Nuclear power station construction. Workers using a crane to lower the cover of a nuclear reactor to the ground. The cover is being prepared for a heat treatment process, one of the final stages in the process of welding metal parts together to produce a single structure. This heat treatment process will help improve the structural integrity, vital for a nuclear power plant to avoid catastrophic structural failures that would allow radioactivity to contaminate the environment. The holes in the cover are where control rods will be lowered into and withdrawn from the reactor. Photographed at the Framatome ANP facility at Chalon/Saint Marcel, France.