Transmutation Characteristics Of MA In Lead-cooled Fast Reactor

We studied the MA transmutation characteristics and transmutation rates in the Lead-cooled Fast Reactor(LFR).We compared the effects of different MA nuclides,three loading patterns and different loading amounts on keff.Calculation results of MCNP code and SCALE code show that,the addition of 237 Np,241Am,243 Am always decrease the keff,while 244 Cm and 245 Cm increase the keff,and 245 Cm raises the keff significantly.The keff of the reactor core will always decrease after the addition of mixed MA,no matter how the loading pattern is.And the keff reduced with the increase of loading amount of mixed MA.Among the three loading patterns,the transmutation rod pattern poses the smallest effect on keff,and the coating pattern affects the keff most considerably.The effect of homogeneous pattern is between this two patterns.We calculated the neutron flux of the LFR core,calculation results show that the neutron spectrum of the core alters slightly by the addition of mixed MA,but the neutron flux in the fast neutron energy region was decreased.The pattern causes the maximum decrease of the neutron flux is coating pattern,then is homogeneous pattern,the transmutation rod pattern decreases the neutron flux at the minimum amount.The neutron spectrum of the PWR core will become harder after the addition of mixed MA transmutation rods,the neutron flux in the thermal neutron energy region will decrease,which indicates that the MA transmutation affect the PWR core more than the LFR core.Calculation results of neutron flux of fuel assemblies show that all of the three pattern of 1 wt% mixed MA addition to the LFR core will affect the power flattening.The homogeneous pattern increases the neutron flux of every fuel assemblies,impact the power flattening;the transmutation rod pattern flattens the radial neutron flux,but reduces the neutron flux of the transmutation assemblies as well.The coating pattern alter the distribution of radial neutron flux significantly.The amount of 37 Np,241Am,and 243 Am decreased after 365-day-expoursure in LFR while the amount of 244 Cm and 245 Cm increased.The decrease rates of homogeneous,transmutation rod,and coating pattern are 89.70%,88.52%,and 89.47% respectively.Compare the transmutation rates of LFR and PWR we have found that the transmutation efficiency of MA nuclides is higher in LFR than PWR.It can also enhance the utilization of nuclear resource since lots of isotopes of Thorium,Uranium,and Plutonium are available when MA transmuting in LFR.