辐照电子直线加速器辐射剂量测定的技术研究

研究了辐照电子直线加速器辐射剂量测定的技术方法,在测量方法上采取实测与蒙特卡洛模拟计算相结合的方法提高辐射剂量测定的准确度和可操作性;用化学剂量计建立电子束吸收能量测量的方法;用平板电离室建立电子束表面剂量、电子束吸收剂量率测量的方法;用半导体探测器阵列建立电子束辐照均匀性测量的方法。     

Irradiation dose for personnel during brachytherapy of malignant neoplasms with 32P microsources

Experimental measurements of the local absorbed radiation dose in the most irradiated parts of the bodies of personnel (the skin of the hands and palms, eyes, thorax, and abdomen of operators) by means of high sensitivity TLD-500K thermoluminescence detectors are reported. It is found that, for ³²P microsources with a total activity of 100 MBq, after 6 hours of work without protective x-ray gloves during a simulation of placing a real preparation in the region of the liver of an adult phantom, the maximum local irradiation dose to the hands (the skin of the left middle finger and thumb) from bremsstrahlung with deduction of the natural background and without special protective measures is 0.54 ± 0.001 mGy, the minimum dose (skin on the palm of the right hand) is 0.1 ± 0.01 mGy, and the irradiation of the thorax, abdomen, and eyes of the operator is less than 0.12 mGy. This presents no radiation hazard, even for repeated work with these sources. Translated from Atomnaya énergiya, Vol. 105, No. 4, pp. 233–235, October, 2008.     

上海辐射中心钴源装置剂量场计算

本文用γ辐照装置剂量场计算简化模型计算了上海辐射中心γ辐照装置剂量场分布,并与实测值进行了比较。计算和测量了辐照产品箱内累积最大和最小吸收剂量、均匀性等参数,介质为空气时符合较好,辐照产品为马铃薯时在10％以内符合。同时也给出了辐照产品为马铃薯时的产量和源利用率的计算值和实测值。     

Depth Smoothing of the Dose under Irradiation by Electrons

Irradiation uniformity is an important problem in radiation technology employing electron beams. One variant of a solution of this problem is the use of filters partially covering the primary beam. A method for optimizing the filter parameters is presented; the method used is the modern certified code package PENELOPE. The influence of filter material on the radiation utilization coefficient of a linear electron accelerator is investigated. For processing of polyethylene with a 6 MeV electron beam, filter parameters giving a high uniformity of the depth distribution of the absorbed dose in the material are obtained.     

CMOS SRAM总剂量辐射及退火效应研究

对1 Mbits的静态随机存储器(SRAM)进行了总剂量辐照及退火试验,试验结果表明:静、动态功耗电流均随总剂量增加而显著增大;静态功耗电流的退化与功能失效有密切相关性,非常适合作为辐射环境下器件功能失效的预警量;SRAM的读写出错数存在辐射剂量阈值,超过阈值时出错数便会指数增加;退火过程可以使器件参数恢复到初始值附近,其中高温退火对出错数的恢复作用更加明显。     

Use of a Two-Dimensional Stationary Radionuclide Migration Model for Predicting the 137Cs Content in the Enisei River System

A mathematical model of the transport of radioactive impurity in a two-dimensional uniform flow is examined. This model is used to predict and reconstruct the levels of radioactive contamination of water, bottom deposits, and flood plain soils of the Enisei on a 250 km long section of the river below the discharges from the Krasnoyarsk Mining and Chemical Combine. The model is based on the two-dimensional turbulent diffusion equation and takes account of the interaction of radioactive substances between the water mass (solution, suspension) and bottom deposits. The input parameters of the model are determined from in situ investigations performed on the Enisei in the period of 1990 to 2000. The Maple V R4 symbolic mathematics program package is used for the calculations.The model is verified on the basis of measurement results obtained in expedition studies of the Enisei River in 1991 (the period when the direct-flow reactors were in operation) and 1998, 2000. Comparing the computed and measured ¹³⁷Cs concentrations in the water in the top layer of the bottom deposits showed good agreement. The model is also used to estimate the contamination of flood plain soil during a flood period. Measurements obtained in model experiments with soil samples, which were performed over several years on the Berezovyi Island, are used to check the calculations.The application of the model for solving the inverse problem makes it possible to estimate from the known concentration of individual radionuclides in the flood plain soil the intensity of the discharges that produced the radioactive contamination during a flood period. The 1996 flood is examined as an example.     

快速估算外照射事故个人剂量的体模实验

本文报道了γ射线外照射个人剂量估算的体模实验结果，给出了特定照射几何条件下的器官剂量、有效剂量当量与个人剂量计吸收剂量或人体中心自由空气场照射量的比值（ＤＲＯＰ、ＤＲＯＴ），并对事故剂量的种常用表达参量作了比较。     

Thyroid-Gland Irradiation Dose in the Russian Population Due to the Fallout of Radioactive Iodine After the Chernobyl Accident

The average irradiation dose to the thyroid gland is estimated for the people living in 4105 populated points in the Bryanskaya, Tul'skaya, Orlovskaya, and Kaluzhskaya oblasts. The basic principles of the method used to reconstruct the dose are presented. The people living in Bryanskaya oblast have the highest irradiation dose to the thyroid gland: in children less than 3 yr old the individual dose reached 10 Gy; the average dose exceeded 2.5 Gy in 12 populated points. In children living in Bryanskaya oblast, for populated points with soil contamination density above 37 kBq/m² the irradiation dose exceeded 0.05 Gy. The highest average irradiation dose to the thyroid gland in children living in Tul'skaya, Orlovskaya, and Kaluzhskaya oblasts is 0.3–1 Gy. The collective irradiation dose for the four most strongly contaminated oblasts is estimated to be as follows: Bryanskaya – 60, Tul'skaya – 20, Orlovskaya – 13, Kaluzhskaya – 3.5 thousand·people·Gy.     

Variation of Radiation Damage with Irradiation Temperature and Dose in CLAM Steel

The dependences of radiation induced defects on irradiation temperature up to 700℃ at 15 dpa and on irradiation dose up to 85 dpa at room temperature have been inves-tigated by the heavy ion irradiation and the positron annihilation lifetime spectroscopy for the CLAM.A void size peak is observed at ～500℃ where the vacancy cluster contains 9 vacancies and has an average diameter of 0.59 nm.The size of the vacancy clusters increases with the increase of irradiation dose at room temperature,and the vacancy cluster at 85 dpa consists of 9 vacancies and reaches a size of 0.60 nm in diameter.The absolute values of the void size at the peak and the increase of void size with dose in the CLAM steel are negligible compared to those of the normal stainless steels,indicating that the CLAM steel has good radiation resistant property.     

MCNP模拟钴-60辐照装置空间剂量场

为模拟辐照室中辐照工位外的周围空间剂量场分布,采用蒙特卡罗粒子输运程序MCNP建立钴-60辐照装置模型。以单板源架中心点为坐标原点的笛卡尔坐标系,考虑钴-60源的γ射线非自吸收和自吸收两种情况,研究坐标轴方向上每隔10 cm间距的空气平面的剂量率和坐标轴上剂量率的变化规律。结果表明,辐照室中辐照产品占满辐照工位的情况下,周围空间剂量场空气面剂量率整体较小;单板源架中心坐标轴上的剂量率变化规律更符合二项式拟合函数。在钴-60源γ射线自吸收情况下,单板源架端面坐标轴附近的空气面剂量率明显偏小,且随着空气面远离单板源架,空气面上的高剂量率区域向两侧移动;在钴-60源γ射线非自吸收情况下,单板源架端面处的空气面高剂量区域始终位于坐标轴附近。MCNP理论模拟计算分析对于利用钴-60辐照装置辐照工位外的周围空间剂量场具有重要的实际指导意义。     

利用MCNPX模拟钴-60辐照装置研发样品吸收剂量的研究

本文采用高能粒子输运程序MCNPX2.5.0对钴-60辐照装置建立几何模型,对位于辐照室中垂直于双板源架中心点3 m处的研发样品的吸收剂量（率）进行模拟计算。根据实际生产,选择辐照室有或无辐照产品两种工况,一是分别模拟12种不同包装规格且不同质量研发样品在不同辐照时间的吸收剂量;二是模拟计算包装规格相同且质量不同的10种样品的吸收剂量率;三是模拟计算包装规格不同但质量相同的9种样品的吸收剂量率。结果表明,在辐照室有或无辐照产品两种工况下,后者的值比前者平均大4.19倍;三类研发样品的吸收剂量（率）及变化规律可以作为实际生产研发的参考。MCNPX理论模拟计算对于辐照新产品具有重要的实际指导意义。     

国产工艺的部分耗尽SOIPMOSFET总剂量辐照及退火效应研究

对国产工艺的部分耗尽SOIPMOSFET⁶⁰Coγ射线的总剂量辐照及退火效应进行了研究。结果表明：随着工艺技术的发展,正栅氧化层具有较强的抗辐照加固能力,背栅由于埋氧层厚度和工艺生长原因而对总剂量辐照较为敏感;辐照引入的深能级界面态陷阱电荷的散射作用,导致了正栅源漏饱和电流的显著降低;退火过程中界面态陷阱电荷的饱和决定了正栅亚阈曲线的平衡位置,而隧穿或热发射的电子只能中和部分背栅氧化物陷阱电荷,使得退火后背栅曲线仍与初始值有一定负向距离。     

国产工艺的部分耗尽SOI MOSFET总剂量辐照效应及可靠性

对国产工艺的部分耗尽SOIMOSFET60Coγ射线的总剂量辐照效应及其可靠性进行了研究。结果表明:辐照引入的氧化物陷阱电荷是阈值电压漂移的主要因素;背栅对总剂量辐照更为敏感,但在背栅特性漂移未超出一定范围的情况下,依然是正栅氧化层质量决定了器件的抗辐照性能;界面态陷阱电荷的散射作用降低了器件的源漏饱和电流;总剂量辐照后器件的常规可靠性可能会降低。     

染色体易位率和辐照剂量关系的建立及应用

采用1#2、#、4#全染色体涂染探针联用的荧光原位杂交（FISH）技术,检测60Coγ射线诱发正常人染色体稳定性畸变的易位率,建立剂量-效应关系,拟合的最佳回归方程为Y=0.0132＋0.0757D＋0.0158D2。实际应用验证结果表明,在远期受照生物剂量估算中,该剂量-效应关系有良好的应用价值和应用前景。