Design and Hazards Report for the Argonne Fast Source Reactor (AFSR)

Abstract

The Argonne Fast Source Reactor is designed to operate at low power (nominally 1000 watts) to supply neutron fluxes, both fast and thermal, for laboratory experiments. It is built around a cylindrical core (with vertical axis) of solid, highly enriched uranium approximately 4 1/2 in. in diam. by 4/4 in. high. The blanket is of solid depleted uranium with a minimum thickness of eight in.; its outer form is cylindrical, 20 5/8 in. in diam. by 20 5/8 in. high. The reactor, contained in a shield of high density concrete of minimum thickness 4 1/2 ft, is freestanding on the floor of the reactor building. A graphite thermal column 4 x 4 x 6 ft is provided. All control and safety mechanisms are located in a pit beneath the reactor. The hazards associated with operation of the reactor have been analyzed. A number of potentially dangerous circumstances were studied to determine the probable severity of the resultant excursions. As an upper limit, a detailed study was made of the extreme case in which the reactor, overloaded by five kilograms of U/sup 235/, goes critical at the air cylinder speed of 18 in./min. It is estimated that the excursion would amount to 3.6 x 10/sup 17/ fissions. This is expected to destroy the core and eject all core material into the pit where it burns, greatly adding to the total energy of the excursion. No rupture of reactor shield or building is expected. The reactor pit and reactor building will be heavily contaminated and some radioactive material will escape from the building. It is nearly certain that the maximum radiation dose to personnel outside the reactor building will not exceed 15 roentgens. (auth)