BS>The use of a lead-bismuth alloy as a coolant in the removal of heat from power-generating nuclear reactors was considered with the possibility that its ternary alloy with uranium or plutonium might be of use in a reactor of the circulating-liquid-fuel type. Information collected from the literature covering phase-equilibrium studies, physicalproperty data, and reactivity of this alloy toward other substances is presented. (auth)

A comprehensive survey of the literature was made in an effort to identify nonmetallic materials of possible usefulness as liquid coolants. Materials having maximum melting points of 1000 deg F and boiling points of l200 deg F were considered, but boiling points above 2200 deg F were preferred. Melting points, boiling points, densities, heat capacities, and thermal conductivities were tabulated. Approximately 190 materials appeared to have melting and boiling temperatures in a suitable range. A paucity of thermal- conductivty and heat-capacity data prevented further estimates of suitability of all but nine of these materials. Of these nine nonmetallics, only sodium hydroxide appeared to offer possibilities when considered according to the NEPA formula. (M.C.G.)

The Hanford metal wastes were divided into four categories: supernate - the liquid waste; hard sludge - dense agglomerates of poorly defined crystalline carbonates approximating the hardness of soft blackboard chalk; soft sludge - an easily slurried semi-solid consisting chiefly of needle-like phosphates; and recombined sludge - a representative sample of the solid wastes as received from Hanford, shown to be a mixture of hard and soft sludges in the ratio 2/3 by weight. The density of supernate, in the temperature range 24 to 74/sup 0/C, varied from 1.130 to 1.103 g/ml. Hard sludge density averaged 3.0 g/ml and that of soft sludge averaged 1.84 g/ml. The consistency, or apparent viscosity, as a function of temperature, shear rate, and solids content was measured individually on slurries of recombined, soft, and hard sludges using supernate as the suspending medium. Settling rates were also run on these 3 slurries as a function of solids content.

Two new positron active isotopes, B{sup 8} and Na{sup 20}, have been found to decay to excited states of Be{sup 8} and Ne{sup 20}, which in turn decay 'instantaneously' by alpha emission. Their half-lives are 0.65 {+-} 0.1 sec. and 1/4 sec. respectively. N{sup 12} is also found to have a low energy positron group which leads to an {alpha}-unstable excited state in C{sup 12}. The masses of B{sup 8} and Na{sup 20} are 8.027 and 20.015 respectively. B{sup 8} decays by a 13.7 {+-} 0.3 Mev positron, through the same excited state of Be{sup 8} as does Li{sup 8}. Estimates of the energies of the excited state in C{sup 12} and Ne{sup 20} are made.

The relative stopping powers for 300 Mev protons of H, Li, Be, C, Al, Fe, Cu, Ag, Sn, W, Pb, and U have been measured. The results are shown in Table I. The energy spent per ion-pair production in the gases H{sub 2}, He, N{sub 2}, O{sub 2}, and A at 340 Mev proton energy has also been measured. The results are shown in Table II.

Measurements of the proton-proton differential scattering cross section using 340 Mev protons show a cross section approximately constant between 41{sup o} and 90{sup o} in the center of mass system. Two methods of counting the scattered protons have been used. The first method uses a counter telescope to count the scattered protons. The second method utilizes coincidences between counters which record the two protons involved in a single scattering process. The first method gives slightly higher cross sections; the average value of the differential cross section is (5.5 {+-} 1.0) x 10{sup -27} cm{sup 2} steradian{sup -1} in the center of mass system. Although the scattering appears isotropic it is larger than can be accounted for with pure S-scattering. There is a strong suggestion, but no positive proof, that n-p and p-p forces are different.

Definite identification has been made of an isotope of the element with atomic number 98 through the irradiation of Cm{sup 242} with about 35-Mev helium ions in the Berkeley Crocker Laboratory 60-inch cyclotron. The isotope which has been identified has an observed half-life of about 45 minutes and is thought to have the mass number 244. The observed mode of decay of 98{sup 244} is through the emission of alpha-particles, with energy of about 7.1 Mev, which agrees with predictions. Other considerations involving the systematics of radioactivity in this region indicate that it should also be unstable toward decay by electron capture. The chemical separation and identification of the new element was accomplished through the use of ion exchange adsorption methods employing the resin Dowex-50. The element 98 isotope appears in the eka-dysprosium position on elution curves containing berkelium and curium as reference points--that is, it precedes berkelium and curium off the column in like manner that dysprosium precedes terbium and gadolinium. The experiments so far have revealed only the tripositive oxidation state of eka-dysprosium character and suggest either that higher oxidation states are not stable in aqueous solutions or that the rates of oxidation are slow. The successful identification …

The recent production and identification of isotopes of elements with atomic numbers up to six higher than the target element through bombardment with hexapositive 120-Mev carbon ions made it seem worthwhile to apply this technique to the transuranium region. Accordingly, small pieces of natural uranium metal (about 0.5 mil thick and 205 cm by 0.6 cm area) were irradiated in the internal carbon ion beam in the Berkeley 60-inch cyclotron. Following the irradiations, the uranium was dissolved in dilute hydrochloric acid containing hydrogen peroxide and a transplutonium fraction was isolated through the use of lanthanum fluoride, and lanthanum hydroxide precipitation steps followed by the ion exchange adsorption column procedure in which concentrated hydrochloric acid is used to separate the tripositive actinide elements from the rare earth elements. The transplutonium fractions in hydrochloric acid were evaporated as weightless films on platinum plates which were placed in the ionization chamber of the 48 channel pulse analyzer apparatus in order to measure the yield and energies of any alpha-particles which might be present. In the best experiment at about one hour after the end of the 90-minute bombardment, some 50 disintegrations per minute of the distinctive 7.1-Mev alpha-particles of Cf{sup 244} were observed …

The recent production by Thompson, Ghiorso, and Seaborg of a radioactive isotope of berkelium (atomic number 97) makes it possible to investigate the chemical properties of this transuranium element by means of the tracer technique. This isotope has been prepared through the bombardment of Am{sup 241} with about 35 Mev helium ions in the 60-inch cyclotron of the Crocker Laboratory and is believed to have the mass number 243, or possibly 244. This Bk{sup 243} has a half-life of 4.6 hours and decays by electron capture with about 0.1% branching decay by alpha-particle emission. In the present tracer chemical experiments, the radiations accompanying the electron capture process were used as a means of detection and were counted in two ways. Where the sample deposits on the platinum plates were essentially weightless, as was the case following the evaporation and ignition of the elutriant solutions in the column adsorption experiments, a high efficiency was obtained by using a windowloess proportional counter to count the Auger electrons. The thicker samples from the precipitation experiments in which carrier materials were used were counted close to the thin window (3 mg/cm{sup 2} mica) of a bell type Geiger counter filled with 10 cm. xenon …

As titanium, zirconium, and other of the high melting electropositive metals become more important, the problem of using suitable refractory materials for their casting becomes more important. This paper discusses the method of choosing and testing possible container materials. To make the discussion more specific, titanium is used as an example. As titanium melt at 2000 {+-} 10 K, it is immediately clear that one is restricted to refractory materials melting considerably above 2000 K. This greatly limits the possible materials that might be considered. The possibility of using any pure high melting element can be quickly eliminated as titanium reacts quite vigorously with non-metals such as carbon and due to its high boiling point and therefore high internal pressure, one can predict that it dissolves even the most refractory metals. Examination of phase diagrams confirms that even metals such as tantalum, tungsten, and rhenium would not be able to resist attack by titanium. One is thus limited to high melting compounds such as the oxides, sulfides, nitrides, carbides, silicides, and borides. The first consideration is that, if possible, one would use a compound which is thermodynamically stable in the presence of titanium metal at 2000 K. Titanium should not …

The lifetime for the decay of a {pi} meson into {mu} meson and neutral particle was first measured by Richardson and later by Martinelli and Panofsky. The method was the same in both cases: The fraction of {pi} mesons surviving various times of flight is measured by placing photographic detectors at various path lengths from the target. In the experiment reported here we observe the time lag between the two bursts of fluorescence due to mesons decaying in a scintillation crystal. The first burst is due to the stopping of the entering {pi} meson, the second to the {mu}-meson. As is shown in Fig. 1, a particle penetrating the first and into the second crystal starts the sweep (10{sup -8} sec/mm) of an oscilloscope. The pulses in the second crystal are delayed 0.5 x 10{sup -6} sec to allow the sweep to start and brighten and are then photographed. If the responsible particle is a {pi}{sup +} meson which stops in the crystal, it undergoes {pi}-{mu} decay and two pulses appear on the trace. The {mu}{sup +} meson has a range of only 2 mm in the crystal. If its decay electron is detected some time (.5-2.5 x 10{sup -6} …

Three new americium activities (Am{sup 238}?, Am{sup 243}, and Am{sup 244?}, the latter two formed by n,{gamma} reactions) are described and some additional information is given on previously reported americium isotopes.

The fission reaction has been observed with high energy accelerator projectiles for elements as light as tantalum but has not been reported for medium weight elements. The present note presents evidence for the occurrence of reactions which are probably most properly described by the term 'fission' and which seem to occur with very small yield throughout the region where this type of reaction is only slightly exoergic or even endoergic with respect to mass balance. In the course of detailed investigation of the spallation of copper and the variation of the product yields with energy of the bombarding particle the threshold for formation of radioactive Cl{sup 38} (38-minute half-life) from elemental studied. The energetically most economical way in which Cl{sup 38} might be spallation reactions is by emission from the bombarded copper nucleus of nucleons in groups such as alpha-particles instead of single nucleons 0 The energetic requirements for the reaction Cu{sup 63}(p,pn6a)Cl{sup 38}, in which the maximum number of alpha-particles are emitted, include (1) the mass difference between the reactants and the products and (2) the excitation energy which the alpha-particles must have in order to pass over the coulombic barrier, Since the reaction is endoergic with respect to …

Definite identification has been made of an isotope of the element with atomic number 98 through the irradiation of Cm{sup 242} with 35 Mev helium ions in the Berkeley Orocker Laboratory 60-inch cyclotron. The isotope which has been identified has an observed half-life of about 45 minutes and probably has the mass number 244. The observed mode of decay of the 98{sup 244} is through the emission of alpha-particles, with energy about 7.1 Mev, which agrees with predictions, and other considerations involving the systematics of radioactivity in this region indicate that it should also be unstable toward decay by electron-capture. The chemical separation and identification of the new element was accomplished through the use of ion exchange adsorption methods employing the resin Dowex-50. The element 98 isotope appears in the eka-dysprosium position on elution curves containing 4.6-hour Bk{sup 243} (formed by a d,n reaction in the same bombardment) and the bombarded Cm{sup 242} as reference points; that is, it preceded berkelium and curium off the column just as dysprosium precedes terbium and gadolinium. The experiments so far have revealed only the tripositive oxidation state of eka-dysprosium character but practically no attempts at oxidation to possible IV and V states have …

The electrostatically deflected beam of the 184-inch cyclotron has been used with the stacked foil and absorber technique to determine the excitation functions for the following reactions: Th{sup 232}(p,6n)Pa{sup 227}, Th{sup 232}(p,3n)Pa{sup 230}, Th{sup 232}(d,7n)Pa{sup 227}, Th{sup 232}({alpha},p8n)Pa{sup 227}, Th{sup 232}({alpha},p5n)Pa{sup 230}, and U{sup 238}(p,{alpha}8n)Pa{sup 227}. The data are presented graphically and discussed individually for each of the reactions. Some rough excitation function data have also been determined for the reactions Th{sup 232}(d,4n)Pa{sup 230}, U{sup 238}(p,{alpha}5n)Pa{sup 230}, Th{sup 232}({alpha},7n)U{sup 229}, and Th{sup 232}({alpha},6n)U{sup 230}. The results are discussed in terms of compound nucleus formation, transparency effects, and other factors in order to arrive at a qualitative picture for the mechanism of high energy nuclear reactions with heavy nuclei.

An isotope of the element with atomic number 97 has been discovered as a product of the helium-ion bombardment of americium. This isotope decays with the emission of alpha-particles of maximum energy 6.72 Mev (30 percent) and it emits lower energy alpha-particles of energies 6.55 Mev (53 percent) and 6.20 Mev (17 percent). The half-life of this isotope is 4.6 hours and it decays primarily by electron capture with about 0.1 percent branching decay by alpha-particle emission. The mass number is probably 243 as indicated by chemical separation of the alpha-particle and electron-capture daughters. The name berkelium, symbol Bk, is proposed for element 97. The chemical separation of element 97 from the target material and other reaction products was made by combinations of precipitation and ion exchange adsorption methods making use of its anticipated (III) and (IV) oxidation states and its position as a member of the actinide transition series. The distinctive chemical properties made use of in its separation and the equally distinctive decay properties of the particular isotope constitute the principal evidence for the new element.

As part of the program for obtaining data to extend the scope of the systematics of alpha-radioactivity and to obtain more data pertaining to the energy surface in the heavy region of elements, they have made some pertinent new measurements on protactinium isotopes. The heaviest isotope of protactinium hitherto reported is that of mass 234 and hence it would be of interest to know the beta-emission properties of heavier isotopes in order to tie them in with the known radioactive data in this general region. Since low-energy deuteron bombardment of U{sup 238} might be expected to lead to Pa{sup 235} and Pa{sup 236} by (d,{alpha}n) and (d,{alpha}) reactions and proton bombardment to Pa{sup 235} by the (p,{alpha}) reaction, these irradiations were made in the 60-inch cyclotron at energies of 19 and 9.5 Mev, respectively. The protactinium was chemically separated following the bombardment of natural uranium by a procedure which involved a number of manganese dioxide cycles coupled with extractions of protactinium from aqueous into organic solvents. The manganese dioxide cycles consisted of precipitating this compound from the solution of uranium in nitric acid, followed by centrifugation, dissolution of the solid with hydroxylamine solution, dilution, and reprecipitation. The dissolved precipitate from …

The X-ray Spectrum Produced by 322 Mev Electrons Striking a Platinum Target. The differential energy spectrum of the photons produced by 322 Mev electrons striking a 20 mil platinum target was measured by observing the energy of 3467 pairs produced in a one mil thick lead foil in a Wilson cloud chamber in a magnetic field of 10,000 gauss. The spectrum is found to agree with that predicted by the Bethe-Heitler bremsstrahlung theory using a Thomas-Fermi model with suitable corrections for the thickness of the target. The energy of the 322 Mev electrons was determined by the spectrum of the photons observed in this experiment. Apparatus used and the experimental data and results obtained are reported fully in UCRL-660.

This progress report discusses the activities of the P Division for the month of January 1950. The B, D, F and H pilan operated throughout the month except for outages listed under Area Activities. Power levels were as follow: B pile -- 275 megawatts (MW) D pile -- 305 MW, F pile -- 275 MW increased to 305 MW during the month, and H pile -- 275 MW increased to 330 MW during the month. The piles operated with a time operated'' efficiency of 88.8%. A total of 53.07 tons of metal at an average of 91.2% of the current goal concentration was discharged from the piles during the month. A new record canning yield of 93.9% for 4 inch canned slugs was established during January.

This report summarizes the measurements made for radioactive contamination in the environs of the Hanford Works for the quarter April through June 1949. This belated document is issued for the records to fill in the gap for the quarterly reports not issued in 1949 because of personnel shortage at that time. Although the data summarized in this report were already reported in the H. I. Evirons Reports for the months involved, it is still of value to study the data combining the three months of data which give better opportunity to evaluate the trends and patterns of the levels of radioactive contamination emanating from the various sources at the Hanford Works. This document discusses: meteorological data and radioactive contamination in vegetation, the atmosphere, rain, Hanford wastes, the Columbia River, and in drinking water and test wells.

This report summarizes the measurements made for radioactive contamination in the environs of the Hanford Works. The principal sources of the radioactivity originating as a result of operations at Hanford which affect the environment in this area are the two waste stacks in the separations area and the cooling water from the four pile areas. Measurements are also made on samples taken from the Hanford waste systems which are primarily confined within the project proper. Although monthly summaries of these data are reported in Health Instrument Divisions Environs reports, a somewhat more detailed discussion of these data is covered in the quarterly report. In this manner, a better evaluation of possible trends can be detected as a result of the increased number of measurements made available by combining the data for a three month period. The following areas are discussed: meteorology, radioactive contamination of vegetation, airborne contamination and air radiation levels, radioactive contamination in Hanford wastes, radioactive contamination in the Columbia and Yakima rivers; beta activity in rain and snow, and radioactive contamination in drinking water and test wells.

A first approximation of the gas required to cool control rods for Pile Area G is presented in the following report. Since the results are based on a number of assumptions and approximations, they should be considered only as a first approximation and subject to revision. A gadolinium-stainless steel control rod can probably be readily cooled by gas. A boron-stainless steel control rod would be difficult to cool with gas and would probably require about 1,000 lbs./hr. of helium per rod. Carbon dioxide has a slight advantage over helium as a cooling agent for control rods. This advantage is so small that the problems of gas cooling control rods should not influence the decision whether to use helium or carbon dioxide in the pile.

Neutron density at the end of the slug is increased appreciably and therefore the heat production in the end of the slug is also increased. The end result is increased heat flow into the cap with correspondingly higher temperatures. The combined results and conclusions of documents CP-1580, CP-1989, and CP-2871 afford a means of calculating the aluminum end cap temperatures with consideration being give to the above mentioned {open_quotes}Wilkins effect,{close_quotes} i.e., that the heat production near the end of a slug with an aluminum end cap is greater than the heat production at the middle (axially) of a slug. The maximum temperature in the aluminum end cap is calculated to be about 278{degrees}F. for the {open_quotes}G{close_quotes} Pile. This temperature occurs at the center of the maximum performance process tube.

The purpose of this memorandum is to present and analyze, in terms of the current status of knowledge of radiation damage to graphite, the data available at the present time on the expansion status of the graphite in the piles, and suggest, in terms of this analysis, several possibly feasible curative and preventive measures. The portion of the data to be covered in this memorandum consists of that obtained during the last four years from pile motion measurements and from tube bowing measurements, and particularly that from graphite mining operations during the last six months. The objective to be attained is twofold: (1) the information developed here should permit a better understanding of the need for and development of future corrective measures to be applied to the present piles, and (2) this summary will serve as a basis for further experimental work necessary to place the conclusions on a more firm foundation. This memorandum is being issued at this time, although present ideas and conclusions are in a somewhat uncertain state, in the hope that the currently most feasible preventive measure might be applied to the DR Pile before startup.