal Request ML22123A3272022-05-0303 May 2022 STP EP Exercise Inspection July 2022 RFI ML22115A2632022-04-19019 April 2022 Email Response to David Lochbaum Regarding Interim Configuration of Holtec HI-STORE FW Spent Fuel Multipurpose Canister at South Texas Project Energy Generating Station ML22105A5642022-04-0505 April 2022 Request for Information for Problem Identification and Resolution at STP Nuclear Operating Company ML21344A0072021-12-0909 December 2021 NRR E-mail Capture - South Texas Project - Acceptance of Requested Licensing Action - Alternative Disposal Request ML21305B8022021-11-0101 November 2021 NRR E-mail Capture - South Texas Project - Acceptance of Requested Licensing Action - Inservice Inspection Impracticality ML21257A2262021-09-14014 September 2021 NRR E-mail Capture - South Texas Project - Acceptance of License Amendment Request Regarding Adoption of TSTF-577, Revised Frequencies for Steam Generator Tube Inspections (L-2021-LLA-0151) ML21160A1522021-06-0909 June 2021 Request for Information NRC Inspection 2021-003 Public Radiation Safety ML21133A2372021-05-0505 May 2021 Request for Additional Information: STP EP Exercise Inspection - July 2021 ML21117A3242021-04-22022 April 2021 NRR E-mail Capture - (External_Sender) STP Questions About Eplan Amendment SE ML21103A0072021-04-12012 April 2021 NRR E-mail Capture - South Texas Project - Acceptance of License Amendment Request to Add a Note to TS 3.6.3 and to Remove the TS Index (L-2021-LLA-0041) ML21058A0002021-02-26026 February 2021 NRR E-mail Capture - South Texas Units 1 and 2 - License Amendment Request to Revise Moderator Temperature Coefficient SRs - Audit Plan and Setup of Online Document Access (L-2021-LLA-0004) ML21049A2652021-02-16016 February 2021 NRR E-mail Capture - South Texas Project - Acceptance of License Amendment Request to Revise the Moderator Temperature Coefficient Surveillance Requirements (L-2021-LLA-0004) ML21039A8902021-02-0808 February 2021 NRR E-mail Capture - South Texas Project - Request for Additional Information - 1RE22 Inspection Summary Report for Steam Generator Tubing ML21029A3312021-01-29029 January 2021 NRR E-mail Capture - South Texas Project - Draft Request for Additional Information - 1RE22 Inspection Summary Report for Steam Generator Tubing ML20244A0222020-08-28028 August 2020 NRR E-mail Capture - South Texas Project - Acceptance of License Amendment Request to Adopt TSTF-374, Revision to TS 5.5.13 and Associated TS Bases for Diesel Fuel Oil. (L-2020-LLA-0172) ML20135H1982020-05-14014 May 2020 NRR E-mail Capture - South Texas Unit 1 - License Amendment Request to Revise Safety Injection System Accumulator Pressure - Audit Plan and Setup of Online Reference Portal ML20125A3312020-05-0404 May 2020 NRR E-mail Capture - South Texas Project - Acceptance of License Amendment Request to Revise the Emergency Plan (L-2020-LLA-0057) ML20111A0052020-04-17017 April 2020 NRR E-mail Capture - South Texas Project - Request for Additional Information - Proposed Alternative to ASME OM Code 2012 Edition - Relief Request PRR-01 ML20050E1192020-02-19019 February 2020 NRR E-mail Capture - South Texas Project - Acceptance of Requested Licensing Actions - Proposed Alternatives to ASME OM Code Requirements (EPID: L 2020-LLR-0007 to L-2020-LLR-0010) ML19344A0092019-12-0909 December 2019 NRR E-mail Capture - South Texas Project - Acceptance of Requested Licensing Action - Proposed Alternative to ASME Code Requirements for the Repair of Essential Cooling Water System Class 3 Buried Piping ML19309F1412019-11-0404 November 2019 Supplemental Information Request - Proposed Alternative to ASME Code Requirements for the Repair of Essential Cooling Water System Class 3 Buried Piping (EPID L 2019-LLR-0096) (Draft) ML19291A0332019-10-17017 October 2019 NRR E-mail Capture - Acceptance Review Results: STP License Amendment Request Regarding Request to Delete E Bar Definition ML19165A1032019-06-14014 June 2019 NRR E-mail Capture - Draft RAI for STP TS 3.8.1.1 Sbdg SR Change ML19162A1162019-05-22022 May 2019 NRR E-mail Capture - Acceptance Review Results: STP License Amendment Request Regarding TSTF-529 ML19095A6562019-04-0404 April 2019 NRR E-mail Capture - (External_Sender) Handout for 4/10/19 Meeting to Discuss a Proposed Request for South Texas Project, Units 1 and 2, Regarding Repair of Piping Using Carbon Fiber Repair Methods ML19081A1512019-03-21021 March 2019 NRR E-mail Capture - Draft Round 2 RAI - Sbdg Voltage and Frequency LAR (L-2018-LLA-0078) ML19078A3792019-03-19019 March 2019 NRR E-mail Capture - Acceptance Review Results: STP RR-ENG-3-23 (L-2018-LLR-0021) ML18292A7272018-10-19019 October 2018 NRR E-mail Capture - Acceptance Review Results: TSTF-522 (L-2018-LLA-0271) ML18283B9522018-10-10010 October 2018 NRR E-mail Capture - Final RAI - South Texas Standby DG TS Change (L-2018-LLA-0078) 2024-06-26
[Table view] Category:Slides and Viewgraphs
MONTHYEARML24080A1292024-03-25025 March 2024 March 25, 2024, Pre-Submittal Meeting for STP QA Plan Change ML22243A1312022-08-31031 August 2022 STP Nuclear Operating Company August 31, 2022 Presentation - Pre-Submittal Meeting for Updated Main Steam Line Break and Locked Rotor Dose Consequence Analysis to Address Extended Cooldown Timelines ML22214A0972022-08-0202 August 2022 Presentation by South Texas Project ML22153A2942022-06-17017 June 2022 richardsd-hv-th28 ML21203A2702021-07-26026 July 2021 Presentation - 7-26-21 Meeting with STPNOC Proposed South Texas Project Moderator Temperature Coefficient TS Change ML20248H5322020-09-0404 September 2020 STP Nuclear Operating Company September 14, 2020, Presentation - Pre-Submittal Meeting for Proposed South Texas Project Moderator Temperature Coefficient Surveillance Requirement Technical Specification Change ML20125A3362020-05-0404 May 2020 STP Presubmittal Meeting Exigent Accumulator LAR 2020-05-05 Presentation L-2020-LRM-0039 ML20034E8192020-02-0606 February 2020 Pre-Application Public Meeting for Proposed License Amendment Request to Revise the STPEGS Emergency Plan ML19095A6562019-04-0404 April 2019 NRR E-mail Capture - (External_Sender) Handout for 4/10/19 Meeting to Discuss a Proposed Request for South Texas Project, Units 1 and 2, Regarding Repair of Piping Using Carbon Fiber Repair Methods ML17004A0292017-01-0404 January 2017 Slides for January 4, 2017, Public Meeting on South Texas Project's Resposne to Aluminum Bronze Aging Management Request for Additional Information ML16356A0612016-12-21021 December 2016 12/21/2016 South Texas Project Aluminum Bronze Aging Management Request for Additional Information ML16350A3272016-11-17017 November 2016 Transcript of Advisory Committee on Reactor Safeguards Plant License Renewal Subcommittee Meeting - November 17, 2016 ML16264A3632016-09-20020 September 2016 Pre-Application Public Meeting for Proposed License Amendment Request to Revise the STPEGS Emergency Plan Staff Augmentation Times ML16172A0192016-07-25025 July 2016 STP Aluminum Bronze Selective Leaching Public Meeting - June 21, 2016 ML16188A3682016-07-0606 July 2016 Audit Presentation - Westinghouse Methodology for South Texas Unit 1 LAR: Operation with 56 Control Rods ML16062A3042016-03-0202 March 2016 TS 5.3.2 LAR Pre-Submittal Meeting Presentation - March 2, 2016 ML16033A0042016-01-19019 January 2016 Applicant's Slides for STP Meeting on Aluminum Bronze Aging Management ML15334A3972015-11-30030 November 2015 TS 5 3 2 Emergency LAR Pre-Submittal Meeting Presentation ML15274A5992015-10-0101 October 2015 10-01-15 Public Phone Call ML15034A1512015-02-0505 February 2015 Integrated Leak Rate Test (ILRT) from 10 Years to 15 Years. NRC Public Meeting Slides - ILRT License Amendment ML15034A1142015-02-0404 February 2015 STP Risk- Informed Approach to GSI - 191 Roverd 2015 Meeting Blue 1 29 15 ML14192A9842014-08-0404 August 2014 Summary of Pre-Licensing Meeting with STP Nuclear Operating Company to Discuss Future License Amendment Request to Revise TS 6.9.1.6.b.9 to the Leading Edge Flow Meter Technology for Feedwater Flow Measurement ML14149A0892014-05-21021 May 2014 NRR E-mail Capture - STP-GSI-191 Presentation ML14120A0112014-04-29029 April 2014 4/29/2014 - South Texas Project Regulatory Approach for Risk-Informed Pilot Submittal Presentation Relating to 10 CFR 50.46c ML13352A1422013-12-16016 December 2013 GSI-191 Licensing Submittal Comparison of Changes Between Rev 1 and Rev 2 ML13352A1242013-12-16016 December 2013 NRC Staff Slides South Texas Project Risk-Informed Generic Safety Issue - 191, December 16, 2013 ML13316B9052013-11-13013 November 2013 Albrz Testing Update for NRR Final ML13150A2162013-05-23023 May 2013 Licensee Slides for 5/23/13 Public Meeting Regarding GSI-191 ML13140A2562013-05-20020 May 2013 Licensee Slides for 5/23/13 Meeting - STP Pilot Submittal for Risk Informed Approach to Resolving GSI-191 ML13023A3342013-02-25025 February 2013 1/15/2013 Summary of Public Meetings Conducted to Discuss Draft Supplemental Environmental Impact Statement Related to Review of South Texas Project, Units 1 & 2, License Renewal Application ML13051A8552013-02-20020 February 2013 Licensee Slides for 3/5/13 Pre-Application Meeting for Proposed Licensing Action to Revise the Fire Protection Program at STP ML13029A4972013-01-15015 January 2013 Slides - Preliminary Site-Specific Results of the Environmental Review for South Texas Project License Renewal ML12297A3312012-11-27027 November 2012 Summary of Prelicensing Meeting with STP Nuclear Operating Company to Discuss Proposed Amendment for Approval of Revised Fire Protection Program Related to Alternate Shutdown Capability for South Texas, Units 1 and 2 ML12264A3202012-10-11011 October 2012 Meeting Handout for 10/11/12 Pre-licensing Meeting License Amendment Request to Revise the Fire Protection Program ML1209004042012-03-30030 March 2012 3-27-2012 - STP Public Meeting Handout from Nuclear Innovation North America, LLC on Fukushima Lessons Learned for South Texas Project Units 3 and 4 ML1204400652012-02-0909 February 2012 Licensee Slides for 2/9/12 Meeting Regarding GSI-191 ML1133505632011-12-0101 December 2011 Licensee Presentation from 12/1/11 Meeting Via Conference Call to Discuss Risk-Informed GSI-191,Assessment of Debris Accumulation on Pressurized Water Reactor Sump Performance ML1130506322011-10-26026 October 2011 Licensee Handouts from November 1, 2011 Meeting with STP Nuclear Operating Company on GSI-191 ML1127702032011-10-0303 October 2011 Licensee Slides from 10/3/11 Meeting LOCA Frequencies, Final Results ML1127701762011-10-0303 October 2011 Licensee Handouts from 10/3/11 Meeting STP LOCA Frequency ML1123508732011-08-22022 August 2011 Models and Methods Used for Casa Grande ML1123508832011-08-22022 August 2011 LOCA Initiating Event Frequencies and Uncertainties Status Report ML1120707072011-07-26026 July 2011 Meeting Notice with South Texas Project, Units 1 and 2 - Licensee Slide Models and Methods Used for Casa Grande ML1120707292011-07-26026 July 2011 Meeting Notice with South Texas Project, Units 1 and 2 - Licensee Slides Computational Fluid Dynamics Validation Plan ML1118903802011-07-0707 July 2011 Licensee Slides, LOCA Initiating Event Frequencies and Uncertainties(Draft) ML1118904202011-07-0606 July 2011 Licensee Slide from 7/7/11 Meeting with STP Nuclear ML11157A0102011-06-0202 June 2011 STP Nuclear Operating Company, Licensee Handouts, 6/2/2011 Meeting Risk-Informed GSI-191 Closure Plan for GSI-191 Resolution ML1114501952011-05-24024 May 2011 Summary of Meeting with South Texas Project Electric Generating Station 2010 Performance ML1105503952011-02-22022 February 2011 Licensee Slides from 2/22/11 Public Meeting with STP Nuclear Operating Company ML1103206432011-01-27027 January 2011 1/27/11 Presentation on Risk-Informed GSI-191 Project Overview 2024-03-25
[Table view] |
Text
NRR-PMDA-ECapture Resource From: Harrison Albon <awharrison@STPEGS.COM>
Sent: Wednesday, May 21, 2014 11:03 AM To: Singal, Balwant Cc: Kee, Ernie; Blossom, Steven; Murray, Michael
Subject:
STP Sensitivity Presentation Attachments: STP-GSI-191 Presentation May 222014.pdf
- Balwant, Our presentation is attached. Also, Alion confirmed the SWRI presentation has no proprietary information.
Wayne 1
CASA Grande Sensitivity Studies May 22,2014
Introductions
- Presenters Mike Murray Wayne Harrison Ernie Kee David Morton Bruce Letellier 2
Introductions
- Contributors Steve Blossom Zahra Mohaghegh Seyed Reihani Jeremy Tejada Don Wakefield 3
Summary
- Summarize approach to sensitivity analyses
- Demonstrate the approach on several parameters
- Review and explain counterintuitive results observed with certain parameters 4
Development Status and Potential Application o Development Status o NOT being proposed for NRC review/approval as part of the Risk-Informed Pilot Application o Will require appropriate validation and verification o Potential Applications o Facilitate evaluation of emergent plant conditions Facilitate identification/prioritization of compensatory actions Quantitative assessment may be required to formalize evaluation o Evaluation of plant modifications 5
Potential Application and Development Status, cont.
o Current and Potential Features (Ref. ML14072A211) o One-way sensitivity, tornado plots (Step 6) o One-way sensitivity studies, UQ plots (Step 7) o One-way sensitivity: Spider Plots (Step 8) o Two-way (two at a time) sensitivity studies (Step 9) o Meta models (Step 10) (response surface correlation)
To support multi-attribute sensitivity and simplified analysis of plant response o Compliance with standard software quality assurance o Importance o Helps show the relative importance of parameters o Helps to identify potential errors (counterintuitive results) and thereby contributes to analysis quality 6
CASA
Grande
Sensi-vity
Studies
John Hasenbein David Morton Jeremy Tejada Alex Zolan May 22, 2014 7
Sensitivity Studies
10-Step Sensitivity Analysis Process
- Step 2: Select Outputs of Interest
- Step 3: Select Inputs of Interest
- Step 4: Choose Nominal Values and Ranges for Inputs
- Step 5: Estimate Model Outputs under Nominal Input Values
- Step 6: One-Way Sensitivity Analysis: Sensitivity Plots & Tornado Diagrams
- Step 7: One-Way Sensitivity Analysis: UQ Plots
- Step 8: One-Way Sensitivity Analysis: Spider Plots
- Step 9: Two-way Sensitivity Analysis: Two-way Sensitivity Plots
- Step 10: Metamodels & Design of Experiments 9
Step 1: Define the Model
- We wont detail CASA Grande here (Volume 3)
- Use CASA Grande to estimate probability of sump failure and boron fiber limit failure, conditional on small, medium & large breaks
- Estimate change in core damage frequency (CDF) in events/year due to GSI-191 issues using these failure probability estimates and corresponding frequencies
- All results here are conditional on all pumps working 10
Step 2: Select Outputs of Interest
- Change in core damage frequency (CDF)
- Sometimes, we report ratio of CDF estimate for a scenario to CDF estimate for baseline and call this the risk ratio
- Use stratified sampling on initiating frequency
- Use IID replications within each cell of stratification
- Use common random numbers across scenarios; i.e., use CRNs across specified changes in input parameters 11
Step 2: Outputs: Estimating CDF Indices and Sets:
i = 1, . . . , F index for cells stratifying frequency replications k = 1, . . . , N index for set of pump states Events:
SL, M L, LL small, medium, large LOCA P Sk pumps in state k Fi initiating frequency in cell i S sump failure B boron fiber limit failure CD core damage Parameters:
fSL , fM L , fLL frequency (events/CY) of a small, medium, large LOCA P (P Sk ) probability mass of P Sk P (Fi ) probability mass of Fi P (SlLOCA, Fi , P Sk ) estimate of probability of S given LOCA = SL, M L, orLL, Fi , P Sk P (BlLOCA, Fi , P Sk ) estimate of probability of B given LOCA = SL, M L, orLL, Fi , P Sk RBASE non-GSI-191 core damage frequency (events/CY)
RCD estimate of core damage frequency (events/CY) 12
Step 2: Outputs: Estimating CDF CDF = RCD RBASE X F X N
= P (Fi )P (P Sk )
fSL
- P (SlSL, Fi , P Sk ) + fSL
+fM L
- P (SlM L, Fi , P Sk ) + fM L
i
+fLL
- P (SlLL, Fi , P Sk ) + fLL
- fSL , fML , fLL from Volume 2s Table 4-1
- P(all pumps working)=1
- P(Fi ): Bounded Johnson fit to NUREG-1829
- We form a variance estimate for the above estimator 13
Step 3: Select Inputs of Interest
- Amount of Latent Fiber in Pool: Existing dust/dirt in containment, based on plant measurement. Assumed to be in the pool at start of recirculation, uniformly mixed. During fill up, latent debris available to penetrate sump screen.
- Boron Fiber Limit: Refers to threshold where boron precipitation occurs for cold leg breaks. Fiber limit comes from vendor testing that shows no pressure drop occurs with full chemical effects. Assume all fiber that penetrates sump screen deposits uniformly on core.
- Debris Transport Fractions in ZOI: Refers to debris transport fractions involving three-zone ZOI. Each insulation type has characteristic ZOI divided in three sections to account for type of damage within each zone.
14
Step 3: Select Inputs of Interest
- Chemical Precipitation Temperature: CASA Grande assumes that, once a thin bed of fiber forms on strainer, chemical head loss factors apply when pool temperature reaches precipitation temperature.
- Total Failure Fraction for Debris Outside the ZOI: CASA Grande uses table of total failure fractions applied to transport logic trees. Fraction of each type (fiber, paint and coatings, etc.) that passes to the pool are used to understand what is in the pool as a function of time during recirculation.
- Chemical Head Loss Factor: Used as a multiplier on conventional head loss calculated in CASA Grande. Multiplier is applied if thin bed is formed and pool temperature is at or below precipitation temperature.
15
Step 3: Select Inputs of Interest
- Fiber Penetration Function: Fraction of fiber that bypasses the ECCS sump screen as a function of the amount of fiber on the screen.
- Size of ZOI: ZOI defined as direct function (multiplier) of break size and nominal pipe diameter; e.g., for NUKON fiber, ZOI is 17 times break diameter. ZOI is spherical unless break is not DEGB, in which case it is hemispherical. Truncated by any concrete walls within the ZOI.
- Time to Turn Off One Spray Pump: If three spray pumps start, then by procedure one is secured. Time to secure the pump is governed by operator acting on the conditional action step in procedure.
16
Step 3: Select Inputs of Interest
- Time to Hot Leg Injection: Similar to the spray pump turn off time, the time to switch one or more trains to hot leg injection operation is governed by procedure.
- Strainer Buckling Limit: Limit is the differential pressure across ECCS strainer at which strainer is assumed to fail mechanically. This limit is based on engineering calculations that incorporate safety factor.
- Water Volume in the Pool: Depending on break size, amount of water in pool, as opposed to amount in RCS and other areas in containment, varies. Smaller breaks tend to result in less pool volume than larger breaks.
17
Step 3: Select Inputs of Interest
- Debris Densities: Depends on amount and type of debris that arrives in pool. These densities are used in head loss correlations to calculate, for example, debris volume.
- Time Dependent Temperature Profiles: Temperature of water in sump affects air release and vaporization during recirculation. Time-dependent temperature profile comes from coupled RELAP5-3D and MELCOR simulations depending on break size.
- Spray Failure Fraction for Debris Outside ZOI: CASA Grande uses a table of failure fractions applied to transport logic trees. Fractions of each type of debris that passes to pool are used to understand what is in pool as function of time during recirculation. The spray failure fraction is fraction of failed coatings that wash to pool during spray operation.
18
Step 4: Nominal Values and Ranges for Inputs Input
Parameter
Level
1
Level
2
Level
3
Level
4
Latent
Fiber
(63)
12.5
6.25
25
50
Boron
Fiber
Limit
(g/FA)
7.5
4
15
50
Debris
Transport
Inside
ZOI
Base
Low
High
Water
Volume
in
Pool
Base
-10%
+10%
Chemical
Precipita-on
Temp
(oF)
140o
160o
Total
Failure
Frac-on
Outside
ZOI
Base
Low
Chemical
Head
Loss
Factor
Base
+50%
Fiber
Penetra-on
Func-on
Base
High
ZOI
Size
Base
-33%
Turn
o
1
Spray
Pump
(min.)
20
1440
Hot
Leg
Injec-on
(min.)
345
450
Strainer
Buckling
Limit
(6.
H2O)
9.35
9.6
Debris
Density
(lbm/63)
Base
+25%
Temperature
Pro"les
(oF)
Base
-5%
Spray
Transport
Frac-on
6%
12%
19
Step 5: Estimate Outputs Under Nominal Values of Inputs
- Sensi7vity
Measure
Expected
95%
CI
95%
CI
95%
CI
CI
HW
%
Mean
CDF
Direc7on
Half-Width
Low
Limit
Upper
Limit
of
Mean
0
Baseline
None
1.817E-08
1.914E-09
1.626E-08
2.009E-08
10.53%
20
Step 6: One-Way Sensitivity Analysis
- Expected
0.95-level
CI
HW
%
of
Sensi7vity
Measure
Mean
CDF
Direc7on
Mean
0
Baseline
N/A
1.817E-08
10.53%
1
Latent
Fiber
Low
(6.25
6^3)
Decrease
1.905E-08
10.12%
2
Latent
Fiber
High
(25
6^3)
Increase
1.669E-08
10.61%
3
Latent
Fiber
Very
High
(50
6^3)
Increase
3.394E-08
42.63%
4
Boron
Low
(4.0
g/FA)
Increase
1.690E-06
67.79%
5
Boron
Very
High
(50
g/FA)
Decrease
1.308E-08
10.80%
6
Boron
High
(15
g/FA)
Decrease
1.329E-08
10.65%
7
Debris
Transport
Inside
ZOI
High
Increase
7.896E-08
28.50%
8
Debris
Transport
Inside
ZOI
Low
Decrease
1.241E-08
12.03%
9
Chemical
Temp
High
Increase
1.905E-08
10.17%
10
Debris
Transport
Outside
ZOI
Low
Decrease
1.770E-08
10.61%
11
Chemical
Head
Loss
Factors
High
Increase
2.287E-08
8.85%
12
Penetra-on:
Low
Envelope
of
Filtra-on
Func-on
Increase
1.552E-07
10.93%
13
ZOI
Size
Small
Decrease
6.795E-09
12.18%
14
Turn
O
1
Spray
Longer
Decrease
1.569E-08
11.23%
15
Hot
Leg
Injec-on
Longer
Increase
1.962E-08
9.96%
16
Strainer
Limit
Higher
Decrease
1.639E-08
10.99%
17
Water
Volume
Low
Increase
2.001E-08
10.13%
18
Water
Volume
High
Decrease
1.655E-08
10.73%
19
Debris
Density
High
Increase
2.567E-08
9.17%
20
Temperature
Pro"les
Low
Increase
1.963E-08
10.14%
21
Debris
Transport
Outside
ZOI
High
Increase
1.798E-08
10.65%
21
Step 6: One-Way Sensitivity Analysis Tornado
Diagram:
Total
CDF
Ra-o
of
Risk
under
the
Scenarios
to
Risk
under
Nominal
Parameter
Values
Decreasing
Risk
Increasing
Risk
0.10
1.00
10.00
100.00
1,000.00
Boron
Fuel
Limit
(4.0
g/FA
-
50
g/FA)
Penetra-on
Low
Envelope
Debris
Transport
Inside
ZOI
ZOI
Size
Small
Scenario
Descrip-ons
Latent
Fiber
(6.25
6^3
-
50
6^3)
Debris
Density
High
Decreased
Parameter
Values
Chemical
Head
Loss
Factors
High
Water
Volume
Increased
Parameter
Values
Turn
O
1
Spray
Longer
Strainer
Limit
Higher
Temperature
Pro"les
Low
Hot
Leg
Injec-on
Longer
Chemical
Temp
High
Total
Failure
%
Outside
ZOI
Low
(80%)
Spray
Transport
%
Outside
ZOI
High
(12%)
22
Step 6: One-Way Sensitivity Analysis CDF
(Total)
1000.0
Mean
Risk
Baseline
100.0
Risk
Ra-os
Increasing
Risk
10.0
1.0
Decreasing
Risk
0.1
3.0
3.5
4.0
4.5
5.0
5.5
6.0
6.5
7.0
7.5
8.0
8.5
9.0
Boron
Fuel
Limit
(g/FA)
23
Step 6: One-Way Sensitivity Analysis CDF
(Vessel)
1000.0
Mean
Risk
100.0
Baseline
Risk
Ra-os
Decreasing
Risk
Increasing
Risk
10.0
1.0
0.1
3.0
3.5
4.0
4.5
5.0
5.5
6.0
6.5
7.0
7.5
8.0
8.5
9.0
Boron
Fuel
Limit
(g/FA)
24
Step 6: One-Way Sensitivity Analysis CDF
(Sump)
10.0
Mean
Risk
Baseline
Decreasing
Risk
Increasing
Risk
Risk
Ra-os
1.0
0.1
3.0
3.5
4.0
4.5
5.0
5.5
6.0
6.5
7.0
7.5
8.0
8.5
9.0
Boron
Fuel
Limit
(g/FA)
25
Step 6: One-Way Sensitivity Analysis Filtration Function Envelope 1$
0.95$
0.9$
0.85$
Filtra'on*
Test$1:$353gpm$
0.8$
Test$2:$353gpm$
0.75$ Test$3:$353gpm$
Test$5:$358gpm$
0.7$
Test$7:$220gpm$
0.65$ Fit$
Upper$Envelope$
0.6$
Lower$Envelope$
0.55$
0$ 500$ 1000$ 1500$ 2000$ 2500$ 3000$ 3500$ 4000$
Strainer*Mass*in*Grams*
26
Step 6: One-Way Sensitivity Analysis CDF
(Total)
100.0
Mean
Risk
Increasing
Risk
10.0
Risk
Ra-os
1.0
Decreasing
Risk
0.1
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
Fiber
Envelope
(0-Lower,
1-Upper)
27
Step 6: One-Way Sensitivity Analysis CDF
(Vessel)
100.0
Mean
Risk
Baseline
10.0
Risk
Ra-os
Increasing
Risk
1.0
Decreasing
Risk
0.1
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
Fiber
Envelope
(0-Lower,
1-Upper)
28
Step 6: One-Way Sensitivity Analysis CDF
(Sump)
10.0
Mean
Risk
Baseline
Risk
Ra-os
Increasing
Risk
1.0
Decreasing
Risk
0.1
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
Fiber
Envelope
(0-Lower,
1-Upper)
29
Step 6: One-Way Sensitivity Analysis
- Alternative distributions used for chemical head loss factor:
- 1. No chemical head loss
- 2. Factors constant at 1x mean (S=2.25/M=2.50/L=3.00)
- 3. Factors constant at 2x mean (S=3.50/M=4.00/L=5.00)
- 4. Factors constant at 3x mean (S=4.75/M=5.50/L=7.00)
- 5. Truncated exponential (S=6/M=3.5/L=2.25) at tail probability of 1E-5
- 6. Truncated exponential (S=3/M=2.5/L=2.25) at tail probability of 1E-5
- 7. Truncated normal (Mean, St Dev = 3x Mean)
Means have base case values of (S=2.25/M=2.50/L=3.00) 30
Step 6: One-Way Sensitivity Analysis Total
CDF
2.0
Min
Temp
140
1.8
No
Minimum
Temp
1.6
Increasing
Risk
Ra-o
of
Total
CDF
to
Base
Case
Baseline
1.4
1.2
1.0
Decreasing
Risk
0.8
0.6
0.4
0.2
0.0
Distribu-on
of
Chemical
Head
Loss
Factor
31
Step 9: Two-Way Sensitivity Analysis CDF
(Total)
as
a
Func7on
of
Fiber
Penetra7on
Limit
and
Filtra7on
Func7on
0
-
1.E-08
1.E-09-1.E-08
1.E-08-1.E-07
1.E-04
1.E-07-1.E-06
1.E-05
1.E-06-1.E-05
CDF
1.E-05-1.E-04
1.E-06
1.E-07
0.000
Filtra7on
Func7on
1.E-08
0.167
0.333
1.E-09
4.0
0.500
5.0
6.0
7.0
1.000
8.5
Fiber
Penetra7on
Limit
(g/FA)
32
Step 9: Two-Way Sensitivity Analysis CDF
(Total)
as
a
Func7on
of
Fiber
Penetra7on
Limit
and
Filtra7on
Func7on
0.000
0
-
1.E-08
1.E-09-1.E-08
1.E-08-1.E-07
CDF
0.167
1.E-07-1.E-06
Filtra7on
Func7on
1.E-06-1.E-05
0.333
1.E-05-1.E-04
0.500
1.000
4.0
5.0
6.0
7.0
8.5
Fiber
Penetra7on
Limit
(g/FA)
33
Step 9: Two-Way Sensitivity Analysis CDF
(Vessel)
as
a
Func7on
of
Fiber
Penetra7on
Limit
and
Filtra7on
Func7on
0.000
0
-
1.E-08
1.E-09-1.E-08
1.E-08-1.E-07
CDF
0.167
1.E-07-1.E-06
Filtra7on
Func7on
1.E-06-1.E-05
1.E-05-1.E-04
0.333
0.500
1.000
4.0
5.0
6.0
7.0
8.5
Fiber
Penetra7on
Limit
(g/FA)
34
Explaining Subtle Modeling Trends Bruce Letellier - Alion Science Jeremy Tejada - University of Texas Austin 35
Nonintuitive Trends
- Extensive usage of CASA Grande for parameter studies reveals four (4) subtle nonintuitive trends in quantitative risk
- Two issues were opened as Error Reports. Two issues were investigated during parameter study. All dispositioned using case study analysis:
- ER01 - Unqualified Coatings Spray Fraction
- Increasing the fraction of UC transport under spray leads to slight reduction in risk
- ER03 - Fiber Inventory Mass Conservation
- Over time, fiber mass increases slightly
- PS01 - Latent Fiber Effect at T0
- Increasing latent fiber slightly decreases risk
- PS02 - TimeStep Effect
- Decreasing time step can significantly decrease risk 36
ER01 - Unqualified Coatings Spray Fraction
- Parameter studies of transport fractions indicate that increasing the 6%
spray washdown fraction to 12% for failed epoxy slightly reduces risk (1% Reduction).
- Spreadsheet calculations for assumed inventory of failed coatings shows very definite reduction in SV for increased spray fraction from 6%
to 25%.
- Holds for both linear mass and volume weighting and for quadratic volume weighting. Simply competition between particulate properties.
- SV is the amount of drag area per unit solid debris volume. SV is independent of porosity. More debris does not imply higher average SV.
- A proper formalism would use total surface area rather than average surfacetovolume ratio so that more of anything always adds drag.
37
ER01 - Unqualified Coatings Spray Fraction (example)
Spherical Material Initial Initial Final Final Diam Density Mass (m1) Mass (m1)
(kg/m3) (kg) (kg) 1 10 1490 100 100 2 150 1986 25 30 SV 512,000 1581
- Surfacetovolume ratio can decrease when the proportion of larger particles increases (volume increases faster than area)
- True at STP for spray fractions because large inventory of 10m enamel has zero spray fraction (other particulates increase in proportion and SV decreases) 38
ER03 - Fiber Inventory Mass Conservation
- Parameter studies and code verification exercises show that fiber inventory increases slightly over the 36h calculation
- Explicit timeforward integration uses leading concentrations for each time step.
Coarse resolution delivers artificial mass at each time step that accumulates above initial inventory.
- Smaller time steps reduce this effect.
39
PS01 - Latent Fiber Effect at T0
- Parameter studies of latent fiber quantity show that increasing latent fiber slightly decreases risk.
- Fiber filtration and shedding model accounts for improved filtration with increasing debris load.
- More latent fiber initializes slightly higher filtration at beginning of recirculation
- User option added to allow some fraction of latent fiber to pass through the strainer.
40
PS01 - Latent Fiber Effect at T0 (cont)
Sensitivity Plot: Common Random Numbers 3.5E08 Mean Risk 3.0E08 Total Core Damage Frequency Increasing Risk 2.5E08 2.0E08 Decreasing Risk 1.5E08 1.0E08 0.0 10.0 20.0 30.0 40.0 50.0 60.0 70.0 80.0 90.0 100.0 Latent Fiber (ft3) 41
PS02 - Time-Step Effect
- Reduction of time step from 5 min to 1 min found to reduce quantitative risk by a factor of 1.5.
- Explict timeforward integration introduces numerical diffusion that advances debris to the strainer artificially rapidly.
- NPSH related failures occur before reduction in temperature regains margin.
- Possible nonconservatism may be introduced by improved filtration on the debris bed that protects core.
No numerical evidence that this dominates.
42
PS02 - TimeStep Effect Trend 43
Summary:
- The four nonintuitive observations discussed here have been explained at a fundamental level
- Changes in numerical approximations and physical descriptions can eliminate undesired behavior
- Subtle trends revealed in model interactions
- Essential to confirming or correcting engineering intuition
- Sensitivity studies create essential QA opportunities to exercise physical models over full parameter ranges
- Identify input errors
- Identify code level errors 44
Conclusions
- Summarized approach to sensitivity analyses
- Demonstrated the approach on several parameters
- Reviewed and explained counterintuitive results observed with certain parameters 45