Formalism and semantics of PyCATSHOO: A simulator of distributed stochastic hybrid automata

“…19 Overall, simulation-based and dynamic risk assessment can be used to evaluate the risks associated with external events in detail. Methods and tools for dynamic PRA have been developed by many organizations; for example, ADS-IDAC (Accident Dynamic Simulator Coupled with the Information, Decision, and Action in a Crew Context), 20 PyCATSHOO (PythoniC Object Oriented Hybrid Stochastic AuTomata), 21 SCAIS (Simulation Codes System for Integrated Safety Assessment), 22 CMMC (Continuous Markov Chain and Monte Carlo), 23 GO-FLOW, which is a success-oriented system analysis technique, 24 MOSAIQUE (Module for Sampling Input and Quantifying Estimator), 25 and DICE (Dynamic Integrated Consequence Evaluation). 26 The Japan Atomic Energy Agency (JAEA) has developed an integrated severe accident code, THALES2 (Thermal-Hydraulic Analysis of Loss of Coolant, Emergency Core Cooling, and Severe Core Damage, version 2), 27 which is used to measure the chemical behaviors of fission products during severe accident.…”

Section: Introductionmentioning

confidence: 99%

Simulation-based dynamic probabilistic risk assessment of an internal flooding-initiated accident in nuclear power plant using THALES2 and RAPID

Kubo

Zheng

Tanaka

et al. 2022

Proceedings of the Institution of Mechanical Engineers, Part O:

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Probabilistic risk assessment (PRA) is a method used to assess the risks associated with large and complex systems. However, the timing at which nuclear power plant structures, systems, and components are damaged is difficult to handle explicitly if the risk of an external event is evaluated using conventional PRA based on event trees and fault trees. A methodology coupling thermal-hydraulic analysis with external event simulations using Risk Assessment with Plant Interactive Dynamics (RAPID) is therefore proposed to overcome this limitation. A flood propagation model based on Bernoulli’s theorem was applied to represent internal flooding in the turbine building of the pressurized water reactor. Uncertainties were also taken into account, including the flow rate of the floodwater source and the failure criteria for the mitigation systems. The simulated recovery actions included the operator isolating the floodwater source and using a drainage pump; these actions were modeled using several simplifications. Overall, the results indicate that combining isolation and drainage can reduce the conditional core damage probability upon the occurrence of flooding by approximately 90%.

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“…Several model-based approaches and software tools to the safety analysis have been employed in previous safety analyses and pertinent studies. These include Hip-HOPS, 17 MADe, 18 COSSMOS, 19 COMPASS, 20 ADS-IDAC, 21 PyCATSHOO, 22 PTC Windchill 23 and many others. 24 Hip-HOPS 17 is based on the system model, which is enriched with failure data and employs a series of rules to move backwards from the top event to the basic events to generate the Fault Tree and the FMECA table.…”

Section: Introductionmentioning

confidence: 99%

“…ADS-IDAC 21 is more suitable for the analysis of human-machine interactions. PyCATSHOO 22 employs Monte Carlo simulations, which can be very expensive computationally. PTC Windchill 23 is a software tool for Fault Tree generation with limited automation support.…”

Section: Introductionmentioning

confidence: 99%

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Safety analysis of a high-pressure fuel gas supply system for LNG fuelled vessels

Milioulis

Bolbot

Theotokatos

et al. 2022

Proceedings of the Institution of Mechanical Engineers, Part M:

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The liquified natural gas (LNG) is currently considered an attractive marine fuel in the short- to medium-terms that can lead to the reduction of the shipping industry carbon emissions. LNG fuelled ocean-going ships have been designed by employing either low-pressure or high-pressure fuel systems. This study aims at enhancing the safety of a high-pressure fuel gas supply system (FGSS) designed for ocean-going LNG fuelled vessels. A model-based safety analysis is performed by employing the MADe™ software. The functional model of the baseline design of the investigated system is developed and subsequently employed to carry out the Failure Modes, Effects and Criticality Analysis (FMECA), as well as the quantitative Fault Tree Analysis (FTA). FMECA provided the risk priority number (RPN) for the identified system failure scenarios, the analysis of which leads to the identification of the FGSS critical components. The FTA results, which include the probabilities of the selected top events and appropriate importance metrics, are used for the FMECA results verification. This study results demonstrate that the FGSS critical components include the process valves responsible for supplying either LNG or natural gas to the gas treatment system and consumers respectively, as well as the pressure feedback controllers. Recommendations for design alterations pertain to the addition of pressure sensors and redundancy of the identified critical system components. The derived results demonstrate that impact of these design alterations on the calculated safety metrics are quite considerable, thus enhancing the safety of the baseline design. This study contributes to the safety analysis of FGGS and supports decisions for the designer and operator of LNG fuelled ships.

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Formalism and semantics of PyCATSHOO: A simulator of distributed stochastic hybrid automata

Cited by 14 publications

References 17 publications

Dynamic Reliability Assessment of PEM Fuel Cell Systems

Dynamic Reliability Assessment of PEM Fuel Cell Systems

Simulation-based dynamic probabilistic risk assessment of an internal flooding-initiated accident in nuclear power plant using THALES2 and RAPID

Safety analysis of a high-pressure fuel gas supply system for LNG fuelled vessels

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