Japan Steel Works

Also known as JSW

The Japan Steel Works (JSW) is a Japanese steel manufacturer founded in Muroran, Hokkaido, in 1907. Its factory on Hokkaido forges very large steel components, and Wikipedia describes it as one of only five manufacturers worldwide of the largest single-piece forgings for reactor pressure vessels, the steel vessel that holds a reactor core. Making the vessel sections in one piece avoids welds, which are potential weak points.