"This is the fourth Quarterly Report on Task II dealing with Methods Development for Radio-Tracing of Coal Product Hydrocarbons With Tritium. The problem of radio-chemical purity of traces is resolved by developing a new method of labeling with tritium that generates essentially no highly tagged side products or impurities."

"This is the third quarterly report on Task II dealing with Methods Development for Radio-Tracing of Coal Product Hydrocarbons With Tritium. The problem of accurate low-level tritium assay for tagged hydrocarbons has been resolved and attention is now primarily directed at the questions of tritium mobility and radio-chemical purity in tagged tracers."

"With careful attention to details, tritium assays of satisfactory accuracy have been achieved on low activity standard samples by dry combustion and liquid scintillations counting of the product water.This method is faster, more accurate and dependable than the zinc fusion-ion chamber method fro low level tritium assays. At 380 degrees C, tritium loses from hydrocarbon tracers by isotopic exchange is significant and must be corrected for in tracer measurements at this elevated temperature."

The spectrum of the mono-energetic neutron transport operator for a homogeneous sphere where the neutrons are scattered with spherical symmetry in the laboratory system is considered.

...Development during this quarter have caused a shift in emphasis of the Pebble Bed Reactor Fuel Element Development Program from coatings on the sphere surface to coatings on individual fuel particles as the major deterrent to fission product leakage. In a high level irradiation test, cracks developed in the coatings of specimens coated with pyrolytic carbon and siliconized silicon carbide. In another high level irradiation test, a graphite sphere fueled with Al2O3 coated with UO2 particles is showing excellent fission product retention. The leakage factors (i.e. rate of release/rate of production) for long lived volatile fission products such as Kr85m, Kr87, Kr88, Xe133, Xe135 are ranging from 10 to the negative 9th to 10 to the negative 6th. If this degree of fission product retention is maintained in a large power reactor, it would result in essentially a "clean" primary loop.

A nuclear model has been developed for homogeneous, two-region reactors possessing a relatively large percentage of epithermal absorption in both the core and blanket region. A number of new IBM 650 programs have been developed and existing programs modified to form a group of programs, compatible with the nuclear model and with each other, which can be used for preliminary evaluation of the effed of design variable on reactor characteristics.

Tests were conducted to determine the friction factor of randomly packed beds of 3/4-inch diameter spheres in 8-inch and 15-1/4-inch diameter beds, and of 1-1/2-inch diameter spheres in 15-1/4-inch diameter bed. The bed depths were varied in an attempt to isolate the effects of entrance and exit losses. The bed Reynolds number, base on sphere diameter, was varied from 5,000 to 50,000.

The coolant stream of all nuclear reactors caries some activity due to one or more of the following: a) neutron activation of coolant atoms, b) neutron activation of corrosion products carried by the coolant stream, c) fission recoil into the coolant stream, d) fission products leaking into the coolant stream. The Pebble Bed Reactor is not concerned with (1) and (b) since the helium working fluid, or coolant, has an activation cross-section which is essentially zero and its inert chemical nature effectively eliminates corrosion as a consideration. We are not concerned with (c) since developments to date, of fuel and particle coatings to reduce fission product leakage, will also prevent fission recoil into the coolant stream.

Previous results from the Pebble Bed Reactor Fuel Element Development Program had shown the excellent promise of vapor-deposited Al2O3 doq5intw on UO2 particles as a low permeability high temperature fission product barrier. However, since the matrix material for the PBR fuel element is a graphite sphere, carbonaceous coatings on the dispersed fuel particles might be of more interest because of improved particle coating-matrix compatibility and no displacement of neutron moderating materials. Since a pyrolytic carbon coating also appeared to be low permeability higt temperature material, emphasis was placed on the development of pyrolytic carbon coated UC2 particles dispersed in a graphite sphere as the reference PBR fuel element.

When light propagates with the wave normal in the direction of an optic axis of a biaxial crystal, the usual ray theory breaks down. This phenomenon can be analyzed by means of an asymptotic solution of Maxwell's equations. The intensity is governed by a partial differential equation within the phase surfaces, instead of ordinary differential equations along rays. This example slows that light does not always propagate along rays. A similar phenomenon occurs in hydromagnetics.

An approximate Boltzmann equation, known as the single relaxation model is studied here. This equation is linearized and the fundamental solution is considered. Following N. Grad, the solution, asymptotic in small values of the ratio of mean-free-path to distance from the origin, is sought. It can be shown that the fundamental solution itself gives the asymptotic description of the flow field past an object. This solution gives the asymptotic description when the distance from the origin is much greater than either the mean-free-path or the body size. This is true independently of the Knudsen number.

Absolute (p,n) cross sections have been measured for Ti47, V51, Cr52, Co59, and Cu63 at energies between 4 and 6.5 Mov. These data plus earlier measurements of the cross section for inelastic proton scattering have been used to estimate total proton absorption cross sections for V51 and Co59. An optical model calculation using parameters giving a good fit to elastic scattering measurements predicts an absorption cross section in good agreement with the measurements for Co59. For V51, some sets of parameters gave good agreement with the measured absorption cross section, but the fit to the elastic scattering data was only fair.

Nuclear processes are random in character, and, accordingly, are amenable to statistical treatment. In 1905, shortly after the discover of natural radioactivity, E. Von Schweldler showed that the analytical description of the decay distribution of radioactive substances followed from probability considerations regardless of the mechanism involved in the process of atomic disintegration.

"This report describes two experiments performed in an effort to supply evidence for the universality of the V-A theory in weak interactions and for the law of conservation of leptons. In this first part the production rate of B to the 12th by the absorption of negative mu mesons in carbon was measured. From the amplitudes of the muon decay curve and the boron decay curve the rate was calculated to be (5.8 plus or minus 1.3) x 10 to the 3rd sec -1, in agreement with the hypothesis of a universal V_A theory. In the second part an attempt was made to measure the helicity of negative mu mesons by stopping longitudinally polarized muons in a carbon target and observing the electron asymmetry in the β-decay of the spin-1 B to the 12th. The results of this part were inconclusive, a consequence attributed to a short boron thermal relaxation time."

"The lifetimes of approximately 6 million positive mesons have been measured using a crystal controlled oscillator as a clock. The resulting decay curve was analyzed on the IBM 650 digital computer and gave a mean life of 2,211 plus or minus 0.003 µsec. The mean life of negative mu mesons in carbon was also measured and found to be 2,043 plus or minus 0.003 µsec. The resulting nuclear capture rate is (0.373 plus or minus 0.011)x10 to the 5th/sec, assuming that the decay rate of a negative mu meson bound in carbon is equal to the decay rate of the positive meson."

"In 1935, Yukawa proposed that a field must exist, analogous to the electromagnetic field but different in nature, which is responsible for the attraction between a proton and a neutron in a nucleus. He was led to the prediction of the existence of particles, quanta of this field, with mass intermediate between that of the electron and proton. In 1947, using photographic plates, the Bristol group led by Powell confirmed the existence of these particles, meons."

"The design of the nuclear track intensifier was further analyzed to compare performance with design objectives. A preliminary analysis of the electron optics showed that the tube design suffers a small degree of astigmatism, which is increased in actual tabes by misalignment of parts, One tube was successfully completed and tested. Transit time of electrons from cathode to screen was determined to be 2.5 x 10/sup -8/ sec, 0.5 x 10/sup -8/ sec. Decay characteristics of several standard phosphors were measured. In the phosphor development phase, a latin square test was designed to evaluate combinations of thallium-activated rubidium iodide and cesium iodide phosphors under various evaporating conditions. Data were taken on various tests and analyzed statistically. On target samples submitted for tube evaluation, a reaction, which reduced light output, occurred between the aluminum and phosphor during vacuum bake. Oue image tube prepared with an alkali iodide mixture showed 10 to 25% improvement in screen resolution as compared to a P-11 screen."

"Development of a nuclear track image intensifier which is to have a cathode dia. of 83 in. and an output screen dia. of 1 in. is reported. Spherical faceplates for the intensifier which were etched to a thickness of 0.025 in. over a dia. of 80 in. withstood a pressure differential of 2 atm. Techniques were developed to measure spectral energy distribution, phosphor burn characteristics, phosphor efficiency, and phosphor persistence. Thallium- activated RbI and CsI were evaluated for use in the first stage of the image intensifier system. A color shift toward the yellow was accomplished in rubidium iodide phosphor by increasing the mole % of Th activator. Burn varied widely in different samples."

"Design and fabrication techniques were improved so that the large area image intensifier now performs well in image intensifier systems for photographing nuclear tracks. Two successful samples meeting most of the objectives were completed and started in circulation among members of the AEC Image Intensifier Committee for evaluation in systems to record nuclear tracks. Except for a reported long decay in the P-15 phosphor performance was quite good. Resolution, gain, and background requirements were met. Magnification was still high (1/6.5 compared to a design objective of 1/8) but can be lowered to 1/8 by a straightforward mechanical change. Evaporated layers of thallium activated rubidium and cesium iodide were improved and further evaluated. Improved control of color and persistence was obtained. Efficiency as high as 1/3 that of P-11 phosphor was obtained in some samples. The current test series confirmed earlier results that an increase in cesium iodide content shifts the emission spectrum towards the yellow. Burn-resistance and light output was poorer for the cesium enriched phosphors while decay time was decreased.

"The grafting of methacrylic acid, styrene (2: 1 mole ratio) co-monomer mixture on polypropylene film and fabric, was studied to compare electron accelerators and isotopes as sources of radiation. An aluminum block that contalns i/8-in.-deep pockets covered with Mylar film for holding sample and monomer during mutual irradiatlon was developed. A preliminary comparison was made in post grafting polypropylene film and fabric preirradiated with Cow and with an electron accelerator source. It was found that post grafting was rapid at 80 ts C but slow at room temperature. Monomer equilibration before irradiation increased the grafting rate. Higher grafts were obtained when samples were irradiated in sparged and sealed containers. The grafting rate increased as dose rate decreased."

"A finite difference approximation to a non-linear set of parabolic differential equations arising in shallow water theory is given. These difference equations were used to determine the shape and rate of propagation of a hum of fluid down a channel of constant depth. The hump of fluid was found to spread instead of steepen, as is the case in the usual shallow water theory."

"The loss of particles through a cusp of a particular containment geometry utilizing cusped magnetic field lies is considered. A velocity space loss criterion analogous to the loss cone in the mirror machine is derived. The effect of a uniform longitudinal magnetic field perpendicular to the containing field is considered and a loss criterion is derived. The effect of the longitudinal field is to decrease cusp losses.

"One of the fundamental concepts of macroscopic physics is that of a homogeneous system. The state of such a system is completely described by a set of intensive parameters which make no reference at all to the size or shape of the system, and by the total number of particles, N (unless otherwise specified we deal with one-component fluid). In actual systems, there are always inhomogeneities due to boundaries and to gravitational body forces."

"A comparison of the grafting of a 2:1 molar mixture of methacrylic acid and styrene to both polypropylene film and fabric using CO60 source and electron accelerator as sources of ionizing radiation is made on the basis of mutual or simultaneous grafting and post-irradiation grafting.