Evaluation of Radiation-Induced Atom Displacement and Mechanical Degradation in MNSR Aluminum Fuel Cladding

Radiation damage is one of the significant factors of degradation in nuclear reactors, leading to changes in material properties. In this study, this effect has been evaluated for the aluminum Grade 303-1 fuel cladding of the MNSR reactor. The MCNPX and SPECOMP codes were used to determine the neutron flux distribution and calculate the atomic displacement and transmutation rates. The highest atomic displacement rate in the cladding was found to be 4.49×10−9 dpa/s, with maximum production rates of 1.6×10−4 Si/s, 4.1×10−13 Mg/s, and 9.2×10−14 Na/s per incident particle. Furthermore, using the RCC-MRx code, the variations in yield and tensile strengths were calculated. A key finding of this study explicitly reveals that the onset of significant degradation in yield and tensile strengths occurs at operational times of 2.5 × 105 h and 3.5 × 105 h, corresponding to total neutron fluences of 6.1 × 1021 n/cm2 and 8.54 × 1021 n/cm2, respectively.