It is desirable that a reactor exhibit a self-regulating effect. If this were not true any disturbance to the reactor would result in a continual increase in the magnitude of the disturbance and the reactor would be unstable. In this investigation the reactor is considered to have two reactivity feed-backs: metal temperature and water temperature reactivity effects. These two variables through a metal temperature coefficient and water temperature coefficient determine not only the reactor stability but also determine many operational characteristics.

"The PRTR Pressured Gas-Cooled Loop Facility, or Gas Loop, is an experimental facility to be installed in the Plutonium Recycle Test Reactor for use in studies contributing to advancement of the technology of gas-cooled reactors. The facility will provide an in-reactor loop for studying phenomena occurring under conditions likely to exist in gas-cooled reactors.

Various methods and procedures for preparing uranium dioxide bodies for metallographic examination and study have been utilized by various investigators. Unfortunately, these methods are not in general satisfactory for use on irradiated uranium dioxide. Since radiation damage studies on irradiated uranium dioxide require use of electron microscopy, and reveal structure by virtue of surface relief. This report covers an investigation of etching methods compatible with radiometallurgy and electron microscopy requirements.

An inventory of the contaminated materials accumulated since the initiation of this project in June 1958, revealed a larger variety and quantity of materials that could be burned, than was specified for the initial scope. Therefore, it is desirable to revise the scope to permit handling the majority of these materials with the initially installed equipment.

It is being considered that the in-reactor portion of the test section of the PRTR Gas-Cooled Loop Facility consist, in part, of two concentric Inconel-X tubes. The outer tube is the main stress member, with 3.5 O.D. and a wall thickness of 0.065. The inner tube is 3.0 O.D. and has a wall thickness of 0.030. The inner tube provides an annular gas space to serve as thermal insulation.

The utilization of gloves wherein heavy element additives have been included is a significant means of reducing exposure to hands and, consequently, increasing allowable working time in operations which require direct contact with low energy isotopes - such as plutonium. The number of such gloves available has been limited considerably by the feasibility of fabrication and the practicality of application. The following study was made on two basic gloves - the first, a heavy zinc-neoprene coated glove and the second, a lead loaded neoprene glove available in two thicknesses. Included in the study was a standard 30 gauge neoprene glove.