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居民受到的照射主要来自天然照射和医疗照射,其它来源的照射(核武器试验和核电站排出物造成的环境污染、职业照射等)在总剂量中所占比例甚小。近年来,与国际放射防护委员会(ICRP)提出电离辐射生物学作用的线性无阈假设有关,人们对居民受到主要辐射源照射的研究给予了很大关注。此项研究的目的是为防护措施提供依据,其重要意义不限于了解照射剂量的大小,而且还在于探讨控制剂量的实际可能性。天然电离辐射源所致剂量在居民总剂量中占有最大的份额。天然辐射源引起的平均有效剂量当量根据联合国原子辐射效应科学委员会(UNSCEAR)的估算约为2mSv·a~(-1)。鉴于大多数天然源引起的剂量大小取决于人类的活动,因而是可能控制的。下面分别讨论各具特色的各种辐射源。
Residents are exposed mainly to natural exposure and medical exposure. Other sources of exposure (nuclear testing and environmental pollution from nuclear power plant discharges, occupational exposure, etc.) account for a very small percentage of the total dose. In recent years, with the ICRP putting forward the linear and non-threshold assumption of ionizing radiation biology, great attention has been paid to the study of residents exposed to the main radiation sources. The purpose of this study is to provide a basis for protective measures, the significance of which is not limited to the size of the irradiated dose, but also to explore the practical possibility of dose control. The dose of natural ionizing radiation sources accounts for the largest share of the total inhabitants dose. The average effective dose equivalent of natural radiation sources is estimated to be about 2 mSv · a -1 by the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR). Given the magnitude of the dose caused by most natural sources, it is possible to control the magnitude of human activity. The following discussion of the different characteristics of the various radiation sources.