A means for decontaminating the primary system of recirculating type reactor is necessary to insure operation and maintenance. This recirculation system can be contaminated by fuel element rupture products and induced corrosion product activities.

Under the stimulus of electronic materials development - particularly thin-film studies - and the need for space environmental simulation chambers, a very rapid increase in the availability of industrial-sized vacuum components and systems operable in the ultrahigh vacuum range has taken place in the last three years. It is the purpose of this paper to explore the design considerations of ultrahigh vacuum systems for metallurgical applications.

Design calculations were made for a system consisting of a pump, one hundred feet of pipe, and a heat exchanger to remove 1 Mw of heat from various aqueous thorium oxide slurries. The rheological properties of the slurries were varied over a range of yield stresses from 0 to 1.5 lb/sq ft and of coefficients of rigidity from 1/2 to 2 centipoise. Two different cases were studied: a heat exchanger having fixed axial and radial delta T in which the tube length was allowed to vary and a heat exchanger having fixed tube length in which the axial and radial delta T were allowed to vary. It was shown that the pump power must be increased by a factor of 15 to 30 in order to maintain satisfactory operation of the heat exchanger as the slurry yield stress is increased form 0 to 1.5 lb/sq ft. However the pump power is essentially independent of heat exchanger tube diameter for any given slurry. The rated capacity of a slurry heat exchange is essentially independent of slurry yield stress and coefficient of rigidity, provided that the tube velocity can be suitably increased as the slurry yield stress in increased.

The following report examines a set of beryllium metal rods through pile radiation, taking measurements, and analyzing differences between irradiated and radiated rod samples.

Abstract: "The sensitivity to fast neutrons of a CP Meter ionization chamber of the type used for health physics beta and gamma survey measurements has been investigated."

The general program established at Argonne National Laboratory in connection with the Fast Power Breeder Reactor (PBR) includes performance of exponential experiments on assemblies having compositions which may exist in the reactor core. This report deals with that phase of the program known as the Fast Exponential Experiment which may be described very briefly as follows. An assembly of fissile (U-235) and fertile material (too small to be self-critical) intermixed with poisons (such as are encountered in the mechanical structure and coolant system of a self-sustaining reactor) is fed with neutrons from an auxiliary source. By measurements of the neutron flux within the assembly, important parameters can be calculated which are necessary to the proport design of an actual critical reactor of the same composition.

This document is the third in a series of progress report that records investigations of graphite bodies. Along with the report, two appendices are given to describe the different graphite bodies: "Synthetic Binders for Carbon and Graphite" and "High Temperature Physical Properties of Molded Graphites".

It was suggested to the writer by K.A. Eschbach that liquid magnesium might offer certain advantages as a reactor coolant. As a result of this suggestion, a preliminary investigation of the possibilities of this material was made. Definite advantages for a restricted class of applications were found, but a detailed evaluation would seem to require further basic experimental research on the heat transfer, corrosion and flux-mechanical properties of the substance.

Abstract: "A model is presented for radiation damage to ductile metals that accounts qualitatively for the effects of radiation on the electrical and mechanical properties. The model consists of an agglomeration of interstitially displaced atoms into stacking faults in the lattice."

Decontamination of stainless steel and carbon steel used in high temperature recirculation systems is currently being studied to obtain an effective and economical decontamination process for use in these systems. This report presents the preliminary investigation process which has demonstrated very effective decontamination and is low in cost.

Abstract. By means of the pulse radiolysis technique a short-lived transient species has been observed in irradiated de-aerated ethanol and methanol, exhibiting an optical absorption throughout the visible and near infra-red. This transient is suggested to be the solvated electron on the basis of the nature of the spectrum, the reactivity with hydrogen ion and with various organic electron acceptors, and the formation of mononegative ions of some of these acceptors. The absolute rate constants have been determined for the reactions of the solvated electron with hydrogen ion, oxygen and benzyl chloride in ethanol and methanol. The diphenylide ion was found to be short-lived in ethanol. The absolute rate constant for the first-order decay of the diphenylide ion has been determined.

This summary of the research progress meeting on June 10, 1948 discusses the following topics: (1) 184-inch cyclotron (J. Vale); (2) Slow neutrons in the shielding of the 184-inch cyclotron (W. Benson); and (3) Fission of thorium with alpha particles (A. Newton).

The purpose of this study was to develop equations for calculating fision product heating in the HRT-CP underflow pot from measured temperatures and to attempt to correlate the rat of solids accumulation in the underflow pot with fission heating and reactor power. Using fission heating data calculated from relating solids accumulation and heating have been tested. In one case an error of no greater than 26% was incurred in the calculation of the total weight of solids collected during chemical plant runs 17-4, 17-5, and 17-6. Further development work will be done on this correlation.

Abstract: "The solubility of oxygen in uranyl sulphate solutions and in water at 212, 275, and 325 F, and at oxygen partial pressures up to 1500 psia was investigated. The results are presented in tabular and graphic form. The solubility is proportional to the partial pressure of oxygen. The ratio of solubility in the uranyl sulphate solution to solubility in water at the same temperature and pressure is a function of the concentration of the salt in solution."

Report discussing tests of the fissionability and capture cross-section of produced U²³².