Plutonium nitride and plutonium nitride base fuel materials

The phase diagram of the PuN system is presented. Considered are the technological methods of production of plutonium nitride and mixed uranium-plutonium nitrides, based on hydride nitration, on melting of uranium-plutonium alloy in the nitrogen with subsequent ingot grinding into powder, on synthesis from elements in solid phase Me+N2, on carbon thermic reduction of oxides in nitrogen. The methods of core fabrication of PuN and (U,Pu)N cold pressing and sintering are described. Considered are physical and mechanical properties (color, thermodynamic properties, heat and formation free energy, entropy, evaporation, thermal expansion, hardness, thermal conductivity, elastic properties, diffusion) and chemical properties (interaction of (U,Pu)N with structural materials, with refractory metals, compatibility) of plutonium nitrides and mixed uranium-plutonium nitrides. The processes occuring in (Pu,U)N and PuN under the irradiation (swelling, gassing, structural changes, nitride thermal stability) are described. The data on nitride fuel application in pile are given