Some models are very tiny. One, for example, would be small enough to fit into a shipping container and would be trucked from site to site, like a diesel generator, with the distinction it would only need to be refueled once every seven years or so.

The Russian company’s name, Akme, stands for atomic complex for small and medium energy and the company sometimes renders its name in English as Acme, though executives say they intended no reference to the cartoon company known for making improbable devices. Its goal is to produce, by 2019, a prototype of a miniature, 100-megawatt nuclear reactor small enough to fit into a typical backyard.

The company founded in December is a joint venture between Rosatom, the state nuclear power company, and a private electricity company owned by the Kremlin-connected oligarch Oleg V. Deripaska. It has $500 million in start-up capital, and one of its mini reactors will probably cost about $100 million.

The design it chose is peculiar for being cooled not with water but a molten lead alloy. In fact, the Soviet Union was the only country to deploy liquid metal reactors at sea. Introduced in the 1970s, they packed enough power to propel submarines more than 45 miles, or 72 kilometers, an hour under water. In fact, they were so powerful they compelled NATO to design an entirely new class of torpedo just to have a hope of hitting the new submarines, known as the Alfa Class.

But this Cold War design is not without its drawbacks. A Norwegian environmental group and authority on nuclear waste in the Arctic, the Bellona Foundation, says the lead alloy coolant tended to freeze in emergencies. Then, the reactor became an inaccessible block of lead, steel and waste.

The group documented an accidental freezing of the core on one submarine, K-123, in the early 1980s after an emergency shutdown in the Kara Sea. The vessel limped back to base. The only way to repair it, though, was to cut out the reactor segment with a blowtorch, a job that took nine years.

The former Russian naval captain working for Bellona who revealed these and other details of reactor failures in a report in the 1990s was put on trial for revealing state secrets.