Fortum has carried out extensive research on liquid waste cementation processes and long-term testing of waste packages performed since late 1970s. Fortum has designed and built an advanced solidification plant using their own technical solutions in several parts of the system. Finnish safety authorities have approved the design and the commissioning of the solidification plant.
The treatment process for radioactive liquid waste can be divided into three phases before final disposal: production of the solidification product, casting of the lid, and intermediate storage of the solidification product (Figure 1).
Figure 1. Operating principle of solidification plant
The main stream of waste to be treated in the solidification plant consists of radioactive spent ion exchange resins and bottom sludges of evaporator concentrate tanks. Also waste generated during interim storage of spent fuel and decommissioning will be solidified.
The solidification plant has been designed to solidify liquid waste generated during 50 years of operation from units 1 and 2 of the Loviisa NPP. The process is based on use of normal cement and additives. The waste package is reinforced concrete container type licensed for final disposal. The containers will be disposed in the repository at the Loviisa site.
The solidification plant is closely connected to the liquid waste storage building in order to allow short transport routes. Also a solution for transport of spent ion exchange resins and evaporator concentrates, originating from radioactive liquid purification, has been developed. Solidification plant is remote controlled from its own control room. The heart of the plant is the solidification line with a transfer car. All the important devices are located nearby this solidification line. Only large cement silos and additive storage tanks, which are filled up from outdoors, are located further.
The construction was started in 2003. The Civil work was finished 2007 and the entire facility was finally commissioned in 2016.
Figure 2. The lifecycle of the solidification plant’s planning, development and operational use.
- In the project, the liquid waste disposal facility was practically built from scratch and it was put into production despite many difficulties. During the project, the most imaginative problems and challenges were solved and one of the world's most effective recipes for cementing liquid waste was created, says manager of the Solidification Plant Ilkka Ropponen.