Immobilization of NPP evaporator bottom high salt-bearing liquid radioactive waste into struvite-based phosphate matrices.

The high salt-bearing liquid radioactive waste (evaporator bottoms, EB) makes up the most voluminous NPP waste and needs solidification. In the paper presented, we introduce a novel formation process study of the struvite-based phosphate matrices ((K, NH)MgPO·6HO) and the developed phosphate matrix compositions for the solidification of high salt-bearing solutions. The solutions simulate the EB of nuclear power plants with pressurized water reactors (NPP PWR).

Structure determination of neptunium(VI) mu3-hydroxobenzoate, [(NpO2)2(mu3-OH)2(H5C6COO)2] x 2 H2O.

Neptunium(VI) benzoate with mu(3)-OH(-) has been isolated and studied by the X-ray method. The main structural motive in the crystal is corrugated ribbons [(NpO(2))(2)(mu(3)-OH)(2)(C(7)H(5)O(2))(2)](n) extended along the c axes in which three neptunium pentagonal bipyramids are linked through the mu(3)-OH(-) ligand. The benzoate ions are arranged at both sides of the ribbons, and each anion binds two adjacent NpO(2).