Naval reactors have an impressive track record of providing more than 134 million miles of safe steam powered by nuclear energy, and have accumulated over 5700 years of safe reactor operation. One type, known as PWR2, is similar to the Astute class, while another, PWR2b, has been modified to improve the security and survivability of the platform. A new Russian test bench submarine runs on diesel, but it also has a very small nuclear reactor for auxiliary power. Nuclear propulsion has been found to be essential in the Russian Arctic, where conditions are too extreme for conventional icebreakers. In 1960, the second nuclear submarine in the United Kingdom was commissioned from Vickers Armstrong and, equipped with the Rolls-Royce PWR1 nuclear plant, the HMS Valiant was the first British nuclear submarine.
The smallest nuclear submarines are the six French Rubis class attack submarines (2600 dwt) in service since 1983, and they use a CAS48 reactor, a 48 MW integral PWR reactor from Technicatome (now Areva TA) with 7% enriched fuel that requires refueling every 7-10 years. From the late 1950s to the end of 1997, the Soviet Union, and later Russia, built a total of 245 nuclear submarines - more than all other nations combined. As expected, the Ministry of Defense (Ministry of Defense) released public consultation documents on the risks of dismantling the reactor at the naval shipyard and its plans to deal with a total of 27 submarines and associated parts of the nuclear reactor. The reactor control rods were then inserted to slow down the nuclear reaction and the core was cooled for several hours. There are credible anecdotal reports that dismantled Russian nuclear submarines have been used to provide electricity to remote communities and oil exploration companies in the Siberian Arctic regions, likely in the 1980s.
The KLT-40S is a four-loop version of the icebreaker reactor for floating nuclear power plants that runs on low-enriched uranium (. The development of nuclear merchant ships began in the 1950s, but overall it has not been commercially successful. CGN then signed an agreement with China's National Marine Petroleum Corporation (CNOOC) apparently to provide energy for offshore oil and gas exploration and production, and to “promote organic integration between offshore oil industry and nuclear power industry” according to CNOOC. This will include nuclear propulsion, floating nuclear power plants, small modular offshore reactors used for hydrogen production and maritime transport of SMR. Despite all this, losing a nuclear reactor underwater is not entirely harmless; it does harm aquatic life, especially in the immediate area where fuel is lost.