The investigation of 137Cs and 90Sr background radiation levels in soil and plant around Tianwan NPP, China

137Cs and 90Sr background levels in soil and plant around Tianwan Nuclear Power Plant (NPP) are reported. Eighty-four soil samples and 44 plant samples were collected from March 2000 to April 2002. The samples were analyzed by gamma spectrometry and radiochemical separation procedure to quantify 137Cs and 90Sr radioactivities. The concentrations (Bq kg−1 dry weight) have been observed in the range of 0.6–1.6 for 90Sr and 1.4–6.9 for 137Cs in soils, their average values are 1.0 ± 0.3 and 4.6 ± 1.6, respectively, which are relatively lower than the reported values in neighboring countries. The mean concentrations (in Bq kg−1 fresh weight except for tea and grass which is expressed in Bq kg−1 dry weight) of 137Cs and 90Sr are 0.1 ± 0.03 and 7.7 ± 4.1 in pine needle, 0.27 ± 0.05 and 3.0 ± 1.1 in tea, 0.65 ± 0.19 and 2.1 ± 0.3 in grass, 0.033 ± 0.021 and 0.084 ± 0.045 in wheat, 0.019 ± 0.01 and 0.23 ± 0.06 in China cabbage, and 0.009 ± 0.007 and 0.024 ± 0.084 in rice, respectively. The pine needle and tea can be regarded as indicator species for 90Sr and 137Cs. The soil-to-plant transfer factor (TF) values of 90Sr and 137Cs are, respectively, 0.022 and 0.031 for rice, 0.066 and 3.83 for China cabbage, 0.0088 and 0.089 for wheat, and 0.037 and 0.56 for grass.