PRELIMINARY DESIGN OF A BASIC RADIATION EFFECTS REACTOR (BRER)

The Basic Radiation Effects Reactor (BRER) is a small fast core surrounded by a segmented radial reflector. The NaK-cooled fast core operates at a thermal power of 1 Mw, with all the reactor heat being rejected to the atmosphere through a secondary heat exchange system. The secondary heat exchange system is another NaK loop which dissipates heat to the atmosphere by means of an air-blast cooler. The reactor core is composed of small-diameter rods of uranium--zirconium alloy, arranged in a close-packed triangular pattern. The maximum core loading is approxi-mately 60 kg of U/sup 235/. Reactor control is effected by moving control rods in the reflector region immediately adjacent to the core. Reactor instrumentation and fuel handling are similar to other heterogeneous reactor systems. Relatively large volumes for experiments are available in the large radial reflector surrounding the core. The physics of the BRER system was investigated, using a 15-group set of cross sections, for a series of reflector materials. The materials studied were lead, aluminum, iron, zirconium, depleted uranium, and natural aranium. Based on the criterion of producing two widely spaced and relatively sharply peaked neutron spectra, these preliminary calculations indicate that a major portion of the reflector would be lead, with an aluminum region starting at some intermediate point and extending to the outer edge of the reflector. (auth