Spent nuclear fuels are stored in a wet storage or others after use as fuels for nuclear generation, but about 96% of them are resources that are recyclable as fuels like 95.6% uranium and plutonium generated from the uranium that is not ready for nuclear fission.
Reprocessing of spent nuclear fuels is a technology of separating and extracting usable materials from spent nuclear fuels for reuse, and it is further divided into wet and dry methods.
This technology is exclusively used by some countries like France, England and Japan and there is a concern for proliferation resistence as it can extract plutonium only.
This technology separates volatile materials and sheaths from light water reactor only through thermal and mechanical process in order to use them for CANDU nuclear fuels. However, this technology was modified in a way that developed the core technology for the back-end fuel cycle.
The pyro-processing technology is a technology using electrochemical reaction with molten salt that exhibits electric conductivity at a high temperature above 500℃ as medium. Most uranium is selectively retrieved for recycling or disposal while plutonium and other ultra uranium atoms are collected together as a nuclear material group for combustion in a fast reactor. Therefore, this technology is known for effective prevention of nuclear expansion by eliminating possibility of selective separation of plutonium.