The Department of Computer Science of the University of Illinois has constructed and put into service ILLIAC II, a large-scale digital computer. ILLIAC II is used both in computer systems research and in general University service.

In the past, in-reactor testing of materials was restricted to gross sorting. It has consequently been the practice to report the exposure of a sample by relating the exposure to the heat energy released by the nearby uranium fuel, usually reported in the familiar MWD/AT (megawatt day per adjacent ton) unit. The measurement is not complicated by the kind of material, geometry factors of the samples, or loading conditions of the reactor. However, these very facts limit the usefulness of the measurement. Current materials programs require refinement beyond the gross sorting phase, and many tests are now aimed at studying the effects of trace amounts of elements upon the structural properties of materials. This type of test requires a more quantitative determination of exposure than the MWD/AT estimate can provide. Therefore, a better definition of the neutron flux in the Hanford Irradiation Facilities is required in order to facilitate analyses of irradiation experiments and to accurately predict irradiation conditions for proposed experiments. The objective of this program is to define the neutron flux at various positions of a representative number of the irradiation facilities. To date, data has been collected, reduced, and partially analyzed for two side-to-side test facilities. This …

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