Progress is reported in the physics and engineering aspects of pile technology.

Four routine shutdowns were experienced during the month. A measurable amount of the excess reactivity held in the control rods at the first of the month has been lost in the decrease in the average accumulated exposure of all the metal in the pile. The vertical safety rod guides have been measured for vertical alignment by the Maintenance Dept. A definite pattern has been found in the misalignment of the guides. The horizontal rod thimbles were borrowed on January 2, 1947 to see if any leaks were present. No leaks were observed but No. 2 Rod and No. 8 Rod had heavy gouge marks along the longitudinal axes. Several thimbles contained white corrosion. During the month two new bismuth tubes were established, 2871-D and 2877-D. This now gives the desired pattern of ten bismuth tubes.