The Characteristics Of Transmutation MA On PWR Fuel Rods

Large scale development of nuclear power will inevitably produce a lot of spent fuel As a long-life and high-level radioactive nuclear waste,Minor Actinides(MA)play a leading role in the radioactive toxicity of spent fuel.The minimization of spent fuel is an important part to ensure the sustainable development of nuclear energy,and the Partitioning&Transmutation technology(P&T)can transform the long-lived nuclide with high radioactivity into the short-lived nuclide or stable nuclide,which is currently recognized as an effective way to dispose the spent fuel safely in the world.PWR is the mature commercial reactor with the largest number on operation and the mature technology.The reactor also contains rich neutron sources for transmutation.Therefore,it is important to study the transmutation characteristics of MA nuclides in PWR.This paper studies the characteristics of transmutation MA on PWR fuel rods through the processes of BEAVRS benchmark core construction,MA nuclides loading scheme design,NJOY temperature cross section library production and boric acid concentrations adjustment.We use MCNP code to calculate some related physical parameters of core under critical state such as reactivity,neutron flux and neutron energy spectrum,temperature coefficients and so on.SCALE code is also used to calculate some quantities associated with MA nuclides burnup.Nine schemes for introducing MA nuclides into the core and the fifteen coating thickness of MA nuclides on fuel rods are proposed.Different configuration schemes are:fuel rods coating in 3.1%enrichment area,fuel rods coating in 2.4%enrichment area,fuel rods coating in 1.6%enrichment area,fuel rods coating in 1.6%and 3.1%enrichment areas,fuel rods coating in 1.6%and 2.4%enrichment areas,fuel rods coating in 2.4%and 3.1%enrichment areas,fuel rods coating in whole core areas,fuel rods coating in the most outer and second outer areas and all fuel rods coating to assemblies areas which have burnable poison rods.The designed thicknesses are:0.00002 cm to 0.00008 cm,and the interval is 0.00002 cm.From 0.0002 cm to 0.0008 cm,with an interval of 0.0002 cm.From 0.001 cm to 0.004 cm at interval of 0.0005 cm.The results show that the following three loading schemes are more feasible.The MA nuclides fuel rods coating with a thickness of 0.0025 cm in 3.1%enrichment area,MA nuclides fuel rods coating with a thickness of 0.0015 cm in 2.4%enrichment area,MA nuclides fuel rods coating with a thickness of 0.002 cm in the outermost and second peripheral fuel assemblies areas.They have less impact on core reactivity and no adverse impact on core safety performance.According to the calculation of core lifetime,transmutation amounts and the transmutation rate,we know that 241Am has the highest transmutation rate among the five main nuclides of MA,and the transmutation rates of the above three schemes are 5.83%,19.85%and 9.14%respectively.Coating with 0.0015cm thickness MA nuclides in fuel rods at 2.4%enrichment area shows the strongest transmutation capacity of MA nuclides,with a transmutation rate of 27.57%.The core lifetime of it decreases from 410 days to 305 days,which compared with the reactor core without MA loading.MA nuclides loading can reduce core reactivity and core lifetime.Considering the influences of various parameters on core performance,the MA nuclides fuel rods coating with a thickness of 0.0015 cm in 2.4%enrichment area is determined to be the optimal loading scheme.