Karunakara N, Somashekarappa H M, Avadhani D N, Mahesh H M, Narayana Y, Siddappa K
University Science Instrumentation Center, Mangalore University, India.
Health Phys. 2001 May;80(5):470-6. doi: 10.1097/00004032-200105000-00007.
Systematic studies on gamma radiation level and the distribution of natural radionuclides were carried out under a pre-operational survey for the establishment of baseline data on background radiation level and the distribution of radio-nuclides in the environment of Kaiga, in the south west coast of India, where a nuclear power reactor of 235 MWe has just been commissioned. The external gamma absorbed dose rates prevailing in the region were measured using a portable plastic scintillometer. Soil samples from 18 stations were collected from depth intervals of 0-5, 5-10, and 10-25 cm and analyzed for their 226Ra, 232Th, and 40K activity concentrations by gamma spectrometry employing a 90 cc PGT HpGe detector coupled to an EG&G ORTEC 8K multichannel analyzer. The activity of 226Ra was found to vary between 15.5-61.2 Bq kg(-1) with a mean value of 31.3 Bq kg(-1), that of 232Th varies between 11.4-41.9 Bq kg(-1) with a mean value of 27.5 Bq kg(-1) and of 40K between 78.3-254.8 Bq kg(-1) with a mean value of 159.9 Bq kg(-1) in 0-5 cm soil profiles of the region. The contributions of 238U, 232Th, and 40K to the total gamma absorbed dose rate were 39.9%, 40.7%, and 16.0%, respectively. The gamma absorbed dose rate in air estimated using the results of activity concentration of 226Ra, 232Th, and 40K are found to compare well with that of the direct measurement. The results of the study were compared with the literature values reported for other environs of the country as well as the world, and conclusions are drawn.
在印度西南海岸的凯加地区，一座235兆瓦的核电站刚刚投入使用，在该核电站运行前的调查中，对伽马辐射水平和天然放射性核素的分布进行了系统研究，以建立背景辐射水平和环境中放射性核素分布的基线数据。使用便携式塑料闪烁仪测量该地区的外部伽马吸收剂量率。从18个站点采集了深度间隔为0 - 5厘米、5 - 10厘米和10 - 25厘米的土壤样本，并使用与EG&G ORTEC 8K多通道分析仪相连的90立方厘米PGT高纯锗探测器，通过伽马能谱法分析其中226镭、232钍和40钾的活度浓度。研究发现，该地区0 - 5厘米土壤剖面中226镭的活度在15.5 - 61.2贝克勒尔每千克之间变化，平均值为31.3贝克勒尔每千克；232钍的活度在11.4 - 41.9贝克勒尔每千克之间变化，平均值为27.5贝克勒尔每千克；40钾的活度在78.3 - 254.8贝克勒尔每千克之间变化，平均值为159.9贝克勒尔每千克。238铀、232钍和40钾对总伽马吸收剂量率的贡献分别为39.9%、40.7%和16.0%。利用226镭、232钍和40钾活度浓度的测量结果估算出的空气中伽马吸收剂量率，与直接测量结果比较吻合。将该研究结果与该国其他地区以及世界其他地区报道的文献值进行了比较，并得出了结论。
