Impact assessment of thermal-discharge from power plants based on combination of numerical simulation and prototype observation

Separation of the natural inhomogeneous background from the observed temperature field is crucial in the post evaluation of thermal discharge impact. In this paper, a heat transport model, based on the multiple nested grid technology, is constructed to simulate the seawater temperature variation in cross scales under the combined action of the hydrologic and atmospheric factors. Combined with the tide, current, and remote sea surface temper-ature data, a method is proposed to extract the thermal discharge impact from the inhomogeneous background and applied to the post evaluation of thermal impact of a coastal nuclear power plant. The proposed model and evalua-tion method show good performance in describing the characteristics of the thermal plume and the natural back-ground high-temperature mass driven by the complex marine and meteorological dynamics. The near shore back-ground temperature shows a similar temporal and spatial variation range with the 1 °C temperature rising area caused by the thermal discharge. The inhomogeneity of the background should be fully considered in the assessments of the thermal discharge in the 1 °C rising scale. The proposed simulation and evaluation method can support eco-environ-mental impact assessments of thermal discharge from thermal power plants under complex environmental conditions. © 2023 China Water Power Press. All rights reserved.