From a windswept corner of Hokkaido, Japan's northernmost island, Japan Steel Works Ltd. controls the fate of the global nuclear-energy renaissance.

There stands the only plant in the world, a survivor of Allied bombing in World War II, capable of producing the central part of a nuclear reactor's containment vessel in a single piece, reducing the risk of a radiation leak.

Utilities that won't need the equipment for years are making $100 million down payments now on components Japan Steel makes from 600-ton ingots. Each year the Tokyo-based company can turn out just four of the steel forgings that contain the radioactivity in a nuclear reactor. Even after it doubles capacity in the next two years, there won't be enough production to meet building plans.