Estimation of Safety Parameters of IRIS Reactor Core with Reduced Fuel Length.,

In this work, neutronics and thermal-hydraulic behaviors are analyzed to illustrate the effect of reduced- fuel rod length for the International Reactor Innovative Secure (IRIS) core. The IRIS core design considered is 1000 MWt and fueled with up to 4.95% enriched uranium dioxide. A three-dimensional Monte Carlo computer code, (MCNP6), is coupled with the thermal-hydraulics code (ANSYS FLUENT), to calculate the safety parameters namely: the effective multiplication factor, axial power distribution, power peaking factor, (fuel, clad, and coolant) temperatures. The results are used to calculate the mechanical parameters such as stresses and fuel rod deformation due to the thermal stress. Stress and deformation are established with the ANSYS-STATIC structure module. In the present work, five cases are considered for the reference reactor core configurations with different fuel rod lengths. In each case, a set value for the ratio of fuel rod length (H) to core diameter (D) by varying the fuel rod length from 4.2672 m to 2 m is used. This is done in five stages depending on the length of the fuel rod: H/D = 1.72, 1.5, 1.25, 1.00, and 0.8, respectively. The results obtained with detailed modeling of the IRIS reactor core are very promising and will increase the accuracy in predicting the main safety parameters with the coupled system codes MCNP6/ANSYS. The results showed that the ratio H/D of the fuel rod must not be less than 1.25.