The concept of the external-fuel thermionic converter, in which the fuel surrounds an inner emitter annulus, is introduced and the major advantages of its use in a thermionic reactor are discussed. In-core reactors, ranging from 15-ekW to megawatts, can be designed based on external-fuel converter modules of fixed emitter and collector dimensions. Sizes and weights of typical reactors in this power range are shown.

None

None

Progress is updated for projects related mostly to biological and ecological radiation effects.

This report details activities of the Reactor and Materials Technology Department during the month of April 1965.

Optimization of the reactor process involves the knowledge of the longitudinal flux distribution on a semicontinuous, routine basis. The nonpoisonous spline was proposed as a way for obtaining flux traverses at any time during reactor operation, in virtually any location in the core. This report summarizes the findings of a feasibility study conducted in conjunction with PITA-18 and thus serves as a termination of the test phase of spline traversing.

The performances of aqueous-homogeneous (AHBR), molten-salt (MSBR), liquid-bismuth (LBBR), gas-cooled graphite-moderated (GGBR), and deuterium- moderated gas-cooled (DGBR) breeder reactors were evaluated in respect to fuel yield, fuel cycle costs, and development status. A net electrical plant capability of 1000 Mwe was selected, and the fuel and fertile streams were processed continuously on-site. The maximum annual fuel yields were 1.5 mills/ kwhr. The minimum estimated fuel cycle costs were 0.9, 0.6, 1.0, 1.2, and 1.3 mills/kwhr at fuel yields of were 0.9, 0.9, 1.5, 1.5, and 1.3 mills/kwhr. Only the AHBR and the MSBR are capable of achieving fuel yields substantially in excess of 4%/yr, and therefore, in view of the uncertainties in nuclear data and efficiencies of processing methods, only these two can be listed with confidence as being able to satisfy the main criterion of the AEC longrange thorium breeder program, viz. a doubling time of 25 years or less. The development effort required to bring the various concepts to the stage where a prototype station could be designed was estimated to be least for the AHBR, somewhat more for the MSBR, and several times as much for the other systems. The AHBR was judged to rank first in …

The performances of aqueous-homogeneous (AHBR), molten-salt (MSBR), liquid-bismuth (LBBR), gas-cooled graphite-moderated (GCBR), and deuterium- moderated gascooled (DGBR) breeder reactors were evaluated in respect to fuel yield, fuel cycle costs, and development status. A net electrical plant capability of 1000 Mwe was selected with continuous processing of fuel and fertile streams. The maximum annual fuel yields were 16, 7, 4, 4, and 4.5%/yr, respectively at a fuel cycle cost of 1.5 mills/kwhr. The minimum estimated fuel cycle costs were 0.9, 0.6, 1.0, 1.2, and 1.3 mills/kwhr at fuel yields of 7, 1, 1, 2, and 3%/yr. At a fuel yield of 4%/yr, the costs were 0.9, 0.9, 1.5, 1.5, and 1.3 mills/kwhr. Only the AHBR and the MSBR are capable of achieving fuel yields substantially in excess of 4%/yr, and therefore only these two can be listed with confidence as being able to satisfy the mdin criterion of the AEC long-range thorium breeder program i.e., a doubling time of 25 years or less. The development effort required to bring the various concepts to the stage where a prototype station could be designed was estimated to be least for the AHBR, somewhat more for the MSBR, and several times as much for …

This report discusses the delayed neutron characteristics of a reactor which are a function of the distribution of fissions in the various fissionable isotopes. The delayed neutron characteristics of the NPRL delayed fraction and decay constants, are presented as functions of exposure to 2000 MWD/T for both room temperature and operating temperature. It is of importance to note that the delayed neutron fraction decreases from 0.693% to 0.539% with increased exposure. Thus 22% less reactivity change represents a prompt critical condition at 2000 MWD/T, compared to the zero exposure condition.

Recently a T = 1 resonance in the {Lambda}-{pi} system called Y{sub 1} has been observed with a mass of 1385 MeV. Two types of resonances have been predicted that might relate this observation to other elementary-particle interactions: (1) P 3/2 resonances in the {Lambda}-{pi} and {Sigma}-{pi} systems predicted by global symmetry, corresponding to the (3,2/ 3/2) resonance of the {pi}-N system, (2) a spin-1/2 Y-{pi} resonance resulting from a bound state in the {bar K}-N system. The position and the width of the observed Y{sub 1} resonance agree with both theories, but since the spin and parity have not yet been determined, they cannot distinguish between the two theoretical interpretations.

BS>Critical studies of a fast reactor core containing a simulated oxide fuel having an oxygen-uranium atomic ratio of 1: 1 are described. Calculated and experimental critical masses are compared. Experimental results are given for fission ratio, central reactivity coefficient, fuel bunching, and distributed worth measurements. (auth)

A second order form of the cylindrical P-3 equations is obtained for the case of an isotropic source. The boundary conditions and numerical method are discussed. Input preparation and operating instructions are included. (auth)

BAND-1 is an IBM-704 program to reduce the experimental data obtained from measurements of the neutron activation distribution within a critical facility. The data reduction consists of correcting the measured data, sorting and ordering it, and calculating the critical buckling parameters by means of a least squares analysis. (auth)

Production of {Lambda} + K{sup 0}, {Sigma}{sup 0} + K{sup 0}, and {Sigma}{sup -} + K{sup +} by 1170-MeV/c {pi}{sup -} mesons has been studied in the Lawrence Radiation Laboratory 72-inch hydrogen bubble chamber, Cross sections, angular distributions, and polarizations are presented. The polarization of the {Sigma}{sup 0} is determined at four center-of-mass angles and found to be small everywhere. Based on published results for the reaction {pi}{sup +} + p {yields} {Sigma}{sup +}, K{sup +}, a comparison of the polarizations of {Sigma}{sup +}, {Sigma}{sup -}, and {Sigma}{sup 0} is made from the charge-independence triangle. A conclusion is reached that the {Sigma}{sup -} polarization should be large, and that the {Sigma}{sup -} and {Sigma}{sup +} polarizations should be opposite in sign.

In uranium with alloying additions of up to 400 ppm Fe and up to 800 ppm of either Si or Al, the various U-containing phases were examined with the electron microscope. These phases were also extracted chemically and identified by electron diffraction. During gamma -phase heat treatments, the alloying additions, as well as impurity atoms, segregate into networks of incipient'' precipitates that can be seen only afier certain etching treatments. (auth)

The projection welded brazed closure is being studied as a possible alternate method of closing coextruded Zircaloy-2 clad uranium fuel elements for the NPR. This closure consists essentially of projection welding the Zircaloy-2 cap to the element cladding followed by a fast resistance heating of the cap and exposed uranium face under pressure to braze the cap to the uranium face. The work to date has been entirely on 0.593 inch OD rods and 1.050 inch OD by 0.500 inch ID tubular elements. This closure has the advantage that the entire closure is completed in less than 5 seconds on one machine and consequently the element is at a temperature which would be detrimental to the Zircaloy-2 cladding and uranium bond for a very short time. The amount of uranium removed for this closure is reduced by a factor of 10 over conventional braze closure methods with a substantial savings in uranium and acid milling time. A braze material which is not toxic can be used to bond the cap to the uranium.

None

None

A class of linear proportional servomechanisms is examined in which an electrical signal proportional to output force is used to improve performance. The effect of this "force feedback" on a positional servomechanism is analyzed as well as the effect on a special type of servomechanism which reflects load forces back to the input. This latter type of servomechanism is called "force reflecting." Laboratory models of these servormechanisms were designed and constructed, and experimental data are presented in support of the analysis. (auth)

This report summarizes releases of radioactive waste to the environs of the Savannah River Plant during the calendar year 1965. Total quantities of radioactive waste released from plant startup through 1965 are also reported. Accuracy is not always implied to the degree indicated by the number of significant figures reported. Values were not rounded off, since data will be used in future cumulative summaries. No explanations are given for unusual releases; this information may be found in the Radiological and Environmental Sciences Division Monthly Reports and in the Semi- annual and Annual Environmental Monitoring Reports for 1965.

This report addresses the contributions by the Atomics International to the 24th High Temperature Fuels Committee Preliminary Information.

The condenser-discharge method of conducting molten metal- water reactions at high temperatures was refined. Two methods to measure energy input to specimen wires and, therefore, to compute initial metal temperatures were developed. Calculated metal temperatures were estimated to be accurate to within 100 deg C. Two reaction cells were designed, one for operation at atmospheric pressure with water at room temperature, and the other for operation at high pressure and with water at elevated temperature. Means were developed to determine the surface area of metal exposed to reaction and to determine the total extent of reaction. Pressure transducers were used to record the rate of reactions. The zirconium- water reaction was studied with initial metal temperatures from 1100 to 4000 deg C with 30 and 60-mil wires in room-temperature water. Initial pressures in these runs were the vapor pressures of water at room temperature (20-30 mm). Runs were made with 60-mil wires in water heated to 200 deg C (225 psi). Results in room-temperature water indicated that the reaction became explosive at an initial metal temperature of 2600 deg C. Below this temperature, 20% or less reaction occurred. At higher water temperatures, reaction ranged from 40 to 70%. Runs in …

Further studies of the Zr-water reaction by the condenser-discharge method are reported. The reaction was studied with initial metal temperatures from 1100 to 4000 deg C with 30- and 60-mil wires in water from room temperature to 315 deg C (1500-psi vapor pressure). Runs in heated water showed markedly greater reactions. This was explained in terms of a 2-step reaction scheme in which the reaction rate is initially controlled by the rate of gaseous diffusion of water vapor toward the hot metal particles and of hydrogen, generated by reaction, away from the particles. At a later time, the reaction becomes controlled by the parabolic rate law, resulting in rapid cooling of the particles. A mathematical model of the reaction of molten metal spheres with water was proposed. Explosive reactions were found to occur with particles smaller than about 1 mm in heated water and 0.5 mm in room-temperature water. The explosive reactions were caused by the ability of the evolving H/sub 2/ to propel the particles through water at high speed. The high-speed motion was detected on motion picture film and had the effect of removing the gaseous diffusion barrier (increasing the Nusselt number), resulting in very rapid reaction. Computed …

The losses of charged particles from a detector aperture, due to multiple scattering of the particles in thin layers of material preceding the detector, are calculated with the aid of a high-speed digitai computer. The rootmean-square multiple-scattering angle is computed after the method of Moliere, and graphs are presented for protons and alpha particles scattering in nitrogen, aluminum, argon, copper, silver, and gold, and for deuterons and tritons scattering in aluminum and copper. The range of particle energy covered is from 5 to 100 Mev. A second program is used to construct a map from which losses, as a function of the root-mean-square multiple-scattering angle and the scattering configuration, may be directly read. The FORTRAN listings for both programs are given. (auth)