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The toxicities and biogeochemical cycles of arsenic, cadmium, chromium, lead and nickel are reviewed in some detail, and other trace elements briefly mentioned. These heavy metals are used as a framework within which the problem of low-level radioactive waste disposal can be compared. (ACR)

Fluidized bed combustors operate in the large-particle (> 1 mm) high-velocity (> 1 m/s) fluidization regime which differs from most previous applications. These characteristics foster a distinctive volatiles evolution structure in the vicinity of the coal injectors of bottom-fed atmospheric fluidized beds (AFBC). The evolution of coal volatiles associated with bottom-fed AFBC was defined as the focal point. The major effort of the work was concerned with a group combustion model of dense gas/solids mixtures of devolatilizing coal being injected into the bottom of an AFBC. Critical development needs were defined in the area of solids circulation and injector design which impact both basic FBC design and NO/sub x/ emissions. Results of model calculations identified important new physical-chemical mechanisms influencing NO/sub x/ emissions.

Fabrication techniques and improved a-Si:H film processing have been achieved to produce a short circuit current density of 7.5 mA/cm/sup 2/ and open circuit voltage of 740 mV on large area (2cm/sup 2/) a-Si cells by the deposition of an inexpensive semitransparent metal (Cr) as a top electrode on a N-I-P structure. This corresponds to a 2% efficiency using AMl illumination. A V/sub oc/ of 830 mV and fill factor of 0.54 have also been separately obtained. A relatively simple and inexpensive deposition technique using a one pumpdown vacuum system, Al grid and thin metal film structure have been applied to reduce the cost of a-Si:H cell fabrication. A SEM study of a-Si film quality shows the substrate texture to greatly influence the film morphology. This in turn serves to influence the uniformity of photovoltaic response on completed solar cells. The studies of optical transmittance of various thin metal films promote the utilization of Cr and Cu as a top electrode. Dark and illuminated I-V characteristics show that current conduction mechanisms and recombination pheonomena are not the same under dark and illuminated conditions. Furthermore, spectral response analysis and reverse illuminated saturation current under different illumination levels show photoconductivity and collection …

The growth rate of the hose instability is derived for a beam with Gaussian radial profile, using the spread mass model of phase mix damping. It is found that the maximum growth rate of a convecting wave packet is 49% larger than that derived for a beam with the Bennett profile, and the inverse group velocity (dz/d tau) is also increased by about this amount. A general discussion of spread mass models is presented along with an explanation of the regurgitation phenomena seen in their numerical treatment.

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This report documents the technical evaluation of the proposed design modification and Technical Specification changes for protection of Class 1E equipment from grid voltage degradation for the Peach Bottom Atomic Power Station, Units 2 and 3. The review criteria are based on several IEEE standards and The Code of Federal Regulations. The evaluation compares the submittals made by the plant with the NRC staff positions and the review criteria. The licensee meets the requirements of the NRC except for the submittal of proposed Technical Specification changes to substantiate the proposed circuit modifications and relay setpoints.

Primarily, Mound was to evaluate both improved-iridium and standard-flight iridium blanks with respect to current GPHS-CVS manufacturing processes and provide example-weld-quality CVS to the Savannah River Plant (SRP) for its weldability study. Additionally, Mound's practice of performing a final outgassing (1500/sup 0/C for 1 hr) of CVS was evaluated with respect to metallurgical properties of iridium cups and electron-beam (EB) welding characteristics of CVS subassembly components.

L-Lake was built in 1985 to receive and cool the thermal effluents from the L-Reactor. The lake was constructed by impounding approximately 7 km of the upper portions of Steel Creek to form a 1000-acre reservoir. Dam construction and reservoir filling were completed in October 1985 and L-Reactor resumed operations at the end of the same month. Since 1985, this system has been developing a biological community comprised of representatives of all trophic levels. The system is impacted by both temperature from the operating reactor and nutrient inputs from the Savannah River ecosystem. A preliminary evaluation of the technical and monetary feasibilities of a number of thermal and/or nutrient mitigation alternatives for the L-Lake ecosystem has been performed by the Ecology Group of SRL/ESD. This report is a summary of the alternatives considered and their applicability.

Work is continuing on: chromosomal inversions and Robertsonians; cytology of inversions; translocations; mutagen test validation; meiotic pairing; and the characterization of induced lethals. (PSB)

Seismic surface-wave generation by underground nuclear explosions releasing tectonic strain is studied through a series of synthetic radiation-pattern calculations based on the earthquake-trigger model. From amplitude and phase radiation patterns for 20-s Rayleigh waves, inferences are made about effects on surface-wave magnitude, M/sub s/, and waveform character. The focus of this study is a comparison between two mechanisms of tectonic strain release: strike-slip motion on vertical faults and thrust motion on 45/sup 0/ dipping faults. The results of our calculations show that Rayleigh-wave amplitudes of the dip-slip model at F values between 0.75 and 1.5 are significantly lower than amplitudes of the strike-slip model or of the explosion source alone. This effect translates into M/sub s/ values about 0.5 units lower than M/sub s/ of the explosion alone. Waveform polarity reversals occur in two of four azimuthal quadrants for the strike-slip model and in all azimuths of the dip-slip-thrust model for F values above about 3. A cursory examination of waveforms from presumed explosions in eastern Kazakhstan suggests that releases of tectonic strain are accompanying the detonation of many of these explosions. Qualitatively, the observations seem to favor the dip-slip-thrust model, which, in the case of a few explosions, must …

The current condition of L Lake/Steel Creek was summarized in a report to SCDHEC in June 1988 which reported that the L Lake and Steel Creek ecosystems were adequately developing towards balanced biological communities. If mitigation for L Lake inputs, specifically temperature and nutrients, are required, several viable alternatives are available. A report prepared by Spencer in 1986 discusses the various options available for cooling L-Reactor discharges. In effect, a small cooling tower is the only realistic solution to reducing effluent temperatures. Nutrient mitigation can take several approaches including upstream sewage treatment, hypolimnetic withdrawal, dilution of input water by Par Pond water, precipitation of nutrients, and sediment oxidation. None of these systems would influence the thermal regime, but would significantly reduce nutrient input into the system. One beneficial use of L-Lake thermal effluents is algaculture, the production of useful algae. A document prepared in 1988 concludes that algaculture is a technically and economically feasible mitigation alternative for L Lake and could allow L Lake to be handled under Section 318 of the Clean Water Act.

Compilation of monthly reports from departments in the city of San Antonio, Texas providing statistics, project updates, and other information about services and activities.