Progress report of the Brookhaven National Laboratory Nuclear Engineering Department providing updates on various projects, experiments, and other work. This report includes a summary of scholarly output from the reactor physics division, the applied chemistry and chemical engineering division, and metallurgy division.

Nusselt numbers have been calculated for heat transfer to fluids flowing through annuli under conditions of uniform heat flux and fully established velocity and temperature profiles. The following cases were considered: (a) laminar flow, (b) slug flow, (c) turbulent flow with molecular conduction only, and (d) turbulent flow with both molecular and eddy conduction. These Nusselt numbers were determined for two conditions: heat transfer from the inner wall only and heat transfer from the outer wall only. The results were correlated by semi-empirical equations. The final results obtained on cases (a), (b), and (c) are applicable to any fluid, whereas those obtained on (d) are for liquid metals only. Wall- and bulk-temperature relationships for the above four cases were also determined. These relationships were treated as dimensionless temperature ratios. Both the Nusselt numbers and temperature ratios were evaluated over the r1/r2 range, zero to unity; the former being the case of the circular pipe, and the latter, the case of infinite parallel plates.

The method of collection and the subsequent analysis of the hematological data accumulated by the Joint Commission of the Investigation of the Early Effects of the Atomic Bomb in Japan, have been described. In the present investigations, an additional analysis of the hematological data was made to investigate a possible relationship between leukopenia and the mortality rate within the first nine weeks following the bombings. It has been frequently observed in laboratory animals exposed to ionizing radiation that the extent of the fall in the white blood count reflects the dose of radiation received. Smith et al have demonstrated that in mice survival can be related to the depression of the granulocyte count at various times following radiation. Cronkite and Brecher and Cronkite, Bond and Dunham inferred that the hematological response could be used as a biologic dosimeter for exposed human beings. This report is concerned with the study of the response of the white blood cells to ionizing radiation resulting from the atomic bomb detonation in Japan.

Before discussing personnel monitoring of high energy radiations, it is appropriate to comment briefly on two basic methods of dosimetry applicable to such situations. In the first of these methods, one measures the rad dose in air with a tissue-equivalent ionization chamber that is operated with enough voltage on the collecting electrode to insure saturation even when the radiation is concentrated in short pulses, as is frequently the case. The linear energy transfer (LET) spectrum of the radiation is then determined and an average value of relative biological effectiveness (RBE) is determined. An experimental evaluation of the depth dose situation completes the data necessary for a full evaluation of the biological hazards. The method is completely general but is most applicable to situations where a substantial proportion of high energy components is present in the mixed radiation. It should be noted that the detailed composition of the radiation need not be known. Thus, components of dosage to which an RBE of 1 is assigned may be due to X-rays, gamma rays, or the ionization tracks produced by protons in the Gev energy range as well as by many other types of radiation. This method is applied frequently to the situation …

It is appropriate that a conference devoted to the interactions of fast neutrons with nuclei begin with a survey of the available sources of such neutrons. Since its discovery in 1932, the neutron has provided a highly useful tool in attempts to understand the nucleus, and the types of nuclear phenomenon which could be studied and the nature of the results obtained are very dependent on the sources available.

In calculating diffusion coefficients for gases diffusing from solids, the numerical solutions tabulated by Darken and Gurry, were found to lack the required precision, and the intervals between the arguments were too great to permit precise interpolations. Consequently the diffusion equation solutions of interest (diffusion from a sphere, cylinder, and plate, for the condition that the concentration of the diffusing species initially uniform) were re-evaluated. Computer programs for the three cases were written in FORTRAN for the IBM 7090. The solutions programmed are given in Crank. Values of the fractional completion were computed at approximately 0.01 increments, to the nearest 0.00001, and are tabulated in Table 1 to the nearest 0.0001. The table covers the fractional range from about 0.04 to 0.99. For smaller fractions satisfactory approximations are available. The table may be conveniently interpolated by plotting points about the region of interest and drawing a curve.

A neutron diffraction study of polycrystalline HCrO2 and DCrO2 (chromous acid) is described. Intensity data from the two substances were refined together by the least-squares method, with the constraint that the Cr-O distance be the same in the two substances. Estimates of individual contributions to multiple peaks were included in the least-squares refinement through the use of a non-diagonal weight matrix. The O-D-O bond is found to be asymmetric, O-D = 0.96 ± 0.04 A, O...O - 2.55 ± 0.02 A. The symmetry of the O-H-O bond cannot be determined, but agreement with observation is as good with a symmetric bond as with any other model. The O-H-O bond length is 2.49 ± 0.02 A. These results are consistent with those from previous studies of the HCrO2-DCrO2 system by nuclear magnetic resonance and infrared techniques.

Methods of calculating the "Snell Experiment" (the exponential experiment in natural uranium) are examined. It is found that integral transport theory is required for accurate predictions. The effect of spatial transients upon measured quantities is studied and it is found that experiments have not been done in a large enough mass of uranium to achieve an asymptotic neutron distribution. However deviations from the asymptotic values of integral quantities are not large and corrections are calculated and applied to recent experiments. It is shown that the use of recent cross section data improves the agreement between theory and experiment. The relaxation length and all spectral indices are in fairly good agreement except for Np237 to U238 average fission cross section ratio.

The History, Current Significance and Status of the Field Hot atom chemistry, like many other fields of scientific research, can trace its origin to a single experiment, that of Szilard and Chalmers, performed in 1934. This is true even though recoil effects had been known and used for a long time. Almost immediately Szilard and Chalmers put their discovery to practical use: they employed the recoil effect in ethyl iodide as a neutron detector and observed the γ,n reaction in beryllium. The ingenuity of Fermi soon provided the correct explanation of the chemical separation observed by Szilard and Chalmers, and Fermi's co-workers, especially D'Agostino put the effect to a further practical use: the preparation of radioisotopes in high specific activity. These Roman scientists carried out the first Szilard-Chalmers studies in solids (sodium bromate, chlorate, iodate, and perchlorate, cacodylic acid and potassium permanganate) and reported some quantitative results: for example a quite accurate recoil yield of 80% of the Mn 56 in potassium permanganate. Perhaps the most striking practical result of a Szilard-Chalmers experiment lay in the discovery, by Kourtchatow and co-workers, of the important isotope Br 82 in extracts from neutron-irradiated ethyl bromide.

The amount by which the field of a magnet bends the path of a charged particle is proportional to the integral of Btds along the trajectory. Instead of making tedious point by point measurements of B in magnets and performing the integrations numerically, it has been found useful to measure directly, by using a search coil whose winding consists of long and narrow turns extending through the magnet gap from z1 and z2 in the direction of the trajectory. It should be noted that the integral Iy is taken along a straight x=constant, y=constant lines and not along the actual curved trajectory path; for small curvature the difference is small.

We undertook the present diffraction study of the bifluoride ion in sodium acid fluoride and the present refinement of the earlier data on potassium acid fluoride with the hope of obtaining more accurate information not only on the position of the hydrogen atom, but also on the vibrations of the ion. We felt that it would be through the combination of information on the motions of the system from diffraction and spectroscopic studies that the question of the symmetry of the ion could be settled. In this paper we summarize briefly the results of our diffraction study and show that these data, in combination with the spectroscopic data, provide new, and we feel convincing, evidence that the F-H-F ion is linear and symmetric.

A pool of material in steady-state turnover is a collection of identical molecules from which deletions are made at a constant rate, along with simultaneous addition of new identical molecules at the same rate, the total pool size remaining unchanged. It is of interest to consider what may be expected in the way of such pools among the various chemical species which can be isolated from biological systems. It is clear what the model requires, i.e. any molecule belonging to the pool must have as much chance as any other pool molecule to make its exit. This situation is approximated by molecules in solution in a well mixed volume of fluid, hence the choice of the word "pool." The mixing brings pool molecules into proximity with the exit mechanism in a random way.