OREANDA-NEWS. The Finnish Radiation and Nuclear Safety Authority (STUK) has on 15.2.2016 granted Loviisa nuclear power plant's solidification plant a permission to start full operation. The plant will solidify the liquid radioactive waste generated during operation and decommissioning of the Loviisa power plant. This waste primarily consists of ion exchange resins used in the purification of process water as well as bottom sludge from evaporator concentrate tanks. The solidification process is highly automated and the process is controlled from a control room at the solidification plant.

The solidification plant is included in the Loviisa power plant's operating licence, and licensing process was handled as a plant modification. The solidification plant operates as an independent facility in its own building in the power plant area, so the separate safety assessment conducted by STUK was more extensive than for a typical plant modification. STUK found the design, construction and commissioning of the solidification plant to be safe and in accordance with regulations.

"Loviisa power plant's solidification plant is a pilot plant; its planning and successful implementation is the result of the long-term development efforts by Fortum's own competent personnel. The plant's commissioning phase started in 2006; during the test runs, the solidification recipes were developed and tested and the manufacturing method for the final disposal containers and the resin transfer systems were improved," says Thomas Buddas, Deputy Director, Loviisa Nuclear Power Plant.

A total of about 900 m3 of intermediate-level radioactive ion exchange resins and evaporator concentrates for solidification have accumulated throughout the Loviisa power plant's history. Now the solidification of this stockpile will begin in full scale. The goal is to get all the liquid waste processed before the Loviisa unit one reactor's operating licence expires in 2027. When the decommissioning of the power plant starts, the liquid waste generated in the purging of the system and in the dismantling work will be processed in the solidification plant.

"The waste will be cemented directly in final disposal containers, which, after intermediate storage, will be deposited into the final repository for power plant waste, located on-site in the power plant area. The advantages of cementation include fire safety and the concrete's ability to effectively absorb radioactive materials. The waste can be handled in small batches, making the process safe and easy to control," Buddas says.