Trans-oceanic transport of 137Cs from the Fukushima nuclear accident and impact of hypothetical Fukushima-like events of future nuclear plants in Southern China

A Lagrangian model was adopted to assess the potential impact of ¹³⁷Cs released from hypothetical Fukushima-like accidents occurring on three potential nuclear power plant sites in Southern China in the near future (planned within 10years) in four different seasons. The maximum surface (0-500m) ¹³⁷Cs air concentrations would be reached 10Bqm^-3 near the source, comparable to the Fukushima case. In January, Southeast Asian countries would be mostly affected by the radioactive plume due to the effects of winter monsoon. In April, the impact would be mainly on Southern and Northern China. Debris of radioactive plume (~1mBqm^-3) would carry out long-range transport to North America. The area of influence would be the smallest in July due to the frequent and intense wet removal events by trough of low pressure and tropical cyclone. The maximum worst-case areas of influence were 2382000, 2327000, 517000 and 1395000km² in January, April, July and October, respectively.Prior to the above calculations, the model was employed to simulate the trans-oceanic transport of ¹³⁷Cs from the Fukushima nuclear accident. Observed and modeled ¹³⁷Cs concentrations were comparable. Sensitivity runs were performed to optimize the wet scavenging parameterization. The adoption of higher-resolution (1°×1°) meteorological fields improved the prediction. The computed large-scale plume transport pattern over the Pacific Ocean was compared with that reported in the literature.