A continuous gamma-monitoring instrument capable of measuring the activity of the product of the Uranium Recovery plant has been developed and applied under process conditions. It has a detection limit of 15% and a normal range of up 1000% of the activity of natural uranium. Activity measurements made with this instrument have shown good correlation with laboratory determinations and are contributing to improved control of the solvent extraction process.

The approaches to the solution of the problem of removing or nullifying the effect of the hydrolysis of uranyl ion on acid titrations were: 1) use of a complexing agent and titration technique suitable for micro samples; 2) addition of a reagent that reacts with uranium to release 1 or 2 equivalents of acid per mole of uranium present (this permits correcting the titration value for the acid contributed by the uranium, or conversely permits an alkimetric titration of uranium); 3) separation of the uranium and acid with subsequent titration of the acid; and 4) direct titration of the sample with base. All these approaches yielded at least one method suitable for titrating acid in micro samples of uranium nitrate solutions.

This is the sixteenth quarterly report of the research and development activities of the Radiological Sciences Department, Hanford Atomic Products Operation, as before, includes some items charged to control but included for general interest. Such are identified as "not charged to research."

An experiment now in progress should give some accurate information about the thermal neutron absorption cross section of carbon 12. This report outlines and summarizes this experiment and analyzes it to determine the main sources of error and the probably error in the final result.

The gas commonly used in the chamber of the Simpson Proportional Alpha Counter (ASP) is the high grade, 99% pure methane. The cost of the gas has often raised the question of finding an adequate substitute and a number of substitutions have been attempted. Commercial methane has been substituted successfully for 99% pure methane and its use is recommended in ASP counters. Neither commercial nor technical methane caused any significant changes in instrument operation.

Many factors are responsible for the rapid growth of analytical chemistry during the past ten to fifteen years. One of the most important of these factors is the greatly increased significance to present day chemistry of many elements that in the recent past were principally chemical curiosities. Since the Atomic Energy program is concerned with many such elements, it is of interest to discuss the cause for this concern and the resulting effect on the field of analytical chemistry. A number of pertinent analytical research problems at Hanford will be cited as examples.

The purpose of the short duration corrosion test was to obtain preliminary data regarding the corrosion resistance of the spring steel wire in Purex process waste solutions and to measure any changes in the tensile properties of the wire resulting from this exposure.

Report from Hanford Laboratories concerning "the design and construction of the 100-N Reactor and heat dissipation plant complete with the necessary auxiliaries" (p. 2). Details of its construction and the plant's systems and instrumentation are described as well as economic considerations.

Report containing supplementary material for "Plutonium Recycle Critical Facility, Final Safeguards Analyses." This material expands upon previously supplied safety information and resolves previously unreviewed safety questions. Appendix begins on page A.1.

Gamma scintillation monitor Model 3 is designed to continuously monitor and record the gamma activity of a process solution.

Report of data for the distributions of elements 90 through 96 between molten salt solutions of their chlorides and molten aluminum (or alloy) at 725 Celsius.

Report regarding "the development of a process suitable for large-scale separation of highly purified promethium from the trivalent fission product rare earth mixture" (p. 3).

Report containing a method for beta-gamma counting of hands, shoes, and clothing via an instrument that employs scintillation detectors and solid-state circuits.

Report containing the dimensions, materials, and fabrication details for swage compacted, mixed oxide (UO2-PuO2), fuel elements for the Plutonium Recycle Test Reactor (MARK I-M).

Report describing the dimensions, materials, and fabrication of vibrationally compacted, mixed oxide (UO2-PuO2) fuel elements for the Plutonium Recycle Test Reactor (MARK I-L). Appendix begins on page 38.

Report containing experimental data testing the hypothesis that aluminum reactor tubes were "the site of most radioisotope production in the deionized water cooled system" and that zirconium tubes provided "only nominal participation" (p. 2).

Report regarding an experimental program by Hanford Laboratories' in order "to determine the long-term irradiation behavior of the graphite used as the moderator in N-Reactor. The primary objectives of the program are to provide data for predictions of the distortion of the N-Reactor moderator and the stress conditions which could arise from the difference in the the rate and extent of contraction between the transverse and parallel orientations of the graphite bars" (p. 1).