Neutronic Analysis of Star Core Gas-Cooled Reactor Core with Truncated Cuboctahedron-Shaped Fuel Elements

StarCore, as a High-Temperature, Gas-Cooled Reactor (HTGR), is in the preliminary design stage in Canada. The safety and control of StarCore shall be assured by neutronic and thermal-hydraulic analysis. In this study, the criticality and neutronic analysis of the StarCore have been assessed using the MCNPX and SuperMC codes. This analysis is crucial to ensure the safe and efficient operation of StarCore. A criticality analysis of  the StarCore has been performed. Based on the design data, axial and horizontal neutron flux distributions within the reactor core have been specified. The arrangement and integral control rod worth have been identified for various insertions into the core. The criticality analysis showed that without considering absorber rods, the reactor core would be supercritical and uncontrollable. The multiplication factor obtained was ۱.۳۸۴۳۵ and ۱.۳۹۷۶۳ based on the criticality analysis of SuperMC and MCNPX codes, respectively. The criticality analysis was reviewed by considering the full insertion of control rods into the reactor core following the determination of control rod arrangements. The multiplication factor decreased to ۰.۹۶۲۴۵ and ۰.۹۷۲۱۳ based on the results of SuperMC and MCNPX codes, respectively. The results demonstrated that sub-criticality of the reactor core could be achieved by full insertion of control rods into the reactor core. Fuel temperature and coolant density coefficients have been evaluated for different conditions. The results indicated that the negative fuel temperature coefficients could be variable between -۰.۸۵۰۷ and -۳.۸۶۳۱۲ with increasing fuel temperature from ۳۰۰K to ۱۲۰۰K. The coolant density coefficient could have changed between -۰.۱۰۷۶۸ and -۰.۹۱۱۰۹ following a reduction in coolant density from ۰.۰۱g/cm۳ to ۰.۰۰۰۰۱g/cm۳. Statistical indicators and a comparison of results from both software programs have been used to verify and validate the accuracy of the calculations. The criticality analysis results showed that the reactor core could be critical and controllable. The negative temperature and coolant density coefficients could achieve inherent safety. It is essential to perform further thermal-hydraulic and neutronic analyses to evaluate the comprehensive safety of the StarCore design.

کلیدواژه ها:

StarCore ، HTGR ، Neutronic Analysis ، Monte Carlo ، TRISO fuel ، Reactor safety ، SMR