In continuing studies to characterize and identify fission product activities formed in the piles and appearing in plant dissolver solutions work was done to determine whether or not long-lived isotopes of certain elements were present. Two of the elements in this category were iodine and arsenic. The iodine isotope of particular interest was I{sup 129}. Its tellurium parent has been identified but no daughter activity attributable to iodine has been observed. The arsenic activities of interest were the long-lived isotopes (16 days and 90 days) which have been produced artificially by several different nuclear reactions.

The B Pile operated 25 MW below rated power level without interruption during the week. The D Pile was shut down on January 29. During the shutdown 103 tubes were discharged. The shut down lasted for 15 hours. During operation after the shut down power was reduced to meet graphite temperature restrictions. The F Pile was run steadily throughout the week at 25 MW below rated level. Iron content in the process water averaged 0.015, 0.011 and 0.010 ppm at B, D, and F Areas, respectively. Examination of the slugs discharged from four corrosion tubes at F has been completed. A summary of conditions found in the vertical and horizontal aluminium thimbles at D and F during a recent inspection are given. Results are given on the graphite expansion problem.

This report discusses the Production Test 105-2-P (Supplement A) -- Activity of Pile Discharge Water. Previous studies of pile discharge water have shown that one of two processes is responsible for the large but variable amount of Mn{sup 56} activity present in the water. One process is the production of Mn{sup 56} by the reaction Mn{sup 55} on manganese impurity in the water. The amount of such impurity has been shown to be too small to produce the observed amount of Mn{sup 56} unless the mean irradiation time is increased by a large factor due to temporary sticking of manganese on the surfaces in the tubes. The other process is the production by the reaction Fe{sup 56} on iron in the film. The present production test was designed to determine which of these processes is responsible for the troublesome Mn{sup 56} activity and to what extent the activity is increased due to sticking of manganese or iron in the tubes. 4 figs.