Radioactive waste is continuously generated during the operation of a nuclear power plant. Process waste comes from the continuous clean-up of the coolant that is circulated through the reactor core. It also comes from the control of releases of water and gas from the reactor facility. Clean-up is achieved by mechanically filtering the water and by ion exchange to demineralize the water. The purpose of the clean-up of the process water is to create a chemically benign environment to reduce corrosion and build­up of debris on the fuel (crud) and also to reduce the source for activation products that can spread through the reactor systems. The purpose of control of releases is to ensure that only small amounts of radioactivity, which are well within the regulatory limits, are released from the reactor facility. The primary waste products produced in the process waste are filter cartridges and sludge of ion exchange resins, other filter material and evap­orator concentrates. The filter cartridges can be handled in a similar way to other technological waste while the sludge needs solidification before further handling as waste. The activity concentration depends on the proc­esses used and the location of the filtering systems in the reactor. Particularly high activity would be found in the ion exchange resins in the primary system. The main radioisotopes are corrosion products, e. g. cobalt-60 and iron-55, and fission products, e. g. cesium-134, cesium-137 and strontium-90. The amount of fission products depends on the integrity of the fuel.

Technological and maintenance waste consists of exchanged components and material (e. g. paper, coveralls, discarded instruments, scaffolding and oils) that is used during maintenance. In most cases the activity concentra­tion is very low in technological and maintenance waste. It contains the same radioisotopes as the process waste. Some exchanged components can have higher activity concentration. This can be reduced by mechanical or chemical decontamination as it is mainly surface contamination.