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P. W. Nickola

Abstract

Puffs of the inert gas 85Kr were released at the surface level and were permitted to drift through a three-dimensional grid of Geiger counter sensors extending to a height of 21 m and to a distance of 800 M. Concentrations were recorded as a series of 4.8-sec duration mean concentrations for each of the 64 sensors. Data specifying the effective speed, the effective height, the magnitude of short-period concentrations, the magnitude of crosswind and downwind concentration integrations, and the dimensions of puffs are reported. It was found that: 1) the speed with which a puff reached a 1.5 m elevation field sensor increased with distance from the source (or with travel time); 2) at the 1.5 m elevation, peak values of short-period concentration, exposure, and crosswind integrated concentration increased with increasing atmospheric stability; 3) regardless of the atmospheric stability, puff dimensions along a downwind axis exceeded those along a crosswind axis, and the crosswind dimension exceeded the vertical; 4) for a given distance, the ratio of cross-wind to downwind dimensions decreased as atmospheric stability increased; 5) the ratio of crosswind to downwind puff dimensions increased with distance (or time) in an unstable atmosphere but decreased slightly in stable atmospheres, 6) the ratio of vertical to downwind puff dimensions decreased with distance (or time) regardless of stability; and 7) the effects of stability on puff dimensions were best shown when dimensions were considered as a function of time rather than distance from the source.

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P. W. Nickola

Abstract

Analysis of a series of 31 field diffusion experiments permitted direct specification of the benefit of increased stack height. In the experiments, two tracers were released simultaneously from two different elevations on a 122 m tower, and were sampled at ground level on a series of arcs concentric about the release point. The ratio of observed concentrations at any sampling distance provides a measure of stack height benefits which is unobscured by differences in meteorology between experiments.

Three combinations of upper/lower release elevations were used: 26 m/2 m, 56 m/26 m and 111 m/56 m. Over the 10 km range of field measurements, ground-level concentration ratios (upper source origin/lower source origin) were larger than similar ratios computed using observed meteorology and a Gaussian plume model. Since a larger ratio implies smaller benefits from increased stack height, the Gaussian model over-emphasized the benefits resulting from increased stack height.

In a plume with minimal initial rise, there is a dilution at stack exit which is directly proportional to the wind speed at the top of the stack. At distances relatively far from the source, the benefits in reduced concentration resulting from increasing source height from 26 m to 56 m were found to plateau at approximately the ratio of wind speeds at the 26 and 56 m levels. Benefits accruing as a result of increasing from 56 m to 111 m exceeded the wind speed ratio at all distances. Conversely, benefits for an increase from 2 m to 26 m were lacking at distances beyond about 4 km.

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J. C. Doran, T. W. Horst, and P. W. Nickola

Abstract

The behavior of the quantity S = σ y/x σ θ for surface releases of tracers is examined. Variations in this quantity for different field programs are shown to be attributable largely to variations in sampling time t and averaging time t; larger values of S are found to be associated with longer τ and t. Other previously disregarded quantities, viz., mean wind speed and atmospheric stability, are shown to have potentially important effects. Two spectral models are presented which reproduce many of the observed features.

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P. W. Nickola, J. D. Ludwick, and J. V. Ramsdell Jr.

Abstract

A brief description is given of the Hanford inert gas tracer system employed in atmospheric diffusion studies. Among the advantages of the system are the detailed histories of concentration generated simultaneously at 64 field positions, and the ability to disperse instantaneous point sources (puffs) as well as longer duration releases (plumes). Concentration measurements are made to a distance of 800 m from the source.

Sample data resulting from a puff and a plume release are given. A minor amount of data analysis follows. Mean effective transport height resulting from the ground-level puff release are found to increase from 0.9 m at 200 m from the source to 1.7 m at a distance of 800 m. For the continuous plume, corresponding effective transport heights from a release 1 m above the surface were found to be 1.2 m and 1.6 m. For the puff, the ratio of σz to σv was found to be 3.9 at 200 m from the source, and 4.2 at 800 m.

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P. W. Nickola, M. O. Rankin, M. F. Scoggins, and E. M. Sheen

Abstract

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