Conference Agenda

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Session Overview
Session
4.02: MSR and Advanced Reactors - II
Time:
Tuesday, 17/Mar/2020:
3:30pm - 5:00pm

Session Chair: DAVID PIALLA, EDF, France
Location: L-2012

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Presentations

IMAGINE – A Possible Way to Develop a New, Innovative Nuclear Energy System

Dzianis Litskevich, Bruno Merk

The University of Liverpool

The energy trilemma and the United Nations sustainable development goals form the key drivers for the future of all kind of energy research. These goals lead to strong, urgent demand for reliable as well as controllable electricity technologies to address low carbon strategies. The development of nuclear technologies has the potential to play a key role in low carbon energy production. However, according to the current IAEA world statistics, 52 reactors are currently under construction, 50 of them are PWR, BWR or PHWR types. All these projects rely on commercially existing technologies and are essentially based on technologies of 50ies and 60ies of the previous century and widely use enriched uranium as fuel. Unfortunately, the amount of “cheap” uranium is limited and mining is the main source of ecotoxicity in nuclear technologies, therefore, closing the fuel cycle is required to ensure a long term sustainable development of the nuclear technologies. Also, the nuclear waste problem creates a demand for developing novel, innovative technologies to deal with spent nuclear fuel of existing and upcoming reactors.

In this study, we propose our approach to the process of developing a new, innovative nuclear energy system. The process of the development of previous nuclear innovative systems is analysed based on historic developments creating the knowledgebase for an updated process for nuclear innovative system development. In contrast to the historical approach, it consists only of four sharply focussed major stages. The process is characterised by: basic studies, advanced studies and zero reactor experiment, small scale demonstrator and the industrial demonstrator. The proposed process is supported by the massive application of modelling and simulation to reduce the number of required experimental facilities. In addition, the requests on financial contribution and the importance of an early by in by major reactor vendors will be highlighted.



Artificial neural network potentials for atomistic simulation in multi-component molten salts

Stephen Lam, Qingjie Li, Lucas Rush, Charles Forsberg, Ju Li

Massachusetts Institute of Technology

The design and development of fully functional molten salt reactors (MSRs) requires detailed knowledge of the molten salt properties in order to understand and predict salt behavior. In these reactors, the salt constituents continuously evolve during operation due to irradiation and burning of nuclear fuel. This results in significant changes to the salt properties and chemistry that can cause corrosion and release of radionuclides to the environment. Due to the dynamic nature of salt chemistry, it is impractical to use experimental results alone to predict reactor behavior across all operating domains through the life of the reactor. Further, experimental data are difficult to collect due to the complexities and cost in handling liquid salts at high temperatures. Computational modeling can elucidate physical mechanisms driving behavior and can thus provide predictive capacity and help guide experimental trials. In this work, ab initio molecular dynamics (AIMD) was used to train neural networks potentials that could be used to run empirical MD. Using neural network potentials accelerates computation by several orders of magnitude and allows exploration of larger system sizes beyond hundreds of atoms. This could enable efficient prediction of physical and chemical properties over a large compositional space of an operating MSR. Flibe (66.6%LiF-33.3BeF2) was studied since it is a prototypical salt for many MSR designs. It was shown that neural network potentials can accurately reproduce multi-component liquid salt system energies with a mean average error of < 4 meV/atom.



Investigation of the validity of the Boussinesq approximation for molten salt natural circulation analysis using OpenFOAM

Dong Hun Lee, In Cheol Bang

Ulsan National Institute of Science and Technology

Molten salt has been studied as a key heat transfer medium of the next-generation energy system. due to its great thermophysical properties. In addition, the design of the system become more safe and compact when the concept of the natural circulation can be used which has recently been studied especially in nuclear engineering fields for the passive safety system. Natural circulation occurs due to buoyancy resulting from density variations between the heat source and heat sink; especially it is independent on the external pumping power. However, the natural circulation are sensitively influenced by geometrical features or thermophysical properties of working fluid due to its weak driving force. The Boussinesq approximation is a commonly used approach in the analysis of natural convection to simplify the conservation equation for reducing the computational resources by assuming density variations as a linear function of thermal expansion coefficient only in the body force term and neglecting the viscosity dissipation. For thermal-hydraulic analysis on molten salt, CFD codes are mostly used due to experimental limit that came from high operating temperature and solidification. But distortion can occur as it involves drastic temperature changes near the wall because high Pr of molten salt induces larger thermal boundary layer near the wall. It is also understood that viscosity has a greater effect on flow because that of molten salt is significantly higher than conventional heat transfer fluids. In this paper, we would like to understand how the two assumptions applied in the Boussinesq approximation; i)property change only in gravitational term, and ii)neglecting viscous dissipation, affect the molten salt natural circulation. Based on analysis results, modified Boussinesq approximation model was proposed. This work will improve the accuracy of the analysis of molten salt, contributing to the reduction of uncertainty of system and optimal design of MSR in the future.



Design optimization and burnup analyze for molten chlorine fast reactor

L.Y. He, S.P. Xia, G.M. Liu, Y. Zou, J.G. Chen

Chinese Academy of Science

Molten salt reactor (MSR), as the only liquid fuel reactor among the six candidate reactors retained by Generation-IV Forum (GIF) shows a great promise as high thermal-electric conversion efficiency, inherent safety, as well as viable on-line reprocessing. Compared with molten fast fluoride salt reactor (MSFR), the molten chloride fast reactor (MCFR) has unique advantages in terms of heavy nuclei (HN) solubility, neutron spectrum and melting point, which make it more suitable for minor actinides (MA) and TRU transmutation as well as fissile isotopes breeding. In this paper, the breeding performance of MCFR in equilibrium state was optimized, in order to improve search efficiency, an automatic program which coupled a novel hybrid algorithm and an equilibrium state search program was developed. Then, the pre-design MCFR was optimized with considering many parameters at the same time such as the volume of the core, the thickness of blanket and power density in case of keeping the total thermal power to be 5000 MW. Moreover, the Th-U cycle performances during transient state of the optimized MCFR were analyzed and compared with other cases, it suggests that the optimized MCFR has better promising breeding performance with good safety performance during the whole operation.



 
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