Development of a steam separator the Pathfinder Reactor is reported. A full-scale separator model was developed through the combination of scale-model testing and the application of principles associated with the existing theory of centrifugal separation. This model was put through full-scale air-water tests which led to modifications and a final design which meets Pathfinder requirements. Design data are included for the reactor and the steam separator. (J.R.D.)

The water-moderated core used for destructive experiments is mounted in the Spent I open-type reactor vessel, which has no provision for pressurization or forced coolant flow. The core is an array of highly enriched aluminum clad, plate-type fuel assemblies, using four bladetype, gang-operated control rods. Reactor transients are initiated at ambient temperature by step-insentions of reactivity, using a control rod which can be quickly ejected from the core. Following an initial series of static measurements to determine the basic- reactor properties of the test core, a series of nondestructive, self-limiting power excursion tests was performed, which covered a reactor period range down to the point where minor fuel plate damage first occurred -approximately for a 10- msec period test. These tests provided power, temperature, and pressure data. Additional kinetic teste in the period region between 10 and 5 msec were completed to explore the region of limited core damage. Fuel plate damage results included plate distortion, cladding cracking, and fuel melting. These exploratory tests were valuable in revealing unexpected changes in the dependence of pressure, temperature, burst energy, and burst shape parameters on reactor period, although the dependence of peak power on reactor period was not significantly changed. An evaluation …

A study was made to determine whether secondary iso tope effects also occur in molecular structure. Electron diffraction studies were carried out on ethane and deuteroethane. In C/sub 2/H/sub 6/ the mean C-C and C-H bond lengths found agreed very closely with values determined for other paraffin hydrocarbons, and the C--H bond showed a normal primary isotope effect (~ 0.005 A) similar to that found in methane when H is replaced by O. The output of the leastsquares analysis suggested that the mean C-- C bond length in C/sub 2/D/sub 6/ is shorter than in C/sub 2/H/sub 6/ and by about 0.004 A. Th e decrease seemed to be real for the apparent uncertainty was not much greater than 0.001 A. (M.C.G.)

This report details benefits of an increase in the flow of water from the lower depths of Grand Coulee Reservoir which used to lower river temperatures at HAPO. A net average daily reduction of over 1.7{degree}C resulted at HAPO. The peak reduction was over 4.0{degree}C. The net production gain from temperature change was 13,350 MWD. The cost of control was: Grand Coulee Charges (Estimated) $37,000, and other 3,500, for a total of $40,500.

This is the monthly report for the Hanford Laboratories Operation, May, 1962. Reactor fuels, chemistry, dosimetry, separation process, reactor technology employee relations, operations research and synthesis operation, programming, and radiation protection are discussed.

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Research progress is reported on water-cooled reactors, liquid-metal- cooled reactors, general reactor technology, plutonium recycle, advanced systems research and development, and nuclear safety. (M.C.G.)

Revisions to Vol. IV of the PL final design report are presented. The changes presented are exclusively in the mechanical and structural design of the core. Most design changes were dictated by fabrication experience or experimental test results. A complete list of the revised drawings is included. (J.R.D.)

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