烟台航空口岸放射性超标物品的检测与分析

目的探讨如何有效进行航空口岸核与辐射监测工作。方法采用放射性检测仪器对出入境人员和行李进行放射性监测。结果从入境人员行李中检出燃油添加剂、负离子粉和汽车冷却系统添加剂3种物品放射性超标,3种物品表面0.1m处γ射线周围剂量当量率分别为3.42、6.50、4.30μSv/h,放射性核素232Th(钍-232)分别超过国家规定的豁免水平的26倍、144倍、28倍,负离子粉中的226Ra(镭-226)也超过了豁免水平的1.96倍。结论应加强对航空口岸核与辐射监管工作,防止放射性超标物品流入我国。     

拟建核电站周边环境放射性元素监测结果

目的调查某县拟建核电站周边环境放射性本底,为核电站建设提供放射性本底资料和建成后改善环境提供依据。方法采用梅花采样法以核电站拟建地址为中心,按东西南北各5、10和20 km设立13个点开展放射性元素监测。结果拟建核电站周边土壤中放射性核素钾40、钴60、镭226、钍232、铀238及人工放射性核素铯137含量均值分别为461.18 Bq/kg、未检出、29.13 Bq/kg、45.23 Bq/kg、71.36 Bq/kg和2.51 Bq/kg;空气放射本底值在(7.07~11.44)×10-8Gy/h范围内,均值为9.24×10-8Gy/h,人均年有效剂量为0.57 m Sv。结论拟建核电站周环境中放射性本底值处于较低水平。     

旅客携带物放射性超标事件的应急处置

目的 探讨如何有效进行物品放射性超标事件的应急处置.方法 对2010年04月11日烟台空港查获一起旅客携带燃油添加剂进行放射性监测.结果 样品表面0.1m处周围剂量当量率为3.42 μSv/h,232Th比活度为26535.7 Bq/kg,超过限量的26.5倍[1].结论 应加强对航空口岸核与辐射监测工作,完善应急处置...     

昆明辐照中心周围环境放射性水平调查

目的 调查昆明三家辐照中心环境放射性水平情况。方法 采用FD-3013A辐射仪和FJ-427A1型热释光剂量仪分别测量辐照中心环境中γ辐射剂量率和辐射工作人员个人剂量;采用γ能谱仪和低本底α、β检测仪分别测量土壤中²³⁸U、²²⁶Ra、²³²Th、⁴⁰K、¹³⁷Cs、⁶⁰Co活度和水体中总α、总β活度。结果 三家辐照中心土壤中天然放射性核素²³⁸U、²²⁶Ra、²³²Th、⁴⁰K的活度范围分别为8.223.6 Bq/kg、10.621.2 Bq/kg、15.129.7 Bq/kg、41.7103.4Bq/kg,未检测出人工放射性核素¹³⁷Cs和⁶⁰Co;贮源井水总β活度分别为0.003 Bq/L、0.002 Bq/L、0.01 Bq/L;三家辐照中心空气中γ辐射剂量率均值分别为0.09μGy/h、0.10μGy/h和0.07μGy/h;工作人员人均年有效剂量当量分别为0.19 mSv、0.16 mSv和0.16 mSv。结论 三家辐照中心辐射环境水平属于正常水平,没有放射性污染。Back     

2007—2011年珠海口岸核与辐射监测情况分析

目的调查2007—2011年珠海口岸核与辐射超标检出情况,防止核与辐射物质通过我国国境口岸传入传出。方法采用通道式、便携式辐射检测设备对入境人员、行李、交通工具、货物、快件和邮寄物等进行α、β、γ射线检测,并对核素进行分析。结果 2007—2011年,珠海口岸共检出核辐射超标22起,其中接受放射性治疗的人员放射性超标14例,快件和邮寄物4例,船载货物4例。结论继续加强珠海口岸核与辐射监测,防止放射性超标物质通过珠海口岸进出国境。     

吉木乃口岸土壤天然放射性核素调查

目的研究吉木乃口岸天然放射性和人工放射性核素含量的情况,为口岸卫生环境改善提供科学依据。方法2012年采用梅花采样法采集吉木乃口岸7处土壤样品,利用γ能谱分析方法得出放射性水平并采用Beck公式法估算出离地面1 m高处的空气吸收剂量率,并计算外照射年有效剂量。结果吉木乃口岸土壤中天然放射性核素铀238、镭226、钍232、钾40和人工放射性核素铯137、铯134含量均值分别为:87.48 Bq/kg、37.32 Bq/kg、44.78Bq/kg、848.84 Bq/kg、1.65 Bq/kg、1.25 Bq/kg;天然放射性核素含量均高于新疆和全国的平均水平,但年有效剂量率低于世界平均值。人工放射性核素铯137、铯134含量水平较低。结论吉木乃口岸土壤的放射性危害较小,对当地居民和进出境人员不会产生辐射伤害。     

乐山市江河介质中放射性核素含量调查

目的调查乐山市境内江(河)介质中水源水体总放射性及消落区泥沙和水生植物中放射性核素含量,为核辐射应急预防措施提供科学依据。方法按国家标准规定的检测方法,采用FJ-2603型低本底总α、β弱放射性测量装置进行总α、β放射性测定,及美国ORTEC公司生产的ADCAMTM918型γ谱仪器进行放射性核素分析。结果核设施下游江(河)枯水期水体中放射性比活度总α平均为0.067±0.127Bq/L,总β为0.067±0.038Bq/L。消落区泥沙中天然放射性核素238U、235U、232Th、226Ra、和40K的含量平均分别为42.8、1.6、53.0、47.4、468.7Bq/kg、水生植物平均分别为10.72、0.23、6.23、9.71、1013.9Bq/kg。泥沙中人工放射性核素137Cs含量平均为0.4Bq/kg,水生植物平均为0.18Bq/kg。结论枯水期水源水体中总α放射性比活度与乐山1990年调查结果处于同一水平,总β放射性比活度有所增加。泥沙及水生植物中天然放射性核素含量K>U>Ra(Th。人工放射性核素137Cs有低水平的检出,其活度为世界因核爆等全球沉降水平。     

广州地铁一号线工程沿线土壤放射性水平

监测了广州地铁一号线工程沿线土壤放射性水平,讨论了放射性核素在不同类型、不同线段土壤中的分布。土壤放射性水平均值:地表天然γ辐射为13.17×10^-8 Gy/h,土壤气氡几何均值为325.5 Bq/m³,²²⁶Ra为37.5 Bq/kg,²³²Th为48.7 Bq/kg,⁴⁰K为501.5 Bq/kg,属正常本底水平。     

黄山市环境辐射水平及居民受照剂量调查分析

目的研究黄山市环境辐射水平及居民受照剂量,为辐射防护和经济建设提供背景资料。方法采用FD-71型闪烁辐射仪,测量室内外、道路γ辐射剂量率;采用低本底闪烁测氡仪,测量氡浓度;采用γ能谱分析方法,测量建材中放射性核素226Ra、232Th、40K的含量。结果室内、室外、道路γ辐射剂量率均值分别为12.2×10-8Gy.h-1、8.5×10-8Gy.h-1、8.6×10-8Gy.h-1。地球γ辐射水平室内比室外高,平均比值为1.44,道路与室外的γ辐射水平差异无统计学意义。室内和室外宇宙射线辐射剂量率分别为2.7×10-8Gy.h-1和3.0×10-8Gy.h-1。室内、室外氡浓度均值分别为27.3 Bq.m-3和13.2 Bq.m-3。建筑材料除碳化砖及个别类型中的样品外,其他建材内、外照射指数均低于国家标准。结论黄山市环境辐射外照射所致居民人均年有效剂量当量为0.92mSv,其辐射水平属正常本底水平;室内、外氡浓度致居民受到的人均年有效剂量当量为1.88 mSv。在世界值范围内,传统建材放射性核素含量与世界建材典型值比较接近,其他建材有部分则高于世界建材典型值,应引起相关部门的注意。     

防城口岸入出境货物及集装箱γ辐射监测结果分析

1995～1997年对防城口岸入出境货物及集装箱实施了γ辐射监测,监测结果显示:锆英砂、独居石的γ辐射剂量当量率平均数(γD)及最大值(γm)均超过国境卫生检疫放射性监测管理标准(1γSv/h),γD分别为6.21、58.63;γm分别为7.12、63.92.[注:独居石β放射性核素表面污染值超过国境卫生检疫管理标准(4Bq/cm2),其值为28.32q/cm2.]其余监测货物及集装箱γD均未超标.但来自俄罗斯的铜精矿γD超过标准的1/3;钾肥γD超过标准的2/3;除锰矿、钢材、废铜外,其余货物及集装箱γm均超过标准的1/3,其中铜精矿、钾肥γm超过标准的2/3,来自俄罗斯的钾肥γm为1.20,已超标.依据分析结果,提出了今后的监测重点.     

乐山市食品中放射性核素含量及其所致居民有效待积剂量当量

目的调查乐山市食品中放射性核素含量，并估算其所致居民有效待积剂量当量。方法按照国家标准规定的分析方法，采用美国ORTEC公司生产的ADCAM^TM 918型γ谱仪进行检测分析。结果对乐山市主要粮食和蔬菜进行了6种放射性核素的检测，其活度大小依次为^40K〉。^238U〉^226Ra〉。^232Th〉^235U〉^137Cs。居民从稻谷、麦类、玉米、豆类食物和蔬菜摄入天然放射性核索成年男女分别为16963．5、15800．6Bq／a，所致有效待积剂量当量202．2、158．9μSv。摄入人工放射性核素^137Cs成年男、女分别为30．9、24．0Bq／a，所致有效待积剂量当量0．883、0．802μ5v。结论乐山市主要食品中U、Th、Ra、K天然放射性核素含量及所致居民的有效待积剂量当量，相对高于国内相关调查资料报道的正常地区平均值，仍属天然辐射水平。人工放射性核素^137Cs含量在世界大气沉降范围。     

An evaluation of radiation and dust hazards at a mineral sand processing plant

This three-part article discusses the results of a 2-y study on radiation and dust hazards in a mineral sand processing plant involving: (1) evaluation of external gamma radiation levels and determination of isotopic composition of the different sand products; (2) evaluation of radiation carried in long-lived radioactive dust (LLRD) particles; (3) evaluation of Rn gas concentrations within the working environs of the plant. Gamma radiation levels had a mean value of approximately 40 nSv h-1, and monazite sand returned the highest activity concentrations of 0.16% and 3.4% for 238U and 232Th, respectively. Low volume gross respirable dust sampling revealed an average long-lived airborne alpha activity concentration of 0.07 +/- 0.02 Bq m-3 and an average dust mass concentration of 3.3 +/- 2 mg m-3. Gamma spectroscopy applied to high-volume air samples showed average airborne 232Th and 238U activities of 0.012 +/- 0.004 Bq m-3 and 0.005 +/- 0.002 Bq m-3, respectively, giving an airborne 232Th: 238U ratio of 2.4:1. Air sampling using a high volume, five-stage cascade impactor indicated an average activity median aerodynamic diameter (AMAD) of 3.2 microns with an associated average geometric standard deviation (GSD) of 2.8. Average radiation dose arising from the inhalation of LLRD was estimated to be 7 mSv per annum. CR-39 (polycarbonate plastic) nuclear track detectors indicated that Rn gas concentrations in the environs of the processing plant dry mill and main product warehouse ranged from 30 Bq m-3 to 220 Bq m-3, with an average value of 100 Bq m-3, which presents a possible inhaled dose from Rn daughters of 1.5 mSv y-1 (assuming an equilibrium ratio of 0.5).     

Evaluation of annual committed effective doses to members of the public in Morocco due to 238U and 232Th in various food materials.

Uranium (238U) and thorium (232Th) concentrations were measured in different foods widely consumed in Morocco by using CR-39 and LR-115 type II solid state nuclear track detectors (SSNTDs). Annual committed effective doses due to 238U and 232Th intakes from the ingestion of the studied food materials were evaluated for different age groups of individuals, using the ICRP ingestion dose coefficients. The influence of the 238U and 232Th intakes and ages of individuals on the committed effective dose was investigated. Total annual intakes of 238U and 232Th for a typical food basket for adult members of the Moroccan population were estimated to be 451 +/- 27 Bq y(-1) and 359 +/- 20 Bq y(-1), corresponding to committed effective doses of (20 +/- 1) x 10(-6) Sv y(-1) and (83 +/- 5) x 10(-6) Sv y(-1), respectively.     

Distribution of natural radioactivity in rocks from Ikogosi-Ekiti, Southwestern Nigeria and its radiological implications

The natural radioactivity in some rock samples in Ikogosi-Ekiti, Southwestern Nigeria, has been measured using a very sensitive gamma spectroscopic system consisting of a 76 mm x 76 mm NaI(TI) scintillation detector system coupled to a versatile Canberra Series 10 plus multichannel analyzer. The average concentrations of natural radioisotopes 238U, 232Th, and 40K are 57.9 +/- 28.1 Bq kg-1, 81.6 +/- 23.8 Bq kg(-1) and 1203.1 +/- 687.2 Bq kg(-1), respectively. These average values give rise to a mean absorbed dose rate of 0.128 +/- 0.051, microGy h(-1) at a height of 1.0 m and an effective dose equivalent of 156.90 microSv (y-1). The results indicate no radiological anomaly. The data presented here will serve as a baseline survey for primordial radionuclide concentrations in rocks of the area.     

Measurement of activity concentrations of natural radionuclides in the topsoil of IITA Ibadan by gamma-ray spectrometry.

The activity concentrations of the natural radionuclides in the soils at the International Institute of Tropical Agriculture, (IITA), Idi-Ose, Moniya, Ibadan, Nigeria were investigated using a NaI (Tl) scintillation detector coupled with a Canberra series 10 plus multichannel analyser as the detecting device for gamma scintillation spectroscopy. The whole area was divided into grids and soil samples were collected from the points of intersection of the grids. The average activity concentrations obtained for the three radionuclides (40K, 238U and 232Th) were 180.08 +/- 90.54 Bq kg(-1) for 40K, 8.901 +/- 5.063 Bq kg(-1) for 238U and 11.01 +/- 7.686 Bq kg(-1) for 232Th. The average values of the absorbed dose rate for each radionuclide were found to be 7.33 nGy h(-1) for 232Th, 7.55 nGy h(-1) for 40K and 3.82 nGy h(-1) for 238U. The average (baseline) of the total absorbed dose rate was found to be 18.72 +/- 8.11 nGy h(-1). The baseline average outdoor annual effective dose equivalent at IITA due to the concentrations of the radionuclides was found to be 22.95 +/- 9.94 microSv y(-1). This value is low compared to the world average of 70 microSv y(-1) specified by UNSCEAR for an outdoor effective dose. Hence the probability of occurrence of any of the health effects of radiation is low.     

Population dose distribution due to soil radioactivity concentration levels in 18 cities across Nigeria.

The natural radioactivity concentrations in soil samples collected from 186 locations across 18 cities in the six geo-political zones of Nigeria have been determined using gamma-ray spectrometry. Results show that the concentrations of (40)K, (238)U and (232)Th in the soil samples varied from below detection limits (BDL) to 1459.4 Bq kg(-1) with a mean of 73.3 +/- 18.5 Bq kg(-1) for (40)K, whereas for (238)U and (232)Th values varied from 9.2 to 113.7 Bq kg(-1) with a mean of 33.9 +/- 7.4 Bq kg(-1) and from BDL to 175.7 Bq kg(-1) with a mean of 12.4 +/- 3.1 Bq kg(-1), respectively. The average gamma absorbed dose rate in air across the cities ranged between 19 +/- 5 and 88 +/- 44 nGy h(-1) and the gross mean was 42.0 +/- 21.0 nGy h(-1). Using available population data in the study areas, about 2.84% of the population is exposed to a radiation dose rate of less than 20 nGy h(-1), 52.40% to a radiation dose rate between 20 and 30 nGy h(-1), 31% to a radiation dose rate between 30 and 60 nGy h(-1) and about 13.76% to dose rates greater than 60 nGy h(-1).     

Assessment of the natural radioactivity and its radiological hazards in Shewa-Shahbaz Garhi igneous complex, Peshawar Plain, NW Pakistan.

Forty-two representative rock samples used for construction purpose were collected from the quarries and outcrops of the rock units forming the Shewa-Shahbaz Garhi igneous complex, North-West Pakistan. Radioactivity of terrestrial radionuclides (238U, 232Th, and 40K) was measured in these samples using gamma ray spectrometry system with an HPGe detector. The samples showed fairly high mean concentrations of 51 +/- 16 Bq kg(-1) of 238U, 70 +/- 20 Bq kg(-1) of 232Th and 1,272 +/- 367 Bq kg(-1) of 40K. Mean absorbed gamma dose rate in air of 119 +/- 29 nGy h(-1) was found. Assessment of radiological hazards was made by calculating radium equivalent activities with external and internal hazard indices. The calculations showed radium equivalent activity ranging from 52 to 346 Bq kg(-1). External and internal hazard indices ranging from 0.14 to 0.94 and 0.17 to 1.1, respectively, were found.     

Statistical analysis of gamma-emitting radionuclide concentrations for three fields in southern Saskatchewan, Canada

During 1988, the spatial variability of the natural gamma-emitting radionuclides (238U, 232Th, and 40K) and the artificial radionuclide 137Cs were studied in three near-level unfertilized fields in Saskatchewan, Canada. One field was used as a native (uneroded) control site; the other two sites have been cultivated, one since 1979 and the other since at least the 1940s. The two cultivated sites have been eroded by aeolian processes and tillage practices. Autocorrelation analysis indicated that most of the radionuclides were not serially correlated for the two depth increments sampled (0-15 cm and 15-30 cm). Autocorrelation is a necessary procedure when equally spaced transect sampling is employed, since sample independence cannot be assumed. Robust and nonrobust statistical summaries are presented for the selected gamma-emitting radionuclide concentrations. Robust statistical estimates of location and dispersion are favored when distributions are not normal or when the distribution is skewed. Median concentrations for the three fields indicated that 238U, 232Th, 40K, and 137Cs were similar to areas in the U.S. and to other areas in southern Saskatchewan. Median 238U activity concentrations were between 31.4 and 34.1 Bq kg-1; 232Th concentrations were between 29.6 and 31.2 Bq kg-1; 40K concentrations were between 471 and 502 Bq kg-1; and 137Cs concentrations were between 10.0 and 12.6 Bq kg-1. The variability of natural radionuclides in a given field for a specific depth increment was generally low, with coefficients of variation less than or equal to 10%. The variability of 137Cs concentrations was greater, ranging from 18% to 23%. Nonparametric tests indicated a significant decrease in 214Bi concentration (238U indicator corrected for 222Rn) with depth of the 1979 field, and an increase in 228 Ac (232Th) with depth in the 1940s field. Significant differences in concentration between fields were indicated for all radionuclides except for 228 Ac. The possible reasons for differences in depth and between fields are briefly discussed.     

Annual committed effective dose from olive oil (due to 238U, 232Th, and 222Rn) estimated for members of the Moroccan public from ingestion and skin application

Olive oil is traditionally refined and widely consumed by Moroccan rural populations. Uranium (238U), thorium (232Th), radon (222Rn), and thoron (220Rn) contents were measured in various locally produced olive oil samples collected in rural areas of Morocco. These radionuclides were also measured inside various bottled virgin olive oils consumed by the Moroccan populations. CR-39 and LR-115 type II solid state nuclear track detectors (SSNTDs) were used. Annual committed effective doses due to 238U, 232Th, and 222Rn from the ingestion of olive oil by the members of the general public were determined. The maximum total committed effective dose due to 238U, 232Th, and 222Rn from the ingestion of olive oil by adult members of Moroccan rural populations was found equal to 5.9 μSv y-1. The influence of pollution due to building material dusts and phosphates on the radiation dose to workers from the ingestion of olive oil was investigated, and it was found that the maximum total committed effective dose due to 238U, 232Th, and 222Rn was on the order of 0.22 mSy y-1. Committed effective doses to skin due to 238U, 232Th, and 222Rn from the application of olive oil masks by rural women were evaluated. The maximum total committed effective dose to skin due to 238U, 232Th, and 222Rn was found equal to 0.07 mSy y-1 cm-2.