Measurements have been at the Pajarito remote control laboratory to determine the effect of change of shape on system reactivity for oralloy cylinders. Systems tested include cylindrical configurations with various height-to-diameter ratios ranging from slabs to rods. Each system reactivity is referred to that of a sphere in the same tamper. Reactivity tests were made on bare (untamped) Oy configurations, as well as on systems In tuballoy tampers 1.12,1.87,and 8.0 thick. The amount of reactivity change associated with a particular cylinder height-to-diameter ratio is feud to be a function of tamper thickness, and is greatest for very thin tampers.

This investigation was begun as a result of a mass spectrometric measurement of two samples of tritium which had been stored for several months in Pyrex glass bulbs using stopcocks. The first of these was originally supposed to be of extremely high isotopic and chemical purity. What was observed at this time was 1.45 H had accumulated, and that tritiated methane, CT4, was also present to the extent of 0.18%. A consistent attempt had been made in this sample to protect the gas from contact with the grease by covering the stopcock with mercury. the second sample was a composite of T2 samples of various degrees of enrichment with an isotopic analysis of 92% T. No protection had been attempted during its storage, and 0.86% CT4 to be present.