Abstract: "The critical mass both of an untamped and water-tamped sphere with parabolic radial variation of the intrinsic buckling is calculated by a perturbation method. The result is applied to finding the minimum critical mass of plutonium in water suspension with infinite water temper; the calculations show that the minimum critical mass at constant concentration may be reduced by an amount of the order of 7.6% when the concentration of plutonium is permitted to vary throughout the suspension."

Introduction: "Evidence of masonite deterioration in test hole plugs was interpreted to mean that a previous estimate of the minimum lifetime of the masonite in a Hanford biological shield might be somewhat optimistic. The importance of understanding the effects of radiations on masonite for both present and future pile shields dictated that masonite be sampled from an operating pile shield and studied. The results and techniques are discussed in the following sections of this report."

As a result of the interest in fission products for use as heat sources and/or radiation sources, in early 1960. Hanford was authorized to supply a semi-refined cerium-144 rare earth product to Oak Ridge National Laboratories. Facilities were installed for collecting this product and a cask war designed for shipping this product as a stabilized, dry powder. Since that time, numerous improvements have been made in the design of the HAPO I cask as described in Revision O of this document. In addition, the development of strontium-90 as a major product requires increased flexibility in the utilization of these casks.

The Fermi age of thermal neutrons in a lattice containing both water and graphite in some sort of weighted average of the age in water and in graphite independently, with correction for volumes of non-moderating elements or voids. The correct weighting function has been in question during design calculations for the NPR. This paper presents a very simple and direct approach to the problem, resulting in a weighting equation which seems to be theoretically sound. Unfortunately, simple theories cannot be guaranteed to give good results in complicated systems; nevertheless, it appears that the weighting dunction derived here is to be preferred over methods involving empirical relationships which are of doubtful validity in the NPR geometry.

The discharge of cooling water from the Hanford reactors introduce radioactive contaminants to the Columbia River. These materials may subsequently bring about exposure to human populations either through the direct use of the water for sanitary purposes or transfers of the radioisotopes into the food chains. It is therefore desirable to keep to a minimum the amounts of radioisotopes released to the river.

Calcination of liquid radioactive wastes, the process of converting metal nitrates and sulfates to oxides by heat, is under development at Hanford as a means of reducing these liquids to a dry powder or solid which can be stored safely. Radiant-heat spray calcination, one of the methods under study, was first investigated at the Oak Ridge K-25 Plant (1) as a possible method of calcining uranyl nitrate to uranium trioxide. The process has also been under extensive development at the Pulp and Paper Research Institute of Canada (2) and is designated by them as the Atomized Suspension Technique.

Pressurized water nuclear reactors may be designed based upon either of two concepts: (1) pressure vessel, wherein the entire core is placed in a large, high strength fuel channels within a low pressure container. The Plutonium Recycle Test Reactor is a pressure tube type reactor. Selection of this basic type of pressurized water reactor depended to an appreciable extent upon the availability of suitable pressure tubing.

A prototype instrument has been designed and built which demonstrates an ultrasonic pulse echo technique of measuring metal thickness in the range .010 to .080 inches. Extension of the range of measurement on the thick side appears straightforward, however, transducer frequency response considerations may limit the extension of the method for very thin sections. The instrument is based upon the principle that sections, when driven by pulses of vibratory energy, resonate at frequencies dependent upon the thickness of the section.