The technical issues have mostly been solved, but the long-term potential peril of radioactive material has made it difficult to find politically acceptable sites.
Inside a nondescript warehouse in an industrial park in Oakville, Canada, sits a squat forklift truck that requires no driver. When activated by its remote operator, the vehicle trundles to a stack of huge clay blocks, each weighing 8,000 kilograms, and carries them into a narrow rock tunnel. Another custom-built machine then fills the spaces around the blocks with crumbled clay.
Each block is made of bentonite clay and encases a copper-coated steel container built to hold spent fuel from a nuclear reactor. The blocks will be sealed behind yet more clay and concrete in tunnels deep underground, and the radioactive material inside will be left to slowly decay over thousands of years. Read more in Nature.