An investigation was made of high-energy neutron damage in Cu and Nb irradiated with approximately 15 MeV neutrons at the Oak Ridge Isochronous Cyclotron. The neutrons were generated by bombarding a thick Be target with 40- MeV deuterons resulting in a high energy neutron spectrum broadly peaked at 15 MeV. Single crystals of Cu and Nb were irradiated at room temperature to fluences of approximately 2 x 10$sup 17$ n/cm$sup 2$. The resulting loop-type defect clusters in the crystals were characterized using x-ray diffuse scattering and transmission electron microscopy. The cluster size distributions were found to be generally similar to those characteristic of fission neutron irradiations in these materials and no multiple clusters or sub-clusters were observed. Additional comparisons with fission reactor irradiations in Cu and Nb indicate that the retained displacement damage in these crystals is approximately 3 times greater for the high-energy neutrons than for an equivalent fluence of fission neutrons. This result is consistent with detailed damage energy calculations for the Be(d,n) neutron spectrum. (auth)

The $sup 252$Cf Activation Analysis Facility at the Savannah River Laboratory (SRL) is used routinely for multielement analyses of a wide variety of solid and liquid samples (e.g., metal alloys, fly ash and other airborne particles, rocks, and aqueous and nonaqueous solutions). An automated absolute activation analysis technique, developed to use neutron transport codes to calculate multienergy group neutron spectra and fluxes, converts counting data directly into elemental concentrations expressed in parts per million. The facility contains four sources of $sup 252$Cf totaling slightly over 100 mg. A pneumatic ''rabbit'' system permits automatic irradiation/decay/counting regimes to be performed unattended on up to 100 samples. Detection sensitivities of less than or equal to 400 ppb natural uranium and less than or equal to 0.5 nCi/g for $sup 239$Pu are observed. Detection limits for over 65 elements have been determined. Over 40 elements are detectable at the one part per million level or less. Overall accuracies of +- 10 percent are observed for most elements. (auth)

A pulsed dc power system provides 120 kA excitation current for the ORMAK toroidal field coils. A drive potential of 1000 volts brings the coils up to full current in about 0.5 seconds. Constant current is maintained for 0.25 seconds, then approximately 20 x 10$sup 6$ joules of stored energy is dumped in a free-wheeling diode and resistance network. The power system contains 8 each, 30 kA, 500 V thyristor controlled dc power modules in a series/parallel combination. A control computer generates thyristor trigger pulses in a programmed sequence as required for the desired duty cycle. A feedback network including current sensing and computer software permits trigger timing adjustments as necessary for constant current operation. (auth)

This paper describes a new rf heating system which has just been completed and is now operational on the ATC machine. The system utilizes four UHF TV klystrons to generate at least 200 kW of power at a frequency of 800 MHz. Pulse widths can be varied from 20 $mu$sec up to 20 msec. A radar type floating deck modulator along with photo-optical transmitting and receiving devices have been incorporated into the system to provide the pulse fidelity and versatility which characterizes this equipment. Modular construction was emphasized in the design, when possible, to reduce maintenance and down time in the advent of component falilure. Hybrid combining techniques are utilized in order to provide two 100 kW feeds into the machine. (auth)

The AMPX system was used to generate a P$sub 3$ 218 neutron group master cross-section library from ENDF/B-IV data for the fuel, structural, and neutron- absorbing materials tabulated. The library is the data base for the generation of broad-group cross sections for shipping cask calculations and other criticality safety analyses using codes such as KENO and ANISN. Selection of the fine-group energy structure for the 3-eV to 20-MeV energy range included consideration of the resonance structure of prominent nuclei, the thresholds of important reactions, and the fission spectra. For 10$sup -5$ less than or equal to E/sub n/ less than 3 eV, 78 closely spaced thermal groups were chosen to examine the effects of low-energy resonances and thermal-neutron upscatter. Distribution of the 218 groups within the Hansen-Roach 16-group boundaries is shown. Adequacy of the group structure and validity of selected data sets from the library were tested by P$sub 3$S$sub 8$ XSDRNPM calculations of k-eff for two benchmark critical experiments; first, the 4.9 percent-enriched UO$sub 2$F$sub 2$- H$sub 2$O solution critical sphere experiment of Johnson and Cronin was analyzed, and, second, the 93.2 percent-enriched UO$sub 2$F$sub 2$-H$sub 2$O solution critical sphere experiment of Fox was analyzed. (auth)

For approximately four years studies have been under way at the Rocky Flats plant to determine contamination patterns and concentrations of Pu in the biota. Contamination of the Rocky Flats environs has resulted from at least three incidents, a September 1957 fire, a May 1969 fire, and leaking barrels containing plutonium-laden cutting oil. The latter incident was considered by far the major source of the plutonium contamination. Results are reported from a study conducted to determine whether snake tissues of the area contained detectable amounts of /sup 239/Pu and, if so, at what concentrations. Eastern yellow-bellied racers (Coluber constrictor flaviventris, bullsnakes (Pituophis melanoleucus sayi, and prairie rattlesnakes (Crotalus viridis viridis, were collected for /sup 239/Pu bioassay of lung, liver, and bone tissues. Snakes were captured using drift fences terminating in funnel traps and by opportunistic sampling. Results led to the conclusion that snakes are not an important organism in the redistribution of /sup 239/Pu. (CH)

The feasibility of constructing a radioisotope scanner using a Ge(Li) detector with adequate efficiency for clinical use is discussed. (WHK)

Small-angle neutron scattering techniques have been used to study the angular distribution of the critical scattering from cobalt above T/sub c/. These measurements have been put on an absolute scale by calibrating the critical scattering directly against the nuclear incoherent scattering from cobalt. In this way the interaction range r$sub 1$, which appears in the classical and modified Ornstein--Zernike expressions for the asymptotic form of the spin pair correlation function and is related to the strength of the spin correlations, has been determined. We obtain r$sub 1$/a = 0.46 +- 0.03 for the ratio of the interaction range to the nearest-neighbor distance in cobalt. This result is in good agreement with theoretical predictions. Lack of agreement among previous determinations of the ratio r$sub 1$/a made in iron failed to provide a definitive comparison with theory. (auth)

None

None

Application of the power iteration method to the multigroup response matrix equations reduces them to a series of one-group problems. Applying acceleration techniques to each of these monoenergetic problems results in substantial reductions in computational effort. The use of point over-relaxation methods in the solution of these equations is described. Over-relaxation is also applied to the outer-iteration eigenvalue and source estimations with considerable success. 10 references. (auth)

None

Acoustic sounder measurements of a vertical profile of the abrupt transition from a laminar to a turbulent atmospheric boundary layer were compared with meteorological measurements made at 10 m and 137 m on an instrumented tower. Sounder data show that conditions necessary for onset of the momentum burst phenomenon exist sometime during a clear afternoon when heat flux changes sign and the planetary surface cools. Under these conditions, the lowest part of the atmospheric boundary layer becomes stable. Prior to this situation, the entire boundary layer is in turbulent motion from surface heating. The boundary layer is then an effective barrier for all fluxes, and as the maximum flux Richardson number is reached at some height close to but above the surface, turbulence is dampened and a laminar layer forms. The profile of this layer is recorded by the sounder. Surface temperature drops, a strong wind shear develops, and the Richardson number decreases below its critical value (Ri/sub CR/ less than 0.25). Subsequently, the laminar layer is eroded by turbulence from above, and with a burst of momentum and heat, it eventually reaches the ground.

A feasibility study has been conducted to evaluate the potential use of acoustic emission to monitor thermal-shock damage in direct electrical heating of UO$sub 2$ pellets. In the apparatus used for the present tests, two acoustic- emission sensors were placed on extensions of the upper and lower electrical feedthroughs. Commercially available equipment was used to accumulate acoustic- emission data. The accumulation of events displayed on a cathode-ray-tube screen indicates the total number of acoustic-emission events at a particular location within the pellet stack. These tests have indicated that acoustic emission can be used to monitor thermal-shock damage in UO$sub 2$ pellets subjected to direct- electrical heating. 8 references. (auth)

The operation of the ANL 4-MeV accelerator for the reporting period September 1, 1974 through August 31, 1975 is described. Some improvements and modifications to the accelerator and associated equipment are reported, and activities on the three research projects are summarized. An outline of work for the next reporting period indicates a shift from the BYU 2-MeV accelerator to the 4-MeV accelerator to take advantage of the higher beam energy. (auth)

Techniques were developed for estimating varying device coefficients in the control system of LBL neutral beam sources. The calibration of the current control is described, and results of a computer simulation are given. (PMA)

None

The major effort during this reporting period was directed toward performing the analytical design task and initiating the laboratory setup for the self-cleaning heat exchanger concept. Analytical design includes the selection of a suitable demonstration site, water chemistry and temperature, and thermodynamic power cycle, and parametric design and sensitivity analysis of a heat exchanger suitable for a 10 MW electric proof of concept plant. (MHR)

The APEX program is designed to investigate the concept that a continuously recirculating flow of fine solid particles in the brine stream will substantially retard the formation of scale in the primary heat exchanger. The primary technical effort during this reporting period has been the buildup of the test facility. Some preliminary testing has been conducted in order to establish process equipment suitability prior to completing the test facility design. Fouling experiments have also been conducted in the chemistry laboratory to preliminarily screen candidate geothermal fluid simulants. (MHR)

None

A description is given of a basic supercritical refrigerator. The present status of the cable enclosure and the types of cooling schemes being considered are presented with some examples of laboratory results and computer analysis. (MOW)

During this reporting period the characteristics of several types of advanced thermionic energy converters were explored, both analytically and experimentally. Two new converter test vehicles were developed and two test stands and a controlled-atmosphere converter processing station were completed for use in the experimental program. Our previous understanding of pulsed converters was confirmed experimentally, and the work of earlier investigators concerning the inert gas ignited triode was substantiated. However, the experimental performances of the cesium vapor ignited and unignited triode converters were found to be significantly less than expected. More detailed analysis of their basic operation has revealed previously unsuspected constraints on the plasma in these advanced modes of operation. Based on both analysis and experimental results, the ignited triode was selected as the most attractive mode of converter operation for more intensive future study. A ''mini-system'', combining a thermionic diode operating in air and a flux-reset circuit, was constructed to demonstrate that inductive output coupling could be used effectively. A variety of thermionic heat exchanger concepts was evaluated, and cylindrical geometry was selected as the reference design concept. System analysis showed this design should be economically attractive for topping central station electricpower plants if 2nd generation performance can be …

None

None