Report issued by the Oak Ridge National Laboratory discussing quarterly progress made by the Homogeneous Reactor Program. Descriptions of progress and studies conducted are presented. This report includes tables, illustrations, and photographs.

A simplified method was developed for calculating wall-scatter gamma radiation escaping through a shield opening. The method was applied to the HRT and the results showed that next to the line of sight contribution, scattering of the wall of the shield opening was the main contribution to the dose at the rear edge of the shield. Design charts were prepared that give the dose as a function of the gamma source location with the reactor cell.

The friction characteristics of a full-scale straight-tube model of the ART fuel-to-NaK heat exchanger were determined experimentally. The presence of the spacers resulted in a transition to semi-turbulent flow at a Reynolds modulus of 350. this semi-turbulent flow persisted up to a Reynolds modulus of 5,000. The circumferential spacers were found to contribute slightly more than the radial spacers to the pressure loss in the heat exchanger.

Nickel is more susceptible to mass transfer in a 100hr non-isothermal dynamic corrosion system than is Inconel when exposed to a NaCl-MgCl2-UCl3 (50.0-33.3-16.0 mole %) bath at a hot zone temperature 1800 F. No nickel mass transfer was observed in a 500-hr test at 1350 F, but Inconel showed some attack under these conditions. Inconel mass transfer was observed in both tests, being more severe at the higher temperature. On the bases of these preliminary tests, it appears that nickel is a more satisfactory container than Inconel for the chloride bath at temperatures in the region of 1350 F. The chromium is more susceptible to selective leaching from Inconel at 1800 F during a short 100-hr test (0.26% Cr in bath) than in a 500-hr test (<0.001% Cr in bath) at a lower temperature (1350 F ).