The problem of controlling the surface temperatures of core vessels in two-region aqueous homogeneous reactors has been examined by analyzing several possible systems for cooling the wall: (1) direction of the inlet core fluid along the wall at a high velocity; (2) passage of heavy water through the wall of a double-wall core vessel; and (3) flow of cool blanket slurry past the wall.

Measurements of flow rate through the fuel high-pressure system sampler indicate that the average flow rates is about 0.29 gpm (145 lb/hr) plus or minus 50%, which affords an adequate purge of from 12 to 36 volumes through the sample line if the full fifteen minutes of purging is allowed before isolating the sample. The fuel sample cooler was fund to have adequate capacity to reduce the temperature of the fuel solution form about 275 to 70 C, using pre-heated cooling water at 70 C. Uncertainties in temperature measurements make it impossible to estimate an observed over-all heat transfer coefficient.