Long-Term Changes and Factors That Influence Changes in Thermal Discharge from Nuclear Power Plants in Daya Bay, China

Zhihua Zhang,Fang Gong,Yinhe Cheng,Difeng Wang

doi:10.3390/rs14030763

Abstract

Thermal discharge (i.e., warm water) from nuclear power plants (NPPs) in Daya Bay, China, was analyzed in this study. To determine temporal and spatial patterns as well as factors affecting thermal discharge, data were acquired by the Landsat series of remote-sensing satellites for the period 1993–2020. First, sea surface temperature (SST) data for waters off NPPs were retrieved from Landsat imagery using a radiative transfer equation in conjunction with a split-window algorithm. Then, retrieved SST data were used to analyze seasonal and interannual changes in areas affected by NPP thermal discharge, as well as the effects of NPP installed capacity, tides, and wind field on the diffusion of thermal discharge. Analysis of interannual changes revealed an increase in SST with an increase in NPP installed capacity, with the area affected by increased drainage outlet temperature increasing to different degrees. Sea surface temperature and NPP installed capacity were significantly linearly related. Both flood tides (peak spring and neap) and ebb tides (peak spring and neap) affected areas of warming zones, with ebb tides having greater effects. The total area of all warming zones in summer was approximately twice that in spring, regardless of whether winds were favorable (i.e., westerly) or adverse (i.e., easterly). The effects of tides on areas of warming zones exceeded those of winds.

Highlights

In recent years, the increasing energy demand of coastal cities has increased both the number and scale of coastal thermal power plants and nuclear power plants (NPPs)
Seasonal and interannual changes and the factors influencing changes in thermal discharge from the NPPs in Daya Bay were examined for the period 1993–2020
(2) Temporal and spatial analyses of the retrieved time series data from the period 1993 to 2020 revealed that the range of warming zones has expanded to a certain extent

Summary

Introduction

The increasing energy demand of coastal cities has increased both the number and scale of coastal thermal power plants and NPPs. Of nuclear energy is converted to electrical energy [1], and most of the remaining energy is discharged as thermal energy in cooling water. The discharge of warm water rapidly increases the temperature of surrounding waters, which in turn directly or indirectly affects the growth and reproduction of aquatic organisms [2]. Many studies have examined algorithms to retrieve sea surface temperatures (SSTs) from thermal infrared remote sensing. First introduced a split-window algorithm (SWA) based on the radiative transfer equation (RTE), which was relatively effective at retrieving SST [4]. Liu and Zhou [5] introduced a multichannel SWA to retrieve SST data for the Yellow and East China seas, and the retrieved data adequately reflected SST distribution patterns. Rozenstein et al [6] and Chen et al [7]

Methods

Results

Discussion

Conclusion