In an Oct. 15 letter, the U.S. Nuclear Regulatory Commission has informed Westinghouse Electric Co. that it will have to modify design of the shield building for its proposed AP1000 nuclear reactor before the agency proceeds on its certification review. The NRC letter says Westinghouse must also retest any design changes to the shield building, the structure that protects the reactor’s primary containment from weather and other impacts, to make sure the structure meets safety requirements. NRC says it won’t know if and how the required redesign could impact the AP1000 review schedule until it meets with Westinghouse. In a
Arch dams, classically curved monoliths situated in narrow valleys, are not as common as other types of dams, such as embankment dams and gravity dams. ENR takes a look at some of the biggest arch dams in the world, both completed and under construction.