At dismantling of a nuclear power station the contaminated equipment is hackled and after that decontaminated. In general this is achieved by means of washing the components thoroughly. In doing so, radioactive contaminated waste water comes into existence which is treated in an evaporation plant.
The purpose of the evaporation plant is to clean the waste waters to such an extent that a re-use or a delivery to the discharge system is possible in compliance with the regulations. The waste water volume is reduced up to a minimum; this results in a considerable decrease of the costs for disposal. The waste waters are stored in raw water tanks and evaporated in the evaporation unit after pre-treatment. In this case the salts and solids contained in the waste water are thickened to a concentrate by extraction of water.
The concentrate is fed from the evaporator into the concentrate tanks and subsequently delivered to the drying unit for further treatment. After drying the residue is stored in disposal sites either for intermediate or final storage. The evaporated vapours are led through drop separators and re-cleaned in a column since a definite decontamination value being extremely low must be kept. In the following the condensation takes place in a surface condenser by means of cooling water. The distillate is fed into the distillate tank and reused as flushing water or supplied to the discharge system after an analysis has been made and release has been given.
The plant is projected for a continuous operation. For design of the plant great importance was attached to highest level of operational reliability and high degree of automation.