Validation of the MCU-PTR computational model of beryllium poisoning using selected experiments at the IRT-T research reactor

This paper presents the results of the validation of the MCU-PTR code computational model of beryllium poisoning caused by 3He and 6Li buildup against selected experiments at the IRT-T research reactor in the National Research Tomsk Polytechnic University. Calculations including the reflector irradiation history modeling for the entire reactor lifetime were performed using the continuous energy Monte Carlo code MCU-PTR. The measured reactivity loss (∼3.2%Δk/k) after the reactor shutdown period of 672 days and the reactivity increase (0.9%Δk/k) after replacement of the part of the reflector beryllium blocks by fresh blocks were compared with the calculated results. The impact of the parameters of beryllium poisoning model on the calculated results was investigated. The calculation underestimates the reactivity loss caused by 3He buildup during the 672-day shutdown by approximately 0.5%Δk/k.