Predictive evaluation of changes in the volumes of radioactive waste to be deeply dispositioned in activated reactor structures in the process of their storage after the final shutdown of the Belarusian NPP power units

Abstract

This paper presents the results of computational studies of the amount of solid high-level and long-lived intermediate level radioactive waste (HLW and ILW-LL) generated during neutron activation of structural materials adjacent to the core of the VVER-1200 reactor of the Belarusian NPP, depending on the time after the final shutdown of the reactor. The assessment of the volumes of HLW and ILW-LL of activation origin, formed over 60 years of operation of the VVER-1200 reactor, was carried out on the basis of computational studies of the induced activity of structural and shielding materials using reactor and Monte Carlo program codes (SERPENT 2, TVS-M, DYN3D, MCU- PD). As a result of calculation studies, it was established that the masses and volumes of activated materials, according to the levels of pollution related to HLW and ILW‑LL, within 10 years after the final shutdown of the VVER-1200 reactor of the Belarusian NPP will be 273 tons and 43 m3 , respectively. In the interval of 30–70 years, the masses and volumes of activated materials of these categories of RW will amount to 262 t and 33 m3 , respectively. From 100 years to 200 years, the masses and volumes of activated materials of these categories of RW will be 118 t and 15 m3 , respectively. Within 10 years after the reactor shutdown, isotopes 55Fe (2.7 years), 60Co (5.27 years), 63Ni (96 years) will make the main contribution to the value of the integral specific activity of the materials of the structures of the fence, shaft, surfacing, reactor vessel, block of protective tubes (BPT), the space under the core, thermal insulation; after 10 years – 63Ni. The main contribution to the value of the integral specific activity of materials of absorbing elements (PEL) with Dy2TiO5 during the entire period of storage will be made by 63Ni.