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Hybrid Methods in Engineering

Modeling, Programming, Analysis, Animation

ISSN for PRINT: 1099-2391

Institutional price:	$396.00
Issues per year:	4

Best Paper Award Selection - Editorial Board Site

2002, Volume4

126 pages

Issue price - $250.00

ANALYSIS OF THE EFFECT OF THERMAL OUTFALL ON A DOWNSTREAM ATOMIC POWER STATION

Katherine H. Hancock
Tetra Tech Research and Development, Lafayette, CA, USA 94549

William B. Mills
Applied Research and Development Division, Tetra Tech, Inc., 3746 Mt. Diablo Blvd., #300, Lafayette, California 94549, USA 94549

ABSTRACT

Thermal effluent from a proposed thermal power plant is to be discharged into an impounded river segment upstream of an existing intake to a power plant. There is a possibility that this discharge may adversely impact the warm water fishery use designation in the pond. The effects of the proposed discharge on water temperature were evaluated using RIVRISK and CORMIX. RIVRISK is a model sponsored by the Electric Power Research Institute and predicts thermal and human health impacts of releases of excess heat and chemical-containing effluents. CORMIX is a United States Environmental Protection Agency (US/EPA) simulation and decision support system for environmental impact assessment of mixing zones resulting from continuous point source discharges. Components of the analysis are described below.

RIVRISK was used to simulate the thermal discharge from the proposed thermal outfall, continuously simulating the entire period of 92 days, with meteorological and hydrological data changing on a daily basis. Results of this analysis demonstrated little difference between predictions based on changing air temperatures throughout the summer and worst-case conditions when the discharge temperature is held constant at its maximum value.

RIVRISK was used to simulate the longitudinal temperature profile in the river for 2 individual days both with and without the proposed thermal plant operating. On both days, the change in temperature resulting from the discharge was between 0.2 °F and 0.4 °F. CORMIX was also used to predict the impact of the thermal plume for extreme summer conditions, assuming a multiport diffuser and a ₇Q₁₀ flow based on historical flow rates. CORMIX predicted that the change in temperature at the intake was approximately 0.15 °F, slightly below the RIVRISK predictions.

Use of both models to solve the same problem provides increased confidence that the proposed discharge will not adversely impact the warm water fishery use designation in the pond. In addition, the analysis provides a basis for comparison of the two models for use in thermal predictions.