Assessment of an isolation condenser performance in case of a LOHS using the RMPS+ Methodology

Transcription

1 Assessment of an isolation condenser performance in case of a LOHS using the RMPS+ Methodology M. Giménez, F. Mezio, P. Zanocco, G. Lorenzo Nuclear Safety Group - Centro Atómico Bariloche, CNEA - Argentina 3 rd IAEA Coordination Research Meeting on Development of Methodologies for the assessment of Passive Safety Systems Performance in Advanced Reactors Vienna, April 2011

2 Summary Introduction Improvements in the RMPS methodology Methodology Application Assessment of an isolation condenser performance in case of a LOHS using the RMPS+ Methodology 2

3 Introduction Interest in knowing the uncertainties influence in a CAREM-like PRHRS RMPS methodology is under development No many RMPS application are know Some methodology improvements come up while it was being applied Assessment of an isolation condenser performance in case of a LOHS using the RMPS+ Methodology 3

4 The RMPS+ methodology proposal Model Development System Identification System mission and scenario Failure criteria Performance indicator definition Definition of the relevant parameters Identification Quantification Sample technique and screening Sampling of many points Sampling of few points Propagation through Response surface Direct propagation through Best Estimate code Best Estimate calc. of the points in the failure domain predicted by the hyper-plane Performance Indicator Evaluation Response surface determination Sensitivity analysis Functional reliability assessment No Convergence reached? Yes Methodology ends Assessment of an isolation condenser performance in case of a LOHS using the RMPS+ Methodology 4

5 The RMPS+ methodology proposal First Step Model Development System Identification System mission and scenario Failure criteria Performance indicator definition Definition of the relevant parameters Identification Quantification Sample technique and screening Sampling of many points Sampling of few points Propagation through Response surface Direct propagation through Best Estimate code Best Estimate calc. of the points in the failure domain predicted by the hyper-plane Performance Indicator Evaluation Response surface determination Sensitivity analysis Functional reliability assessment No Convergence reached? Yes Methodology ends Assessment of an isolation condenser performance in case of a LOHS using the RMPS+ Methodology 5

6 The RMPS+ methodology proposal First Step System: PRHRS of a CAREM-Like reactor Proposed Scenario: Loss of Heat Sink Short Term Long Term Assessment of an isolation condenser performance in case of a LOHS using the RMPS+ Methodology 6

7 The RMPS+ methodology proposal First Step System: PRHRS of a CAREM-Like reactor Proposed Scenario: Loss of Heat Sink Mission: Remove the heat produced and stored in the Primary Assessment of an isolation condenser performance in case of a LOHS using the RMPS+ Methodology 7

8 The RMPS+ methodology proposal First Step Success criteria: Avoid primary safety valves demand It is a design criteria, imposed by the Nuclear Safety Area Assessment of an isolation condenser performance in case of a LOHS using the RMPS+ Methodology 8

9 The RMPS+ methodology proposal First Step Performance Indicator: It is necessary for analytical assessment It have to: Measure the distance to fail Be continuous Be capable to be implement Be sensible to the parameters in their domain Assessment of an isolation condenser performance in case of a LOHS using the RMPS+ Methodology 9

10 Entalpía Presión Pow Presión Power Entalpía Potencia Poten 0 The RMPS+ Qc methodology 1 1 proposal First Step Qc Performance Indicator: E psp Apertura válvula de seguridad 3 3 Energy Power Pressure Energy EI E psp P psp EI Qnet Q total Qc 3 = Qc psp Apertura válvula de seguridad Apertura válvula de seguridad Pressure Safety Valve set point Qc 1 Qc 1 0 Qc PI PRHRS PRHRS necessaryto fail 1 Pressure 0 t 0 td t d t 1-1 t 2 t 1-psp t 3 Apertura válvula de seguridad time PSystem psp evolution 3 modifying the PRHRS efficiency 2 1 Assessment of an isolation condenser performance in case of a LOHS using the RMPS+ Methodology 10

11 The RMPS+ methodology proposal Second Step Model Development System Identification System mission and scenario Failure criteria Performance indicator definition Definition of the relevant parameters Identification Quantification Sample technique and screening Sampling of many points Sampling of few points Propagation through Response surface Direct propagation through Best Estimate code Best Estimate calc. of the points in the failure domain predicted by the hyper-plane Performance Indicator Evaluation Response surface determination Sensitivity analysis Functional reliability assessment No Convergence reached? Yes Methodology ends Assessment of an isolation condenser performance in case of a LOHS using the RMPS+ Methodology 11

12 The RMPS+ methodology proposal Second Step System code chosen: RELAP5 Dome Modeling: Complex zone inside the RPR: It have diverse components that: Produce Steam condensation Makes complex flows paths Controls the Primary System: Pressure Sub-cooling It is difficult to model: 3 Dimensional phenomena attempted to be reproduced by 1 Dimensional plant code Several dome nodalisation were developed and applied in RMPS to see the user effects Primary circuit Model Assessment of an isolation condenser performance in case of a LOHS using the RMPS+ Methodology 12

13 The RMPS+ methodology proposal Second Step Progressive modeling technique Dome 1 Dome 2 Dome 3 Assessment of an isolation condenser performance in case of a LOHS using the RMPS+ Methodology 13

14 The RMPS+ methodology proposal Second Step Sub-cooling Void fraction Assessment of an isolation condenser performance in case of a LOHS using the RMPS+ Methodology 14

15 The RMPS+ methodology proposal Second Step LOHS nominal model s evolution Assessment of an isolation condenser performance in case of a LOHS using the RMPS+ Methodology 15

16 The RMPS+ methodology proposal Third Step Model Development System Identification System mission and scenario Failure criteria Performance indicator definition Definition of the relevant parameters Identification Quantification Sample technique and screening Sampling of many points Sampling of few points Propagation through Response surface Direct propagation through Best Estimate code Best Estimate calc. of the points in the failure domain predicted by the hyper-plane Performance Indicator Evaluation Response surface determination Sensitivity analysis Functional reliability assessment No Convergence reached? Yes Methodology ends Assessment of an isolation condenser performance in case of a LOHS using the RMPS+ Methodology 16

17 The RMPS+ methodology proposal Third Step Expert judgment Nominal Values Variation range PDFs 1 Power operational 2 SCRAM delay 3 SCRAM: safety rods total drop time 4 Decay power factor (ANS79-3) 5 Reactor nominal pressure 6 SCRAM: pressure set point 7 PRHRS: pressure set point 8 RPV dome water level 9 Primary circuit mass flow rate 10 PRHRS pool temperature 11 PRHRS tube thickness 12 PRHRS fouling 13 RPV dome (steam zone) heat losses 14 Safety Valves Set-Point 15 PRHRS pool s boiling heat transfer coefficient 16 PRHRS tube s condensation heat transfer coefficient 17 Feedback reactivity coefficients Assessment of an isolation condenser performance in case of a LOHS using the RMPS+ Methodology 17

18 The RMPS+ methodology proposal Fourth Step Model Development System Identification System mission and scenario Failure criteria Performance indicator definition Definition of the relevant parameters Identification Quantification Sample technique and screening Sampling of many points Sampling of few points Propagation through Response surface Direct propagation through Best Estimate code Best Estimate calc. of the points in the failure domain predicted by the hyper-plane Performance Indicator Evaluation Response surface determination Sensitivity analysis Functional reliability assessment No Convergence reached? Yes Methodology ends Assessment of an isolation condenser performance in case of a LOHS using the RMPS+ Methodology 18

19 The RMPS+ methodology proposal Fourth Step Simple Random Sampling Number of samples based on Wilk s Formula 1 N Cobweb plot Assessment of an isolation condenser performance in case of a LOHS using the RMPS+ Methodology 19

20 The RMPS+ methodology proposal Fifth Step Model Development System Identification System mission and scenario Failure criteria Performance indicator definition Definition of the relevant parameters Identification Quantification Sample technique and screening Sampling of many points Sampling of few points Propagation through Response surface Direct propagation through Best Estimate code Best Estimate calc. of the points in the failure domain predicted by the hyper-plane Performance Indicator Evaluation Response surface determination Sensitivity analysis Functional reliability assessment No Convergence reached? Yes Methodology ends Assessment of an isolation condenser performance in case of a LOHS using the RMPS+ Methodology 20

21 The RMPS+ methodology proposal Fifth Step Possible Failure Zone Assessment of an isolation condenser performance in case of a LOHS using the RMPS+ Methodology 21

22 The RMPS+ methodology proposal Seventh Step Model Development System Identification System mission and scenario Failure criteria Performance indicator definition Definition of the relevant parameters Identification Quantification Sample technique and screening Sampling of many points Sampling of few points Propagation through Response surface Direct propagation through Best Estimate code Best Estimate calc. of the points in the failure domain predicted by the hyper-plane Performance Indicator Evaluation Response surface determination Sensitivity analysis Functional reliability assessment No Convergence reached? Yes Methodology ends Assessment of an isolation condenser performance in case of a LOHS using the RMPS+ Methodology 22

23 The RMPS+ methodology proposal Seventh Step Reliability analysis: None of the 100 simulated cases, for each dome model, have failed It can be assured, at least, a 95% of reliability, with 95% of confidence Assessment of an isolation condenser performance in case of a LOHS using the RMPS+ Methodology 23

24 The RMPS+ methodology proposal Seventh Step Sensibility analysis Lineal assumption Standardized regression coefficients Dome 3 ranking: 1.PRHRS Partial fouling correlation (12) coefficients 2.Decay Determination power factor (ANS79-3) coefficients (04) 3.PRHRS tube s condensation heat transfer coefficient (16) R 4.PRHRS pool s boiling heat transfer coefficient (15) 2 R *2 Dome 1 Dome 2 Dome Assessment of an isolation condenser performance in case of a LOHS using the RMPS+ Methodology 24

25 The RMPS+ methodology proposal Surrogate model Model Development System Identification System mission and scenario Failure criteria Performance indicator definition Definition of the relevant parameters Identification Quantification Sample technique and screening Sampling of many points Sampling of few points Propagation through Response surface Direct propagation through Best Estimate code Best Estimate calc. of the points in the failure domain predicted by the hyper-plane Performance Indicator Evaluation Response surface determination Sensitivity analysis Functional reliability assessment No Convergence reached? Yes Methodology ends Assessment of an isolation condenser performance in case of a LOHS using the RMPS+ Methodology 25

26 The RMPS+ methodology proposal Surrogate model Response surface: Relatively high failure probability (95% of confidence level): Y N 0 i 1 i X i Dome 1 Dome 2 Dome 3 9*10-3 5*10-3 2*10-3 Dome 1 Dome 2 Dome 3 Assessment of an isolation condenser performance in case of a LOHS using the RMPS+ Methodology 26

27 The RMPS+ methodology proposal Feedback Procedure Model Development System Identification System mission and scenario Failure criteria Performance indicator definition Definition of the relevant parameters Identification Quantification Sample technique and screening Sampling of many points Sampling of few points Propagation through Response surface Direct propagation through Best Estimate code Best Estimate calc. of the points in the failure domain predicted by the hyper-plane Performance Indicator Evaluation Response surface determination Sensitivity analysis Functional reliability assessment No Convergence reached? Yes Methodology ends Assessment of an isolation condenser performance in case of a LOHS using the RMPS+ Methodology 27

28 The RMPS+ methodology proposal Feedback Procedure Pressure evolution of the cases nearest of the boundary failure domain Possible Failure Zone Assessment of an isolation condenser performance in case of a LOHS using the RMPS+ Methodology 28

29 The RMPS+ methodology proposal Feedback Procedure Region of interest Assessment of an isolation condenser performance in case of a LOHS using the RMPS+ Methodology 29

30 The RMPS+ methodology proposal Feedback Procedure Response surface improvement Results convergence Surface Coefficients Precision was increased in the boundary region Extrapolated system failure cases were reduced Dome 1 Dome 2 Dome 3 RELAP Plant model (100 cases) Base Response surface ( cases) st feedback nd feedback Failure probability [*10-6 ] (with 95% of confidence): Cases N er Dome 1 Dome 2 Dome Assessment of an isolation condenser performance in case of a LOHS using the RMPS+ Methodology 30

31 Conclusions Assessment of an isolation condenser performance in case of a LOHS using the RMPS+ Methodology 31

32 Conclusions It has been observed that in the original RMPS proposal the response surface may be poorly built, and therefore the system reliability The methodology was improved by means of an iterative process in order to build a response surface with new performance indicator values in the boundary failure domain, obtained trough the plant model The proposed methodology was useful: To identify efficiently odd events To rank the influence of the parameters with uncertainties To estimate CAREM-like PRHRS functional reliability to verify a design criterion Assessment of an isolation condenser performance in case of a LOHS using the RMPS+ Methodology 32

33 Thank you very much for you kind attention Questions? Assessment of an isolation condenser performance in case of a LOHS using the RMPS+ Methodology 33