The plutonium disposition is presently acknowledged as one most urgent issue at world level. Inert matrix and thoria fuel concepts for Pu burning in LWRs, show good potential in providing effective and ultimate solutions to this issue. In non-fertile (U-free) inert matrix fuel, plutonium oxide is diluted within inert oxides such as stabilized ZrO2, Al2O3, MgO or MgAl2O4. Thoria additions, which helps improve neutronic characteristics of inert fuels, appears as a promising variant of U-free fuel. In the context of a R&D activity aimed at assessing the feasibility of the fuel concept above, simulated fuel pellets have been produced both from dry-powder metallurgy and the sol-gel route. Results show that they can be fabricated by matching basic nuclear grade specifications such as the required geometry, density and microstructure. Some characterisation testing dealing with thermo-physical properties, ion irradiation damage and solubility also have been started. Results from thermo-physical measurements at room temperature have been achieved. A main feature stemming from solubility testing outcomes is a very high chemical stability which should render the fuel strongly diversion resistant and suitable for direct final disposal in deep geological repository (once-through solution).

Preliminary Fabrication and Characterisation of U-free Inert Matrix and Thoria Fuels for Plutonium Disposition in LWRs

Zappa, G.;La Torretta, T.
1998-10-19

Abstract

The plutonium disposition is presently acknowledged as one most urgent issue at world level. Inert matrix and thoria fuel concepts for Pu burning in LWRs, show good potential in providing effective and ultimate solutions to this issue. In non-fertile (U-free) inert matrix fuel, plutonium oxide is diluted within inert oxides such as stabilized ZrO2, Al2O3, MgO or MgAl2O4. Thoria additions, which helps improve neutronic characteristics of inert fuels, appears as a promising variant of U-free fuel. In the context of a R&D activity aimed at assessing the feasibility of the fuel concept above, simulated fuel pellets have been produced both from dry-powder metallurgy and the sol-gel route. Results show that they can be fabricated by matching basic nuclear grade specifications such as the required geometry, density and microstructure. Some characterisation testing dealing with thermo-physical properties, ion irradiation damage and solubility also have been started. Results from thermo-physical measurements at room temperature have been achieved. A main feature stemming from solubility testing outcomes is a very high chemical stability which should render the fuel strongly diversion resistant and suitable for direct final disposal in deep geological repository (once-through solution).
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/20.500.12079/5785
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