Global Progress on Molten Salt Reactors: A Companion to Dolan’s Molten Salt Reactors and Thorium Energy

By Thomas James Dolan

Global Progress on Molten Salt Reactors: A Companion to Dolan’s Molten Salt Reactors and Thorium Energy, Second Edition presents global perspectives on the latest research and technological advances. Each case study utilizes a comprehensive template that guides the reader through country specific research. Useful data which can be applied to work and research is included, along with a list of references for further research. Researchers, professional engineers and policymakers will gain a broad picture of worldwide MSR activity and a deep understanding of how theory and practical guidance is applied in a variety of settings, including budgets, approaches and constraints.

• Provides a collection of case studies from 23 countries, presenting their latest research and activities on Molten Salt Reactors
• Based on chapter 26 of the first edition of Dolan’s Molten Salt Reactors and Thorium Energy, this companion title presents expanded and more complete coverage of global activities and research
• Includes advanced technologies, reactor designs and safety and management strategies

• Language: English
• Publisher: Elsevier Science
• Release date: Feb 5, 2024
• ISBN: 9780323993777

Book preview

Preface

There is growing awareness that nuclear energy is needed to complement intermittent energy sources and to avoid pollution from fossil fuels. Light water reactors are complex, expensive, and vulnerable to core melt, steam explosions, and hydrogen explosions, so better technology is needed. Thorium energy and molten salt reactors could make nuclear energy safer and less expensive.

The book Molten Salt Reactors and Thorium Energy (Elsevier 2017) has served as a reference for engineers and scientists. Since then, nuclear power has become more accepted, and there is growing interest in molten salt reactors. Therefore, a Second Edition has been prepared. The volume of information is so large that we have split off the 25 country/organization reports into this separate volume, entitled Global Progress on Molten Salt Reactors. In this companion volume 3 chapters are completely new, 10 have substantial revisions, 7 have minor revisions, and 4 chapters are picked up from the First Edition. We look forward to more updates in the years to come.

Thomas James Dolan

Chapter 1

Canada

Cyril Rodenburg,    Terrestrial Energy Inc., Oakville, ON, Canada

Abstract

MSR activities in Canada are concentrated in the Integral Molten Salt Reactor (IMSR), which is a uranium-fueled, graphite-moderated, fluoride chemistry, thermal spectrum molten salt reactor system designed by Terrestrial Energy Incorporated. It is described in Chapter 16, Switzerland.

Keywords

Integral Molten Salt Reactor (IMSR)

MSR activities in Canada are concentrated in the Integral Molten Salt Reactor (IMSR), which is a uranium-fueled, graphite-moderated, fluoride chemistry, thermal spectrum molten salt reactor system designed by Terrestrial Energy Incorporated. It is described in Chapter 18 Integral molten salt reactor of Molten Salt Reactors and Thorium Energy (Elsevier 2023), and also in the following site.

Website: https://nam11.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.terrestrialenergy.com%2F&data=05%7C01%7Cf.fathima.1%40elsevier.com%7Cac7c3c22af5640ed579608dbe9bb8bdd%7C9274ee3f94254109a27f9fb15c10675d%7C0%7C0%7C638360763955370239%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=hsv%2FdIjE5fVuqJrxZnXyTKQE1yoiSDQcqgX3JWpAWYg%3D&reserved=0.

Chapter 2

Czech Republic

Jan Uhlíř,    Research Centre Řež, Husinec, Czech Republic

Abstract

This chapter describes the research and development activities in MSR technology in the Czech Republic in the period of 1999–2021.

Keywords

MSR technology in the Czech Republic

The technology of nuclear reactor systems with liquid molten salt fuel has been investigated in the Czech Republic since 1999. The original effort came from the national partitioning and transmutation concept based on the subcritical accelerator-driven system for the incineration of transuranium elements with liquid fluoride fuel and fluoride pyrochemical partitioning fuel cycle technology. After 2005, the original R&D intentions were gradually converted to a classical molten salt reactor technology and to the thorium–uranium fuel cycle. Arguments for this decision were presented by a group of prominent Czech nuclear scientists. These arguments were based on the fact that the Czech Republic should support the development of a technology that can minimize environmental impact of nuclear power, save natural resources, and has a potential to be deployed also in nonsuperpower countries, whereas fast reactors, which need highly enriched uranium or a high plutonium content, will represent the future of nuclear power for superpowers.

The theoretical and experimental development of MSR and liquid thorium fuel technology has been realized by a national consortium of institutions and companies originally led by the Nuclear Research Institute Řež.

After the first R&D activities in 2000–03, devoted mainly to subcritical molten salt system for incineration of transuranium elements, since 2004, the main R&D effort has been focused on critical MSR systems; and since 2005, the thorium–uranium fuel cycle technology has also been under intensive study.

The Ministry of Industry and Trade of the Czech Republic supported two important R&D projects devoted to MSR system and thorium–uranium fuel cycle. The first, which was opened in 2004, was called Nuclear system SPHINX with molten fluoride salts based liquid nuclear fuel, the second, opened in 2006, was Fluoride reprocessing of GEN IV reactor fuels. The investigations were based on experience obtained by US Oak Ridge National Laboratory during the Molten-Salt Reactor Experiment project in 1960s (Rosenthal et al., 1971) and also from the exchange of scientific information with the French EDF team on the AMSTER project in 2000 (Vergnes et al., 2000).

The SPHINX project was devoted to the broad spectrum of the MSR technology covering theoretical and experimental activities in MSR physics, fuel salt and fuel cycle chemistry, molten salt thermohydraulics, structural material development, and testing of apparatuses for molten fluoride salt media. The project was carried out by a consortium of institutions and companies lead by the Nuclear Research Institute Řež in cooperation with ŠKODA JS (ŠKODA—Nuclear Machinery), Nuclear Physics Institute of the Academy of Sciences of the Czech Republic, Faculty of Nuclear Sciences and Physical Engineering of the Czech Technical University in Prague and Energovyzkum Ltd. Brno, and later also with the Research Centre Řež and COMTES FHT. The main aims of the project were to contribute to the knowledge of MSR reactor physics, core design and safety, structural material development, MSR fuel cycle technology; to verify experimentally selected important areas of MSR technology; and to contribute to the solution of existing bottlenecks. The research work under the SPHINX project was divided into following work packages:

1. WP1—MSR core and primary circuit;

2. WP2—MSR fuel cycle technology;

3. WP3—experimental MSR core and its control system;

4. WP4—secondary circuit and its components;

5. WP5—structural materials for MSR technology;

6. WP6—system study of MSR-SPHINX;

7. WP7—experimental program SR-0.

The second project Fluoride reprocessing was devoted to the experimental development of two fluoride partitioning technologies, specifically to the fluoride volatility method and to electrochemical separation processes from fluoride molten salt media. As the fluoride volatility method can be used for oxide fuels from fast reactors, the investigation of electrochemical separation processes has been exclusively devoted to the thorium–uranium fuel cycle of the molten salt reactor system. The work within this project also covered the experimental verification of fresh liquid molten salt fuel processing—a technology of ThF4 and UF4 preparation from ThO2 and UO2, respectively, and final processing of MSR fuel salts LiF-BeF2-ThF4 and LiF-BeF2-UF4. Other objectives of the MSR fuel cycle investigation were system studies focused on the material balance calculations and a conceptual flow-sheet design of MSR on-line reprocessing. Both one-fluid (single-fluid) and two-fluid (double-fluid) systems of MSR core design were investigated, and conceptual flow-sheets were designed for both design systems. Finally, the project also covered the nonproliferation and physical protection aspects of Th-U MSR fuel cycle technology.

Although the MSR design and operation were already verified by ORNL in the 1960s, the on-line reprocessing was never fully realized and still represents a crucial problem of MSR technology, which must be solved before MSRs can be deployed in the future. The Fluoride reprocessing project was solved by the Nuclear Research Institute Řež.

The main achievements of both projects were:

1. Challenging reactor physics experiments with inserted molten salt zones were realized in LR - 0 and LVR -15 and VR-1 reactors at the Nuclear Research Institute Řež, the Research Centre Řež, and the Czech Technical University.

2. Computer codes for calculation of neutronic characteristic of the MSR system and for calculation of the composition evolution during the burnout of liquid fuel were developed.

3. In the Fluorine chemistry laboratory of the Nuclear Research Institute Řež, handling with beryllium-containing molten salts was mastered, fresh thorium and uranium molten salt fuel processing for MSR systems was verified in semipilot conditions, and the basic studies of electrochemical separation of actinides (Th, U) from fission products were realized. These electrochemical studies were devoted to MSR on-line reprocessing development.

4. MSR fuel cycle mass balance calculations and conceptual flow-sheets of on-line reprocessing were designed.

5. A special nickel alloy called MONICR, resistant to molten fluoride salt media, was developed by ŠKODA JS and COMTES FHT companies. Irradiation and corrosion tests of the MONICR alloy and metallographic studies were performed and experimental production of sheets, tubes, and rods was realized.

6. Basic design and theoretical and experimental development of impellers and valves for molten fluoride salts and salt/salt and salt/air heat exchangers were realized by the Energovyzkum Ltd.

7. Faculty of Nuclear Sciences and Physical Engineering of the Czech Technical University in Prague opened new facultative topics Liquid nuclear fuels and MSR system technology for regular and Ph.D. students.

The LR-0 reactor, operated by the Research Centre Řež, has proved to be extremely suitable equipment for measurement of molten salt neutronics. The measurements were realized in molten salt zones inserted in the central part of the reactor core. The standard VVER fuel served as the neutron driver (Fig. 2.1). Basic critical parameters (the critical height of the moderator, the moderator level coefficient) were determined for each arrangement using the approved methodology of the initial critical experiments for the LR-0 reactor. These, along with a description of the fuel quantity, enrichment, and filling material, represent the fundamental data needed to determine the effects of the filling on the physical properties of the core, and serve as the input for calculations and benchmark comparisons. The initial critical experiments were followed by measurements of neutron flux and reaction rate to determine the characteristics of the neutron and photon field using the following methods. The increase in reactivity was determined by differences in the critical moderator level with and without the salt (Hron and Matal, 2008; Frýbort and Vočka, 2009).

Figure 2.1 View into the LR-0 reactor core with inserted salt zone and the manipulation with the salt zone before the insertion into reactor core.

The theoretical and experimental investigations of MSR fuel cycle technology at the Nuclear Research Institute Řež have been focused mainly on the electrochemical separation processes in fluoride media suitable for usage within the MSR on-line reprocessing technology. The main objective of experimental activities on electrochemical separation technology has been to survey the separation possibilities of the selected actinides (uranium, thorium) and fission products (lanthanides) in selected fluoride melt carriers. The cyclic voltammetry method was used to study the basic electrochemical properties.

The first step was the choice of fluoride melts suitable for electrochemical separations. The melt should meet some basic characteristics—low melting point, high solubility, high electrochemical stability, and appropriate physical properties (electrical conductivity, viscosity, etc.). A special reference electrode based on the Ni/Ni²+ red-ox couple was developed to provide reproducible electrochemical measurements in fluoride melts (Straka et al., 2009, 2011) and to facilitate the on-line reprocessing flow-sheet design (Uhlíř et al., 2012a).

Results obtained from the measurements were interpreted in following way:

1. In FLIBE melt, there is a good possibility for electrochemical separation of uranium. Although the electrochemical studies of protactinium have not been realized yet, based on the thermodynamical properties of PaF4, there is a presumption that protactinium could be separated from this melt as well.

2. In FLINAK and in LiF-CaF2 melts, both uranium and thorium and most of the fission products (lanthanides) can be electrochemically separated.

The national projects described above were successfully finalized in 2009 (SPHINX) and 2012 (Fluoride reprocessing) (Hron et al., 2009; Uhlíř et al., 2012b). The main goals were achieved in both projects, and the obtained knowledge and experience created a good basis for international collaboration of Czech companies in further collaborative R&D projects of MSR technology. In 2012, the Ministry of Industry and Trade of the Czech Republic and US Department of Energy concluded a Memorandum of Understanding focused on the collaborative investigation of the fluoride-salt-cooled high-temperature reactor (FHR) and molten salt reactor technologies. Current Czech activities in this field cover mainly the areas of:

1. theoretical and experimental reactor physics of MSR and FHR;

2. chemistry and chemical technology of MSR;

3. further development of nickel alloys for molten fluoride salt technologies;

4. development of equipment and components for MSR/FHR technology.

These areas were also solved within the last project entitled R&D of Fluoride-cooled Nuclear Reactor Systems, which was completed in 2021 (Mareček et al., 2021). The project was carried out by a consortium of institutions and companies managed by Research Centre Řež in cooperation with ÚJV Řež (Nuclear Research Institute), COMTES FHT, MICo Ltd, and ŠKODA JS. The project was financed by the Technology Agency of the Czech Republic and supervised by the Ministry of Industry and Trade.

One of the main objectives of the project in the area of reactor physics was to measure the neutronic characteristics of the fluoride salt FLIBE (⁷LiF–BeF2) over the operating temperature range of the MSR and FHR reactors (500°C–750°C) in order to determine the reactivity coefficients keff (Losa et al., 2020). For these experiments, a so-called Hot FLIBE Inserted Zone was constructed. The measurements were carried out in the experimental LR-0 reactor of the Research Centre Řež. Because the LR-0 reactor did not allow heating of the Zone inside the reactor vessel, the Zone was preheated outside the reactor before each experiment (Fig. 2.2).

Figure 2.2 Loading the instrumented Hot FLIBE zone into the LR-0 reactor vessel. Source: Courtesy CV Řež.

In the field of chemistry and chemical technology of MSR, in addition to the technology of electroseparation, the technology of uranium removal from FLIBE salt using the Fused salt volatilization method was also studied (Straka et al., 2019). In the field of further development of nickel alloy MONICR, the problems of its welding, high-temperature microstructure stability, high-temperature mechanical stability, and radiation embrittlement were addressed.

In the area of component development, flange and gasket designs were tested and the development of impeller pumps for fluoride salts was underway. The project also included a loop program to test the design and operation of freeze valves (Fig. 2.3).

Figure 2.3 View on the forced FLIBE test loop with freeze valve. Source: Courtesy CV Řež.

Czech activity in R&D of MSR technology has also enabled individual Czech research teams to participate in several international projects devoted to MSR technology (MOST, ALISIA, EVOL and SAMOSAFER projects of the 5th, 6th, and 7th Framework Programme and Horizon 2020 Programme of EC-EURATOM, selected CRP projects of IAEA, and studies of OECD-NEA). Czech representatives also participate in the work of Provisional System Steering Committee of MSR System of the Generation Four International Forum under the membership of the EURATOM team.

References

Frýbort and Vočka, 2009 Frýbort, J., Vočka, R., 2009, Neutronic analysis of two-fluid molten salt reactor. In: Proceedings of the ICAPP 2009, Tokyo, Japan, May 10–14.

Hron et al., 2009 Hron, M., et al., 2009, Jaderný Transmutační Systém SPHINX s Kapalným Jaderným Palivem na Bázi Roztavených Fluoridů (Nuclear System SPHINX with Molten Fluoride Salts Based Liquid Nuclear Fuel). Final report MPO ČR FT-TA/055, ÚJV Řež (in Czech).

Hron and Matal, 2008 Hron, M., Matal, O., 2008, R&D program in the frame of the MSR-SPHINX actinide burner concept development. In: Proceedings of the ARWIF 2008, Fukui, Japan, February 20–22.

Losa et al., 2020 Losa, E., Košťál, M., et al., 2020, Neutron field mock-up development for fluoride salt reactors neutronic research. In: Proceedings of the PHYSOR 2020, Cambridge, UK, March 29–April 2.

Mareček et al., 2021 Mareček, M., et al., 2021, Závěrečná Zpráva Projektu TAČR č. TH02020113 (Final report of TACR Project TH02020113), CV Řež (in Czech).

Rosenthal et al., 1971 Rosenthal MW, Haubenreich PN, McCoy FE, McNeese LE. Recent progress in molten-salt reactor development. Atom Energy Rev. 1971;9(3):601–650.

Straka et al., 2009 Straka, M., Chuchvalcová Bímová, K., Korenko, M., Lisý, F., 2009, Development of electrochemical separation methods in molten fluoride salts FLINAK and FLIBE. In: Proceedings of the GLOBAL 2009, Paris, France, September 6–11.

Straka et al., 2019 Straka, M., et al., 2019, Technological aspects of MSR fuel cycle. In: Transactions ANS, 120, Minneapolis, MN, June 9–13, pp. 361–362.

Straka et al., 2011 Straka M, Korenko M, Szatmáry L. Electrochemistry of praseodymium in LiF-CaF2. J Radioanal Nucl Chem. 2011;289(2):591.

Uhlíř et al., 2012a Uhlíř, J., Straka, M., Szatmáry, L., 2012a, Development of pyroprocessing technology for thorium-fuelled molten salt reactor. In: Proc. ICAPP 2012, Chicago, IL, June 24–28, 2012.

Uhlíř et al., 2012b Uhlíř, J., et al., 2012b, Fluoridové Přepracování Paliva Reaktorů 4. Generace (Fluoride Reprocessing of GEN IV Reactor Fuels), Final report MPO ČR 2A-1TP1/030, ÚJV Řež, (in Czech).

Vergnes et al., 2000 Vergnes, J., et al., 2000, The AMSTER concept (Actinide Molten Salt TransmutER). In: Proceedings of the PHYSOR 2000 Conference, Pittsburgh, PA, May 7–12.

Chapter 3

China

Ritsuo Yoshioka,    International Thorium Molten-Salt Forum, Yokohama, Japan

Abstract

After ORNL in the United States stopped the operation of their experimental MSR (MSRE: Molten Salt Reactor Experiment) in 1969, China started an MSR project in 1970. A major institution in China was the Shanghai Institute of Applied Physics (SINAP); and in 1971, they constructed a first zero-powered experimental reactor using frozen salt. However, this history has not been known outside China for long time, and it gave a surprise to Western countries when they told this history in an international conference. In 2011, SINAP started a long-term development program for their Thorium Molten Salt Reactor, which is described later.

Keywords

China; Shanghai Institute of Applied Physics; molten salt reactor experiment; thorium molten salt reactor; Institute of Nuclear Energy Technology; high assay low enriched uranium

After ORNL in the United States stopped the operation of their experimental MSR (MSRE: Molten Salt Reactor Experiment) in 1969, China started an MSR project in 1970. A major institution in China was the Shanghai Institute of Applied Physics (SINAP); and in 1971, they constructed a first zero-powered experimental reactor using frozen salt. However, this history has not been known outside China for long time, and it gave a surprise to Western countries when they told this history in an international conference (Xu, 2012). In 2011, SINAP started a long-term development program for their Thorium Molten Salt Reactor (TMSR), which is described later.

Besides the study in SINAP, Tsinghua University in Beijing investigated molten salt application to nuclear energy at Institute of Nuclear Energy Technology (INET) in the 1970s. They have made various studies, and one of them was a molten salt loop using HTS (nitrate) with 8 m³/h flow by a pump, operated by a 100kWe heater at 550°C (Yoshioka, 1999).

In the 2011 development program for TMSR, SINAP started a wide range of studies in parallel (Xu, 2013). These are material development such as molten salt, Nickel-based super-alloy, graphite, and enriched ⁷Li. Components such as pumps, valves, and reactor vessel have also been developed. In order to establish offline reprocessing, which is a separate facility from TMSR, SINAP is developing dry-processing technology based on the previous study in