Letter Sequence Other |
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Administration
- Meeting, Meeting, Meeting, Meeting, Meeting, Meeting, Meeting, Meeting, Meeting, Meeting, Meeting, Meeting, Meeting, Meeting, Meeting, Meeting, Meeting, Meeting, Meeting, Meeting, Meeting, Meeting, Meeting, Meeting, Meeting, Meeting, Meeting, Meeting
Results
Other: ML111640211, ML111861529, ML111890408, ML111890413, ML112130165, ML112350873, ML112350883, ML112630673, ML112630676, ML112770237, ML112770246, ML112770251, ML113050623, ML113060606, ML113060615, ML113060623, ML113210411, ML113330116
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MONTHYEARML1104105052011-02-10010 February 2011
2/22/11 Notice of Forthcoming Public Meeting with STP Nuclear Operating Co., Units 1 & 2, to Discuss Risk-informed GSI-191, Assessment of Debris Accumulation on Pressurized-Water Reactor Sump Performance, Resolution Option Approach
Project stage: Meeting
ML1107700052011-04-0505 April 2011
Summary of Meeting with STP Nuclear Operating Company to Discuss a Risk-informed GSI-191, Assessment of Debris Accumulation on Pressurized-Water Reactor (PWR) Sump Performance, Resolution Option Approach for South Texas, Units 1 and 2
Project stage: Meeting
ML1113302442011-05-16016 May 2011
Notice of Meeting with STP Nuclear Operating Company to Discuss Risk-Informed GSI-191, Assessment of Debris Accumulation on Pressurized-Water Reactor (PWR) Sump Performance, Resolution Approach for South Texas, Units 1 and 2
Project stage: Meeting
ML1114706522011-05-16016 May 2011
Correction 06/02/2011 Notice of Meeting with STP Nuclear Operating Company to Discuss Risk-Informed GSI-191, Assessment of Debris Accumulation on Pressurized-Water Reactor (PWR) Sump Performance, Resolution Approach for South Texas, Units 1
Project stage: Meeting
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
Project stage: Meeting
ML1116401602011-06-21021 June 2011
Summary of Meeting with STP Nuclear Operating Company Regarding Risk-Informed GSI-191, Assessment of Debris Accumulation on Pressurized-Water Reactor (PWR) Sump Performance; Resolution Approach for South Texas, Units 1 and 2 (TAC ME5358-ME5
Project stage: Meeting
ML1116402112011-06-24024 June 2011
Notice of Conference Call with STP Nuclear Operating Company to Discuss Risk-Informed GSI-191, Assessment of Debris Accumulation on Pressurized-Water Reactor (PWR) Sump Performance, Resolution Approach for South Texas, Units 1 & 2
Project stage: Other
ML1118903912011-07-0606 July 2011
Email Additional Materials for Teleconference on 7/7/11 with STP to Discuss Risk Informed GSI-191
Project stage: Meeting
ML1118904082011-07-0606 July 2011
Licensee Handout Loca Frequencie Approach and Example Application
Project stage: Other
ML1118904132011-07-0606 July 2011
Licensee Slide Regarding Questions on LOCA Frequency Analysis and Responses to Comments
Project stage: Other
ML1118904202011-07-0606 July 2011
Licensee Slide from 7/7/11 Meeting with STP Nuclear
Project stage: Meeting
ML1118903762011-07-0707 July 2011
Email Licensee Slides for 7/7/11 Teleconference with STP to Discuss Risk Informed GSI-191
Project stage: Meeting
ML1118903802011-07-0707 July 2011
Licensee Slides, LOCA Initiating Event Frequencies and Uncertainties(Draft)
Project stage: Draft Other
ML1118615292011-07-12012 July 2011
Notice of Conference Call with STP Nuclear Operating Company to Discuss Risk-informed GSI-191, Assessment of Debris Accumulation on Pressurized-Water Reactor (PWR) Sump Performance, Resolution Approach for South Texas, Units 1 and 2
Project stage: Other
ML1120707292011-07-26026 July 2011
Meeting Notice with South Texas Project, Units 1 and 2 - Licensee Slides Computational Fluid Dynamics Validation Plan
Project stage: Meeting
ML1120707072011-07-26026 July 2011
Meeting Notice with South Texas Project, Units 1 and 2 - Licensee Slide Models and Methods Used for Casa Grande
Project stage: Meeting
ML1121301822011-08-0202 August 2011
Meeting Notice with STP Nuclear Operating Company to Discuss Risk-Informed GSI-191, Assessment of Debris Accumulation on Pressurized-Water Reactor (PWR) Sump Performance, Resolution Approach for South Texas, Units 1 and 2 (TAC ME5358-ME5359
Project stage: Meeting
ML1119500942011-08-0404 August 2011
Summary of Meeting with STP Nuclear Operating Company to Discuss Risk-Informed GSI-191, Assessment of Debris Accumulation on Pressurized-Water Reactor (PWR) Sump Performance, Resolution Approach for South Texas, Units 1 and 2
Project stage: Meeting
ML1121301652011-08-19019 August 2011
7/26/11 - Summary of Conference Call with STP Nuclear Operating Company to Discuss Risk-Informed GSI-191, Assessment of Debris Accumulation on Pressurized-Water Reactor (PWR) Sump Performance, Resolution Approach for South Texas, Units 1 an
Project stage: Other
ML1123508732011-08-22022 August 2011
Models and Methods Used for Casa Grande
Project stage: Other
ML1123508832011-08-22022 August 2011
LOCA Initiating Event Frequencies and Uncertainties Status Report
Project stage: Other
ML1125101482011-09-15015 September 2011
Notice of Meeting by Conference Call with STP Nuclear Operating Co. to Discuss Risk-Informed GSI-191, Assessment of Debris Accumulation on Pressurized-Water Reactor (PWR) Sump Performance, Resolution Approach for South Texas, Units 1 and 2
Project stage: Meeting
ML1126306732011-09-20020 September 2011
Email, NRC Staff Questions, Loss-of-Coolant Accident Frequency Analysis, Resolution Approach for Risk-Informed GSI-191, Assessment of Debris Accumulation on Pressurized-Water Reactor (PWR) Sump Performance
Project stage: Other
ML1126306762011-09-20020 September 2011
NRC Staff Questions, Loss-of-Coolant Accident Frequency Analysis, Resolution Approach for Risk-Informed GSI-191, Assessment of Debris Accumulation on Pressurized-Water Reactor (PWR) Sump Performance
Project stage: Other
ML1127702372011-09-30030 September 2011
LOCA Frequencies for STP GSI-191( Final)
Project stage: Other
ML1127701702011-10-0303 October 2011
E-mail Licensee Handouts for 10/3/11 Public Meeting
Project stage: Meeting
ML1127701762011-10-0303 October 2011
Licensee Handouts from 10/3/11 Meeting STP LOCA Frequency
Project stage: Meeting
ML1127702032011-10-0303 October 2011
Licensee Slides from 10/3/11 Meeting LOCA Frequencies, Final Results
Project stage: Meeting
ML1127702302011-10-0303 October 2011
E-mail Documents for 10/3/11 Teleconference
Project stage: Meeting
ML1127702462011-10-0303 October 2011
E-mail Questions Associated with LOCA Frequency Analysis
Project stage: Other
ML1127702512011-10-0303 October 2011
STP Responses to Questions Associated with LOCA Frequency Analysis
Project stage: Other
ML1124114192011-10-0404 October 2011
8/22/11 Summary of Meeting with STP Nuclear Operating Company to Discuss Risk-Informed GSI-191, Assessment of Debris Accumulation on Pressurized-Water Reactor (PWR) Sump Performance, Resolution Approach for South Texas, Units 1 and 2 (TAC M
Project stage: Meeting
ML1127901512011-10-11011 October 2011
Notice of Meeting by Conference Call with STP Nuclear Operating Company to Discuss Risk-Informed GSI-191, Assessment of Debris Accumulation on Pressurized-Water Reactor (PWR) Sump Performance, Resolution Approach for South Texas, Units 1 &
Project stage: Meeting
ML1127900992011-10-11011 October 2011
Notice of Meeting by Conference Call with STP Nuclear Operating Company to Discuss Risk-Informed GSI-191, Assessment of Debris Accumulation on Pressurized-Water Reactor (PWR) Sump Performance, Resolution Approach for South Texas, Units 1 an
Project stage: Meeting
ML1130606232011-10-20020 October 2011
Technical Review of STP LOCA Frequency Estimation Methodology
Project stage: Other
ML1130506322011-10-26026 October 2011
Licensee Handouts from November 1, 2011 Meeting with STP Nuclear Operating Company on GSI-191
Project stage: Meeting
ML1130506232011-10-26026 October 2011
Alion- Expected Impact of Chemical Effects on GSI-191 Risk Informed Evaluation for South Texas Project
Project stage: Other
ML1130606152011-10-31031 October 2011
LOCA Frequencies for STP Nuclear Operating Company GSI-191
Project stage: Other
ML1128401142011-10-31031 October 2011
10/3/11 Summary of Meeting Via Conference Call with STP Nuclear Operating Company to Discuss Risk-Informed GSI-191, Assessment of Debris Accumulation on Pressurized-Water Reactor (PWR) Sump Performance, Resolution Approach for South Texas
Project stage: Meeting
ML1129701092011-11-0101 November 2011
Notice of Meeting Via Conference Call with STP Nuclear Operating Company to Discuss Risk-Informed GSI-191, Assessment of Debris Accumulation on Pressurized-Water Reactor Sump Performance, Resolution Approach for South Texas, Units 1 & 2
Project stage: Meeting
ML1132104112011-11-0101 November 2011
Revised Notice of by Conference Call with STP Nuclear Operating Company to Discuss Risk-Informed GSI-191, Assessment of Debris Accumulation on Pressurized-Water Reactor (PWR) Sump Performance,
Project stage: Other
ML1130606062011-11-0202 November 2011
Questions Associated with Loss-of-Coolant Accident (LOCA) Frequency Analysis
Project stage: Other
ML1133301162011-11-29029 November 2011
Email, 11/1/2011 Pre-Licensing Conference Call to Discuss the Topic of Expected Impact of Chemical Effects on GSI-191 Risk-Informed Evaluation, Phenomena Identification and Ranking Table Items (TAC ME5358-ME5359)
Project stage: Other
ML1131201292011-11-29029 November 2011
Summary of 11/1/11 Meeting by Conference Call with STP Nuclear Operating Company to Discuss Risk-Informed GSI-191, Assessment of Debris Accumulation on Pressurized-Water Reactor (PWR) Sump Performance,Resolution Approach for South Texas, Un
Project stage: Meeting
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
Project stage: Meeting
ML1131801962011-12-0505 December 2011
Summary of Meeting with STP Nuclear Operating Company Discuss Risk-Informed GSI-191, Assessment of Debris Accumulation on Pressurized-Water Reactor (PWR) Sump Performance, Resolution Approach for South Texas Units 1 and 2
Project stage: Meeting
ML1134300872011-12-23023 December 2011
Summary of 12/1/11 Meeting by Conference Call with STP Nuclear Operating Company to Discuss Risk-Informed GSI-191, Assessment of Debris Accumulation on Pressurized-Water Reactor (PWR) Sump Performance, Resolution Approach for South Texas Un
Project stage: Meeting
2011-05-16
[Table View] |
Text
8/22/11 Pre-Licensing Meeting 1
LOCA Initiating Event Frequencies and Uncertainties Status Report Risk Informed GSI-191 Resolution Monday, August 22, 2011 8:00 am - 5:00 p.m EDT Public Meeting with STP Nuclear Operating Company Karl N. Fleming KNF Consulting Services LLC Bengt O. Y. Lydell
8/22/11 Pre-Licensing Meeting 2
Discussion Topics
- Refinements of Approach for Conditional Rupture Probabilities
- Independent Review by Ali Mosleh
- Issues to Complete Risk Informed GSI-191
LOCA Frequencies Objectives Incorporate insights from previous work on LOCA frequencies Characterize LOCA initiating events and their frequencies with respect to:
Specific components, materials, dimensions Specific locations Range of break sizes Damage / Degradation mechanisms and mitigation effectiveness Other break characteristics, e.g. speed Quantify both aleatory and epistemic uncertainties; augment with sensitivity studies Support interfaces with other parts of the GSI-191 evaluation LOCA initiating event frequencies for PRA modeling Break characterization for evaluation of debris formation Participate in NRC workshops 3
8/22/11 Pre-Licensing Meeting Risk Informed GSI-191
Current Status
- Defined homogenous pipe failure rate categories
- Refined method for deriving conditional rupture probabilities vs. break size
- Obtained preliminary results for each pipe category
- Obtained preliminary results for total LOCA frequencies from pipe failures
- Independent reviews by MIT and Ali Mosleh in progress 8/22/11 Pre-Licensing Meeting 4
Homogeneous Pipe Failure Rate Cases 8/22/11 Pre-Licensing Meeting 5
Step by Step Procedure 1.
Determination of weld types (i) 2.
Perform data query for failure counts (n) 3.
Estimate component exposure (T) and uncertainty 4.
Develop component failure rate prior distributions for each DM 5.
Perform Bayes update for each exposure case (combination of weld count and DM susceptibility) 6.
Apply posterior weighting to combine results for different hypothesis yield conditional failure rate distributions; compute unconditional failure rates for locations with uncertain DM status 7.
Develop conditional probability of rupture size given failure probabilities for each weld type and associated epistemic uncertainties 8.
Combine the results of Step 6 and Step 7 by Monte Carlo in Eq. (1) for component LOCA frequencies and total LOCA frequencies for each component 9.
Apply Markov Model to specialize rupture frequencies for differences in integrity management 10.
For intermediate LOCA categories and break sizes, interpolate the results of Step 10 via log-log linear interpolation 11.
Calculate total LOCA frequencies from all components and reconcile differences with earlier LOCA frequency estimates 8/22/11 Pre-Licensing Meeting 6
Step 7 Conditional Probability of Pipe Rupture
- Step 7.1 Benchmark of Lydells Base Case LOCA frequencies for PWR hot leg, surge line, and HPI line
- Step 7.2 Compare results of individual expert elicitation LOCA Frequencies from NUREG-1829 to base case
- Step 7.3 Set Target LOCA frequencies that encompass elicitation results (method revised since July meeting)
- Step 7.4 Derive conditional rupture probability distributions that when combined with Lydell failure rate estimates match the target LOCA frequencies
- Step 7.5 Perform Bayes updates that incorporate evidence on pipe failures without LOCAs 8/22/11 Pre-Licensing Meeting 7
Selection of Target LOCA Frequencies Used expert distributions from NUREG-1829
- Input from 9 experts for component level LOCA frequencies at different plant ages; using data for 40 years
- Bengt Lydell base case results in Appendix D Evaluated alternative approaches to aggregating into composite distributions for different components
- Mixture distribution of NUREG-1829 data - rejected
- Geometric mean distribution of NUREG-1829 data Geometric means of 50th percentiles and range factors - accepted Geometric means of input 5%tiles and 95%tiles - rejected
- Hybrid of geometric means and Lydell base Use of worst case 5% tiles and 95%tiles (Method described in July meeting)
Mixture distribution of geometric mean and Lydell (Method recommended by Dr.
Mosleh)
Performing sensitivity studies on alternative models 8/22/11 Pre-Licensing Meeting 8
Comparison of Geometric Mean and Mixture Distributions from NUREG-1829 Data 8/22/11 Pre-Licensing Meeting 9
Use of Worst-Case Percentiles from NUREG-1829 GM and Lydell Base Case 8/22/11 Pre-Licensing Meeting 10
Selected Approach for Target LOCA Frequencies
- Probabilistic mixture of two models
- Model 1 Geometric mean of 9 expert distributions
- Develop 40 year composite distribution of 9 experts using geometric mean method
- Combined lognormal distribution for Current day and 40yr multipliers for each expert preserving median and range factors
- Developed composite distribution based on geometric means of each experts medians and range factors
- Model 2 Bengt Lydell Base Case analysis
- Results of Models 1 and 2 combined giving equal weight to each yielding a mixture distribution of the two models
- This method produces somewhat greater uncertainties than using Model 1 by itself 8/22/11 Pre-Licensing Meeting 11
Comparison of Hybrid Methods STPHotLegTargetLOCAModel WorstCase5%tileand95%tile LOCACat. BreakSizeMean 5%tile 50%tile 95%tile RF 1
0.5 5.79E07 3.55E09 8.72E08 2.14E06 24.6 2
1.5 1.95E07 2.10E10 1.09E08 5.68E07 52.0 3
3 1.05E07 8.33E11 4.89E09 2.87E07 58.7 4
6.76 3.75E08 3.03E11 1.77E09 1.03E07 58.3 5
14 2.02E08 1.16E11 7.75E10 5.17E08 66.8 6
31.5 2.41E09 5.44E12 2.08E10 7.94E09 38.2 STPHotLegTargetLOCAModel ProbabilisticMixture 1
0.5 5.08E07 5.30E09 1.05E07 1.91E06 19.0 2
1.5 9.32E08 3.91E10 1.46E08 3.68E07 30.7 3
3 4.54E08 1.60E10 6.39E09 1.76E07 33.1 4
6.76 1.64E08 5.73E11 2.05E09 6.32E08 33.2 5
14 8.37E09 2.03E11 7.64E10 2.92E08 37.9 6
31.5 1.80E09 5.85E12 1.80E10 5.83E09 31.6 8/22/11 Pre-Licensing Meeting 12
Preliminary Results
- Results shown here use worst case percentile method for combining the NUREG-1829 GM and Lydell base case distributions
- Some modest reductions in means and range factors expected from incorporation of mixture method
- Current results only address LOCAs caused by pipe failures
- Non-pipe contributions to be considered in 2012 8/22/11 Pre-Licensing Meeting 13
Example Results - Hot Leg B-F Weld at RPV Nozzle BF Weld Mean 5%tile 50%tile 95%tile RF Failure Rate 2.72E-04 1.04E-04 2.32E-04 5.77E-04 2.4 Cumulative LOCA Frequencies Vs. Break Size (in.)
0.5 4.42E-07 1.89E-08 1.74E-07 1.63E-06 9.3 1.5 1.46E-07 8.90E-10 2.22E-08 5.45E-07 24.7 1.99 1.13E-07 5.98E-10 1.57E-08 4.14E-07 26.3 2.0 1.15E-07 5.96E-10 1.58E-08 4.19E-07 26.5 3.0 8.21E-08 3.44E-10 9.92E-09 2.89E-07 29.0 4.0 5.81E-08 2.42E-10 7.00E-09 2.02E-07 28.9 5.99 3.49E-08 1.45E-10 4.22E-09 1.25E-07 29.3 6.0 3.41E-08 1.43E-10 4.24E-09 1.20E-07 29.0 6.8 2.89E-08 1.25E-10 3.60E-09 1.05E-07 29.0 14.0 1.57E-08 4.67E-11 1.57E-09 5.41E-08 34.0 20.0 8.93E-09 2.65E-11 8.93E-10 3.07E-08 34.0 31.5 4.15E-09 1.26E-11 4.21E-10 1.42E-08 33.7 44.5 3.02E-09 8.95E-12 3.12E-10 1.04E-08 34.2 8/22/11 Pre-Licensing Meeting 14
Example Results - Hot Leg B-F Weld at RPV Nozzle 8/22/11 Pre-Licensing Meeting 15
Preliminary Results for Initiating Event Frequencies from Pipe Breaks InitiatingEvent BreakSize Mean 5%tile 50%tile 95%tile RF SLOCA
.5to2" 2.68E04 4.44E05 1.75E04 7.85E04 4.2 MLOCA 2"to6" 6.69E05 2.94E06 2.53E05 2.44E04 9.1 LLOCA
>6" 3.34E06 3.49E08 6.37E07 1.23E05 18.8 8/22/11 Pre-Licensing Meeting 16
Preliminary Results for Total LOCA Frequency from Pipes 8/22/11 Pre-Licensing Meeting 17
Preliminary Results - System Contributions to LOCA Frequency 8/22/11 Pre-Licensing Meeting 18
Major Tasks to Complete
- Provide input to CASAGRANDE with appropriate conditional probabilities vs. break size given the initiating event
- Conditional probability that the break occurs in each location
- Conditional probability that the break is in different size at each location
- Provide input to RISKMAN on the initiating event frequencies and uncertainties
- Finalize the draft report and submit for NRC review meeting in mid-September 8/22/11 Pre-Licensing Meeting 19
