Spent nuclear fuel (SNF) from nuclear facilities such as from accumulated SNF commercial reactors becomes one of the important issues in term of reducing environmental impact and fuel sustainability as well as nuclear nonproliferation point of view when those SNF materials can be recycled and utilized as new fuel loaded into the reactors. Minor actinides (MA) as one of the important material of spent nuclear fuels can be recycled and transmuted into some useful materials which can be utilized to increase the fuel breeding capability as well as for increasing protected plutonium production from the view point of nuclear nonproliferation issue. Increasing some even mass isotopic plutonium compositions are estimated to increase the level of proliferation resistance level in term of material barrier point of view. The objective of this study is to analyze the proliferation resistance aspect of nuclear fuel based on plutonium production of different loading materials in the FBR blanket. Evaluation is based on some basic parameters of reactor operation analysis, such as reactor operation time which is adjusted to 800 days operation per cycle for 4 fuel batches systems which is refered to the large FBR type of Japan Sodium Fast Reactor (JSFR) design. The results show some nuclear fuels behavior during reactor operation for different loading materials and cycles. Minor actinide (MA) material loading as doping material gives some significant plutonium productions during reactor operation. Some obtained actinide productions have different profiles such as some reducing compositions in americium and neptunium actinide compositions with the time which depends on initial loading material. Some plutonium vector compositions are evaluated from Pu-238 to Pu-242 to estimate the proliferation resistance level as isotopic material barrier of plutonium. Some significant contributions for increasing even mass plutonium as plutonium protected material are shown by Pu-238 from all doping material as well as additional production of Pu-240 and Pu-242 in certain conditions.

We report our study of the safety analysis in design of small power reactor which design based on the concept of a long-life core reactor cooled by lead-bismuth eutectic (LBE). The motivation of these studies is in order to design a next generation of reactors, we need to design a type of reactor that has inherent safety. We designed the small Pb-Bi cooled reactor with MOX-Nitrate as a fuel. In order to study the safety analysis of this reactor we conducted studies of chimney length effect to coolant flow rate in natural circulation and dependency of outlet temperature with coolant flow rate. From this work we obtained the optimum height of chimney at 15 m for the lead-bismuth eutectic flow rate 3500 kg/s and also we found the dependency of outlet temperature with lead-bismuth eutectic flow rate.

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.