Fort St. Vrain high temperature

Fig. 18. General reactor arrangement of Fort St. Vrain high-temperature gas-cooled reactor. (GA Technologies)...

The Fort St. Vrain High Temperature Gas-cooled (HTGR) power reactor, operated by Public Service Company of Colorado is located approximately iJO miles north of Denver at the confluence of the South Platte river and St. Vrain creek. It is the only gas-cooled power reactor in the country and while it has had operating difficulties, the nuclear aspects of the design have great promise for the following reasons ... 

Fig. 8.5. Coolant circulation system for Fort St. Vrain high-temperature gas-cooled reactor (courtesy of General Atomic Company and Nuclear Engineering International). A, Fueling penetrations B, control rods C, orifice valves D, reflector E, reactor core F, core floor G, hot helium H, cold helium J, pressurized concrete reactor vessel K, steam generator L, helium circulator.

In the United States, General Atomics was the main promoter of the high-temperature reactor (HTR). The company built one HTR, at Fort St. Vrain, Colorado. It had several other orders, but the program was halted in the mid 1970s. In Germany, the Nuclear Research Center at Jiilich was the focal point for development of the so-called pebble-bed HTR for both electricity production and coal gasification. A 500-megawatt reactor was expected to go on line by 1990 but never did. 

Several development programmes led to demonstration of high temperature gas cooled reactor features, in particular the coated fuel concept. This has been based on the Dragon project in the UK, Peach-bottom Nol and Fort St. Vrain in the US and the THTR in the Federal Republic of Germany. Currently, the HTTR, of the prismatic type, in Japan will be the first to be used for a process heat application with an outlet temperature of 850°C or above. 

A second type of GCR used the pebble bed concept with helium as a coolant. The uranium and thorium fuel was imbedded in graphite spheres and cooled with helium. The high temperature thorium fueled reactor (THTR) operated between 1985 and 1989 in Germany. It produced 760 MWt and 307 MWe. The thorium in the fuel pellets was used to breed Two GCR power plants have been operated in the United States. The first was Peach Bottom Unit 1, which provided 40 MWe. The second was the Fort St. Vrain reactor, which provided 330 MWe. 

Spherical fuel elements used in the MARS concept have undergone various technological and reactor tests. In particular, they were validated for use in the VG-400 and VGM high temperature gas cooled reactors that were under development in the Russian Federation previously, as well as for the HTR MODUL reactor in Germany. In addition to this, spherical fuel elements based on coated particles were successfully operated in the reactors of the Peach Bottom and Fort St. Vrain NPPs in the USA and in the AVR and the THTR-300 reactors in Germany. 

In another power generation example, approximately one million dollars worth of liquid nitrogen per year was used to purify the helium coolant used in the High Temperature Gas Cooled fission reactor at the Fort St. Vrain nuclear power plant in Colorado. 

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