Changes in the structure of (Mo /sub 6/Ru /sub 4/)/sub x/B/sub 1-x/ amorphous alloys were observed in positron annihilation analysis using both positron lifetime and Doppler broadening techniques. The changes were introduced into the alloy either by varying the boron fraction or by neutron irradiation. Similar results were observed both in the irradiated alloys and those with vacant boron sites. The positron annihilation data suggest that the modified structure contains regions of open volume and that the positrons interact with those regions.

The key properties of spark counters include their capability of precision timing (at the sub 100 ps level) and of measuring the position of the charged particle to high accuracy. At SLAC we have undertaken a program to develop these devices for use in high energy physics experiments involving large detectors. A spark counter of size 1.2 m x 0.1 m has been constructed and has been operating continuously in our test setup for several months. Some details of its construction and its properties as a particle detector are reported. 14 references. (WHK)

Fusion blanket designs have for almost a decade considered the use of a solid breeder relying on available data and assumed performance. The conclusion from these studies is that acceptable neutronic and thermal hydraulic performance can be achieved. In the future, it will be necessary to establish that a particular material can tolerate the thermal and irradiation environment of the fusion blanket while still providing the required functions of tritium recovery, power production and neutron shielding.

In the Tandem Mirror Experiment Upgrade (TMX-U), the formation of a thermal barrier and the potential plugging of ion end loss were achieved at central-cell densities up to 2 x 10/sup 12/ cm/sup -3/. The presence of a thermal barrier was confirmed by direct measurement, and ion axial-confinement times in the range 50 to 100 ms were measured. The ECRH in the end cells (a) initiates plasma startup, (b) generates hot, mirror-confined electrons to form thermal barriers, and (c) creates the plugging potential for central-cell ions. The ECRH system consists of four 200 kW, 28 GHz gyrotrons each feeding power to a separate heating location (two in each end plug). Fundamental heating is used at the potential plug, and second harmonic is used in the thermal barrier. Hot-electron plasmas are produced at total end-cell antenna power levels up to 300 kW. Strong single-pass absorption and net hot-electron heating efficiencies exceeding 40% are observed. Hot-electron parameters achieved are: n/sub eh//n/sub et/ up to 0.8, volume-average beta <..beta..> approx. = 0.15, and T/sub x/ (x-ray tail above 40 keV) in the range 75 to 200 keV.

Irradiation embrittlement of the neutron shield tank (NST) A212 Grade B steel from the Shippingport reactor, as well as thermal embrittlement of CF-8 cast stainless steel components from the Shippingport and KRB reactors, has been characterized. Increases in Charpy transition temperature (CTT), yield stress, and hardness of the NST material in the low-temperature low-flux environment are consistent with the test reactor data for irradiations at < 232{degrees}C. The shift in CTT is not as severe as that observed in surveillance samples from the High Flux Isotope Reactor (HFIR): however, it shows very good agreement with the results for HFIR A212-B steel irradiated in the Oak Ridge Research Reactor. The results indicate that fluence rate has not effect on radiation embrittlement at rates as low as 2 {times} 10{sup 8} n/cm{sup 2}{center dot}s at the low operating temperature of the Shippingport NST, i.e., 55{degrees}C. This suggest that radiation damage in Shippingport NST and HFIR surveillance samples may be different because of the neutron spectra and/or Cu and Ni content of the two materials. Cast stainless steel components show relatively modest decreases in fracture toughness and Charpy-impact properties and a small increase in tensile strength. Correlations for estimating mechanical properties of cast …

As part of the effort to employ a plasma focus as a driver for fusion micro-explosions, many target concepts were explored and extensive imposion calculations have been carried out. Some of the basic principles of micro-explosion design are presented.

The techniques used in implementing two applications of real time analysis of data from the DIII-D tokamak are described. These tasks, which are demanding in both the speed of data acquisition and the speed of computation, execute on hardware capable of acquiring 40 million data samples per second and executing 80 million floating point operations per second. In the first case, a feedback control algorithm executing at a 10 kHz cycle frequency is used to specify the current in the poloidal field coils in order to control the discharge shape. In the second, fast Fourier transforms of Mirnov probe data are used to find the amplitude and frequency of each of eight toroidal mode numbers as a function of time during the discharge. Data sampled continuously at 500 kHz are used to produce results at 2 msec intervals.

State-of-the-art hot cell examination techniques are being used to evaluate spent fuel performance during exposure to simulated geologic repository environments. Forty-five pressurized light water reactor fuel rods were examined prior to emplacement in geologic disposal tests. Sufficient data were collected on both cladding and fuel to provide a basis, along with post-test examination data, for assessing the ability of the spent fuel to retain radionuclides.

Experiments that measure the strength of different transfer reactions in heavy reaction systems at energies in the vicinity of the Coulomb barrier are discussed. A short discussion is given of experimental techniques that are available in this field and their advantages and shortfalls. The main features of the transfer reactions are summarized. Questions concerning the system dependence and energy dependence of the strongest reaction channels are addressed. A systematic picture of the strength of the neutron transfer cross sections is presented. Some examples for correlations between fusion exchangement and transfer cross sections are given.

The sequential emission of /sup 4/He is demonstrated in the reaction Ho + Ta and the /sup 4/He angular distribution is used to test the rigid rotation limit in the reaction Ho + Ag. A more refined analysis of the dependence of continuum ..gamma..-ray multiplicities upon Q-value and gamma ray energy shows that reasonable agreement with the statistical model is obtained if one assumes the presence of low energy aligned dipole transitions in the reactions Ho, Yb, Sm, Ag + Ho. Sequential fission angular distributions from very asymmetric reactions U, Au + Ne provide a severe test for the statistical model.

A technique for beam based alignment of sextupole system is developed exploiting the enhancement effect of orbit differences by the sextupoles. This technique can in principle be applied to sextupole or sextupole strings with controlled orbit pattern and BPM configurations. This paper will discuss the theoretical basis, special optimization considerations and expected accuracy. Application to the SLC final focus is also discussed.

The similarities and differences of a universal network to normal neural networks are outlined. The description and application of a universal network is discussed by showing how a simple linear system is modeled by normal techniques and by universal network techniques. A full implementation of the universal network as universal process modeling software on a dedicated computer system at EBR-II is described and example results are presented. It is concluded that the universal network provides different feature recognition capabilities than a neural network and that the universal network can provide extremely fast, accurate, and fault-tolerant estimation, validation, and replacement of signals in a real system.

The physics that can be explored with multi-TeV supercolliders is reviewed, including parton distributions, hadron jet production, the standard electroweak theory and minimal extensions to it, technicolor, supersymmetry, and compositeness. 19 refs., 11 figs. (LEW)

Experimental results on incomplete fusion for light systems are discussed by studying the velocity distribution of fusion-like residues in the energy range of 6 to 20 MeV/nucleon. Original experimental work and results from other groups including the Hahn-Meitner Institute and the Argonne National Laboratory are also cited. Reactions between /sup 14/N, /sup 16/O, /sup 19/F, and /sup 20,22/Ne projectiles and /sup 24,26/Mg, /sup 27/Al, /sup 28/Si, /sup 40/Ca and /sup 58,60/Ni targets have been studied. 19 refs., 15 figs., 1 tab.

None

Abstract titles are: Recent developments in modeling variably saturated flow and transport; Unsaturated flow modeling as applied to field problems; Coupled heat and moisture transport in unsaturated soils; Influence of climatic parameters on movement of radionuclides in a multilayered saturated-unsaturated media; Modeling water and solute transport in soil containing roots; Simulation of consolidation in partially saturated soil materials; modeling of water and solute transport in unsaturated heterogeneous fields; Fluid dynamics and mass transfer in variably-saturated porous media; Solute transport through soils; One-dimensional analytical transport modeling; Convective transport of ideal tracers in unsaturated soils; Chemical transport in macropore-mesopore media under partially saturated conditions; Influence of the tension-saturated zone on contaminant migration in shallow water regimes; Influence of the spatial distribution of velocities in porous media on the form of solute transport; Stochastic vs deterministic models for solute movement in the field; and Stochastic analysis of flow and solute transport. (DMC)

Residual inventories of special nuclear materials (SNM) remaining in processing facilities (holdup) are recognized as an insidious problem for both safety and safeguards. This paper identifies some of the issues that are of concern to the safeguards community at-large that are related to holdup of SNM in large-scale process equipment. These issues range from basic technologies of SNM production to changing regulatory requirements to meet the needs of safeguarding nuclear materials. Although there are no magic formulas to resolve these issues, there are several initiatives that could be taken in areas of facility design, plant operation, personnel training, SNM monitoring, and regulatory guidelines to minimize the problems of holdup and thereby improve both safety and safeguards at nuclear material processing plants. 8 refs.

New materials and developments in the field of advanced composites have created the opportunity to take a fresh look into the design of the cryogenic supports for SSC collider dipole cryostats. Although the present reentrant post design meets the structural and thermal requirements, its assembly requires precision and proficiency. The objective of the proposed alternate concept is to reduce the overall cost of the support post by means of simplifying and optimizing its component design and assembly process. The present shrink fitted tube assembly may potentially be replaced by injection molded parts. New resin systems with lower thermal conductivity and high strength properties enable the utilization of automated production techniques such as injection molding and filament winding. This paper will provide analysis and design information for the alternate support post concept and compare its test performance and cost to the present support post. 3 refs., 12 figs., 4 tabs.

The equilibrium hydrogen absorption isotherm using annealed, strain-free FeTi, exhibits only one plateau up to a composition of FeTiH/sub 1.95/. However, the desorption isotherm, determined immediately after the first hydriding step, exhibits the usual two plateaux. X-ray diffraction results of samples with compositions within the absorption plateau limits indicate the major phases present to be ..cap alpha.. and ..gamma.., although a small amount of ..beta.. phase was always detected. Apparently the absorption isotherm represents the direct conversion of ..cap alpha.. ..-->.. ..gamma.. and ..beta.. phase precipitation is almost completely suppressed. Thermodynamic quantities for this conversion are given. The results are attributed to the influence of lattice strain upon the behavior of the ..beta..1 and ..beta..2 phases. A practical consequence of the effect is the distortion of the pressure-composition isotherm in the ..beta..-..gamma.. region as a function of hydriding-dehydriding cycles. This is caused by an increase in H solubility of the ..beta.. and ..gamma.. phases and the widening of the phase composition limits as the strain increases with cycle number. However, after many hundreds of cycles there is no further significant increase in strain and the isotherm shape becomes essentially fixed and reproducible. The distortion is reversible by mild annealing.

Various crystallographic faces of sapphire, the undoped single crystal {alpha}-Al{sub 2}O{sub 3}, have been widely used as substrates fro depositing thin films of metals, semiconductors, and insulators for basic scientific studies and for microelectronic applications. Epitaxial TiO{sub 2} and VO{sub 2} thin films were successfully grown on (0001), (1102) and (1120) surfaces of sapphire substrates by the Metal Organic Chemical Vapor Deposition (MOCVD) technique in our experimental program. The present paper is one of our theoretical efforts in parallel with the experimental program to gain microscopic understandings of the effects of substrate structure on the epitaxial relationship and the overlayer lattice structure of thin film deposition. The first principles energetic calculations on the complicated surfaces like sapphire can now be carried out because of the recent development in our computer programs and availability of high speed super computers. The phase first principles means that the calculations are based only on the know physical laws and approximations, and are free of any adjustable parameters. A complete discussion of the theoretical formalism has been presented in our previous works.

This paper summarizes the technical efforts for resolving issues on rock mechanics as applied to development of a nuclear waste repository in a crystalline rock formation. This section provides background information and definitions pertinent to rock mechanics. Section 2.0 presents the rock mechanics issues related to licensing, design, and construction of a waste repository. Section 3.0 presents the technical approach to the resolution of issues and concludes that a multi-faceted approach involving principally site characterization, laboratory testing, numerical modeling and analysis, and in situ testing and monitoring is required. While this technical approach is directed to further scientific understanding and quantification of the phenomena involved accompanying the thermal heating of rock from nuclear waste, it is emphasized that formulation of a design basis for an engineered rock structure will precede the development of a large waste repository. Section 4.0 summarizes the status of resolution activities in the areas of thermomechanical effects, coupled thermal, mechanical, and hydrological phenomena, mine-induced fracturing, mine stability, and seismicity. Section 5.0 gives a concluding statement. Under the present project plans, technical activities are proceeding on multiple fronts involving field, laboratory, and numerical modeling and analysis studies of the important phenomena related to the disposal of radioactive …

This paper examines methods of handling tritiated waste from a fusion facility, concentrating on handling requirements specific to tritium. Gaseous effluent from a fusion reactor can currently be transported from a fusion facility in two forms )endash) as a gas or solidified on uranium beds. Tritiated water can be transported if it is solidified by absorption onto molecular sieve beds or on clay or cement. Solid waste being shipped for disposal can be transported in low specific activity (LSA, less than 0.3 mCig(1.1 )times) 10/sup 7/Bqg)), type A (less than or equal to 1000 CI(3.7 )times) 10/sup 13/Bq)) or type B (greater than 1000 CI(3.7 )times) 10/sup 13/Bq)) standard containers. The method chosen for transport depends on the amount and level of activity of the tritiated material and whether or not it will be reprocessed at another facility. 4 refs., 4 figs., 4 tabs.

Allied-General Nuclear Services recently performed studies to evaluate alternative proliferation-resistant flowsheets of the uranium-based LWR fuel cycle. The alternatives evaluated consist of coprocessing schemes with either a gamma or a heat spike added. A literature search and evaluation were performed to select a process technology for mixed oxide coconversion. The COPRECAL process was chosen as the most suitable conversion process technology. Three alternative mixed oxide conversion facility design concepts were prepared based on the COPRECAL technology. These alternative concepts are compared to a pure plutonium conversion facility. Facility designs, relative proliferation resistance, and cost estimates are discussed.

Results on vector meson, and strange and charmed-baryon production are presented for data taken during the period 1982--1986 using the TPC/2{gamma} detector at PEP. Vector mesons ({rho}{sup 0}, K{sup *} and {phi}) with 0, 1 and 2 strange quarks are used to obtain redundant measures of strange-quark suppression and of the vector to pseudoscalar ratio in hadronization. Measurements of the production rates of {Lambda}, {Xi}{sup {minus}}, {Omega} and {Xi}{sup *0} hyperons and for the {Lambda}{sub c} and of rapidity correlations between {Lambda}{bar {Lambda}} pairs provide sensitive tests of baryon production in fragmentation models. In addition, two- and three-particle correlations between like sign pions provide further evidence for the Bose-Einstein effect in e{sup +}e{sup {minus}} interactions including the relativistic motion of particle sources. 9 refs., 7 figs.