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The knowledge of the fraction of decay-heat which is absorbed in fuel elements after a reactor is shutdown is important for many reasons. For example, allowable, reduced flow-rates after shutdown are very sensitive to the manner in which the decay-heat is distributed. Also, the temperature-rise in a discharged, uncooled fuel element is dependent on the total heat generated in the slug. Apart from any heat consideration, the escape of rays from a discharged fuel element is also of importance in certain applications. A significant refinement in the knowledge pertaining to decay-heat in irradiated uranium in recent years warrants a complete review of the fractional heat generation in the Hanford reactors. Earlier work was based on very qualitative aspects of fission product decay rates and energy spectra following reactor shutdown. The results of these early calculations on the original, solid, Hanford slug indicated that about 20 per cent of the energy generated in a fuel element from both fission product decay and delayed fission escaped from slug. The results reported here show a much smaller escape-fraction. Also, the time-dependence of the escape-fraction is considered for times greater than 100 seconds after reactor shutdown. Fractional heat-generation rates are calculated for various Hanford …

The compatibility of Dowex 1x4 nitrate form anion resin with nitric acid, and the compatibility of several types of plastic tubing with nitric acid were investigated. Ignition properties of resin extract, treated resin and mixtures of tubing extract with either resin extract or treated resin were also investigated.

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The Pebble-Bed Reactor Experiment (PBRE) was designed to advance the pebble-bed concept by providing a test of characteristic features and make contriliutions to the general development of all-ceramic gas-cooled reactors. The following objectives were established for the reactor experiment: to investigate key features of the pebble-bed concept, including on-stream fuel handling, movement of fuel through bed, and performance of core; to obtain operation and maintenance experience with a system contaminated with fission- product activity; and to investigate the behavior of graphite fuel elements. A fourth objective, study of the behavior of core materials at conditions occurring with exit gas temperatures in the range 2000 to 2500 deg F, was tentatively included. The preliminary design oE a 5-Mw(t) reactor for achieving these objectives was prepared. The core of the PBRE is a 2 1/2-ft-diam, 4-ft-tall cylinder containing approximately 12,000 spherical graphite fuel elements 1 1/2 in. in diameter. Fuel spheres are added to and removed from the core by gravity flow, and these operations are performed while the reactor is at power by using pairs of valves for passage of elements into and out of the high-pressure system. Exposed fuel can be recycled to the top of the core. Helium coolant …

In some recent theories of the equation of state of classical ionized systems, the free energy depends on integrals of the form {integral}{sub 0}{sup {infinity}}[e{sup -{beta}V{sub s}}-1+{beta}V{sub s}-{beta}{sup 2}V{sub s}{sup 2}/2]r{sup 2}dr, where V{sub s} is a "screened" potential obtained from the real potential by summing certain infinite series of diagrams. This integral has been tabulated for V{sub s} appropriate to a potential {+-}(e{sup 2}/ r)(1 - e{sup -{gamma}r}). The equation of state is also given for a one-component electron gas in a uniform background of positive charge (limit{gamma}{approaches}{infinity}).

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The development of the system and techniques to permit determination of strains at right angle to the axis of loading in the specimen was continued. An additional optical system was developed to accept the lateral image of the gage points and project a vertical image of the same proportion to the apertures of the strain analyzer. Using a dummy specimen of steel in the load train, the automatic pressure control system for the gas-bearing universals was operated. A fluctuation of gas pressure occurred within the bearings. Multiple progressive fracture planes were observed throughout the gage length of fractured graphite and tungsten. (M.C.G.)