Abstract: Monitoring results of tritium concentration in the rainwater and atmosphere around Tianwan Nuclear Power Station (TNPS) are introduced, and relevant factors influencing tritium concentration are analyzed. Before and after TNPS commercial service, the result shows that tritium concentration in the rainwater and atmosphere around TNPS rises from background level to twice background level or so and there is not obviously change beyond ten kilometers. Relative factors influencing tritium concentration in the rainwater and atmosphere mainly include gas tritium discharge, the distance to discharge point, the direction and frequency of wind, and amount of precipitation.

Key words: nuclear power station, tritium, atmosphere, rainwater