Fort St. Vrain Generating Station - Unique Features of The Design

Unique Features of The Design

The Fort St. Vrain HTGR was substantially more efficient than modern light water reactors, reaching a thermal efficiency of 39-40%, excellent for a steam-cycle power plant. Operation of the HTGR design could be readily attenuated to follow the electrical power demand load, rather than be required to generate its nameplate power all the time. The reactor was also comparatively fuel efficient, with a maximum burnup of 90,000 MW days thermal compared to Light Water Reactors with burnups of 10,000 - 40,000 MW days thermal). The basis of this improved run time is that the core design "fertilizes" the thorium pellets within the fuel with neutrons, and then burns the bred fissiles through normal neutronic processes without requiring removal from the core. Like all HTGRs, the Fort St. Vrain precluded the possibility of major core damage or radioactive releases in such a quantity that could seriously threaten public safety, and the Nuclear Regulatory Commission allowed operation with much smaller safety zones compared to LWR designs. It was also notable that plant personnel received negligible exposure to ionizing flux during the course of operations. Further, the PCRV reflected an innovative RPV that had the potential to be substantially less costly than the metallic RPVs then in service, which were made of expensive nickel-manganese superalloys (e.g. Inconel, Hastelloy, and Monel) in the case of PWRs or surgical grade stainless steel 316L in the case of BWRs. The fuel, by omitting Zircalloy sheathing (allowed due to the inert, non-aqueous core) was made far less expensive.

Fort St. Vrain worked, and once debugged, it worked well for a first of a kind facility, demonstrating a promising new concept for the future. However, the problems that occurred leading to its debugging led to its early demise.