Distribution laws for radioisotopes in receiving freshwater of Inland Nuclear Power Plant

Abstract

The framework for transportation of radioisotopes in receiving freshwater from Inland Nuclear Power Plant (INPP) is proposed. This work studies the radioactive concentration under normal operation of INPP, and analyzes the relationship between consequences of accidents (IC, CFE, BP) and meteorological factors. Results show that the direct liquid release item is the main source item under INPP normal operation, 137Cs has a good representative for the variation of total radioisotopes concentration against downstream distance. As for the non-precipitation situation, the position where the maximum 137Cs concentration appears downstream is positively correlated with atmospheric stability, while negatively correlated with wind direction offset θ (referred to ENE direction). 137Cs concentrations of maximum, at the point of downstream 1 km and at the dam from dry deposition are all negatively correlated with wind direction offset θ, but they show complex correlations with atmospheric stability which depend on wind directions. As for the precipitation situation, there are two opposite relationships between the recover time for Lim1, Lim2, Lim3 and precipitation rate. Both dry deposition and wet deposition are dominant factors in the short-term, but the contribution from run-off, which gradually increases after a longer period, turns to be the dominant factor in the long term. Results of annual statistical are analyzed through field monitoring data.