Concentration of LRW

Concentrator-bituminizer unit

Bituminization is the process of including radioactive waste, largely liquid or ‘wet’, in bitumen materials which normally result from distillation of natural oil or black coal. Bituminization has been used in nuclear industry for over 40 years. Many countries use this process to solidify vat residue, sludge, ion-exchange resins, ash residue and other low- and medium-level waste.

Bitumen has a broad application thanks to its thermal plasticity and waterproof properties which make it possible to obtain, through heating, waste components with production of stable homogeneous product, and helps obtaining water-resistant compounds. Besides, bitumen is broadly used, readily available and cheap as the initial material for waste immobilization.

The LRW (liquid radioactive waste) bituminization process involves evaporation of water and mixing of residual salts with bitumen at a high temperature. The mixture cooling results in a compound with waste particles uniformly distributed in bitumen.

The work on including low- and medium-level radioactive waste in a bitumen matrix was started at RADON in the 1970s. RADON was the first in the USSR to launch (in 1976) commercial bituminization of low- and medium waste using a thin-film rotary evaporator. A facility built based on a KRT-600 serial rotary thin-film evaporator is used for bituminization. Following the stages of evaporation and the salt-bitumen mixing, the mixture is cooled for 48 hours to solidify, after which it is shipped for disposal. The evaporated water is condensed and purified.