Research and Development of Innovative Modular Thorium Reactors in Nuclear-Producing Countries
Source abstract
Abstract
This review examines current research and development directions in thorium-based nuclear fuel cycles and reactor systems, including innovative and modular reactor concepts being investigated in several nuclear-producing countries. The analysis considers the feasibility of integrating thorium-containing fuels into both existing and emerging reactor technologies. Particular attention is paid to the potential use of thorium-based fuels in pressurized water reactors (PWRs) as transitional platforms that can enable gradual introduction in thorium without requiring immediate deployment of entirely new reactor architectures. This study synthesizes representative quantitative results reported in the recent literature, including neutronic performance metrics, conversion ratio estimates, and fuel behavior characteristics of mixed Th–U oxide fuels under typical operating conditions. These results are evaluated together with broader system-level considerations, such as fuel cycle closure potential, materials performance, and technology readiness across different reactor classes. A comparative assessment of light water reactors (LWRs), heavy water reactors (HWRs), and molten salt reactors (MSRs) demonstrates that each platform offers distinct advantages and limitations for thorium deployment. While LWR systems provide the most realistic near-term pathway for partial thorium introduction within the existing nuclear infrastructure, HWR and MSR concepts offer more favorable conditions for efficient thorium utilization and potential Th–U fuel cycle closure. These reactor classes are currently being explored within national research and development programs focused on advanced and modular nuclear technologies. By integrating neutronic analysis, materials considerations, fuel cycle strategies, and techno-economic factors, this review provides a system-level perspective on the research and development of innovative thorium reactor concepts and outlines realistic pathways for their gradual implementation in evolving nuclear energy systems.
Source: crossref · Quality: baseline
Research context
OpenAlex topics: Nuclear reactor physics and engineering · Nuclear and radioactivity studies · Molten salt chemistry and electrochemical processes
SciVX discovery tags are terminology-based. OpenAlex topics are source-provided classifications.
Affiliations
Private Institution “Nazarbayev University Research Administration”, Nazarbayev University, Astana 010000, Kazakhstan
School of Nuclear Engineering, Purdue University, West Lafayette, IN 47907, USA
Institute of Combustion Problems, Kazakh National State University, Almaty 050012, Kazakhstan
Engineering Center for Organic Agricultural Technologies, Seifullin Kazakh Agrotechnical Research University, Astana 62 Zhenis Ave, Astana 010000, Kazakhstan
Funding
Ministry of Science and Higher Education of the Republic of Kazakhstan
References (60)
Show source-provided references
1. International Atomic Energy Agency (IAEA) (2005). Thorium Fuel Cycle—Potential Benefits and Challenges, IAEA. IAEA-TECDOC-1450.
2. OECD Nuclear Energy Agency (NEA) (2015). Introduction of Thorium in the Nuclear Fuel Cycle, OECD Publishing. NEA No. 7224.
3. Thorium fuel cycle research and literature: Trends and insights from eight decades of diverse projects and evolving priorities10.1016/j.anucene.2017.06.026 ↗
4. Thorium fuel revisited10.1016/j.pnucene.2023.104839 ↗
5. The molten salt reactor (MSR) in Generation IV: Overview and perspectives10.1016/j.pnucene.2014.02.014 ↗
6. World Nuclear Association (WNA) (2026, March 18). Thorium. Available online: https://world-nuclear.org/information-library/current-and-future-generation/thorium.
7. International Atomic Energy Agency (IAEA) (2019). World Thorium Occurrences, Deposits and Resources, IAEA. IAEA-TECDOC-1877.
8. International Atomic Energy Agency (IAEA) (2023). Status of Molten Salt Reactor Technology, IAEA. Technical Reports Series No. 489.
9. Insepov, Z., Lesbayev, B.T., Tanirbergenova, S., Alsar, Z., Kalybay, A.A., and Mansurov, Z.A. (2025). Small modular nuclear power reactors as a driver of development of nuclear technologies. Energies, 18.10.20944/preprints202508.1157.v1 ↗
10. OECD Nuclear Energy Agency (NEA) (2016). Small Modular Reactors: Nuclear Energy Market Potential for Near-Term Deployment, OECD Publishing.
11. World Nuclear Association (WNA) (2026, March 18). The Nuclear Fuel Cycle. Available online: https://world-nuclear.org/information-library/nuclear-fuel-cycle.aspx.
12. Radioactive waste partitioning and transmutation within advanced fuel cycles: Achievements and challenges10.1016/j.ppnp.2010.10.001 ↗
13. Recycling the Actinides, The Cornerstone of Any Sustainable Nuclear Fuel Cycles10.1016/j.proche.2012.10.055 ↗
14. OECD Nuclear Energy Agency (NEA) (2013). The Economics of the Back-End of the Nuclear Fuel Cycle, OECD Publishing.
15. International Atomic Energy Agency (IAEA) (2015). Impacts of Partitioning and Transmutation on Fuel Cycle Facilities, IAEA. IAEA-TECDOC-1766.
16. International Atomic Energy Agency (IAEA) (2022). Climate Change and Nuclear Power 2022, IAEA.
17. OECD Nuclear Energy Agency (NEA) (2014). Generation IV Nuclear Energy Systems: Status and Prospects, OECD Publishing.
18. Generation IV International Forum (GIF) (2014). Technology Roadmap Update for Generation IV Nuclear Energy Systems, OECD Publishing.
19. OECD Nuclear Energy Agency (NEA) (2012). The Role of Nuclear Energy in a Low-Carbon Energy Future, OECD Publishing.
20. International Atomic Energy Agency (IAEA) (2022). Advances in Small Modular Reactor Technology Developments, IAEA.
21. The Serpent Monte Carlo code: Status, development and applications in 201310.1016/j.anucene.2014.08.024 ↗
22. Review of thorium-containing fuels in LWRs10.1016/j.pnucene.2024.105136 ↗
23. Thoria and inert matrix fuels for a sustainable nuclear power10.1016/j.pnucene.2008.03.006 ↗
24. International Atomic Energy Agency (IAEA) (2006). Thermophysical Properties Database of Materials for Light Water Reactors and Heavy Water Reactors, IAEA. IAEA-TECDOC-1496.
25. Diffusion of helium in uranium and thorium dioxide single crystals
26. Long, Y. (2002). Thoria and Urania PWR Fuel. [Ph.D. Thesis, Massachusetts Institute of Technology].
27. U.S. Nuclear Regulatory Commission (NRC) (2014). Safety and Regulatory Issues of the Thorium Fuel Cycle, NRC. NUREG/CR-7176.
28. Olson, G.L., McCardell, R.K., and Illum, D.B. (2002). Fuel Summary Report: Shippingport Light Water Breeder Reactor—Rev. 2, Idaho National Laboratory.10.2172/910649 ↗
29. Todreas, N.E., and Kazimi, M.S. (2021). Nuclear Systems Volume I: Thermal Hydraulic Fundamentals, CRC Press. [3rd ed.].10.1201/9781351030502 ↗
30. International Atomic Energy Agency (IAEA) (2002). Heavy Water Reactors: Status and Projected Development, IAEA. Technical Reports Series No. 407.
31. International Atomic Energy Agency (IAEA) (2012). Role of Thorium to Supplement Fuel Cycles of Future Nuclear Energy Systems, IAEA. Nuclear Energy Series NF-T-2.4.
32. International Atomic Energy Agency (IAEA) (2016). Nuclear Technology Review 2016, IAEA.
33. Kakodkar, A. (2008). Evolving Indian Nuclear Programme: Rationale and Perspective, Indian Academy of Sciences Lecture.
34. International Atomic Energy Agency (IAEA) (2017). Nuclear Technology Review 2017, IAEA.
35. World Nuclear Association (WNA) (2023). The Nuclear Fuel Report 2023, WNA.
36. Experience with the Molten Salt Reactor Experiment
37. Rosenthal, M.W., Briggs, R.B., Haubenreich, P.N., and Kasten, P.R. (1970). Molten-Salt Reactor Program Semiannual Progress Report for Period Ending February 28, 1970, Oak Ridge National Laboratory. ORNL-4548.10.2172/4780471 ↗
38. Brooksbank, R.E., McDuffee, W.T., and Rainey, R.H. (1978). A Review of Thorium Fuel Reprocessing Experience, Oak Ridge National Laboratory.
39. Thorium fuel cycle option screening in the United States10.13182/NT15-119 ↗
40. Modelling the thermal conductivity of (UxTh1−x)O2 and (UxPu1−x)O210.1016/j.jnucmat.2015.07.022 ↗
41. Liquid fuel molten salt reactors for thorium utilization10.13182/NT15-124 ↗
42. Analysis of key safety metrics of thorium utilization in LWRs10.13182/NT15-100 ↗
43. Reactor physics analysis of thorium fuel cycles using molten salt reactors
44. Investigation of CANDU reactors as a thorium burner10.1016/j.enconman.2005.10.013 ↗
45. Molten salt reactors: A new beginning for an old idea10.1016/j.nucengdes.2009.12.033 ↗
46. The Dual Fluid Reactor—A novel concept for a fast nuclear reactor of high efficiency10.1016/j.anucene.2015.02.016 ↗
47. International Atomic Energy Agency (IAEA) (2000). Thorium Based Fuel Options for the Generation of Electricity: Developments in the 1990s, IAEA. IAEA-TECDOC-1155.
48. International Atomic Energy Agency (IAEA) (2002). Thorium Fuel Utilization: Options and Trends, IAEA. IAEA-TECDOC-1319.
49. International Atomic Energy Agency (IAEA) (2022). Near-Term and Promising Long-Term Options for the Deployment of Thorium Based Nuclear Energy, IAEA.
50. Atamanova, T., Lesbayev, B., Tanirbergenova, S., Alsar, Z., Kalybay, A., Mansurov, Z., Atamanov, M., and Insepov, Z. (2025). Advanced techniques for thorium recovery from mineral deposits: A review. Appl. Sci., 15.10.3390/app152111403 ↗
51. Development and outlook of advanced nuclear energy technology10.1016/j.esr.2021.100630 ↗
52. Kurbanova, B., Sizyuk, Y., Aryngazin, A., Alsar, Z., Hassanein, A., and Insepov, Z. (2025). Thermal hydraulics and solid mechanics multiphysics safety analysis of a heavy water reactor with thorium-based fuel. J. Nucl. Eng., 6.10.20944/preprints202509.2208.v1 ↗
53. Alsar, Z., Gajimuradova, A., Mansurov, Z., Gubaidullin, N., Hassanein, A., and Insepov, Z. (2025). Thorium in energy and ecology: Prospects for clean fuel sources and environmental protection. Energies, 18.10.3390/en18236177 ↗
54. International Atomic Energy Agency (IAEA) (2007). Nuclear Fuel Cycle Simulation System (VISTA), IAEA. IAEA-TECDOC-1535.
55. OECD Nuclear Energy Agency (NEA) (2006). Advanced Nuclear Fuel Cycles and Radioactive Waste Management, OECD Publishing.
56. Review of molten salt reactor off-gas management considerations10.1016/j.nucengdes.2021.111529 ↗
57. Wu, J., Chen, J., Cai, X., Zou, C., Yu, C., Cui, Y., Zhang, A., and Zhao, H. (2022). A Review of Molten Salt Reactor Multi-Physics Coupling Models and Development Prospects. Energies, 15.10.3390/en15218296 ↗
58. Molten salt reactor neutronics and fuel cycle modeling with SCALE10.1016/j.anucene.2016.11.040 ↗
59. Olander, D.R. (2009). Nuclear Fuels and Materials: Science and Technology, Cambridge University Press.
60. Towards the thorium fuel cycle with molten salt fast reactors10.1016/j.anucene.2013.08.002 ↗