Periodic Reporting for period 1 - MIMOSA (MultI-recycling strategies of LWR SNF focusing on MOlten SAlt technology)
Reporting period: 2022-06-01 to 2023-11-30
While the EU has the highest share of spent nuclear fuel (SNF) reprocessing worldwide, most spent nuclear fuel is still declared waste. The MIMOSA project has been the response to develop an accessible, cost/risk optimized and sustainable multi-recycling strategy of light-water reactor (LWR) spent nuclear fuel, based primarily on multi-recycling of plutonium and reprocessed uranium in light water reactors, combined with one of the most promising advanced nuclear energy systems, the fast-spectrum chloride molten-salt reactors (Cl MSRs). The ambition is to provide a real option towards a closed nuclear fuel cycle in the EU while securing energy supply and using already available infrastructure in the EU such as the Orano reprocessing plant in La Hague (France). MIMOSA has identified six general scientific and technological objectives which the Consortium will seek to achieve in four years’ time:
1. Perform a global analysis of tangible strategies for multi-recycling of spent nuclear fuel from LWR in the EU, based on multi-recycling in LWRs and Cl MSRs,
2. Assess chloride molten salt properties to support studies of reactor process,
3. Conduct simulations of chloride molten salt composition evolution in the reactor to support fuel cycle calculations, safety evaluation and the analysis of valuable isotopes,
4. Demonstrate several key aspects of technical feasibility and performance of Cl MSRs,
5. Study chloride molten salt recycling and back-end options in synergy with La Hague plant,
6. Evaluate the capacity of MSRs to produce valuable isotopes for other applications, and the way to extract, separate and purify them.
1. Perform a global analysis of tangible strategies for multi-recycling of spent nuclear fuel from LWR in the EU, based on multi-recycling in LWRs and Cl MSRs,
2. Assess chloride molten salt properties to support studies of reactor process,
3. Conduct simulations of chloride molten salt composition evolution in the reactor to support fuel cycle calculations, safety evaluation and the analysis of valuable isotopes,
4. Demonstrate several key aspects of technical feasibility and performance of Cl MSRs,
5. Study chloride molten salt recycling and back-end options in synergy with La Hague plant,
6. Evaluate the capacity of MSRs to produce valuable isotopes for other applications, and the way to extract, separate and purify them.
After 18 months of work, the project has achieved several technical and scientific intermediate results which pave the way for the next steps.
Spent nuclear fuel inventories, energy needs projections, nuclear fleet assumptions and potential evolutions have been assessed for all EU countries. In parallel, a Reduced-Order-Model of MSR has been developed and integrated in the scenario analysis tool. A first simulation round of scenarios, including MSRs, is ongoing.
Several salt mixtures in NaCl-MgCl2-PuCl₃ and NaCl-ThCl₄-PuCl₃ have been selected based on thermochemical properties and neutronics, and synthesis of selected salts is underway in order to perform characterization and further experimental work. At the same time, most of the salt properties measurement equipment has been set up and tested, and measurements have started.
Three MSR configurations have been selected. Neutronic depletion simulations in these reactor configurations have started, including first dose rate calculations and evolution of salt mixtures composition, in particular fission products. The results will be used to assess used salt treatment processes and valuable isotopes management processes.
In parallel, a special container has been prepared for the salt irradiation experiment to be performed in the LR-0 reactor in the Czech Republic.
The test matrix for structural materials static and dynamic corrosion tests has been completed, as well as the literature review on corrosion mitigation methods. Selected material samples to be tested are under fabrication. The testing methods, the corrosion products measurement methods and the corrosion test set ups and loops are under development. In parallel, the molten salt neutron irradiation feasibility study has been completed, and a corrosion / irradiation test bench has been constructed.
The study of used salt treatment in synergy with La Hague plant has been initiated with data collection and the definition of 8 scenarios, for which the used fuel compositions are being calculated. These will be used as input parameters for the technical study of used fuel treatment in La Hague.
The identification of the pyrochemical salt treatment alternative has also started, with literature review and preliminary thermodynamic calculations being carried out to define an experimental plan. First vitrification experiments are ongoing with fluorides, before moving to chlorides.
Valuable isotopes produced in MSRs among other fuel salt mixtures isotopes have been assessed and quantified. The applications for these isotopes and the associated market is been described.
A thermodynamic database on the platinoids chloride phases is under development, and some experiments are performed to validate the metallic state of the platinoids and noble metals. A device to extract by flotation the solid fission products from the molten salt is under construction.
Spent nuclear fuel inventories, energy needs projections, nuclear fleet assumptions and potential evolutions have been assessed for all EU countries. In parallel, a Reduced-Order-Model of MSR has been developed and integrated in the scenario analysis tool. A first simulation round of scenarios, including MSRs, is ongoing.
Several salt mixtures in NaCl-MgCl2-PuCl₃ and NaCl-ThCl₄-PuCl₃ have been selected based on thermochemical properties and neutronics, and synthesis of selected salts is underway in order to perform characterization and further experimental work. At the same time, most of the salt properties measurement equipment has been set up and tested, and measurements have started.
Three MSR configurations have been selected. Neutronic depletion simulations in these reactor configurations have started, including first dose rate calculations and evolution of salt mixtures composition, in particular fission products. The results will be used to assess used salt treatment processes and valuable isotopes management processes.
In parallel, a special container has been prepared for the salt irradiation experiment to be performed in the LR-0 reactor in the Czech Republic.
The test matrix for structural materials static and dynamic corrosion tests has been completed, as well as the literature review on corrosion mitigation methods. Selected material samples to be tested are under fabrication. The testing methods, the corrosion products measurement methods and the corrosion test set ups and loops are under development. In parallel, the molten salt neutron irradiation feasibility study has been completed, and a corrosion / irradiation test bench has been constructed.
The study of used salt treatment in synergy with La Hague plant has been initiated with data collection and the definition of 8 scenarios, for which the used fuel compositions are being calculated. These will be used as input parameters for the technical study of used fuel treatment in La Hague.
The identification of the pyrochemical salt treatment alternative has also started, with literature review and preliminary thermodynamic calculations being carried out to define an experimental plan. First vitrification experiments are ongoing with fluorides, before moving to chlorides.
Valuable isotopes produced in MSRs among other fuel salt mixtures isotopes have been assessed and quantified. The applications for these isotopes and the associated market is been described.
A thermodynamic database on the platinoids chloride phases is under development, and some experiments are performed to validate the metallic state of the platinoids and noble metals. A device to extract by flotation the solid fission products from the molten salt is under construction.
The maturity of Cl MSR is currently considered low. This is why MIMOSA’s choice has been to focus on the demonstration of several key aspects of technical feasibility and performance, which, linked to the use of this specific type of salt, will push this advanced technology beyond the current state of the art and contribute to acceleration of its deployment.
The technology readiness level (TRL) of the whole concept based on fast-spectrum Cl MSRs can be assessed at around 1 or 2. There are mainly three parts to be considered in the concept: the reactor itself and its neutronics aspects, the materials and salt interreacting between each other, and the fuel cycle aspects (recycling and waste management). The first part, mainly physics, is not covered in MIMOSA. Concerning the materials and salt, the objective of MIMOSA is to raise the chemistry TRL from 1 or 2 to 3 (even 4 for new Cl salt synthesis method). This will be a great leap forward.
The project has achieved its objectives and milestones for the first 18 months with relatively minor deviations. The main tangible results will be generated in the coming years and it seems premature to develop on the results potential impacts at this early stage of the research.
The technology readiness level (TRL) of the whole concept based on fast-spectrum Cl MSRs can be assessed at around 1 or 2. There are mainly three parts to be considered in the concept: the reactor itself and its neutronics aspects, the materials and salt interreacting between each other, and the fuel cycle aspects (recycling and waste management). The first part, mainly physics, is not covered in MIMOSA. Concerning the materials and salt, the objective of MIMOSA is to raise the chemistry TRL from 1 or 2 to 3 (even 4 for new Cl salt synthesis method). This will be a great leap forward.
The project has achieved its objectives and milestones for the first 18 months with relatively minor deviations. The main tangible results will be generated in the coming years and it seems premature to develop on the results potential impacts at this early stage of the research.