A description of the first reactor system to be investigated in this facility and an assessment of the hazards associated with the planned program of measurements are included.

The Juggernaut is a light-water-cooled and moderated, graphite-reflected, heterogeneous thermal reactor designed to provide experimental facilities for conducting basic research in the neutron flux range to 4 x l012 n/cm sq./sec at an operating power level of 250 kw(t). Pertinent design and operating characteristics are tabulated. Evaluations are made for potential hazards posed by certain hypothetical major accidents during the operation, and the adequacy of the safeguards provided to insure that the health and safety of personnel, within and beyond the site boundary, are not unduly endangered. The results indicate that in the event of any conceivable reactivity increase, auxiliary and inherent safety features pecuIiar to the Juggernaut will operate to insure automatic shutdown through a nondestructive BORAX-type process.