Thorium Fuel Cycle Research Articles

Development and Verification of a Multi-Physics Transport Code of Molten Salt Reactor Fission Products

The transport of fission products in molten salt reactors has attracted much attention. However, few codes can completely describe the transport characteristic, though the migration of fission products in the molten salt reactor is essential to estimate the source term, decay heat, and radiation shielding. This study built a program named ThorFPMC (Thorium Fission Products Migration Code) that can handle the multi-physics transport characteristic based on the flow burnup code ThorMODEc (Thorium MOlten Salt Reactor Specific DEpletion Code). A problem-related depletion chain compression method was applied to decrease the order of the solve matrix. The matrix exponential and splitting methods were applied to solve the steady state and transient calculation, respectively. Error analysis showed that for a specific problem, the simplified depletion chain matrix index method could solve the fission products migration equation with an arbitrary time-step with high speed (s) and high precision (10−4); the splitting method could reach a precision of 10−2 level for the full fuel depletion chain, multi-nodes, and transient problems. Compared to the Strang splitting method, the perturbation splitting method has higher precision and less time consumption. In summary, the developed programmer could describe the migration effect of fission products in molten salt reactors, which provides a significant tool for the design of molten salt reactors.

Comparative analysis on small modular reactor (SMR) with uranium and thorium fuel cycle

The utilization of Small Modular Reactors (SMRs) and micro-reactors holds significant potential advantages. The primary benefits include their smaller size, accessibility to remote regions, and reduced land requirements. One noteworthy SMR is the NuScale Power Module (NPM), which has a thermal capacity of 160 MWt and operates on a 2-year cycle. However, there is a growing interest in exploring alternative fuels to enhance SMR performance and safety, and thorium has emerged as an appealing option due to its superior neutron characteristics and potential for higher fuel efficiency. This research aims to do preliminary research into adapting fuel for a thorium fuel cycle in the integral PWR (iPWR). The thorium cycle excels with an initial neutron multiplication factor of 1.134, almost the same as uranium (1.129). Additionally, the thorium cycle boasts superior neutron flux and Conversion Ratio (CR) in the thermal neutron energy range, enhancing sustainability with an average CR of 0.765, compared to 0.574 and 0.692 for uranium and uranium–thorium cycle. The addition of thorium improves efficiency in converting fertile material into fissile material with an enough criticality, where fuels incorporating thorium have a higher CR (Conversion Ratio). Furthermore, thorium fuel cycle has significantly lower production of plutonium isotopes compared to other fuel cycles. However, it faces a challenge with a high power peaking factor (PPF) of 1.923 at the Beginning of Cycle (BOC), requiring further research for mitigation.

Neutronic Assessment of High-Temperature Gas-Cooled Thorium Burner using Monte Carlo Calculation Method with Full Core Model

In this study, the effective reactivity and burnup analyses have been performed for heterogeneous three-dimensional high-temperature gas-cooled thorium reactor (HTGR) which has 60 MWth full core geometry by using continuous-energy multi-purpose three-dimensional Monte Carlo particle transport Serpent code with ENDF/ B-VII data libraries. Nuclear fuel have been selected as 50 % ThO2+50% RG-PuO2. Firstly, effective reactivity for three different qualities of graphite for operation period have been determined. The effective reactivity showed better performance with increasing densities of graphite. Secondly, it has been also examined to ZrC and SiC cladding materials effect on the effective reactivity. It is observed that SiC has a positive effect on reactivity compared to ZrC. As a results, the full core life low-power thorium-burner HTGR have been calculated as up to ~4500 days depending on the graphite material whereas, the corresponding burn−ups came out to be ~ 189 GWd/ton, for end of life.

Core-Optimization of Ritm-200 Reactor Fuel Considering Thorium Fuel Cycle

Core-Optimization of Ritm-200 Reactor Fuel Considering Thorium Fuel Cycle

Neutronic design performance of 100 MWe MSR with thorium-enriched uranium and thorium-plutonium-minor actinide fuel

Molten Salt Reactors offer fuel flexibility, allowing the use of different starting fuels, including U-233, U-235, and Pu-239. U-233 is not a fissile nuclide that is commercially accessible. However, it can be produced through the utilization of the thorium cycle. In this paper, the neutronic performance of MSR with a power output of 100 MWe is analyzed for Th-U(enriched) and Th-Pu-MA as a starting fuel. The fuel composition is varied to show the neutronic parameter change and obtain the reactor criticality for five years of operation time. The calculation used SRAC Program and JENDL 4.0 as nuclear data libraries. It was found that the reactor with a Th-U fuel case can be operated in critical condition with a minimal fuel loading of UF4 of 7.30 mol%. Similarly, in the Th-Pu-MA fuel case, a minimal amount of PuF4 is at least 3.87 mol%. The Th-U fuel case exhibits a higher initial keff and reactivity swing compared to the Th-Pu-MA fuel case. At the end of the reactor cycle, the Th-U fuel produces several plutonium isotopes, such as Pu-238, Pu-239, Pu-240, Pu-241, and Pu-242. In contrast, the density of plutonium isotopes in the Th-Pu-MA fuel decreases during operation such as Pu-239 and Pu-241. Therefore, using Th-Pu-MA fuel is a viable approach to reducing spent nuclear fuel, as it reduces the number of plutonium isotopes.

A micro-sized high-temperature thorium reactor with Duplex TRISO fuel with enhanced thorium utilization compared to the SBU configuration

This study offers a neutronisc core calculation to assess the potential of the compact microheterogeneous thorium-uranium TRistructural ISOtropic (TRISO) fuel design for the micro-modular high temperature reactor. The Duplex-fueled core and the Seed-and-Blanket-Unit (SBU)-fueled core were modelled and compared using the MCNPX 2.7 Monte Carlo code. The Th:U ratio and initial fissile mass of both cores were set to be the same. The dispersion of thorium and uranium in the Duplex-fueled core is more uniform compared to that in the SBU-fueled core. The study demonstrates that Duplex TRISO fuel offers both improved core power distribution uniformity and superior neutronic performance compared to SBU fuel in a core. The utilisation of a Duplex-fueled core leads to a 5 % higher core conversion ratio and resonance capture rate, which ultimately results in an extra long-term production of 233U. Additionally, its FTC value is lower. The required material and thickness of the neutron reflector, are also discussed, though only as a preliminary analysis. Nevertheless, the findings clearly demonstrate that the Duplex TRISO fuel design concept offers valuable flexibility and optimization in the distribution of fertile and fissile material mass. These characteristics are of utmost importance for the advancement of thorium reactors, as they significantly enhance neutronic performance.

A laboratory-scale process for producing dilithium beryllium tetrafluoride (FLiBe) with dissolved uranium tetrafluoride

Flibe Energy, Incorporated (FEI)'s conceptual Lithium Fluoride Thorium Reactor (LFTR) incorporates a chemical processing facility aimed at recovering uranium and other valuable volatile radionuclides while managing harmful radionuclides from the used fuel. The fuel utilized in this reactor is a combination of dilithium beryllium tetrafluoride (Li2BeF4 or FLiBe) and uranium tetrafluoride (UF4), (FLiBe/U). FEI's plan involves extracting the uranium and other valuable volatile fluoride-forming radionuclides using nitrogen trifluoride (NF3). To facilitate laboratory-scale testing of uranium extraction using NF3 and address the toxicity and physical hazards associated with beryllium and beryllium fluoride (BeF2), we used a two-step process to prepare the simulated fuel salt. The first step entailed thermally decomposing ammonium beryllium tetrafluoride [(NH4)2BeF4] (ABeF) through a nominal 3-step process, combined with appropriate amounts of lithium fluoride (LiF) and UF4, resulting in the formation of beryllium fluoride (BeF2). In the second step, the mixture was repeatedly melted and frozen at the melting point of FLiBe to prepare the eutectic FLiBe with dissolved UF4. Although the concept appears straightforward, the production of FLiBe/U involved various challenges. These challenges included transporting the gaseous decomposition products of ABeF, hydrogen fluoride (HF) and ammonia (NH3), while preventing the formation of ammonium fluoride (NH4F). Additionally, it was necessary to control the reaction between the higher-than-anticipated water content in the commercial ABeF with NH3, HF, and the condensed NH4F, protect UF4 from forming an unknown black compound, select suitable structural materials to mitigate fluoride corrosion, address the risks associated with beryllium toxicity through equipment design and operational protocols, and monitor process conditions. This article provides an account of the thermal decomposition chemistry observed in the commercial ABeF, describes the FLiBe/U production apparatus, describes the experiences and process refinements developed to prepare FLiBe/U, and presents our characterizations of prepared FLiBe/U.

The Challenges of Nuclear Power Plant Development in Indonesia: A Case of Thorium Power Plant in Bangka Island, Indonesia

This paper discusses the challenges of nuclear power plant development in Indonesia. With a growing belief among policymakers that nuclear power could play a vital role in energy transition and diversification, it is important to analyse the process of nuclear decision-making. Drawing on the case of the development of the Thorium Molten Salt Reactor (TMSR) in Bangka Island, this paper aims to understand the social, political, and institutional aspects of thorium power plant development. More specifically, this paper elaborates on public acceptance and the regulatory environment of nuclear power development. This paper is mainly based on secondary data such as official reports, online media, and relevant academic research. We argue that nuclear power development requires not only good technological and risk management capacity but also strong public trust in the government and nuclear industry through information transparency and openness.

An overview of thorium as a prospective natural resource for future energy

Thorium is a naturally occurring radioactive element that has been identified as a potential alternative fuel for nuclear energy production. Additionally, thorium-based nuclear reactors have inherent safety features that reduce the risk of nuclear accidents and proliferation. As a result, there has been growing interest in the development of thorium-based nuclear energy as a viable alternative to fossil fuels. This paper looks at the present status of thorium nuclear fuel technology, providing an overview of thorium as a prospective natural resource for future energy, the global availability of mineral supplies, and discusses the technical, economic, and environmental factors that may influence its implementation. Potential advantages and challenges critical to further development associated with thorium-based nuclear energy are highlighted as well, and an outlook on its future prospects is provided. Thorium offers advantageous physical and chemical properties over uranium, has a higher energy density, and produces less waste, in addition to its greater natural abundance, making it to be considered a “future nuclear fuel”. There are concerns about the cost and scalability of thorium-based nuclear energy, with uncertainty around the cost to develop, build, and operate thorium reactors, as it has not yet been demonstrated in large-scale commercial reactors—although almost all current reactor types have been built and run using thorium—as it is the case with Uranium-based nuclear technology—the dominant form of nuclear energy for over half a century, having received much more investment and attention than thorium-based technology. Thorium has the potential to contribute towards a more sustainable nuclear industry, including lower lifecycle emissions and more efficient resource utilization, but for this, an acceleration of efforts to date is needed to ensure that this becomes an important climate change stabilizing wedge by the mid-21st century.

West Kalimantan Government Readiness for Thorium Power Plant in Support of Regional Energy Security and National Defense

West Kalimantan Government Readiness for Thorium Power Plant in Support of Regional Energy Security and National Defense

Feasibility to Convert the NuScale SMR from UO<sub>2</sub> to a Mixed (U, Th)O<sub>2</sub> Core: A Parametric Study of Fuel Element—Seed-Blanket Concept

Delays in the construction of nuclear reactors due to licensing issues have been a problem across the world, affecting projects in Finland, France, and the United States. Small Modular Reactors (SMRs) emerge as a transition between Generations III+ and IV in order to make nuclear energy more competitive with other energy sources, including renewables. In this study, the SMR NuScale, one of the most promising projects today, is investigated for its conversion into a U-233-producing reactor through the Radkowsky seed-blanket fuel element concept, applied in the Shippingport reactor, in a parametric study. Initially, a validation of the reference reactor (NuScale) was carried out with data from technical documents and papers, thus demonstrating the agreement of the computational model carried out with the SERPENT code. Then, a parametric study is carried out to define the area of the seed and blanket region, proportions of enrichment and pitch length. Finally, a comparison is made between the production of U-233, TRU reduction, burn-up extension and neutronic and thermohydraulic safety parameters. This study demonstrates an improvement in the conversion factor and a considerable reduction in the production of TRU, in addition to the production of U-233 with a low proportion of other uranium isotopes that can lead to the beginning of the thorium cycle with already consolidated technologies.

Radiation and Nuclear Physics Aspects of the Use of the Thorium Fuel Cycle in a Hybrid Fusion Facility

This paper presents the results of the experimental determination and computational simulation of the ambient dose equivalent rate for a metallic thorium cylindrical miniblock and the (n,2n), (n,f), and (n,γ) reaction rates in a thin 232Th metal foil irradiated with neutrons of the NG-24M generator spectrum. The ambient dose equivalent rate was determined by dosimeters-radiometers. The reaction rates were determined by the activation method using Ge spectrometers without destroying the irradiated samples. Computational simulations of ambient dose equivalent and reaction rates were performed, respectively, using the radiation transport codes PHITS, MCNP5, and KIR2, which use various nuclear data libraries: JEFF-3.2 and -3.3; JENDL4.0; ENDF/B-VII.0, -VII.1, and -VIII.0; ROSFOND; FENDL; and TENDL. The authors give an estimate of the 232U/233U relative accumulation upon natural thorium irradiation in a fusion facility blanket with defined neutron spectrum. The nonirradiated and irradiated thorium nuclide composition change simulation and visualization were performed using analytical solutions of an ordinary system of homogeneous linear differential equations describing nuclide transmutations.

Comparative Assessment of the Range of Spectral Regulation of Reactivity Margin for Fuel Burnup in Pressurized Water Reactors Using Zirconium Displacers for Uranium and Thorium Fuel Cycles

Comparative Assessment of the Range of Spectral Regulation of Reactivity Margin for Fuel Burnup in Pressurized Water Reactors Using Zirconium Displacers for Uranium and Thorium Fuel Cycles

Low-spin excitations in Br89 populated in β− decay of Se89

Low-spin, excited states of the $^{89}\mathrm{Br}$ nucleus, populated in ${\ensuremath{\beta}}^{\ensuremath{-}}$ decay of $^{89}\mathrm{Se}$ have been studied for the first time. The $^{89}\mathrm{Se}$ nuclei were produced in proton-induced fission of natural thorium using the IGISOL facility and separated using a dipole magnet and the coupled JYFLTRAP Penning trap. Gamma radiation following the ${\ensuremath{\beta}}^{\ensuremath{-}}$ decay of $^{89}\mathrm{Se}$ was measured with an array of high-resolution germanium detectors. Levels scheme of $^{89}\mathrm{Br}$ was extended by 12 new levels and 31 new $\ensuremath{\gamma}$ transitions. Spin-parity (3/${2}^{+}$) has been proposed for the ground state of the $^{89}\mathrm{Se}$ mother nucleus, replacing the (5/${2}^{+}$) assignment reported in data bases. The observed Gamow-Teller ${\ensuremath{\beta}}^{\ensuremath{-}}$ transition to the 1754.5-keV level indicates a $\ensuremath{\pi}{g}_{9/2}$-based configuration. The level scheme of $^{89}\mathrm{Br}$ has been compared to large scale shell-model calculations. Excitations based on $\ensuremath{\pi}{p}_{3/2}$ and $\ensuremath{\pi}{f}_{5/2}$ single-particle levels as well as their anomalous coupling are proposed to explain the low-energy excitation scheme of $^{89}\mathrm{Br}$.

The role of deformations and orientations in an alpha ternary fission of Thorium

The role of deformations and orientations in an alpha ternary fission of Thorium

MSR Simulation with cGEMS: Fission Product Release and Aerosol Formation

The release of fission products and fuel materials from a molten-salt fast-reactor fuel in hypothetical accident conditions was investigated. The molten-salt fast reactor in this investigation features a fast neutron spectrum, operating in the thorium cycle, and it uses LiF-ThF4-UF4 as a fuel salt. A coupling between the severe accident code MELCOR and thermodynamical equilibrium solver GEMS, the so-called cGEMS, with the updated HERACLES database was used in the modeling work. The work was carried out in the frame of the EU SAMOSAFER project. At the beginning of the simulation, the fuel salt is assumed to be drained from the reactor to the bottom of a confinement building. The containment atmosphere is nitrogen. The fission products and salt materials are heated by the decay heat, and due to heating, they are evaporated from the surface of a molten salt pool. The chemical system in this investigation included the following elements: Li, F, Th, U, Zr, Np, Pu, Sr, Ba, La, Ce, and Nd. In addition to the release of radioactive materials from the fuel salt, the formation of aerosols and the vapor-phase species in the modeled confinement were determined.

Fusion-fission hybrid reactor facility: neutronic research

The authors investigate the neutronic characteristics of the operating mode of a hybrid nuclear-thermonuclear reactor. The facility under study consists of a modified core of a high-temperature gas-cooled thorium reactor and an extended plasma neutron source penetrating the near-axial region of the core. The proposed facility has a generated power that is convenient for the regional level (60–100 MW), acceptable geometric dimensions and a low level of radioactive waste. The paper demonstrates optimization neutronic studies, the purpose of which is to level the resulting offsets of the radial energy release field, which are formed within the fuel part of the blanket during long-term operation and due to the pulsed operation of the plasma D-T neutron source. The calculations were performed using both previously developed models and the SERPENT 2.1.31 precision program code based on the Monte Carlo method. In the simulation, we used pointwise evaluated nuclear data converted from the ENDF-B/VII.1 library, as well as additional data for neutron scattering in graphite from ENDF-B/VII.0, based on the S (α, β) formalism.

Potential of Thorium Power Plant as a New Energy Source in Supporting State Defense (Case Study: West Kalimantan)

Potential of Thorium Power Plant as a New Energy Source in Supporting State Defense (Case Study: West Kalimantan)

Thorium cycle models into DIONISIO code: Species, thermomechanical behaviour and fission gas release

• A thorium cycle model was developed to include in DIONISIO fuel performance code. • The model shows an acceptable performance in comparison with results from CONDOR neutronic code. • The main thermomechanical properties of Thorium based nuclear fuel were simulated. • An existing FGR model was modified to simulate the phenomena for Thorium based nuclear fuel. • All the mentioned models shows an acceptable performance in comparison with experimental data. In this work we present the main developments made to include the thorium cycle in the DIONISIO fuel code. For this, models for species evolution, thermomechanical behaviour and fission gas release development are incorporated. First of all, a simplified neutronic behaviour model was developed, which adds the capability of simulating the whole cycle at the least possible computational cost. We start from the balance of nuclides in the thorium chain, considering fresh ThO 2 mixed with PuO 2 , which works as fissile species for the initial stages of operation. This simple model shows an acceptable performance in comparison with results from dedicated neutronic codes like CONDOR. Afterwards, the main thermal and mechanical parameters were adapted for thorium mixed oxide materials. For fission gas release, an existing model based on diffusion equations was also modified on the same way as thermomechanical parameters. Finally, results of the whole code with the included modifications were compared to some experiments over mixed fuels (Th,Pu)O 2 andl (Th,U)O 2 .

Reactions

OPINION Reactions ShareShare onFacebookTwitterWechatLinked InRedditEmail C&EN, 2021, 99 (41), p 4November 8, 2021Cite this:C&EN 99, 41, 4Letters to the editorMore on nuclear powerI am not sure we can stop or reverse climate change using current approaches, since Earth’s climate has changed significantly over time, much more than our short-term projections. We should strongly reconsider using thorium nuclear reactors for US and world energy needs to significantly reduce carbon dioxide emissions.Thorium is over three times as abundant and more safely mined than uranium. Thorium power is safer because it cannot develop a runaway uncontrolled reaction like a uranium reactor. The thorium reactor by-products cannot make a nuclear bomb since the wrong isotopes are produced. Thorium reactors would produce less radioactive waste. These by-products are safe after about 100 years, versus 24,000 years for uranium reactors, and safe storage of thorium nuclear waste is much less complex. Uranium was chosen for nuclear power originally since it can be turned into nuclear weapons.Notably, Edward Teller (father of the H-bomb), Glenn Seaborg (a former chair of the Atomic Energy Commission), Alvin Weinberg (a former Oak Ridge National Laboratory administrator), Kirk Sorensen, Carlo Rubbia (Nobel laureate and a former CERN director general), Hans Blix (a former International Atomic Energy Agency head), and V. J. Stenger—all noted nuclear physicists, have come out very strongly in favor of thorium reactors.CANDU (Canadian deuterium uranium) thorium reactors have already been built. The US military has built megawatt-scale prototypes and evaluated them for up to 20 years, indicating that development work has been significant. Grid connection is not an issue since the electricity is continuously produced and is therefore steady and reliable. Many other nations could be provided safe and reliable electricity using thorium nuclear power.Wind and solar energy are not steady and reliable. California and Texas had significant disruptions in 2020 and 2021. A proposed solar project in Nevada that was withdrawn would have been 36 km2 and would have generated only 0.85 GW of energy. Eighty percent of the solar panels are produced in China. The production is an environmental issue. Now is the time for thorium to be in the energy discussion. The US and the world need it.Lawrence IngramAliquippa, PennsylvaniaI totally agree with the comments of David Hauber in the C&EN issue of Sept. 27, 2021 (page 4).Nuclear energy, especially produced by the newly developed thorium reactors, is the choice to minimize the amount of emitted carbon dioxide.Renewables are not the ideal solution. In Germany, all nuclear reactors will be closed at the end of 2022. And then? These nuclear reactors have to be dismantled at a huge cost. The reactors that will be closed at the end of 2021 and 2022 could be running several years more. The technology is German. But no, one tsunami in Japan, and its consequences were enough to make this decision. In Europe, we do not have tsunamis, however.Wind mills will now be built in the North Sea in huge parks. The beach visitors will like it, a nice view. The wind mills are killing many birds with their huge blades.The word nuclear energy cannot be spoken about, a dirty word. Especially for climate-fascinated young people. Quo vadis these people?Joop KosterGland, SwitzerlandGreen airlinesThe cover story of the Sept. 6, 2021, issue of C&EN, “Airlines Want to Go Green” (page 28), which focused on carbon dioxide emissions, included on page 34 “Supersonic Flight’s Sustainability Challenge.” But carbon emissions are only a part of going green. Before Mario Molina and F. Sherwood Rowland described stratospheric ozone layer depletion from chlorofluorocarbons, Paul Crutzen warned of oxone layer depletion from the nitrogen oxides (NOx) that would be emitted as a combustion by-product from a fleet of stratospheric flying supersonic transports (SSTs). Congress then held hearings on the SST environmental challenge. Crutzen, Molina, and Rowland, received the Noble Prize for their work.I am disappointed the stratospheric NOx threat to the environment from SSTs was not mentioned. It remains a significant concern.Ronald SheinsonSilver Spring, Maryland CorrectionsSept. 27, 2021, page 48: The Newscripts story about a portrait of Antoine-Laurent and Marie-Anne Lavoisier inadvertently leaves out the first name of the artist, Jacques-Louis David.Oct. 25, 2021, page 22: The feature story on RNA editing incorrectly says ADARx Pharmaceuticals’ RNA-editing technology could begin clinical trials in the second half of 2022. That trial is likely a year or more away.Nov. 1, 2021, page 14: A news story about Mark P. Vergnano’s award of the 2022 SCI Chemical Industry Medal misstates Vergnano’s title. He is chairman of the board of directors of Chemours, not the firm’s CEO.Nov. 1, 2021, page 17: The news story about a study confirming lengthening time to get a science PhD incorrectly states the name of the firm where Stephanie Cheng works. It is Edgeworth Economics, not Edgeworth Analytics.