日本福岛核电站事故后山西辐射环境监测结果及分析

日本福岛核电站事故发生后,山西省开展了相应的辐射环境监测,内容包括γ辐射剂量率监测、空气中131I活度浓度监测、气溶胶、沉降灰和降水中放射性核素活度浓度监测,监测结果表明福岛核事故后山西省内环境γ辐射剂量率连续监测值在90.0～132.0 nGy/h范围内;环境γ辐射剂量率瞬时监测结果范围为38.7～89.4 nGy/h;气溶胶中检测到131Ⅰ、134Cs和137Cs,其活度浓度最大值分别为(5.02±0.40)mBq/m3、(0.48±0.05)mBq/m3和(0.54±0.05)mBq/m3;沉降灰中检测到131Ⅰ沉降量最大值为(0.12±0.02)Bq/(m2d);降水中检测到的131Ⅰ、137Cs和134Cs活度浓度最大值分别为(0.29±0.02)Bq/L、(0.015±0.002)Bq/L和(0.016±0.002)Bq/L。但是日本福岛核电站事故对山西辐射环境影响很小。     

降雨过程中环境地表γ辐射剂量率变化的数值模拟

对降雨过程中的环境地表γ辐射剂量率升高的原因进行了分析,参考大气科学领域降水对气溶胶粒子清除过程的相关研究成果,对剂量率升高的过程进行模型分析,并进行了理论模拟计算,结果证明一般情况下理论计算曲线和实际测量曲线可以较好地符合,通过理论推导,结合实测的降雨强度数据,可以较好地模拟计算降雨过程的剂量率升高幅度,为判断降雨过程中监测数据可信度及是否存在人工辐射异常提供了理论参考。     

乏燃料干式贮存设施辐射屏蔽计算

以干式贮存设施内部装载32组不同初始富集度、不同燃耗的乏燃料组件为研究对象,用MCNP程序,计算了不同冷却时间、不同位置处的中子剂量、γ剂量和总剂量,结果表明,随着冷却时间的延长,γ剂量率、中子剂量率和总的剂量率均在逐步减小。总的辐射剂量最大值出现在贮存设施表面活性段的中部,最大辐射剂量率约为2.47mSv/h,相当于核电厂辐射分区的高辐射区,应限制进入。为满足保护工作人员和公众所受剂量尽量低的要求,建议采取相关的措施例如增加屏蔽层厚度或者划定控制区域等,限制人员的进入。     

辐射检验场最佳使用环境的实验确定

介绍了广东省环境辐射监测中心粤西分部辐射检验场的设计建设方案。采用RSS131型高压电离室作为传递仪器,在不同测量条件下,检验6150AD型和FH40G型便携式辐射监测仪的刻度系数及宇宙射线响应。检验结果表明:辐射检验场γ辐射剂量率最大值小于500 nGy/h时,较适合直线拟合计算宇宙射线响应值;γ辐射剂量率最大值大于500 nGy/h时,较适合直线拟合计算刻度系数。     

福岛核事故期间山西地区辐射环境应急监测

日本福岛核电站受地震影响发生事故后,中国辐射防护研究院随即启动了应急监测,监测内容包括γ辐射剂量率,以及气溶胶、空气碘、沉降灰、降水、地表水、生物和土壤等环境介质的放射性水平.监测结果表明:γ辐射剂量率没有发生明显变化;气溶胶、空气碘、沉降灰、降水、地表水和生物样品中均测出了131 I ,部分样品中测出了137 Cs和134 Cs ;土壤样品中131 I 低于探测限.     

1E级设备γ辐照鉴定技术研究

本文介绍了沉箱式堆照钴靶辐照装置及核级设备辐照试验的剂量特性要求。采用建立辐射场空间剂量率计算模型、编制计算程序的方法,对堆照钴靶辐射场装载方案进行了设计;采用化学剂量计多点测量的方法,测定了装载后辐射场的剂量率分布;通过对辐射场空间分布特性的分析,确定了辐照样品的摆放位置及其对应的辐照剂量率;最后给出了总辐照剂量的主要影响因素及评估方法。结果表明,在辐照装置的全尺寸空间范围内,剂量率分布均在0.14~0.42Gy·s-1范围内,且最大有效辐照空间可达1 200mm×1 200mm×1 000mm,各项指标均满足1E级设备辐照鉴定试验的要求。     

江西省环境天然贯穿辐射水平调查研究

本文主要报道江西省环境天然贯穿辐射水平的调查方法和结果。全省以10×10km 网格均匀布点,共布设网格点1360个,各类加密点460个。调查结果表明:(1)全省原野γ辐射剂量率(离地1m高处的空气吸收剂量率,下同)按点、面积和人口的加权均值分别是7.33、7.24和6.91×10~(-(?))Gyh~(-1);(2)全省道路γ辐射剂量率按点平均为7.36×10~(-(?))Gyh~(-1);(3)全省建筑物室内γ辐射剂量率按点和按人口加权均值分别为10.67和10.39×10~(-(?))Gyh~(-1);(4)宇宙射线电离成分所致空气吸收剂量率,室内按点和按人口加权均值分别是2.56和2.54×10~(-(?))Gyh~(-1),室外相应为2.95和2.92×10(?)Gyh~(-1);(5)天然贯穿辐射(不包括中子贡献)剂量率,室内按点和按人口加权均值分别为13.23和12.93×10~(-8)Gyh~(-1),室外相应的分别为10.28和9.83×10~(-8)Gyh~(-1);(6)江西省天然γ辐射、宇宙射线和天然贯穿辐射所致人均年有效剂量当量分别为0.58、0.23和0.81mSv;相应的集体年有效剂量当量分别为1.93、0.76和2.69×10~4人·Sv。文中还给出了江西各主要种类矿区的γ辐射剂量率,并指出部分非铀矿山周围的γ辐射剂量率比铀矿山的高,应引起重视。     

不同偏置条件下NPN双极晶体管的电离辐照效应

对NPN双极晶体管进行了不同剂量率、不同偏置条件下的电离辐射实验。研究结果表明：同一剂量率辐照时,无论是低剂量率还是高剂量率,辐照损伤均是基-射结反向偏置时最大,零偏置次之,正偏置最小。NPN双极晶体管在3种偏置下均可观察到明显的低剂量率辐照损伤增强（ELDRS）效应,且偏置条件对ELDRS效应很明显,表现为基-射结正向偏置ELDRS效应最为显著,零偏次之,反向偏置最次。对出现这一实验结果的机理进行了探讨。     

多功能、宽量程GM计数管个人剂量仪的研制

本文报道了一种宽量程、多功能的GM计数管电子个人剂量仪的主要设计特点和基本性能。该仪器可以显示剂量率、累积剂量和最大剂量率，记录累积剂是、最大剂量率及其出现时间和8h内的160个剂量历史值，可将全部记录数据以红外通讯方式直接输入微机。     

基于89S51单片机的放射性剂量仪研制

介绍一种基于89S51单片机技术的宽量程、多功能放射性剂量仪的主要设计特点和电路的软、硬件工作原理.该仪器可以显示剂量率、累积剂量和最大剂量率,记录累积剂量、最大剂量率及分类值.     

PMSE dependence on frequency observed simultaneously with VHF and UHF radars in the presence of precipitation

Using PMSE (polar mesosphere summer echoes) observations in combination with particle flux measurements obtained with detectors onboard the Geostationary Operational Environmental Satellite (GOES) a special condition is shown for the occurrence of rare observed UHF PMSE. When electron flux observed from GOES satellites show a decrease, then after being in the presence of precipitation UHF PMSE occurs. The heating effect on PMSE is small when the UHF electron density is enhanced at 90 km due to particle precipitation. We analyzed and compared the frequency dependence of PMSE under the condition of high energy particle precipitation in July of 2004 and 2007 at well separated frequencies (224 and 930 MHz) at the same site, height, and time. The frequency index varies with height and time. At different heights, the maximum as well as the minimum value of volume reflectivity at VHF is greater than that at UHF with 2 to 3 orders of magnitude. A new qualitative method for the analysis of dust distribution is used by analyzing the relationship between volume reflectivity and frequency index. In agreement with the results of the model it is shown that dust particles of smaller size generally did not occur at the edges, instead they occurred in the middle PMSE regions.     

江苏省溧阳市放射性水平调查

本文给出了2008—2009年江苏省溧阳市地表γ辐射剂量率、大气氡浓度、土壤和岩石中放射性核素水平、水中放射性核素水平的调查测量结果。调查结果表明, 溧阳市地表γ辐射剂量率平均为78 nGy/h, 溧阳火山盆地的外缘及庙西花岗岩接触带外延γ辐射剂量率较高(最高800 nGy/h);大气氡浓度平均为14.5 Bq/m³;水中²³⁸U、²³²Th、²²⁶Ra、⁴⁰K和总α、总β水平分别为6 mBq/L、0.085 mBq/L、17.1 mBq/L、212 mBq/L、0.028 Bq/L和0.146 Bq/L。该地区公众人均年本底剂量为1.175 mSv/a。     

线性稳压器不同偏置下电离总剂量及剂量率效应

为对工作在空间电离环境中稳压器的电离总剂量及剂量率效应进行研究,选择一种常用的低压差线性稳压器进行了不同偏置的高低剂量率的电离辐照和退火实验。结合电路特征和电离辐射效应,对线性稳压器产生蜕变的原因进行分析。结果显示,器件输出电压、线性调整率、负载调整率等关键参数在电离辐射环境下发生不同程度变化。在零偏条件下,低剂量率（LDR）下损伤明显大于高剂量率（HDR）条件,表现出低剂量率损伤增强效应;而在工作偏置条件下,高剂量率辐照损伤大于低剂量率的,退火实验中,发生损伤恢复现象,表现为时间相关效应。在整个辐照和退火过程中,零偏置损伤比工作偏置损伤大。     

Dose-rate effects of low-dropout voltage regulator at various biases

<正>A low-dropout voltage regulator,LM2941,was irradiated by ~(60)Coγ-rays at various dose rates and biases for investigating the total dose and dose rate effects.The radiation responses show that the key electrical parameters, including its output and dropout voltage,and the maximum output current,are sensitive to total dose and dose rates, and are significantly degraded at low dose rate and zero bias.The integrated circuits damage change with the dose rates and biases,and the dose-rate effects are relative to its electric field.     

EFFECT OF HEATING RATE ON NONLINEARITY OF DOSE RESPONSE IN TL BY KINETICS MODEL

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辐射接枝NVP对聚L-乳酸分子量的影响

以甲醇为溶剂,采用辐射接枝法制备了聚L-乳酸(Poly-L-lactic acid,PLLA)/N-乙烯基吡咯烷酮(N-vinyl pyrrolidone,NVP)接枝共聚物。研究了醋酸(Acetic acid,HAc)浓度、单体浓度和剂量率对接枝共聚物分子量的影响,并采用傅立叶变换红外光谱(Fourier transform infrared spectrometer,FT-IR)、核磁共振氢谱(Nuclear magnetic resonance,1H-NMR)、热重分析法(Thermogravimetry analysis,TGA)对接枝共聚物进行了表征。结果表明,在相同吸收剂量下,接枝共聚物的分子量与反应介质中HAc浓度、单体浓度以及剂量率相关。当HAc浓度为0.05 mol/L,单体浓度为30%,剂量率为500 Gy/h时,接枝共聚物的分子量分别出现极大值。随着接枝率的增大,接枝共聚物的两个热失重阶段变得更为明显。     

Mechanisms and kinetics of precipitate restructuring during irradiation

Irradiations were performed at temperatures from 400 to 700°C using 3.0-MeV ⁵⁸Ni⁺ ions in order to investigate γ'-precipitate restructuring in two model alloys: Ni-12.8 at% Al and Ni-12.7 at% Si. The precipitates coarsened, with the third power of the average diameter proportional to the damage dose. The temperature dependence of the rate constants for irradiated specimens is described in terms of a modified Lifschitz-Slyozov-Wagner coarsening model that includes radiation-enhanced diffusion. Redistribution of precipitate by enhanced precipitation (Ni-Si) or precipitate dissolution (Ni-Al) at point-defect sinks caused maxima in γ' size with dose. Precipitate redistribution at the free surfaces of irradiated thin foils and at γ/γ' particle interfaces is described.     

Estimation of infiltration and surface run-off characteristics of radionuclides from gamma dose rate change after rain

A method to estimate the infiltration and surface run-off characteristics of radionuclides on three types of ground surface from gamma dose rate change due to rain has been developed. We proposed the estimation methods based on the differences in the dose rate increases between monitoring stations caused by different attenuation of gamma ray due to infiltration and by the different run-off characteristics. The gamma dose rate data used for the estimation were measured at near-by monitoring stations in which the ground type around the detector differed from each other. Rain events were selected by the criteria in which ²¹⁴Pb and ²¹⁴Bi deposition amounts are considered to be uniform with in the area in which objective monitoring stations are deployed. We also calculated the surface concentration considering both infiltration and surface run-off processes. As a result, it was shown that the calculated surface concentration was about 40% larger than that considering neither processes of the infiltration and surface run-off.     

核电厂运行现场高能γ射线的剂量调查

在核电厂正常运行期间,反应堆冷却剂系统内存在能够发射高能γ射线的¹⁶N等放射性核素。为了初步掌握核电厂运行期间不同区域内高能γ射线的辐射水平,利用NaI(Tl)谱仪在国内某核电站测量了反应堆厂房内的γ能谱,并根据γ测量谱和测量系统的响应函数计算了能量大于3 MeV的γ射线的场所剂量率。结果显示:在15个测量位置中,6个位置的γ测量谱中存在明显的高能成分,其对应的剂量率在1.02～30.14 μSv/h范围内。