Search

Pollution control policies have been an outgrowth of increased awareness that measures must be taken to handle the increasing amounts of wastes and by-products of human activity. A particular problem in the policies is how to address wastes that have large natural variations due to natural sources and changing environmental conditions. This is especially true for the control of thermal discharges from steam-electric generating facilities into large bodies of water also influenced by solar heating and inflows of water from natural sources., The basis for most pollution control policies in the United States is the set of regulations specifying ambient and effluent standards. Technology-based effluent standards have been increasingly used to provide a conservative basis for environmental protection. Ambient standards, based on impacts on humans or other life forms, however provide a viable regulatory approach for those effluents with costly treatment, particularly where large natural variability indicates the environment has a significant capacity to assimilate additional inputs. A major problem with ambient temperature standards indicated by two case studies of large thermal discharges, is the variability in induced and natural conditions which affect facility siting, design, and operation, and verification of compliance., The Browns Ferry Nuclear Plant is an example of a large thermal discharge into a varying river environment. The final set of ambient temperature limiting standards for the site which have values near naturally occurring conditions, required the owners of the plant to redesign the heat dissipation system. The final design included the use of supplemental cooling (open, helper, or closed mode) to provide flexible plant operation under varying river flow conditions. Problems with real-time monitoring for compliance with the standards led to a study of various methods of verification. Simulation of plant operation found that adjusting the standards higher than naturally occurring values had larger effects than various monitoring strategies utilizing spatial and temporal averaging. A one-dimensional natural change in temperature model used in conjunction with real-time monitoring reduced power losses due to natural variation by about one half, but could not account for all the short-term variations in natural temperatures caused by topographic and river flow changes and density effects., The Millstone Nuclear Power Station, located in a coastal environment is an example of a thermal discharge into an area with relatively constant long-term mixing conditions. Concerns over natural temperature variation were present throughout the site's history, although this has not affected plant operation since the ambient standards, based on biological evidence, were set to include full open-cycle operation. A natural temperature model, based on finite element circulation and dispersion models was developed as one means of addressing the natural variability issue. The model produced reasonable resolution of the horizontal temperature distribution and relative changes over a tidal cycle. The model had some limitations in those areas where solar heating significantly affects the vertical temperature distribution. If properly combined with baseline temperature monitoring, the natural temperature model provides an assessment tool for characterizing the physical environment around a thermal discharge. It also has potential in verification of compliance by combining with thermal plume monitoring and modeling efforts to define the ambient baseline conditions and the effects of natural conditions on the extent of a thermal plume., It is recommended that ambient standards continue to be used in the control of thermal discharges to take into account the natural assimilative capacity of large bodies of water. Real-time monitoring of compliance with maximum rise temperature standards should not be used in areas of high natural variability. Natural temperature models which cannot adequately predict highly variable situations should not be used to correct real-time monitoring efforts. Therefore, flexible effluent standards which adapt to large changing conditions should be used based on modeled plant effects and potential biological impacts. Natural temperature modeling (including extensive monitoring of baseline temperature conditions) in both preoperational and operational studies should be used to provide a balance of the understanding between physical and biological characteristics in complex environments.

Missoula, MT

Natural recharge is one of the most poorly constrained components of the water budget. In semiarid environments, quantifying natural recharge is difficult due to the relatively low fluxes and the thick unsaturated zones. Measuring deep recharge to great depths in multiple locations is impractical and cost prohibitive for most measurement methods. An alternative method to estimate deep percolation utilizes temperature profiles measured from the ground surface to the water table. Temperature measurements taken in existing cased wells provide an economical and useful vantage for accessing many locations within a basin. A controlled infiltration experiment was conducted to test the feasibility of using downhole temperature measurements to estimate the infiltration flux. VS2DHI (Healy and Ronan, 1996), an interactive numerical model, was used to predict and interpret coupled water-flow and heat-transport occurring in the subsurface during infiltration and redistribution. A sequential sensitivity analysis showed that downhole temperature profiles were most sensitive to the temperature of the applied water, the water flux, and the heat capacity of the dry soil. This downhole temperature method was extended to a natural setting. Temperature profiles were measured at six sites within the Tucson Basin. The temperature profiles varied throughout the basin, and the factors affecting the temperature profiles were numerous. Profiles from the in-channel and intrabasin boreholes showed effects of focused recharge, mountain-front recharge, and stream-channel recharge. Results suggest that this temperature method may be transferable to other basins in semiarid regions.

A new high pressure combustion facility was built to investigate mixing in axisymmetric, turbulent jets exiting into quiescent reservoirs. The facility uses fluorine and nitric oxide, diluted with nitrogen, for chemical product formation that is accompanied by heat release. The average temperature was measured by a set of long, thin, resistance wire thermometers stretched across the jet centerline at 16 downstream locations from x/do = 30 to 240. The Reynolds number was varied through density, i.e., pressure, while the jet exit velocity and exit diameter were held constant. The main result of the work is that the flame length, as estimated from the temperature measurements, varies with changes in Reynolds number, suggesting that the mixing process is not Reynolds number independent up to Re = 150,000. Additionally, the measurements revealed a 'mixing virtual origin,' defined as the far-field flame length extrapolated to phi = 0, that increases with increasing Re for Re 20,000 and then decreases with increasing Re for Re = 20,000. The transition of the jet flow from a momentum-dominated to a buoyancy-dominated regime was identified in another set of experiments.

It was suggested by Munk and Forbes (1989) that climate induced changes in ocean temperature may be monitored by measurements of cross-basin acoustic travel time variability. The feasibility of such a monitoring system depends on the spatial and temporal variability of the cross-basin acoustic paths in the presence of ocean variability of many different scales. For this thesis the variations in arrival position, azimuthal arrival angle, ray trajectory and the corresponding changes in travel times along the three- dimensional multipaths due to meso- and gyre scale ocean temperature fluctuations were analyzed. Emphasis was placed on the acoustic paths from Heard Island in the Indian Ocean, the proposed location for the sound source, to the west coast of the United States. An optimal receiver site location was found to exist in the vicinity of Monterey Bay, California. The possibility of a proposed listening site location near Coos Bay, Oregon, was also examined. However, the ray paths to Coos Bay interact with the bottom frequently, thus rendering them less reliable. All the ray traces for this study were carried out using the recently upgraded Hamiltonian raytracing code HARPO, interfaced with output form the Semtner-Chervin eddy resolving global ocean general circulation model. This interface allows for a realistic simulation of the effects of meso- and gyre scale processes on the variability of the various cross-basin paths., http://archive.org/details/spatialndtempora1094527641, Lieutenant, Royal Netherlands Navy, Approved for public release; distribution is unlimited.