Thorium Molten Salt Reactor Research Articles

Possible Configurations for the Thorium Molten Salt Reactor and Advantages of the Fast Nonmoderated Version

Molten Salt Reactors based on the thorium cycle were studied in the 1950 to 1960s to lead to the Molten Salt Breeder Reactor concept, which was finally discontinued prior to any industrial development. In the past few years, this concept has once again been studied in order to generalize it and seek configurations ensuring a high intrinsic safety level, an initial inventory compatible with intensive deployment on a worldwide scale, and a not-too-demanding salt chemical reprocessing scheme.The Thorium Molten Salt Reactor (TMSR) thus defined is studied in the Th-233U cycle in various configurations obtained by modulating the amount of graphite in core to obtain a thermal, an epithermal, or a fast spectrum. In particular, configurations of a fast spectrum TMSR have been identified with outstanding safety characteristics and minimal fuel-reprocessing requirements.

Influence of the Processing and Salt Composition on the Thorium Molten Salt Reactor

Molten salt reactors (MSRs) are one of the six systems retained by Generation IV as a candidate for the next generation of nuclear reactors. The MSR is a very attractive concept especially for the thorium fuel cycle, which allows nuclear energy production with a very low production of radiotoxic minor actinides, so it has been selected by the Generation-IV International Forum. Its main characteristic is a strong coupling between neutronics and salt processing. Such nuclear reactors use a liquid fuel that is also the coolant. Elements produced during the reactor’s operation, like fission products or transuranic elements, modify the neutronic balance of the reactor by capturing neutrons. As the fuel is liquid, partial processing of a limited amount taken from circulating salt is possible, in order to remove the poisoning elements, without stopping reactor operation. In this paper, we present a configuration that we consider to be a reference one for a thorium molten salt reactor (TMSR), and we study the influence of efficacy of different types of processing on the neutronic behavior of this reactor. By considering both the possibilities in chemistry and the neutronic effects, our aim is to work out an efficient, reliable, and realistic processing scheme.The processing includes in fact two components: an in-line bubbling system within the reactor that extracts the gaseous and metallic fission products quickly and a slower external processing unit that extracts the other fission products. A salt volume equal to the core volume is thus cleaned in several months. We have studied the influence of different processing rates on the reactor’s behavior. This mainly affects the breeding ratio.Properties of the salt are also crucial. We choose in our simulations of the TMSR a 78 mol% LiF–22 mol% [heavy nuclei (HN)] F4 salt for the fuel, but lower HN proportions in the fuel salt are also examined in order to minimize the 233U inventory in the reactor. The neutron spectrum is largely modified by the HN proportion and has a deep impact on the reactor behavior. Our simulations evaluate the degradation of the breeding ratio from >1 for the reference configuration down to 0.86 due to a decrease of the HN proportion in the fuel salt.We conclude that the simplification of the salt processing that is addressed in this work improves the feasibility of the TMSR system.

Reactor physic and reprocessing scheme for innovative molten salt reactor system

The molten salt reactor is one of the six concepts retained by the Generation IV forum in 2001. Based on the MSRE and MSBR concepts developed by ORNL in the 60s which involve a liquid fuel constituted of fluorine molten salt at a temperature close to 600 °C, new developments with innovative approach and technology have been realized which contribute to strongly improve the concept. The thorium breeder potentiality is closely related to the use of a liquid fuel which is able to be periodically treated. A reprocessing scheme has been established to treat used fuel by extraction of fission products. According to the Gen IV philosophy for closed cycle nuclear reactor, the actinides are sent back in the reactor core. In this way, the wastes radiotoxicity is strongly decreased and the use of natural resource is optimized. This paper describes an innovative reactor concept, the TMSR-NM (non-moderated thorium molten salt reactor), from the nuclear physic point of view and the different steps involving in the reprocessing scheme from the chemical point of view.

Characteristics of Thorium Molten-Salt Reactor with Self-Sustainability

In this paper, the burn-up characteristics of a 200 MWe molten-salt reactor are studied. This reactor has a three-region core in order to reduce the peak in fast neutron ‰ux distribution. The reactor is operated for 30 years with the load factor of 0.75. The fuel is fed to the reactor every 33 days. The chemical processing of the fuel salt is performed every 7.5 years. Based on calculations using the nuclear analysis code SRAC2006 and the burn-up analysis code ORIGEN2, the following results have been obtained. (1) The graphite moderators can be used throughout the reactor lifetime without replacement. (2) The reactor is self-sustainable having an average fuel conversion ratio of 1.01. (3) The initial inventory of 233 U is 1.13 t, net feed in 30 years is 0.34 t; thus, the necessary amount of 233 Ui s 1.48 t.(4) Pu isotopes are produced at 1.5 kg and minor actinides at 27 kg per 1 GWe output in 30 years, which are absolutely small compared with those produced by BWR.

ICONE15-10493 PRE DESIGN OF A MOLTEN SALT THORIUM REACTOR LOOP

This study is a contribution to the 2004 PCR-RSF program of the Centre National de la Recherche Scientifique (CNRS) devoted to research on high temperature thorium molten salt reactors. A major issue of high temperature molten salt reactors is the very large heat duty to be transferred from primary to secondary loop of the reactor with minimal thermal losses. A possible inner loop made of a series of conventional graphite filter plate exchangers, pipes and pumps was investigated. The loop was assumed to use two counter current flows of the same LiF, BeF_2, ZrF_4, UF_4 molten salt flowing through the reactor. The 3D model used the coupling of k-ε turbulent Navier-Stokes equations and thermal applications of the Heat Transfer module of COMSOL Multiphysics. For a reactor delivering 2700 MWth, the model required a set of 114 identical exchangers. Each one was optimized to limit the heat losses to 2882 W. The pipes made of a succession of graphite, ceramics, Hastelloy-N alloy and insulating Microtherm^[○!R] layers led to a thermal loss limited to 550 W per linear meter. In such conditions, the global thermal losses represent only 0.013 % of the reactor thermal power for elements covered with an insulator only 3 cm thick.

06/02628 Potential of thorium molten salt reactors detailed calculations and concept evolution with a view to large scale energy productionNuttin, A. et al. Progress in Nuclear Energy, 2005, 46, (1), 77–99

06/02628 Potential of thorium molten salt reactors detailed calculations and concept evolution with a view to large scale energy productionNuttin, A. et al. Progress in Nuclear Energy, 2005, 46, (1), 77–99

The thorium molten salt reactor: Moving on from the MSBR

A re-evaluation of the molten salt breeder reactor concept has revealed problems related to its safety and to the complexity of the reprocessing considered. A reflection is carried out anew in view of finding innovative solutions leading to the thorium molten salt reactor concept. Several main constraints are established and serve as guides to parametric evaluations. These then give an understanding of the influence of important core parameters on the reactor's operation. The aim of this paper is to discuss this vast research domain and to single out the molten salt reactor configurations that deserve further evaluation.

New Primary Energy Source by Thorium Molten-Salt Reactor Technology

New Primary Energy Source by Thorium Molten-Salt Reactor Technology

Potential of thorium molten salt reactorsdetailed calculations and concept evolution with a view to large scale energy production

We discuss here the concept of Thorium Molten Salt Reactor dedicated to future nuclear energy production. The fuel of such reactors being liquid, it can be easily reprocessed to overcome neutronic limits. In the late sixties, the MSBR project showed that breeding is possible with thorium in a thermal spectrum, provided that an efficient pyrochemical reprocessing is added. With tools developed around the Monte Carlo MCNP code, we first re-evaluate the performance of a MSBR-like reference system with 232Th/ 233U fuel. We find an important reduction of inventories and induced radiotoxicities at equilibrium compared to other fuel cycles, with a doubling time of about thirty years. We then study how to start this interesting reference system with theplutonium from PWR spent fuel. Such a transition appears slow and difficult, since it is very sensitive to the fissile quality of the plutonium used. Deployment scenarios of 232Th/ 233U MSBR-like systems from the existing French PWRs demonstrate the advantage of an upstream 233U production in other reactors, allowing a direct start of the MSBR-like systems with 233U. This finally leads us to explore alternatives to some MSBR features, for energy production with 232Th/ 233U fuel from the start. We thus test different options, especially in terms of core neutronics optimization and reprocessing unit adaptation.

トリウム燃料に関する総合的研究

Introduced is the activities of the Joint Research Project Team on Thorium Fuel organized by mainly university researchers in Japan and supported by the Ministry of Education, Science and Culture for seven years since 1980. Four major groups were organized; (1) nuclear data, reactor physics and design, (2) nuclear fuel, (3) down stream and (4) biological effects of thorium.The first group covered measurements and analysis on nuclear data of thorium related nuclides, experiment and analysis on nuclear characteristics of thorium containing cores, basic engineering on a thorium molten salt reactor, and designs of several types of reactors. Fabrication and irradiation tests of thorium oxide fuel, and basic studies on new type thorium fuels (e.g. carbide and nitride) were studied by the second group. The third group covered the use of solutions in reprocessing of spent fuel, behavior of fission products, immobilization of high level radioactive waste, and continuous reprocessing for a molten salt reactor. The fourth group performed the trace study for patients who had been intravascularly injected with thorotrast for diagnosis of war injuries during the Second World War.

新しいトリウム溶融塩発電システムの開発

新しいトリウム溶融塩発電システムの開発