دانلود رایگان مقاله انگلیسی بررسی اثرات خصوصیات طراحی برج خنک کننده بر روی محیط نزدیک میدان - نشریه الزویر

ABSTRACT

In a nuclear power plant, ultimate heat sink (UHS) and circulating water system (CWS) cooling towers both ultimately remove heat from the essential service water system, main condenser, and non-essential service water system during all operation modes including accident conditions. Since the visible plume from the cooling tower has an adverse effect on the environment, however, an environmental impact assessment of the cooling tower is required for the construction of a new nuclear power plant. In this study, the environmental impact of UHS and CWS cooling towers of an APR1400 standard design plant was assessed for the purpose of testing and demonstrating the recently-updated SACTI2 model. Because the site for the APR1400 standard design plant had not been decided, one-year meteorological data from the Spokane International Airport weather station, WA, USA, were used as hypothetical input data for the environmental impact assessment. The quantitative effect of cooling tower design changes on the environment was analyzed in terms of index-value dispersion area (AD) and dispersion ratio (δ) for nine environmental assessment indexes. Scenario test conditions were varied by changing cooling tower arrangement, distance between cooling towers, length of cooling tower, exit port height, exit port diameter, the number of exit ports, heat load per tower, and air flow rate per tower.

1. Introduction

Since 1980, in the United States, closed-cycle cooling design such as in cooling towers has been applied to most new nuclear power plants on account of environmental regulations and policies relating to the effect of the increased temperature of discharged water on the environment, the impact of the cooling intake structures on underwater organisms, and fresh water availability (EPRI, 2012). However, plumes from cooling towers can generate adverse impacts on the environment such as through plume shadowing, water and salt deposition, ground level fogging and icing, and solar energy loss, among others (Davis, 1998; U.S. NRC, 2007). The environmental impact of cooling towers operating on the plant site can be investigated by measurement devices placed near the cooling tower region. On the other hand, the evaluation of the environmental impact of a cooling tower under construction or to be constructed in the future should be conducted through experiment or numerical analysis based on past meteorological information. Full-scale experiments for predicting the dynamic behavior of cooling tower plumes are expensive; scale model experiments (Michioka et al., 2007; Ruiz et al., 2016) have their limitations; therefore, many studies (Carhart and Policastro, 1991; Carhart et al., 1992; Orville et al., 1980; Moore, 1977) on the environmental impact of cooling towers have focused on developing an analytical plume prediction model. Policastro et al. (1981a) developed an improved mathematical model, more wellknown as the seasonal/annual cooling tower impact (SACTI) model, for predicting plume and drift behavior occurring from cooling towers. They also developed a user manual of the improved mathematical model (Policastro et al., 1984) and updated it in terms of user friendliness (Dunn et al., 1987). The single plume behavior using the SACTI model was tested and validated with data from the Chalk Point Dye Tracer Study (Policastro et al., 1981a). The behavior of multiple plumes using the SACTI model was also validated against the multiple unit cooling towers at Pittsburgh, CA (Policastro et al., 1981b). The original SACTI code has been available in public domain and accepted by both the United States Environmental Protection Agency (U.S. EPA) and the United States Nuclear Regulatory Commission (U.S. NRC) (EPRI, 2015).