The normal prompt gamma-ray neutron activation analysis for either bulk or small beam samples inherently has a small signal-to-noise (S/N) ratio due primarily to the neutron source being present while the sample signal is being obtained. Coincidence counting offers the possibility of greatly reducing or eliminating the noise generated by the neutron source. The present report presents our results to date on implementing the coincidence counting PGNAA approach. We conclude that coincidence PGNAA yields: (1) a larger signal-to-noise (S/N) ratio, (2) more information (and therefore better accuracy) from essentially the same experiment when sophisticated coincidence electronics are used that can yield singles and coincidences simultaneously, and (3) a reduced (one or two orders of magnitude) signal from essentially the same experiment. In future work we will concentrate on: (1) modifying the existing CEARPGS Monte Carlo code to incorporate coincidence counting, (2) obtaining coincidence schemes for 18 or 20 of the common elements in coal and cement, and (3) optimizing the design of a PGNAA coincidence system for the bulk analysis of coal.

As the Hanford Site transitions into remediation of contaminated soil waste sites and tank farm closure, more information is needed about the transport of contaminants as they move through the vadose zone to the underlying water table. The hydraulic properties must be characterized for accurate simulation of flow and transport. This characterization includes the determination of soil texture types, their three-dimensional distribution, and the parameterization of each soil texture. This document describes a method to estimate the soil hydraulic parameter using the parameter scaling concept (Zhang et al. 2002) and inverse techniques. To this end, the Groundwater Protection Program Science and Technology Project funded vadose zone transport field studies, including analysis of the results to estimate field-scale hydraulic parameters for modeling. Parameter scaling is a new method to scale hydraulic parameters. The method relates the hydraulic-parameter values measured at different spatial scales for different soil textures. Parameter scaling factors relevant to a reference texture are determined using these local-scale parameter values, e.g., those measured in the lab using small soil cores. After parameter scaling is applied, the total number of unknown variables in hydraulic parameters is reduced by a factor equal to the number of soil textures. The field-scale values …

The work performed during the past three years has been extremely productive. Ferrographic capture was utilized in analysis of several thousand field samples collected from arrays of multilevel samplers during three intensive field campaigns conducted at two shallow sandy aquifer sites in Oyster, VA. This work has shown resulted in three important conclusions: (1) Ferrographic capture provides unparalleled low quantitation limits for bacterial cell enumeration (Johnson et al., 2000). (2) The high-resolution analyses provided by ferrographic capture allowed observation of increased bacterial removal rates (from groundwater) that corresponded to increased populations of protozoa in the groundwater (Zhang et al., 2001). This novel data allowed determination of bacterial predation rates by protists in the field, a consideration that will be important for successful bioaugmentation strategies. (3) The high-resolution analyses provided by ferrographic capture allowed observation of detachment of indigenous cells in response to breakthrough of injected cells in groundwater (Johnson et al., 2001). The implication of this unique observation is that bacterial transport, specifically bacterial attachment and detachment, may be much more dynamic than has been indicated by short-term laboratory and field studies. Dynamic attachment and detachment of bacteria in groundwater may lead to greatly increased transport distances over long terms …