Radioactive waste management at the Dalat Nuclear Research Institute

The Dalat Nuclear Research Institute (DNRI) uses the reactor for isotope production, activation analyses and basic research in neutron and solid-state physics. It is the main producer of radioactive waste in Vietnam. The whole institute generates about 100 m3 - 150 m3 of liquid waste and about 3 m3 - 5 m3 of dry and wet radioactive waste per year. The system for radioactive waste management at the DNRI consists of two main parts: Radioactive liquid waste treatment station; Storage and disposal unit. The treatment station is located at the basement of the building No. 2. The designed capacity of the treatment station is 5 m3 per day. The station collects radioactive wastes from the reactor operation and from radioisotope production and other laboratories. At the DNRI, the treatment methods currently used for liquid wastes are coagulation and precipitation, mechanical filtration and ion-exchange. After being treated, the beta and gamma activities of the solution reaches levels lower than 0.01 nCi/l. Dry and wet radioactive wastes are collected and stored in a disposal unit in the building No. 5. In this building, six concrete pits (100 m3 each) have been constructed for disposal and solidification of radioactive wastes. Up to now, cementation has been performed for 10 m3 of sludge waste with the proportion of waste to cement (W/C-ratio) of 0.47 - 0.5. Although the existing treatment systems for radioactive waste management at DNRI can in principle meet the needs of the nuclear center, there is still a need to re-evaluate some of its major components and also to optimize the operation of the system. There is an urgent need to re-evaluate and renovate the cementation and volume reduction facilities for sludge and solid wastes. (author). 4 refs, 1 fig., 3 tabs