Physics

Biography

Biography: Leonid Ponomorev

Abstract

Fast reactor is the nesessary element of of the future nuclear power. But the contemporary fast reactors are not inherently safe (in Weinberg’s definition) and have the serious problems with the fuel nuclear cycle closing: the low fuel element burning and their repited fabrication from the hot spent fuel. Molten salt reactors (MSR) are free from these shortages: their void and temperature coefficients are negative, they do not need in the fuel elements fabrication and give the opportunity to organize on line hot spent fuel reprocessing. First MSR was in operation during almost 5 years with Th-U fuel and thermal neutron spectrum, which is adequete for this fuel (MSRE, Oak Ridge, 1964-1969). However its neutron balance  is poor in comparison with U-Pu fuel and fast neutron spectrum. Till recently there was impossible to combine all three ideas (fast spectrum, molten salt and U-Pu fuel) because the PuF₃ solubility in the fluoride salts was too small. 5 years ago it was established experimentally that PuF₃, UF₄ and AmF₃ solubility in the eutectic 46.5 LiF-11.5 NaF-42.0 KF (FLiNaK) is equal 33, 45 and 43 mole % respectively at 700°C. This observation opens the way for the development of the Fast Molten Salt Reactor with U-Pu fuel cycle (U-Pu FMSR) as well as the effective FMSR reactor-burner of Am. U-Pu FMSR based on FLiNaK can work in the equilibrium mode at the concentration UF₄ and PuF₃ 22 and 7 mole % respectively using as a fuel ²³⁸U only. FMSR reactor-burner can transmute ~ 300 kg Am/year·MWth without Pu feeding, i.e.    one 1GWth FMSR-burner can disintegrate Am from the spent fuel of ~ 40 standart 1GWel thermal reactors after 5 years of cooling.