The calculation of uranium metallic Fuel (U-10%wtZr) cell with helium coolant using SRAC 2K6

In this study, pin-shaped natural metallic uranium fuel cells with a diameter of 1.4 cm were designed with and without enrichment of 2-10% by using helium as a coolant. The calculations were conducted by using SRAC software and the results show that the greater the enrichment level, the more significant the value of the infinite-multiplication-factor (kinf), meanwhile the conversion ratio is smaller. Basically, uranium exists in two isotopic forms namely, U-235 and U-238 which are transformed into other element such as Pu-239 when they both go through fission and transmutation reactions in the reactor core. Therefore, to obtain the optimum reactor core design, the performance information of nuclear fuel cells from the variations of burn-up time needs to be taken into consideration.

Microstructural Changes and Chemical Analysis of Fission Products in Irradiated Uranium-7 wt.% Molybdenum Metallic Fuel Using Atom Probe Tomography

Understanding the microstructural and phase changes occurring during irradiation and their impact on metallic fuel behavior is integral to research and development of nuclear fuel programs. This paper reports systematic analysis of as-fabricated and irradiated low-enriched U-Mo (uranium-molybdenum metal alloy) fuel using atom probe tomography (APT). This study is carried out on U-7 wt.% Mo fuel particles coated with a ZrN layer contained within an Al matrix during irradiation. The dispersion fuel plates from which the fuel samples were extracted are irradiated at Belgian Nuclear Research Centre (SCK CEN) with burn-up of 52% and 66% in the framework of the SELENIUM (Surface Engineering of Low ENrIched Uranium-Molybdenum) project. The APT studies on U-Mo particles from as-fabricated fuel plates enriched to 19.8% revealed predominantly γ-phase U-Mo, along with a network of the cell boundary decorated with α-U, γ’-U2Mo, and UC precipitates along the grain boundaries. The corresponding APT characterization of irradiated fuel samples showed formation of fission gas bubbles enriched with solid fission products. The intermediate burnup sample showed a uniform distribution of the typical bubble superlattice with a radius of 2 nm arranged in a regular lattice, while the high burnup sample showed a non-uniform distribution of bubbles in grain-refined regions. There was no evidence of remnant α-U, γ’-U2Mo, and UC phases in the irradiated U-7 wt.% Mo samples.