WP1 Study of plutonium management in connection
• The flexibility of the Gen IV FR has been proven for the management of plutonium with a complete set of scenarios for fuel cycle
• Stabilization, breeding and burning (same or different design) of Pu in advanced scenarios: more than 1000 configurations
• Quantitative results have been released on fissile material inventory, transportation, non-proliferation, waste, cost, decay heat
• Uncertainties have been propagated, and main contributors have been revisited or discovered: reprocessing strategy/cooling times, reactor size, installed power, content of 239Pu in the FR…
• Management of U and MA (not covered in this project) may help optimizing the management of Pu and other magnitudes of the fuel cycle
WP2 Fuel Pin behaviour in reactor with high Pu content: Nominal and transient
• Pu management with a 45Pu-MOX fuel has overall good behaviour under irradiation: with a lower fuel temperature (pin design, high l, low LHR), no enhanced corrosion, and no closure of central hole with fuel fragments. All safety issues that were considered before the irradiation.
• Evaluated impact of pellet-clad or central hole excentration has been calculated and observed on the irradiated samples: respectively (200K and 300K) in the case selected (CAPRIX or TRABANT).
• A first experimental demonstration of Pu burning rate in Fast Reactors has been provided: 97 to 105 kg/TWe.h
• Fuel performance codes validation has been extended for 45Pu-MOX fuels thanks to CAPRIX and TRABANT2 irradiations
• Large discrepancies among the codes were noticed.
WP3 Fuel properties with high PU content: Measurements and modelling
• Melting point: Thanks to ESNII+, ESFR-SMART, PuMMA: whole Pu range UO2PuO2; Revision of melting temperature of MOX fuel with a different minimum value (2940±30K) at a different %Pu (60-65); New law suggested for Pu content effect
• Thermal diffusivity: 550-2800K: constant at very high temperature; Small %Pu effect and Small effect of O/M ratio for small variation (1.98 to 2.0). Need for measurements with low O/M (1.93 to 1.98).
• Heat capacity: Small %Pu effect at low T and No clear effect of O/M ratio for small variation; Significant increase at high temperature
• Thermal conductivity: Small %Pu effect at low T but significant at high temperature. Effect of O/M at low temperature that disappears at high temperature
• Thermal expansion: Thanks to these new measurements, thermal expansion is higher than Martin (1988) law at high temperature (>1200K for high Pu content)
WP4 Comparison of irradiation results in fast spectrum vs thermal spectrum (MTR)
• Irradiations for FR fuel qualification : MTR vs FR
• Mastering irradiation conditions in MTR for representativity and control of conditions is still challenging
• MTR irradiations can effectively simulate FR conditions with appropriate experiment design
• Neutron spectrum tailoring is achievable in MTRs through shield optimization
• Additional results include Shielding parametric studies for MTRs and Quantification of representativeness
• For nominal FR cases, fuel and cladding temperatures can be approximated and fuel performance codes remain essential for comparative analysis
• Nominal and transient conditions are examined at mini-pin level
• The study can contribute to advancing MOX fuel TRL.
• Experiments are carried out in series within single design, easing execution, increasing data generation
• Feed back from 40 years of experiments in MTR for FR fuel development was summurized with an emphasis on somme specific experimental devices and its use.
WP5 Impact of plutonium content on fuel dissolution
• 65 small scale unirradiated MOx powder dissolution tests (UKNNL).
• 3 intermediate scale unirradiated MOx pellet/powder dissolution tests (CEA).
• 2 irradiated CAPRIX MOx dissolutions and characterizations have been carried out using HNO3, with Ag(II) and using chemical fusions and HNO3-HF dissolutions (CEA).
• 3 irradiated Trabant2 MOx dissolution tests using HNO3, Ag(II) and HNO3/HF (NRG, contributed in kind).
• 2 radiolysis solvent extraction models have been developed independently.
• The development of an industrial head-end dissolution process for irradiated 45%Pu MOx is feasible. Head-end process equipment will need to be changed to achieve efficient dissolution. Future work is needed to support process and equipment design.
• A Pu recovery was enhanced thanks to an optimisation of the conditions (time, temperature, acidity) with the addition of an head-end step in the process (voloxidation). The values of Pu recovery reached 86% before optimisation and 98% after.
WP6 Education & training, dissemination and communication
• 10 publications in peer-reviewed scientific journals, participation in various conferences (conference proceedings, presentations)
• A Database created of 56 Euratom funded projects with courses on fuel (freely accessible on Zenodo)
• 4 students secondments to other European labs for several weeks or months
• Massive On-line Open Course production based on workshops and uploaded on the ENEN platform, with more than 1k downloads
• Various workshops were conducted for the wider public, namely: Workshop 1 on fuel cycle scenarios (CIEMAT, Madrid, 2021), Workshop 2 on fuel qualification and code validation for advanced reactors (JRC, Petten, 2022), Workshop 3 on fuel advanced reprocessing (NNL, Manchester, 2022), Workshop 4 on fuel properties (ENEA, Bologna, 2023)
