Reprocessing spent nuclear fuel recovers 97% of valuable, reusable materials (see graphic below), and separates out the remaining 3%, which is ultimately high-level radioactive waste (HLW).
The HLW is conditioned by turning it into a solid glass form by a process called vitrification. It is widely accepted around the world that vitrification of HLW is a safe and secure method of treating, transporting and storing these forms of nuclear waste.
In Japan, vitrified waste is stored at a vitrified waste storage center at the JNFL facilities in Rokkasho Village in northern Japan. These vitrified wastes will be stored at the center for 30 to 50 years before being transferred to a final subterranean disposal facility, also to be located within Japan.
(Note: The above graphic on spent fuel contents refers to the case of 3% enrichment level.)
The vitrified waste program is an integral segment of the "closed" nuclear fuel cycle. Since Japan's domestic fuel cycle is still in the process of construction, reprocessing contracts are being continued with partners in Europe. This is leading to the transport of vitrified residues from Europe to Japan, as provided for by these reprocessing contracts. These contracts lay down that conditioned final residues are returned to the country of origin.
In contrast to the plutonium and uranium, which are recycled since they have an important energy value (1 gram of plutonium is equivalent to 1 ton of oil), the HLW has no use at all and cannot be recycled. After having been separated by reprocessing operations, it is vitrified (i.e. incorporated within a very stable glass matrix). The glass is poured into a stainless steel container 1.34 m in height and 0.43 m in diameter, where it solidifies. The weight of this canister is around 500 kg.
Currently, all vitrification of Japanese nuclear waste is being conducted in Europe, meaning that these wastes are being transported on a regular basis by sea to the interim storage site for vitrified waste, part of the JNFL facilities in Rokkasho. As part of the reprocessing plant being constructed in Rokkasho, there will also be a HLW vitrification plant created at the site. Thus, the vitrified waste program will be a purely domestic program in the future.
