Management of radioactive effluents from research Reactors and PHWRs

Indian nuclear power programme is mainly based on pressurized heavy water reactors (PHWRs). In addition we have research reactors namely Apsara, CIRUS, Dhruva at Trombay. The operation and maintenance activities of these reactors generate radioactive liquid waste. These wastes require effective management so that the release of radioactivity to the environment is well within the authorized limits. India is self reliant in the design, erection, commissioning and operation of effluent management system for nuclear reactors. Segregation at source based on nature of effluents and radioactivity content is the first and foremost step in the over all management of liquid effluents. The effluents from the power reactors contain mainly activation products like 3H. It also contains fission products like 137Cs. Containment of these radionuclide along with 60Co, 90Sr, 131I plays an important part in liquid waste management. Treatment processes for decontamination of these radionuclide include chemical treatment, ion exchange, evaporation etc. Effluents after treatment are monitored and discharged to the nearby water body after filtration and dilution. The concentrates from the processes are conditioned in cement matrix and disposed in Near Surface Disposal Facilities (NSDFs) co-located at each site. Some times large quantity of effluents with higher radioactivity concentration may get generated from the abnormal operation such as failure of heat exchangers. These effluents are handled on a campaign basis for which adequate storage capacity is provided. The treatment is given taking into consideration the required decontamination factor (DF), capacities of available treatment process, discharge limits and the availability of the dilution water. Similarly large quantities of effluents may get generated during fuel clad failure incident in reactors. In such situation, as in CIRUS large volume of effluent containing higher radioactivity are generated and are managed by delay, ion exchange, chemical treatment on a campaign basis. (author)