ESBWR passive safety system performance under loss of coolant accidents

Rassame, Somboon; Hibiki, Takashi; Ishii, Mamoru

doi:10.1016/j.pnucene.2016.12.005

Cited by 17 publications

(5 citation statements)

References 8 publications

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“…The exploitation of natural circulation to passively remove the decay heat during shutdown operations is of significant interest to the nuclear industry as it does not require active systems, thus increasing the overall safety of the system. It has already been adopted in the current-generation reactors, such as the AP-1000 (Sutharshan et al, 2011) and the ESBWR (Rassame et al, 2017), and it is currently a primary target of research for the development of the safety system for Gen-IV nuclear reactors, in particular for the molten salt fast reactor (MSFR) (Serp et al, 2014). Natural circulation as a passive heat removal strategy relies on the system's ability to sustain the temperatures required to achieve the necessary mass flow rate; natural circulation arises as a result of the balance between buoyancy forces, which drive natural circulation, and the friction losses, which may hinder fluid mobility, leading to oscillatory phenomena (e.g., inversion of the fluid's motion).…”

Section: Introductionmentioning

confidence: 99%

1D modelling and preliminary analysis of the coupled DYNASTY–eDYNASTY natural circulation loop

et al. 2023

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In the continuous strive to improve the safety of current-generation and next-generation nuclear power plants, natural circulation can be used to design passive safety systems to remove the decay heat during the shutdown. The Molten Salt Fast Reactor (MSFR) is a peculiar type of Gen-IV nuclear facility, where the fluid fuel is homogeneously mixed with the coolant. This design leads to natural circulation in the presence of an internally distributed heat source during the shutdown. Furthermore, to shield the environment from the highly radioactive fuel, an intermediate loop between the primary and the secondary loops, able to operate in natural circulation, is required. To analyze the natural circulation with a distributed heat source and to study the natural circulation of coupled systems and the influence of the intermediate loop on the behaviour of the primary, Politecnico di Milano designed and built the DYNASTY-eDYNASTY facility. The two facilities are coupled with a double-pipe heat exchanger, which siphons heat from DYNASTY and delivers it to the eDYNASTY loop. This work focuses on modelling the coupled DYNASTY-eDYNASTY natural circulation loops using DYMOLA2023®, an integrated development environment based on the Modelica Object-Oriented a-causal simulation language. The 1D Modelica approach allows for building highly reusable and flexible models easing the design effort on a complex system such as the DYNASTY-eDYNASTY case without the need to rewrite the whole model from scratch. The coupled models were developed starting from the already-validated single DYNASTY model and the double-pipe heat exchanger coupling. The models were tested during the whole development process, studying the influence of the numerical integration algorithm on the simulation behaviour. A preliminary analysis of both the adiabatic and the heat loss models analyzed the effect of the secondary natural circulation loop on the behaviour of the DYNASTY loop. The simulation results showed that the eDYNASTY loop dampens the behaviour of the primary DYNASTY loop. Furthermore, a parametric analysis of the DYNASTY and the eDYNASTY coolers highlighted the influence of the cooling configuration on the facility’s behaviour. Finally, the simulation results identified the most critical aspects of the models in preparation for an experimental comparison.

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Section: Introductionmentioning

confidence: 99%

1D modelling and preliminary analysis of the coupled DYNASTY–eDYNASTY natural circulation loop

et al. 2023

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“…The simulation predictions and the experimental data were found in plausible agreement. 4 The PCCS concept in the KERENA reactor 9 is the same as it is in the ESBWR. The decay heat is removed using four containment cooling condensers.…”

Section: Introductionmentioning

confidence: 99%

“…Various PCCS designs have been developed over time. They have evolved into an integral part of advanced reactor designs such as the AP1000/AP600, 2,3 ESBWR (GE), 4 APR + (KEPCO), 5 and KERENA (AREVA). 6 The following subsection classifies the PCCS.…”

Section: Introductionmentioning

confidence: 99%

Thermal‐hydraulic investigation of a proposed concept for a passive containment cooling system and evaluation of heat exchanger performance

Ilyas

Hengra

Nauman

et al. 2022

Proceedings of the Institution of Mechanical Engineers, Part A:

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Reduction in ambient pressure within the containment of a light water reactor in the event of a hypothetical Loss of Coolant Accident (LOCA) is crucial for containment integrity. This article introduces the distinct concept of a Passive Containment Cooling System (PCCS). In the proposed PCCS concept, the containment is divided into two compartments with appropriate volumes. An external heat exchanger is connected between the two compartments of the containment for heat transfer and pressure reduction in the case of LOCA. This concept has unique characteristics and provides many advantages over previous designs. A RELAP5 model was developed to perform thermal-hydraulic analysis of the proposed PCCS concept. The performance of the PCCS after its deployment on a small reactor (998.6 MWth) has been assessed under various conditions following LOCA. The results indicate that partitioning of the containment creates a differential pressure that acts as a driving force for flow through the PCCS heat exchanger. Consequently, a decrease in long-term containment pressure is observed. In the case of equal volume fractions in the two containment compartments, the PCCS reduces long-term pressure in the containment by 16.5%. Sensitivity analysis was conducted in which the flow area of the PCCS inlet line, the heat transfer area, and the size of the heat exchanger tank were varied. The PCCS heat transfer capacity increases as these parameters are increased. However, the former is less sensitive than the latter two. The performance of the PCCS heat exchanger under steady-state conditions was validated using RELAP5 simulations, empirical correlations, and analytical models. The evaluation of heat exchanger parameters by various methods (presented in Appendix 1 ) was found in close agreement.

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“…For this reason, advanced reactors development foresees the employment of safety passive systems only, to guarantee the most efficient mitigation of severe accidents consequences. Examples of passive NPPs are: the AP1000 (Schulz, 2006;Jiang et al, 2017), the Economic Simplified Boiling Water Reactor (ESBWR) (Challberg et al, 1998;Rassame et al, 2017), the Advanced Heavy Water Reactor (AHWR) (Jain et al, 2013;Dasgupta et al, 2017) and the innovative Power Reactor (iPOWER) (Lee et al, 2017;Kang et al, 2019). Moreover, the interest for passive safety systems is confirmed in the so-called Generation IV (GEN-IV) reactors, as the Advanced Lead Fast Reactor European Demonstrator (ALFRED) (Alemberti et al, 2020).…”

Section: Introductionmentioning

confidence: 99%

Improvements of RELAP5/Mod3.3 heat transfer capabilities for simulation of in-pool passive power removal systems

Narcisi

Melchiorri

Giannetti

2021

Annals of Nuclear Energy

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Despite system thermal-hydraulic codes were extensively validated for transient simulations of LWR, several activities highlighted limited capabilities of these tools to model heat transfer within in-pool passive power removal system. Discrepancies with experimental results were related to the underestimate of pool boiling and film condensation heat transfer coefficients. Thus, the DIAEE of "Sapienza" University of Rome developed a modified version of RELAP5/Mod3.3, able to handle fundamental heat exchange phenomena involved in passive in-pool safety systems. A primary validation procedure has been performed for separated and integral effects. Dealing with nucleate boiling, the Root Mean Squared Relative Error (RMSRE) of wall superheat has been reduced from 1.290 to 0.182. Concerning film condensation, wall temperature RMSRE has been reduced from 0.192 to 0.058. The integral effect assessment has involved an experimental test of the PERSEO facility. The qualitative comparison between experiments and calculations has highlighted significant improvements of the modified RELAP5/Mod3.3.

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ESBWR passive safety system performance under loss of coolant accidents

Cited by 17 publications

References 8 publications

1D modelling and preliminary analysis of the coupled DYNASTY–eDYNASTY natural circulation loop

1D modelling and preliminary analysis of the coupled DYNASTY–eDYNASTY natural circulation loop

Thermal‐hydraulic investigation of a proposed concept for a passive containment cooling system and evaluation of heat exchanger performance

Improvements of RELAP5/Mod3.3 heat transfer capabilities for simulation of in-pool passive power removal systems

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