西藏自治区环境天然贯穿辐射水平调查研究

INVESTIGATION OF ENVIRONMENTAL NATURAL PENETRATING RADIATION LEVEL IN THE TIBET AUTONOMOUS REGION

本文报道了西藏自治区环境天然贯穿辐射水平调查的方法和结果。全区以５０ｋｍ×５０ｋｍ的网格布点，实测网格点１８９个，各类加密点１３６个。调查结果表明：（１）西藏自治区原野γ辐射剂量率按测点、面积和人口的加权均值分别为８２．０、７８．０和８４．２ｎＧｙ·ｈ￣（－１）；（２）道路γ辐射剂量率按测点平均值为８３．３ｎＧｙ·ｈ￣（－１）；（３）室内γ辐射剂量率按测点和人口加权均值分别为１１８．２和１１８．７ｎＧｙ·ｈ￣（－１）；（４）宇宙射线电离成分（不包括中子成分，下同）所致空气吸收剂量率按测点和人口加权均值，室内分别为１０２．９和９６．６ｎＧｙ·ｈ￣（－１），室外分别为１２１．４和１１２．１ｎＧｙ·ｈ￣（－１）；（５）天然贯穿辐射剂量率，按测点和人口加权均值，室内分别为２２１．２和２１５．３ｎＧｙ·ｈ￣（－１），室外分别为２０３．４和１９６．３ｎＧｙ·ｈ￣（－１）；（６）宇宙射线、天然γ辐射和天然贯穿辐射所致居民人均年有效剂量当量分别为０．８８、０．６７和１．５５ｍＳｖ；所致集体年有效剂量当量分别为０．１８、０．１３和０．３１×１０￣４人，Ｓｖ。

The methods and results of the investigation on natural penetrating radiation levelin the Tibet Autonomous Region are presented.189 50 km ×50 km- grid measuring pointswere set uniformly up all over the region,with 136 densely measuring points of differenttypes added.The results show that:(1)The point-weighted,area-weighted and population-weighted average value of natural γ radiation dose rate for field is 82.0,78.0 and84.2 nGy·h￣(-1),respectively;(2)The point-weighted average value of natural γ radiation dose rate forroad is 83.3 nGy·h￣(-1);(3 )The point-weighted and population-weighted average value ofnaturaI γ radiation dose rate inside buildings is 118.2 and 118.7 nGy·h￣(-1),respectively;(4)The point-weighted and population-weighted average value of the dose rate inside buildingsfrom cosmic ray is 102.9 and 96.6 nGy·h￣(-1),and outside buildings is 121.4 and 112.1nGy·h￣(-1),respectively;(5)The point-weighted and population-weighted average value ofnatural penetrating radiation dose rate inside buildings is 221. 2 and 215. 3 nGy·h￣(-1),outsidebuildings is 203.4 and 196. 3 nGy·h￣(-1),respectively;(6)The annual effective dose equiva-lent from cosmic ray,naturaI γ radiation and natural penetrating radiation is 0.88,0.67 and1.55 mSv,respectively;and correspondingly,the annual collective effective dose equivalent is0.18,0.13 and 0. 31×10￣4 man·Sv,respectively.