The following quarterly report covers the period from May 16 to August 15, 1962. This report summarizes the progress being made on the study of the saturation and recovery of the hole which can be burned into the magnetic resonance band associated with the F-center in KCl.

Abstract. Refractory metals and their alloys are good container materials for alkali metal coolants. Thermodynamics of interaction with contaminants have been correlated with experimental test and show the need for high purity materials. Structural metal solubility data to 1600F can be used to correlate and predict engineering systems.

Abstract: In the March-April 1962 shutdown of SM-1 Core II, the SM-28 element will be re-inserted in SM-1 Core II and an SM-1 Core I element will be removed. An SM-1 Core II europium absorber will be replaced by a Ag-Cd-In absorber, and surveillance specimens will be inserted above the core support structure. Analysis of these changes concludes that re-insertion of the SM-2B stationary element and insertion of surveillance specimens do not affect hazards potential previously defined for SM-1. Replacement of the europium absorber by the Ag-Cd-In absorber will have negligible effect on reactivity control worth of the rod. The absorber meat section is encapsulated to prevent exposure of silver alloy to the primary coolant; postulated release of silver due to a cladding defect, after 2 years irradiation in SM-1, would not cause a hazard such as to restrict access to the vapor container. Possibility of steam formation in the air gap between the absorber core and cladding, causing a cladding failure, is remote. Deformation of the absorber section sufficient to cause the rod to stick, would not impair the ability of the other rods to shut down the reactor safely.

The analyzer can be operated either internally or externally. The 10 ma germanium discriminator is quiescently biased to 8.5 ma in its low-voltage state. An input signal current of 3.5 ma or more triggers it to its high voltage state. This triggers the oscillator. The oscillator signal is buffered and mixed in the bridge modulator with the reference radiofrequency signal from the cyclotron. The low-frequency beat note from the bridge modulator is squared up and passed to the beat zero univibrator which generates 0.7 mu sec signals each time the beat note passes through zero from positive to negative. The trailing edge of the beat zero univibrator is employed to terminate the time-of-flight measurement and to control the servo measurement. Drawings are included. (M.C.G.)

The power supplies designed and constructed to power high intensity flash tubes used in bubble chamber experiments are briefly described and are accompanied by a schematic diagram of the layout. (D.C.W.)

The favorable combination of physical properties such as heat capacity, viscosity, electrical resistivity, thermal conductivity and high temperature liquid range make alkali metals, in principle, among the best heat transfer fluids available for use in nuclear reactor and other esoteric powerplant systems. Unfortunately, many of these properties are not known with sufficient certainty in the high temperature region to permit optimization of design criteria for developing maximum efficiency coolant systems. For this reason, Pratt & Whitney Aircraft-CANEL, have been concerned for some time in extending the physical properties data of alkali liquid metals in the high temperature region. A supplemental program is being initiated to study some of the properties of alkali metals in the gas phase. This information is required for designing systems where the alkali vapor is the working fluid. In addition, programs are under way to study the solubility of noble gases in alkali liquid metals and wetting characteristics of these liquid metals with structural materials.

The Program fuel element has continued under irradiation in the Vallecitos Boiling Water Reactor, thermal energy group transfer cross sections for UO2 have been computed, and data have been reduced from the resonance wire activations performed last quarter. Future plans are included.

This is a report of work completed during the period January 1, 1962, to March 31, 1962. Work was done on fuel irradiation, activation studies and UO2 scattering experiment

The work described in this report represents progress toward an agreement signed by the United States and the European Atomic Energy Community which provides a basis for cooperation in programs for the advancement of peaceful applications of atomic energy.

In order to perform the various experiments with a bubble chamber, a high intensity flash tube is used. This report briefly describes the power supplies designed and constructed to power these lamps.