BEIJING — China said Friday it had hooked its first so-called "fourth generation" nuclear reactor to the grid, a breakthrough that could eventually reduce its reliance on uranium imports. The experimental fast-neutron reactor is the result of more than 20 years of research and could also help minimise radioactive waste from nuclear energy, the state-run China Institute of Atomic Energy (CIAE) said. China is the ninth country to develop a fast-neutron reactor, which uses uranium 60 times more efficiently than a normal reactor, helping the country to reduce its reliance on imports of the mineral. Beijing has stepped up investment in nuclear power in an effort to slash its world-leading carbon emissions and scale down the country's heavy reliance on coal, which accounts for 70 percent of its energy needs. But China's uranium reserves are limited, and it will have to import increasingly large amounts as its civilian nuclear programme gathers speed.