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[en] On the path to deployment of any reactor, modeling tool verification and validation is a key step. Fluoride-Salt-Cooled High Temperature Reactors (FHR) pose challenges to neutronics modeling and simulation tools due to several design features of the reactor type. This paper presents a categorized list of phenomena that pose challenges to FHR modeling using current neutronics tools. These phenomena are presented in four categories: Fundamental Cross Section Data, Material Composition, Computational Methodology, and General Depletion. A short path forward for these phenomena is also presented. In addition, a discussion of the resulting gaps in current codes is presented.
[en] The research program of the CEA in the field of molten salt nuclear reactors has been concerned with MSBR type reactors (Molten Salt Breeder Reactor). The papers written after having performed the theoretical analysis are entitled: core, circuits, chemistry and economy; they include some criticisms and suggestions. The experimental studies consisted in: graphite studies, chemical studies of the salt, metallic materials, the salt loop and the lead loop
[fr]Le programme de recherches du CEA dans le domaine des reacteurs nucleaires a sels fondus a porte sur les reacteurs de la filiere MSBR (Molten Salt Breeder Reactor). Les documents rediges a la suite de l'analyse theorique s'appellent: coeur, circuits, chimie, economie; ils contiennent des critiques et des suggestions. les etudes experimentales ont consiste en: etudes de graphites, etudes chimiques du sel, materiaux metalliques, boucle sel et boucle plomb
[en] Preliminary results of the dynamic analysis of a two-fluid molten-salt breeder reactor (MSBR) system are presented. Based on an earlier work on the preliminary dynamic model of the concept, the model presented here is nonlinear and has been revised to accurately reflect the design exemplified in ORNL-4528. A brief overview of the model followed by results from simulations performed to validate the model is presented. Simulations illustrate stable behavior of the reactor dynamics and temperature feedback effects to reactivity excursions. Stable and smooth changes at various nodal temperatures are also observed. Control strategies for molten-salt reactor operation are discussed, followed by an illustration of the open-loop load-following capability of the molten-salt breeder reactor system. It is observed that the molten-salt breeder reactor system exhibits “self-regulating” behavior, minimizing the need for external controller action for load-following maneuvers
[en] Fluoride salt-cooled high-temperature reactors (FHRs) are one of the new reactor concepts proposed in the Generation IV International Forum. The main distinguishing features of the FHR are its high operating temperature, lithium beryllium fluoride salt (Li2Be4F) coolant, known as FLiBe, and graphite moderator. Most FHR studies focus on the use of tri-structural-isotropic (TRISO) particulate fuels that are compacted with a graphite matrix to form various fuel shapes. Although TRISO fuel offers some potential performance advantages, it is much more expensive than conventional UO2 fuel. This study investigates the performance potential of pin-type fuel assembly designs in an FHR, by seeking the ideal assembly configuration and the minimum enrichment level needed to achieve a target (13 months) cycle length for a small (125 MWth) FHR, while ensuring that the coolant and fuel temperature reactivity coefficients remain negative throughout the cycle. Three different assembly configurations (with 36, 60 and 90 fuel pins respectively) were analysed using the deterministic lattice physics code WIMS, over a range of 235U enrichments (from 1 wt.% to 20 wt.%) to investigate the minimum enrichment level. In addition, to estimate the cycle length of the reactor, a leakage probability analysis was performed by modelling a 2D whole-core reactor. (authors)
[en] Outline: • Modeling of SFR cores using the Serpent-DYN3D code sequence; • Core shielding assessment for the design of FASTEF-MYRRHA; • Neutron shielding studies on an advanced Molten Salt Fast Reactor (MSFR) design
[en] The Molten Salt Fast Reactor (MSFR) with its liquid circulating fuel and its fast neutron spectrum calls for a new safety approach including technological neutral methodologies and analysis tools adapted to early design phases. In the frame of the Horizon2020 program SAMOFAR (Safety Assessment of the Molten Salt Fast Reactor) a safety approach suitable for Molten Salt Reactors is being developed and applied to the MSFR. After a description of the MSFR reference design, this paper focuses on the identification of the Postulated Initiating Events (PIEs), which is a core part of the global assessment methodology. To fulfil this task, the Functional Failure Mode and Effect Analysis (FFMEA) and the Master Logic Diagram (MLD) are selected and employed separately in order to be as exhaustive as possible in the identification of the initiating events of the system. Finally, an extract of the list of PIEs, selected as the most representative events resulting from the implementation of both methods, is presented to illustrate the methodology and some of the outcomes of the methods are compared in order to highlight symbioses and differences between the MLD and the FFMEA
[en] Creation fast critical molten salt reactor for burning-out minor actinides and separate long-living fission products in the closed nuclear fuel cycle is the most perspective and actual direction. The reactor on melts salts - molten salt homogeneous reactor with the circulating fuel, working as burner and transmuter long-living radioactive nuclides in closed nuclear fuel cycle, can serve as an effective ecological cordon from contamination of the nature long-living radiotoxic nuclides. High-flux fast critical molten-salt nuclear reactors in structure of the closed nuclear fuel cycle of the future nuclear power can effectively burning-out / transmute dangerous long-living radioactive nuclides, make radioisotopes, partially utilize plutonium and produce thermal and electric energy. Such reactor allows solving the problems constraining development of large-scale nuclear power, including fueling, minimization of radioactive waste and non-proliferation. Burning minor actinides in molten salt reactor is capable to facilitate work solid fuel power reactors in system NP with the closed nuclear fuel cycle and to reduce transient losses at processing and fabrications fuel pins. At substantiation MSR-transmuter/burner as solvents fuel nuclides for molten-salt reactors various salts were examined, for example: LiF - BeF2; NaF - LiF - BeF2; NaF-LiF ; NaF-ZrF4 ; LiF-NaF -KF; NaCl. RRC 'Kurchatov institute' together with other employees have developed the basic design reactor installations with molten salt reactor - burner long-living nuclides for fluoride fuel composition with the limited solubility minor actinides (MAF3 < 2 mol %) and have estimated its basic characteristics. On the basis of these data employees RRC KI and VNIPIET carry out conceptual binding reactor installations with molten salt reactor - burner to the project of a factory on processing 500 tons spent fuel of reactors of type WWER-1000 in a year. During a settlement-experimental research in RRC KI it is shown, that fluoride fuel composition with high solubility minor actinides (MAF3 > 10 mol %) allows to develop in some times more effective molten salt reactor with fast neutron spectrum - burner/ transmuter of the long-living radioactive waste. In high-flux fast reactors on melts salts within a year it is possible to burn ∼300 kg minor actinides per 1 GW thermal power of reactor. The technical and economic estimation given power-technological complex shows on economic efficiency of use such burner/transmuter. After separation from spent fuel power reactors minor actinides go on burning out in molten salt reactor. The offered concept power-technological complex with high-flux fast reactor on melts salts, intended for burning out and transmutation long-living radiotoxic nuclides, at practical realization will allow minimizing quantity of the long-living radioactive waste in system of a nuclear power. Accommodation of such reactors at the enterprises of a fuel cycle will provide with their energy and will facilitate the decision of a problem of radioactive waste management with the minimal losses. Small share MSR (5-7) % from full electric power in structure of the future nuclear power provides practically full burning of all minor actinide (Authors)
[en] Molten Salt Reactors are investigated in the entire world because of their use of thorium fuel and their possibility to transmute transuranium elements. After the disaster of TEPCO's Fukushima nuclear power plant, the release of radioactive fission products from the plant has been investigated. In this study, the evaporation behavior of Cesium (Cs) and Iodine (I) in FLiNaK molten salt was investigated by using mass spectrometry. (authors)
[en] Fusion–Fission Hybrid System (FFHS) is one of the promising options for waste transmutation (WT) of spent nuclear fuel (SNF). Various studies for FFHS has been conducted by many organizations including Kyung Hee University (KHU) design team. Recently, molten-salt reactor (MSR) type-FFHS using liquid fuel has attracted attention as a new concept. The use of liquid molten-salt (MS) plays dual role as fuel and coolant providing significant benefit; high compatibility with complex blanket geometry. There is no need to consider integrity of the fuel structure such as cladding in high temperature and high neutron irradiation environment by using liquid fuel. In this paper, FFHS with dual fluid (DF) concept is proposed. DF concept is combining MSR with fast reactor. The MS as a fuel flows in the pipe and PbBi or Na coolant which can maintain fast spectrum flows out of the pipe. In other words, advantages of MSR as already mentioned are maintained, the FFHS becomes more suitable for WT by using DF concept. In addition, because fuel and coolant are separated, high power density is acceptable compared to conventional MSR. In this paper, preliminary nuclear design of FFHS with dual fluid concept for WT was conducted. Transmutation performance was evaluated to the various design options; strategy of online-refueling, refueling cycle time and blanket geometry.