HTGR Knowledge Base

Conference Article: Operational experience at Fort St. Vrain

Bramblett, G.C.; Fisher, C.R.; Swart, F.E. (General Atomic Co., San Diego, CA (USA))

Abstract

The Fort St. Vrain (FSV) station, a 330-MW(e) single reheat steam cycle powered by a high-temperature gas-cooled reactor (HTGR), is the first HTGR to enter commercial operation. Designed and built by General Atomic Company (GA), the plant is owned and operated by Public Service Company of Colorado (PSC). Many unique design features have been incorporated into this reactor system, including high-pressure helium as the primary system coolant, a graphite-moderated prismatic block core design, fission-product-containing carbide coatings on both fissile and fertile fuel particles, steam-driven helium circulators turning on water bearings, and once-through steam generators. All of these systems are contained in a prestressed concrete reactor vessel (PCRV). Extensive testing has been conducted during the rise to power following first criticality early in 1974 to verify system design performance. During this period, the plant has operated at power levels up to 70% and produced over one billion kilowatt hours of electricity. In 1979, the first refueling was conducted in conjunction with an extensive in-core inspection, the addition of in-core instrumentation, and a planned removal of a circulator for inspection. Later in the year, a scheduled shutdown was undertaken for surveillance tests, insertion of core region constraint devices (RCDs), and other maintenance. Fort St. Vrain has encountered problems of the type that would be expected in a first-of-a-kind system. The plant is currently restricted to 70% of design power by the Nuclear Regulatory Commission (NRC) pending resolution of the core region gas outlet temperature fluctuation problem. Even so, the basic performance of the HTGR concept and all of the unique design features have been successfully demonstrated. The system has been characterized by low personnel radiation exposures, operational flexibility, and long time afforded for status evaluation and response.

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key words: performance testing; reactor commissioning; reactor components; reactor licensing; reactor operation; reactor safety; reactor shutdown; reactor start-up; vrain reactor; enriched uranium reactors; gas cooled reactors; graphite moderated reactors; htgr type reactors; licensing; operation; power reactors
Reference:
International Atomic Energy Agency, Vienna (Austria). International Working Group on Gas-Cooled Reactors. Specialists meeting on gas-cooled reactor safety and licensing aspects, Lausanne, Switzerland, 1-3 September 1980. Summary report. Jan 1981
International Atomic Energy Agency, Vienna (Austria). International Working Group on High-Temperature Reactors.
IWGGCR--1, pp:6-10