Abstract

Investigation of neutronics parameters of the nuclear reactor cores is one of the most important and key topics in the nuclear reactor design, that by analysis of these parameters such as cores reactivity at the BOC amd during the cycle, how to control reactivity, axial and radial power distribution and core burn-up, we can understand the difference in reactor design according to their application.
Nowadays, many countries through the world they have shown great interest in using a nuclear reactor as a Propulsion for merchant ships for a variety of reasons. For this reason, in this study, the neutronics parameters of a soluble boron-free propulsion reactor core that proposed for a commercial ship have been investigated. The results show that a reactor used for nuclear propulsion has many neutronics capabilities and differences compared to land-based SMRs. Studies show that due to the high reactivity required for long life cores, how to control the reactor without soluble boron at BOC and during the cycle, how to distribution of power safely in the core and the behavior of Xenon in different reactor conditions, including Xenon build-up after shutdown, one of the major challenges is designing a reactor as a Propulsion. Studies show that the propulsion system with a thermal power of 440 MW can be used for 15 years and also for various reasons, soluble boron is not used as a core reactivity controller, which has been suggested to control reactivity. Use Gadalina burnable absorbers mixed with fuel, which in the desired core using the optimal arrangement designed in addition to being able to control the reactivity of the core during the cycle has reduced the power peaking in the radial direction. Also, with the special design of this type of reactor and low thermal flux, the buil-up of xenon after shutdown is significantly reduced, which leads to a reduction in reactor restart time.