Irradiation and Cooling Process Effects on Material Barrier Analysis Based on Plutonium Composition of LWR

Abstract

Nuclear fuel utilization program from front-end up to back-end processes especially spent fuel management have been monitored and safeguarded by the IAEA in order to ensure the utilization of nuclear fuels from all nuclear facilities including nuclear fuel reprocessing facilities are dedicated only for civil and peaceful purposes. Nuclear fuel production processes including reactor criticality condition is one of the major topics in term of nuclear fuel sustainability which related to energy security issues. Meanwhile, reduction level or preventing processes of nuclear fuel utilization from its potential risk from nuclear explosive purposes should be also strengthened and prioritized. To increase the intrinsic proliferation resistance of nuclear fuel, one of the potential ways is by increasing the material barrier level such as isotopic barrier. In case of plutonium, increasing the intrinsic properties of plutonium isotopes can be used by increasing material barrier of even mass number (Pu-238, Pu-240 and Pu-242). In this study, the effect of different irradiation process during reactor operation which related to discharged fuel burnup have been used and decay time to analyzed its dependeny to plutonium production as well as plutonium production dependency to decay or cooling time processes. Fuel production analysis of the reactor are based on the spent fuel of light water reactor (LWR) with different discharged fuel burnup (33 GWd/t, 50 GWd/t and 60 GWd/t) and different decay or cooling time process (1 to 30 years cooling time). Fuel behavior optimization of LWR design are obtained by using ORIGEN code by employing some modules for analyzing fuel production dependencies to burnup and decay time processes. In this study, two parameters for investigating the material barriers are adopted such as decay heat (DH) and spontaneous fission neutron (SFN) compositions. The compositions of DH and SFN are sensitive to the composition of isotopic plutonium especially more sensitive to even mass plutonium composition. Higher discharged fuel burnup level produces more even mass plutonium compositions and effectively reduce Pu-239 production because of more fissile Pu-239 are consumed for higher burnup. Isotopic Pu-238 gives the highest DH contributor, while Isotope Pu-240 obtains the highest contribution of SFN followed by other plutonium isotopes. DH and SFN compositions of plutonium can be increased effectively by increasing burnup process. Longer decay time is also effective to increase SFN compositions because of its dependency to all even mass plutonium while it gives less DH compositions because of its dependency to the contribution of Pu-238.