China launched its nuclear-powered submarine program in 1958, soon after starting its nuclear weapon program. To avoid the nuclear submarine program competing with the nuclear-weapon program for scarce HEU, according The Secret Course, an authoritative book on China's nuclear history, the decision was made to use LEU fuel for naval reactors.
A land-based prototype naval reactor began tests in May 1970, becoming fully operational in July 1970. The test of this reactor core ended in December 1979 and the spent fuel was discharged in 1981. China's first nuclear-powered strategic ballistic missile submarine (Type 092 Xia-class) was launched in 1982.
China's official nuclear history (Modern China's Nuclear Industry, published in 1998) indicates that the first generation naval reactors in both the Type 091 and the Type 092 vessels may have used LEU enriched below 5% uranium-235 (comparable to modern nuclear power reactor fuel). The first generation naval reactors were mainly in use from the early 1970s to mid-2000s.
Zhang Jinlin, the chief designer of China's second generation nuclear-powered submarines, has said that the first of the second generation nuclear-powered attack submarines, the Type 093 Shang-class, was delivered in 2006, and the first of the second generation ballistic missile submarines, the Type 094 Jin-class, was delivered in 2014. China currently possesses five nuclear powered attack submarines and four nuclear-powered ballistic missile submarines. These are all believed to use LEU fuel.
It is possible that China has adapted its second generation naval reactor for use as a small commercial power reactor. The China National Nuclear Corporation's ACP100 reactor is said to be derived from naval reactor technology. The ACP100 reactor is described as a 310 MWt (100 MWe) small modular PWR, using 4.2% enriched LEU fuel, with the core and cooling system integrated inside the pressure vessel and a passive safety system. This may suggest China has developed a compact integrated naval reactor, similar to ones previously developed by France and Russia.