Study of Helium Cooled Fast Reactor Core Design Fuelled by Thorium Carbide-Uranium Carbide with Modified Candle Axial Direction Scheme

Human need of energy will increase time to time. Therefore, a safe, renewable, and efficient source of energy, which is Nuclear Energy, is needed. Nuclear Power Plant (NPP) is the most compatible solution to provide electricity to human race in the future. The problem that came within NPP is the danger of proliferation issues. The method that has been developed to overcome this problem is CANDLE [5] and has been modified by Prof. Zaki Su’ud (Modified CANDLE scheme). This research use Axial Modified CANDLE Scheme to Helium-Cooled Fast Reactor with Natural Uranium Carbide-Thorium Carbide as fuel and applied to various size of core as optimization. Neutronic aspect such as, burn up level, multiplication factor, and conversion ratio are utilized in this paper in order to analyse the behaviour of the reactor. Other than that, percentage of Uranium has been varied to reduce power peaking. The neutronic calculation has been done using SRAC and core design calculation by FI-ITB-CH1. This research concludes that power peaking reduction is able to achieve by combining Uranium Carbide and Thorium Carbide to the fuel. The optimum reactor design reached at 360 cm of core radius and 303 cm of core height.

Study on combustible gas generation and radionuclide release during underwater handling of the AM reactor spent fuel

Introduction. The paper addresses studies on the accumulation of combustible gases during underwater handling simulations for the leaky spent nuclear fuel from the AM reactor. Two fuel compositions were studied- uranium-molybdenum dispersed in magnesium and uranium carbide dispersed in calcium. Methods. The 137Cs release rate was measured during underwater storage of the uranium-molybdenum fuel. The kinetics of hydrogen release for both fuels and methane release for the carbide SNF were obtained. The kinetics approximate most with exponential dependences that formally correspond to first-order chemical reactions. A contribution of radiolytic hydrogen to the gases generated during the experiments was estimated. It was demonstrated that the determining source of the gases is the chemical interaction between the spent fuel and the water. The experiment with the uranium-molybdenum fuel demonstrated a pronounced passivation effect of the chemical processes on the fuel surface due to insoluble corrosion products. For the carbide SNF, an incubation period of about 20 hours was observed followed by an intensive release of hydrogen and methane. Results. The obtained results were subject to a comparative analysis against publications on the behavior of the fuel components in water. Conclusion. The findings can be applied to justify fire and explosion safety of underwater handling techniques for the damaged spent nuclear fuel with the considered fuel compositions (the spent fuel from reactors AM, AMB, EGP-6, etc.), e.g., to justify underwater preparations of the AMB spent fuel for reprocessing.

Uranium Carbide Fibers with Nano-Grains as Starting Materials for ISOL Targets

This paper presents an experimental study about the preparation, by electrospinning, of uranium carbide fibers with nanometric grain size. Viscous solutions of cellulose acetate and uranyl salts (acetate, acetylacetonate, and formate) on acetic acid and 2,4-pentanedione, adjusted to three different polymer concentrations, 10, 12.5, and 15 weight %, were used for electrospinning. Good quality precursor fibers were obtained from solutions with a 15% cellulose acetate concentration, the best ones being produced from the uranyl acetate solution. As-spun precursor fibers were then decomposed by slow heating until 823 K under argon, resulting in a mixture of nano-grained UO2 and C fibers. A last carboreduction was then carried out under vacuum at 2073 K for 2 h. The final material displayed UC2−y as the major phase, with grain sizes in the 4 nm–10 nm range. UO2+x was still present in moderate concentrations (~30 vol.%). This is due to uncomplete carboreduction that can be explained by the fiber morphology, limiting the effective contact between C and UO2 grains.