Fort St. Vrain Generating Station - Historical Overview

Historical Overview

Fort Saint Vrain Generating Station was built as Colorado's first and only nuclear power plant and operated as such from 1977 until 1989. It was one of two high temperature gas cooled (HTGR) power reactors in the United States. The primary coolant was helium which transferred heat to a water based secondary coolant system to drive steam generators. The reactor fuel was a combination of fissile uranium and fertile thorium microspheres dispersed within a prismatic graphite matrix. The reactor had an electrical power output of 330MW (330 MWe), generated from a thermal power 842 MW (842 MWth).

The Fort St. Vrain gas-cooled nuclear power plant was proposed in March 1965 and the application was filed with the Atomic Energy Commission in October 1966. Construction began in 1968. The building was unique for U.S. commercial reactors, as it had a rectangular shape instead of the usual cylindrical domed buildings housing other reactor designs. The HTGR design was considered safer than typical boiling water designs of the time, so the typical steel-reinforced, pre-stressed concrete containment dome structure was omitted in favor of a steel-frame containment structure while the reactor core was partially contained within a prestressed concrete reactor pressure vessel (PCRV). The construction cost reached $200 million, or approximately $0.60/installed watt. Initial testing began in 1972 and the first commercial power was distributed in December 1976.

The plant was technically successful, especially towards the very end of its operating life, but was a commercial disappointment to its owner. Being one of the first commercial HTGR designs, the plant was a proof-of-concept for several advanced technologies, and correspondingly raised a number of early adopter problems that required expensive corrections.