This report records two samples of Xe-135 that have been isolated with activities sufficient for the measurement of the cross section of Xe by the velocity spectrometer technique.

This report follows a study that was aimed at the collection of experimental data needed to estimate the maximum safe temperatures and dispersed UO2 contents for MoSi2--UO2 fuel elements exposed to air.

In a manner somewhat analogue to that employed by R. Margulies in his memo (BNL Log No. C-2985) on fast source corrections in sigma piles, corrections to be applied to the data obtained on the laid-up graphite in the BNL reactor have been calculated. The correction was computed for a Ra-Be source using the data of Seren and using a standard graphite density for the BNL pile of 1.69. Values of the correction for different experimental sets of data were computed for each of three different diffusion lengths measured parallel to the channels. A correction for diffusion lengths perpendicular to the channels was also determined.

From Present Programs: "There has been a gradual expansion of the Sr^90 food analysis program to include vegetable foods and finally entire diets. In some cases the analyses have also been extended to other nuclides but these data are so limited that they will not be emphasized in this report. It is expected that considerable data on Ra^226 and other naturally occurring radionuclides will be generated in coming year."

A series of experiments has been conducted during the past eighteen months with the objective of degerming the accuracy with which precision parts can be duplicated using a castable tooling plastic as a test shape to be reproduced. A precision ground ground 1/4 inch-thick, 90° steel sector of 4'' radius was chosen. The plastics used in the experiments were the die surfacer mixes of the Devon Cooperation and Ren Plastics, Inc. These were selected for use in the test because of their dimensional stability and wear resistance. Ordinary paste type floor wax was used as a mold release. The first series of tests were primarily intended to gain facility in handling this material. After achieving some familiarity with the use of these castable plastics a technique was devised which seemed to hold promise of precision duplication.