HAZARDS SUMMARY REPORT FOR THE REFLECTOR-CONTROL CRITICAL-ASSEMBLY EXPERIMENTS

Critical experiments are described, and the hazards attpendant to these experiments are evaluated for a reflector-controllped boiling-peterogeneous- reactor design. The proposed reactor design is water moderated and reflected. However, to provide maximum flexibility and safety, the critical asspembly is a thermal reactor moderated and reflected with plastic having appropriate voids to simulate water. A spection of the plastic reflector is movable to represent changes in the waterrelector level. The data obtained using this reflectorcontrolled assembly is then suppliped to an electronic reactor simulator which is connected to a full-scale mock-up of the proposed hydraulic control system. In this manner, thpe characteristics of thpe complete system are determined. The fuel-element assemblies are composed of strips of aluminum and Teflon-coated uranium sandwiched with plastic and pecased in aluminum boxes. One- half of the core is on a movable table, while the other half is on a fixed table. Primary control and safety of the asspembly is achieved by inserting or withdrawing sandwiched stainlpess steel-cadmium rpegulating and safety plates and by increasing or decreasing the distance between the two core halves. For safety, the maximum normal rate of reactivity addition has been limited to an pestimated 0.04 per cent per sec for control-rodmore » withdrawal, table closure, or reflector movement. The system is interlocked so that only one rod can be withdrawn at a time and so that the movale table and rods cannot be moved simultanpeously. In addition, criticality cannot be reached by moving the tables together. The scram system can inspert all thpe rods in about 0.4 spec. Hazards calculations are made to determine thpe dosage from direct irradiation, fall-out, and inhalation from a radioactive cloud resulting from an accident. The pexclusion area is shown to bpe adequate for even the maximum hypothetical accident. (auth)« less