The Heavy Water Components Test Reactor (HWCTR) is used to test prototype fuel elements for power reactors that are moderated with heavy water and fueled with natural or slightly enriched uranium. During the initial critical experiments in the HWCTR, it was observed that there were unexpected variations in nuclear reactivity. Investigations revealed that this effect was due to bubble of helium gas appearing and disappearing in the moderator. An examination of the expected operating conditions of the HWCTR and the solubility of helium in D2O showed that it was possible during normal operation for the helium content of the moderator to exceed saturation and thus for helium to appear as bubbles in the moderator. The possibility of helium bubbles appearing in the moderator because of solubility characteristics was eliminated by modifications to the process system so as to maintain the gas content of the moderator appreciably below saturation.

Abstract. the direct and inert-gas radiolysis, as well as the vacuum ultra-violet photolysis of CD3CH2CD3, CH3CD2CH3 and C3H2+C3D3 mixtures have been investigated in the presence of radical scavengers. The major conclusions are : (a) at atmospheric pressures, neutral propane decomposition contributes to the observed products although to a lesser extent than parent ion decompositions ; (b) a variation in pressure has a pronounced effect on the fragmentation of the parent ion ; (c) the hydrogen atoms in the ethyl ion are randomized in the direct as well as in the inert-gas sensitized radiolysis ; (d) rearrangement in the parent ion is of minor importance in the radiolysis ; (e) although the formation of propylene is related to the propyl ion, it is not necessarily produced by the neutralization of this ion.

A measurement of the yield of the aerated, ferrous sulfate-sulfuric acid (Fricke) dosimeter for 14.6-Mev neutrons gave a value of GF /sub Fe/sup +5/= 11.5 plus or minus 1.8. G/sub Fe/ number of ferric ions produced per 100 ev deposited. The determination combined an analysis of the energy deposit by scattering and charged particle reactions with a determination of the neutron flux by two independent means: (1) a "long counter" method and (2) an activation technique. The result is in reasonable agreement with a prediction for G/sub Fe// sup plus or minus 5/ based on measured yields of the dosimeter to irradiations by monoenergetic charged particles.

Introduction. Under AEC contract the Martin Company has followed up the design and construction of the PM-1 and PM-3A nuclear power plants with R&D efforts seeking improved plant efficiency, increased core life and higher operating power. The Advanced PM cores have evolved step by step, with the addition of degrees of freedom to design latitude. A first replacement core, Core 2, has been designed to achieve 50 percent greater life than PM-1 through relatively minor design changes. Core 3 realizes the potential extensive modifications in the fuel element and control element configurations. This paper outlines an analysis effort undertaken to define what may be called a performance profile over a range of configurations of interest for Core 3. It should be emphasized that this is a parametric or concept study and not a final design effort. The results of this study clearly indicate that a lifetime of 100 Mw-yr can be obtained from a 7 ft pressurized water core. If employed as a 10-Mw heat source for present PM equipment, this core has a lifetime approaching that of the plant equipment, 90,000 full-power hours. Core 3 will be suitable for applications demanding up to 40-Mw operating thermal power.

The reactivity lifetime of a water-moderated, thermal, power reactor using a low enrichment fuel is, in part, dependent upon the conversion ratio. The High Conversion Critical Experiment (Hi-C) was initiated at Argonne to extend the rage of investigations with light water moderated, slightly enriched, oxide-fueled cores. Bucklings were obtained from the clean critical core size and reflector savings values. The so-called "integral" technique was used to measure the disadvantage factor.

Summary: The use of dimensionless-parameter frequency response diagrams to determine accuracies of lumped-parameter approximations is demonstrated by two examples: calculation of the heat flux at the surface of a semi-infinite solid due to temperature fluctuations of an adjacent fluid; and the response of a counterflow heat exchanger to inlet fluid temperature perturbations. Dimensionless system parameters make it possible to use general-purpose plots to find the error in particular approximations as a function of the frequency of perturbation. Such plots are directly applicable to control-system stability problems, where the highest frequency of interest is usually apparent.

Abstract: To assess diffusion's importance, the temperature distribution in a cylindrical reactor is derived for a coolant with uniform properties and velocity, taking into account both radial and axial diffusion, for a cosine-J0 power distribution. The fractional temperature rise of the coolant is found to be [chemical formula] where E(z) = [sin(z) + sin(Z)]/2 sin(Z), z= π x/2′, x is the axial distance from the core center, -H and ′ are the core half-height and extrapolated half-height, -H≤x≤H; Fn = 1/J0(Pn)·[(Pn/2.405P)2-10, J1(Pn) = 0, P= R/R′ = core radius/extrapolated radius, ρ = r/R, r = radial distance from axis, 0≤r≤R; an = = βnH/Z, 2 Aβn + 1 =[1 + 4αβ(Pn/R)2]½, A = axial diffusivity /u, B = radial diffusivity /u, u = coolant axial velocity, and [chemical formula]. The expression is evaluated for a variety of values for all the parameters, and the results are discussed analytically and presented in tables and graphs. The effect is dependent upon the relative size of the diffusion eddies in comparison with the dimensions of the reactor. The eddy diffusivity is proportional to the size of the particles in the bed and is about ten times larger axially than radially. A small core …

Abstract: the goal of research on elastic scattering of atomic (or molecular) beams is the elucidation of the interaction potential V(r). the present discussion is confined to thermal energy collisions ([less than]1 ev), sensitive primarily to the attractive part of the potential. Studies of the velocity dependence of the differential and total elastic scattering cross sections have yielded information as follows: (1) The functional form of the long-range attraction : V[tilde]-C/r6, from differential cross sections I(0), at low angles: I(0) oc 0-7/3. (2) The attractive potential constant C, from total cross sections: Q oc (C/v)2/5, (3) The depth of the potential well [epsilon], from the rainbow effect in I(0): 0r=f(1/2mv2/[epsilon). (4) The equilibrium separation rm, from de Broglie interference producing undulations in (I0). (5) the product [epsilon]rm, from extrema in Q(v), and thus rm (from absolute Q's). (6) Observations of m maxima in plots of vQ5/2 vx. v-1 (termed elastic impact spectra) implied the existence of at least m bound states (discrete vibrational levels of zero angular momentum for the composite system).

Abstract: the goal of research on elastic scattering of atomic (or molecular) beams is the elucidation of the interaction potential V(r). the present discussion is confined to thermal energy collisions ([less than]1 ev), sensitive primarily to the attractive part of the potential. Studies of the velocity dependence of the differential and total elastic scattering cross sections have yielded information as follows: (1) The functional form of the long-range attraction : V[tilde]-C/r6, from differential cross sections I(0), at low angles: I(0) oc 0-7/3. (2) The attractive potential constant C, from total cross sections: Q oc (C/v)2/5, (3) The depth of the potential well [epsilon], from the rainbow effect in I(0): 0r=f(1/2mv2/[epsilon). (4) The equilibrium separation rm, from de Broglie interference producing undulations in (I0). (5) the product [epsilon]rm, from extrema in Q(v), and thus rm (from absolute Q's). (6) Observations of m maxima in plots of vQ5/2 vx. v-1 (termed elastic impact spectra) implied the existence of at least m bound states (discrete vibrational levels of zero angular momentum for the composite system).

Abstract. A review has been made of the effects of fluoride ions on the corrosion behavior of zirconium alloys in high-temperature water. Corrosion was found to occur as the result of contamination of the water or the zirconium surface. A major source of fluorides is undue delay in rinsing the HF-HNO3 pickling solution during surface preparation. The oxide on corrosion-resistant material has been found to contain up to 7600 ppm fluoride from this source. The threshold concentration of fluoride in the oxide film which produces poor corrosion resistance ranges from 8500 to 17,000 ppm. Accelerated corrosion from fluorides in water at 300 to 360 C occurs at about 100 ppm, although increased corrosion has been reported at 10 ppm fluoride in water at 300 C. Fluorocarbon plastics degrade and contribute fluorides to the high-temperature water or to the alloy surface when in direct contact with zirconium. Chlorides (1 to 10,000 ppm) and iodides (1270 ppm) do not adversely affect the corrosion behavior of zirconium alloys in water at 360 C. The mechanism of corrosion is not well understood but apparently is related to the formation of insoluble zirconium oxyfluorides during pickling and during exposure to fluoride-contaminated water.

Summary. Cattle in Reno, Nevada, exhibit a constant very low concentration of I 131 in their thyroid glands in the absence of known releases of I 131 to the atmosphere. This concentration is about 1 picocurie per gram of fresh thyroid tissue. ; This I 131 appears to originate below the tropopause

First paragraph of report: M. Neumann and H. Sherrard reported the development of a wire spark chamber experiment toward receiving digitized spark information. Since late 1962 our effort has been directed toward a wire-chamber with a core memory, using standard ferrite cores, and toward an on-line operation between spark chamber and computer.

Abstract: A thermal K beam was velocity selected, and scattered by Ne, Ar, and Xe gases. The dependence of the total cross section on relative velocity is approximately v/sup -0.4/ for K--Ar and K--Xe, and v/sup 0.8/ for K--Ne. The average relative velocity ranges were 400 to 1430 m/sec for Ne, 480 to 1350 m/sec for Ar, and 380 to 1320 m/sec for Xe. The dependence of the cross section on relative velocity was obtained by removing the cross section from the collision frequency integral. For the v/sup -0.4/ dependences, this gives results correct to 3%. For the v/sup -0.8/ dependences, the error is most likely greater. Three gas temperatures were used: liquid air, room, and 200 deg C. The results for a given gas at different temperatures are consistent with kinetic theory predictions.

At the Chemonuclear Workshop held at Brookhaven National laboratory in November 1962 it was pointed out that the production of ozone from oxygen by a liquid phase fission fragment chemonuclear process appears to have reasonable economic potential. The maximum theoretical reaction yield for the formation of ozone from oxygen is a "G" value of 68 molecules for 100 ev based on heat of reaction data. The authors felt a "G" value of 15 to be reasonable for this study. the reactor system chosen has liquid oxygen as its moderator and the operating pressure and temperature were selected so as to allow boiling of the oxygen-ozone mixture. The total plant investment cost is estimated to be in the range of $100,000,000. Other system designs will be considered in the future.

Abstract. Some diffusion parameters of water are computed with various thermal-neutron scattering laws. It is found that the diffusion cooling coefficient, in particular, is reasonably sensitive to the scattering law, but that the diffusion cooling coefficients predicted by the Radkowsky and Nelkin kernels are in fortuitious agreement. The coefficients computed for the Nelkin kernel, when treated in a manner consistent with the way in which experimental data are treated, are in reasonable agreement with the results of a recent experiment.

Abstract: Progress is reported in several areas of development of fueled graphite containing coated particles for nonurged gas-cooled reactor systems. The sol-gel process has been modified for making spherical particles of both thorium-uranium carbide and thorium-uranium oxide suitable for coating. Equipment has been assembled and methods have been developed for deposition of pyrolytic-carbon coating under well-controlled conditions. Damage to coated particles during fabrication into a graphite matrix depends on the molding pressure and the volumetric content of coated particles. Vendor-supplied coated particles and fueled graphite spheres have been evaluated extensively in both in- and out-of-reactor tests. Duplex- and triplex-coasted particles have excellent fission-gas retention at 2050 degree F to burnups of 15 at. % burnup. Fueled graphite spheres containing coated particles have good irradiation performance, but the fission-gas release rates are somewhat higher than for unsupported coated particles. Fueled graphite spheres react with water vapor about as rapidly as do Speer Mod-2 and ATJ grades of graphite. The diffusion rates in pyrolytic carbon are the same for uranium, thorium, and protactinium. The diffusion rates in the direction parallel to the deposition plane are much higher than those in the perpendicular direction.

Many measurement of neutron spectra have been made in water assemblies. In these system a large part of the spectrum is given by an essentially Maxwellian distribution at the moderator temperature which is insensitive to the scattering model. Hence, the test of the energy exchange scattering kernel is in the difference of the spectrum and the fundamental or Maxwellian component. The figure shows the spectrum for the Nelkin model. Once the fundamental has been subtracted neither theoretical model seems to fit the data extremely well. Below kT the Nelkin model is a closer fit than the gas model but it underestimates the deviation from the Maxwellian whereas in the joining region it overestimates the distortion.

Gell-Mann and Pais were the first to suggest that the non-leptonic decay processes of strange particles may be subject to an isospin selection rule, allowing only those decay transitions which involve a change [delta]I = 1/2 in to total isopin of the system. At present, however, there is really no theoretical framework for the description of weak interactions into which this selection rule fits in a natural and compelling way. The report includes sections on the 91) decay processes of the [caret] hyperon, (2) decay processes, (3) [complex conjugate] decay processes, and (6) K[pi]3 decay processes. We have considered the evidence on all of the known non-leeptonic non-radiative decay modes of strange particles. All of this evidence is in good qualitative accord with the [delta]I = 1/2 selection rule.

To improve gamma discrimination and eliminate d-c cable leakage interference currents, mean square voltage fluctuation measurements have been made on neutron sensitive ion chambers.

A sector gauge was developed for routine measurement and recording of wall thicknesses between the ribs and at the top of installed aluminum reactor power tubes. The basic criteria selected for the device were that it would measure and record wall thickness over the length of the tube with an accuracy of plus or minus 2 mils at an average rate of 3 min per tube. An eddy-current measuring system was used in the device.

One-region buckling measurements that were made on a series of D/sub 2/O- moderated lattices of heavy uranium metal tubes in the Process Development Pile at Savannah River Laboratory are presented. The purposes of these measurements are to provide normalization points for lattice bucklings and to extend the study of natural uranium- D/sub 2/O systems. The dependence of buckiing on the moderator-to-fuel ratio is studied for two types of lattices.

The program KRUDE, which solves the slowing down and adjoint equations for a mixture of resonance and nonresonance isotopes in an infinite homogeneous medium, was used to evaluate some resonance capture approximations (variational and successive) that use linear combinations of narrow and wide resonance fluxes. Results obtained for resonance capture in the 291-ev resonance of Zr/sup 91/ and the 192-ev resonance of U/sup 238/ are compared, and three methods for including Doppler effects in the variational method are considered.

Diffusion coefficients and bucklings are measured for UO/sub 2/ fuel tube assemblies in D/sub 2/O moderated lattices. The effects of H/sub 2/O fogs and air in the coolant channels in place of D/sub 2/O are studied.

From American Nuclear Society Meeting, New York, Nov. 1963. The use of the asymptotic solution to the one-velocity transport equation is considered. The angular distribution for fast neutron elastic scattering by heavy elements is discussed. An exponential angular distribution on is assumed to simplify the decay length calculation. The diffusion length of 1 to 15 Mev neutrons in iron is calculated, as well as the vector flux angular dependence. The asymptotic solution for an arbitrary angular distribution of a plane delta -function source is also found. An isotropic source is investigated, and some applications of the model are examined.