This report gives weekly progress in pile technology. An exposure of over 96 hours was made with the slug radiographing apparatus from May 22 to May 26. The three pieces subjected to the exposure included one of the special pieces designed for installation of a thermocouple. The thermocouple well in the special pieces showed up satisfactorily and for the first time it was possible to detect spots which could be due to small voids. Crushing and breaking strength measurements made on graphite pieces after an exposure of 1,465 MD/AT in a test hole show no significant changes in these properties as compared with pieces having an exposure of 1,215 MD/AT. Thermal and electrical conductivity measurements have been made on unexposed samples of coke base and lampblack base graphite recently supplied by National Carbon Co. A calculation has been made of the contribution of Sm{sup 149} to the graphite temperature coefficient of reactivity. Corrosion tube 2480-P was discharged. The tube contained 2 unblistered, 24 slightly blistered, 9 moderately blistered, and no extensively blistered pieces. The rear Van Stone flanges of twenty-nine tubes distributed in the B Pile were inspected. Qualitative results showed conclusively that the worst attack occurs in the fringe …