Minor actinide transmutation in the lead-cooled fast reactor

Abstract

The minor actinides are introduced to a lead-cooled fast reactor (LFR) core in three different approaches to study minor actinide (MA) transmutation characteristics. Power peaking factor calculation results indicate that loading appropriate amount of minor actinide to LFR core does not disturb the neutron flux distribution or power density distribution in LFR core remarkably. This is an advantage of transmutation minor actinides in LFR compared to the minor actinide transmutation characteristics in the PWR reactor.After MA loading to LFR, keff curves deviate from keff curves without minor actinides loading obviously; there is no distinct difference between keff curves of three minor actinide loading approaches. The LFR core loaded with minor actinides can prolong the fuel cycle to some extent. This is because the created new fissile 238Pu, 242Am, 244Am, 243Cm and 245Cm can compensate the reactivity loss due to the consumption of nuclear fuel and sustain the criticality of LFR core.After minor actinide 550-day-exposure in LFR, the concentration of 237Np, 241Am and 243Am decreases, while the concentration of 244Cm and 245Cm increases. This is because the 241Am and 243Am capture neutrons and generate 244Cm and 245Cm. The lead-cooled fast reactor with the thermal power of 750 MW and loading 1 wt % MA nuclides can consume the annual minor actinide yields from about 1.5 typical PWRs. The fraction of plutonium isotopes from LFR reactor spent fuel after MA transmutation is about 85%, the rest being made up of other transuranic isotopes. Plutonium isotopes are important nuclear fuel. Most importantly 238Pu is a very powerful alpha particle emitter; this makes 238Pu an ideal material for fabricating radioisotope batteries.In general, transmutation of minor actinides in lead-cooled fast reactors can achieve the goals of elimination of MA nuclide long term radioactive hazards and creation of important 238Pu material. Therefore, it is feasible to transmute the MA nuclide in lead-cooled fast reactors.