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The relative probabilities for alternate processes initiated by a nucleon-nucleon collision depend on the dynamics involved and on the volume in phase space accessible to each final state. According to Fermi this last aspect alone may be of decisive importance. Such an assignment would follow were an approximate statistical equilibrium reached. The volume occupied by the incident nucleons and the associated pion clouds will have very large energy density at the instant of collision. Knowing that the interactions of the pion fields are strong, Fermi assumes that this energy is suddenly distributed among the various degrees of freedom present in the interaction volume in accord with statistical laws. He then computes the statistical probability that a certain number of pions will be created with a given energy distribution. It is then assumed that the energy will rapidly dissolve and that the particles into which the energy has been converted will fly out in all directions. Fermi argues that this approach may give a fairly good approximation to the actual case; since the number of possible states of the given energy is large and the probability of establishing a state to its average statistical weight will be increased by the number …

In the initial uranium solution testing of the Purex prototype facility uranium evaporator, failure of the concentrator feed pump, along with other contributing circumstances discussed later, resulted in an overconcentration of the uranyl nitrate solution to the point of incipient denitration. The overconcentration was accompanied by the evolution of brown nitrogen dioxide fumes from the concentrator. Examination of the evaporator contents after the incident has led to the conclusion that a rapid rection of nitric acid with organic material may also have occurred. The pressure buildup surmised to have accompanied the nitric acid-organic reaction apparently jarred the ceramic Raschig-ring packing in the stripping tower surmounting the concentrator tubes sufficiently to chip many of them badly. Ceramic dust and chips from the Raschig rings were found mixed with the uranium-bearing concentrator residue in almost the entire concentrator pot and filling more than half of the tubes.

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The general program established at Argonne National Laboratory in connection with the Fast Power Breeder Reactor (P BR) 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/sup 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 neutr ons from an auxiliary source. By measurements of the neutron flux within the assembly, important parameters can be calculated which are necessary to the proper design of an actual critical reactor of the same composition. (auth)

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This document from Savannah River Plant reports monthly progress on the following topics: heavy water corrosion, reactor materials, reactor technology, separations technology, and instrument development.

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The formation of more complex carbon compounds from simple ones through the action of radiation is used in an interpretation of the original formation of such compounds on earth. The relation of plants and animals and evolution of photosynthesis is discussed in the light of the participation of sulfur compounds in the metabolism of both group.

Six determinations have been made of the half life of polonium with four different steady-state, resistance-bridge calorimeters and five different samples of polonium. These six values of the half life have been weighted and combined to give a grand-mean value of the half life of 138.4005 + - 0.0051 days.

This document from Savannah River Plant reports progress in January 1953. Heavy water studies include corrosion inhibitors and sulfide deposition. Reactor materials studies include uranium fuel elements and aluminium sheaths and special materials to include thorium and bismuth. Reactor technology studies include control systems, tritium production, CMX, moderator purification, concrete shield heating. Separations technology studies include Purex process, 221 building equipment, and fuel element handling.

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