The purpose of this memorandum is to transmit revisions to the goal exposure plans of reference (1). The plans, herein, supersede the previous recommendations. Similar to the plans of reference (1), the exposures calculated from these plans are designed to maximize plant return on the basis that the only restraint on metal usage is that imposed by the economics of the plutonium production process and associated uranium cycle, as described and defined in references (2) and (3). When metal throughput is limited by ex-reactor physical capabilities to a level lower than the unrestrained requirements, exposures higher than those recommended in this document would be indicated, as explained in reference (4). In essence then, these plans represent minimum economical exposures for current production fuel types, on the basis of attempting to maximize plant returns. The adjustments recommended herein, stem solely from revised estimates of the metal performance level indices (C{sub R} values) of the various metal types.

An all-transistor system has been developed to be used in measuring the reactivity of the reactor in the Sandia Engineering Reactor Facility. In operation, the system triggers a pulsed neutron source (PNS) in the reactor and counts the resulting neutron flux, thus giving a measure of the time constant of the reactor. The counting is done in eleven time-sequenced counting channels. The reactor time constant is a measure of the reactor reactivity.

The purpose of this document is to describe the design and construction of a full-scale, electrically-heated model of a 19-rod PRTR fuel element for use in heat transfer experiments.