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The operation of the Fast Reactor is considered in terms of normal equilibrium conditions and normal shut-down. The proposed loading, control rod adjustment and subsequent "floating" operation are discussed. Safety devices and interlocks are described. Temperature and reactivity changes are examined with respect to various system failures, phase changes, and "flashing" of the reactor. Slow changes due to faulty slug cooling are also considered. The calculations were initially based upon 10 kw operation. Performance tests of the mercury system now indicate that 20-kw operation may be feasible. (D.E.B.)

This progress report discusses activities of the P Division for the month of April, 1948. The D and F Piles operated at 275 megawatts throughout April except for scheduled outages. Each operating area had an extended outage to remove a portion of the brick from the wall which runs across the rear edge of the top of the unit and to replace the vertical neoprene seal between the front face and the experimental side shields. This program described in detail under Mechanical Experience. The B-Pile was maintained in standby condition with a water flow of 10,150 gallons/minute. The 100 Area discharge rate continued at 60 tons per month. The exclusive use of lead dipped 4 inch slugs fabricated from alpha rolled or alpha extruded metal was started effective April 1. Work was stated April 12 in the 300 Area on a program of decanning 160 tons of 8 inch gamma extruded triple-dip canned pieces which were not considered good risks for pile operation. The slug recovery operation was placed on a 2 shift per day schedule on April 19 to expedite this work so that the metal can be recast and rolled at the earliest moment. The 300 Area canning …

The fission and spallation reactions caused in uranium by bombardment with high energy protons (340 t o 350 MeV) were investigated. The reaction products were separated from the target by chemical processes and identified by their radioactive properties. The relative yields of the observed fission products were measured, and the results plotted as a function of mass number. Several of the spallation products were identified and their yields estimated. An attempt was made to determine the most probable atomic number for a nuclide of given mass formed directly from fission. Studies were made of the relative yields along several isobaric chains as a function of atomic number. From these data predictions of the mass and charge of the fissioning nucleus are made.

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The slow neutron transmission of several samples of plutonium is being investigated with the Columbia Neutron Velocity Spectrometer. The spectrometer, which has been described previously (Rainwater et al., Phys. Rev. 71, 65 (1947)), was recently improved, recalibrated, and the operational factor reevaluated (CUD-59). Results reported here were obtained by the procedure described in that report.

At the time the first UO{sub 3} from so-called ``full-level`` Redox runs was shipped from 224U, the % U{sub 235} as determined in 222-S appeared high when compared with theoretical values from the burn-out curve. Close agreement between the 222-S results and % U{sub 235} determined by K-25 on lots 007, 008, and 009, however, indicated that a considerable heel of cold uranium in Redox had been blended with the first ``full level`` material. This explanation has been verified by data collected over the past weeks and provided this report. It has also been verified by the % U{sub 235} found in lots later than 010* (after most of cold uranium flushed out of Redox) which ranged from 0.66% to 0.64%.

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A permissible limit for the release of waste cooling water from the Hanford reactors into the Columbia River must be determined not only from the effect on humans of assimilation of the radioactive isotopes in the water, but also from the effects of temperature, submersion dose, and metabolism of radioisotopes on fish and other aquatic life in the river, and of concentration in plants of the radioisotopes in irrigation water from the river, with eventual consequences to humans. This report derives permissible limits for human assimilation. 10 refs., 4 tabs.

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The Nevada Test Site (NTS) Use Committee met Tuesday morning, May 28, 1957, at Mercury, Nevada. This document provides a summary of the meeting.

Various heat transfer mechanisms which have been previously proposed are analyzed in the light of recent experiments. Evidence is presented in favor of a liquid-vapor exchange mechanism and against the widely accepted "micro-convection" mechanism. The vapor-liquid exchange rnechanism is shown to explain the insensltivity of boiling heat flux to the level of subcooling. A "Reynolds Analogy" for nucleate boiling is presented in some detail. A procedure is given for calculating the superheat at which the liquid bulk velocity ceases to contribute to the heat flux. An expression for the growth of a vapor bubble in a highly superheated liquid is deduced. A method is presented which allows the deduction of correlations for nucleate boiling which give the dependence of heat flux on superheat and system pressure. Two such correlations are presented and results are compared with experiment. It is shown that one correlation yields the heat flux for different liquids varying from water to mercury, without necessitating any change in constant or exponent of the correlation. (auth)

An investigation of trim from the HRP Dump Valve Test Loop revealed that performance improved with increasing poppet hardness. From this it was hypothesized that deformation of softer poppets increased the poppet-seat contact area, thus reducing the closing pressure. The deformation areas of a number of poppets were measured and the closing pressures calculated. A plot of closing pressure against leak rate showed a fair correlation and tends to support the hypothesis. (auth)

A three-stage mass spectrometer that utilizes two consecutive magnetic focusing;lenses of 20-in. radii followed by a 20-in. radius-of-curvature electrostatic analyzer is described. An abundance sensitivity of 1010 was measurcd for this instrument in the low mass region. Application of this instrument to analytical and research problems in the field of mass spectrometry and the results obtained are discussed. (auth)

The demand plot has a 5-set, modified pump decay curve; it shows that 20,000 gpm emergency flow would be required within 80 seconds of complete pump power failure. Bases for the demand curve are constant bulk inlet temperature of 2 C, constant bulk outlet temperature of 95 C, K-3 I&E fuel elements, and initial reactor flow of 188,000 gpm.

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The defueling of the S2G Reactor which was conducted at the Electric Boat Division, General Dynamics Corporation Groton Connecticut during January 1959, is reported from the viewpoint of the participating personnel from Knolls Atomic Power Laboratory. The sequence of events is outlined, difficulties encountered during the operation are described, and conclusions of possible interest to other naval nuclear reactors are given (auth)