The crack in a stainless steel pipe that leaked radioactive cooling water at the No. 2 reactor of the Tsuruga nuclear power station in Fukui Prefecture, Japan may have been caused by torsional forces, it was learned Wednesday. The power station is operated by Japan Atomic Power Co. (Genden). The crack was probably created as the pipe was twisted, according to officials investigating the incident. When a pipe is welded to other materials without following the construction design, it may be strained, resulting in reduced strength.