食品辐照用~(60)Co辐照装置剂量场计算

近年来,食品辐照保藏保鲜已达到商业化规模。不少地区正在建设和筹建商用辐照装置。剂量场计算不仅可为建造辐照装置提供设计依据,而且还为食品辐照加工、质量监控提供装置的运行参数。由此可见,剂量精确计算对辐照装置的设计,保证辐照产品产量、质量有着重要意义。     

60Co γ射线辐照营养霜临界剂量研究

对辐照营养霜的氧化还原电位、超微弱发光、色泽三刺激值以及理化指标进行了分析，认为辐照营养霜的临界剂量为8kGy。     

^60Co辐照装置运行的辐射防护评价

从辐射防护角度，对一座２．８ＰＢｑ＾６０Ｃｏ辐照装置运行近１０年的辐射安全进行总结与评价。     

60Co单板源堆码辐照剂量不均匀度分析

本实验在3.9PBq、1m×1m的单板源辐射场中,利用重铬酸银剂量计,在正对源1.4m×1.4m实际辐照面控制范围内,对桔红丸、利咽丸、妇炎灵三种中成药产品箱中吸收剂量及其不均匀度进行了测量,以检验辐照工艺质量.可根据辐照灭菌产品的包装尺寸与密度、菌种及细菌总数的含量设计照射方案,确定辐照工艺和运行参数.中成药所含细菌与辐照剂量的关系一般遵循公式SD＝D10 1g(N0/N)+K,式中,SD为灭菌剂量,D10为杀死90%细菌所需的吸收剂量,N0为样品未辐照前的初始菌数,N为样品辐照后的存活菌数,K为经验校正因子,可正可负,取决于中成药辐照条件[1].在具体选择辐照剂量时,首先应考虑辐照产品的辐照目的、要求,以及辐照产品所含菌种及含菌基数,然后根据公式推算出所需辐照剂量.实验采用堆码辐照,四周和中间对调并前后翻转的双面辐照工艺.监测实验辐照产品最小吸收剂量的剂量计布放于各箱体中心,照射完成后通过测量剂量计的吸光度读出受照产品的吸收剂量.实验测得各受照产品最大、最小吸收剂量值依次为4.61 kGy与2.98kGy,2.00kGy与1.03kGy,2.24kGy与1.37kGy,不均匀度U依次为1.55、1.94、1.64,证明产品箱中的剂量不均匀度均能满足质量控制标准(U≤2)的要求,表明该辐照工艺是可行的,辐照面大小的选择是合适的.     

一起^60Co源辐照事故中受照人员的剂量估算

本文报道了一起~(60)Co 源辐照事故中受照人员的剂量模拟测量结果。经调查和现场模拟实验,确定了受照条件。使用组织等效人体模型和 LiF(Mg,Cu,P)热释光剂量计测定了受照人员的器官吸收剂量。事故受照人员 F(男)和 L(男)的造血干细胞活存计权等效剂量分别为1.24和0.3 Gy,红骨髓计权平均剂量分别为1.29和0.31 Gy,全身平均吸收剂量分别为1.22和0.32 Gy。     

60Coγ辐射剂量场分布理论计算的计算机程序开发

钴源辐照装置的剂量场分布对提高射线利用率和产品辐照质量至关重要，利用Visual Basic编制了辐射剂量场分布计算程序。程序将计算、排源及参数调整独立分开，操作简便，主要适用于3层排列板源结构。程序经过用于本中心板源，辐射剂量场分布的计算结果基本反映了辐射剂量场的实际分布。     

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。     

4名^60Co源辐照事故中受照者的剂量估算

对一起＾６０Ｃｏ源辐照事故中受到过量照射的人员，通过现场调查和模拟试验，确定了照射的几何条件和受照时间，估算了４名受照者的造血干细胞活存计权等效剂量。最后将物理方法与生物学方法估算的剂量数据作了比较。     

酒类专用辐照站的设计

本文扼要介绍了酒类专用辐照站的设计原则、物理方案、工艺流程、建筑结构及其安全特性。该辐照站现装钴源0.925×10~(15)Bq,辐照酒量每天10t。它结构简单,操作方便,安全可靠,射线利用率高,很适于在地方小企业推广应用。     

γ辐射加工中剂量控制技术研究

针对γ辐射加工过程中的剂量控制问题,结合某单位现有的单板源动态γ辐照装置特点,系统分析了影响剂量控制水平的因素,从剂量测量体系建立和辐照装置改进两方面开展了辐照剂量控制技术研究。通过大量剂量测试和统计分析,检验评估了整个辐射加工过程中的剂量控制能力。结果表明:剂量测量体系标准化和辐照装置优化改进,很好地控制了辐照稳定性和剂量不均匀度,显著提高了产品辐照剂量的控制水平,对辐射加工生产具有指导意义。     

^60Coγ辐照装置的安全防护及装源技术的改进

以多年的实践经验结合过去操作时出现的事故和可能出现的故障对~(60)Coγ辐照装置作了改进,屏蔽门与源升降联锁;增设了万能转换开关,超程时能自动切断主电源;装设γ报警和闭路电视系统;采用电磁吸源法安装钴源。     

滤光片及X射线二极管响应面均匀性研究

介绍了用于软X光能谱测量的滤光片及X射线二极管能量应均匀性研究。实验利用北京同步辐射装置3WIB束线,流强40－80mA的运行条件,在100－1600eV能区对滤光片及X射线二极管（XRD）作能响曲线标定。重点对C滤片及Al阴极XRD的灵敏面作能响面均匀性研究,最后给出响应面均匀性测量结果及计算分析。     

Dose intercomparison studies for 60Co gamma-ray and electron beam irradiation in the year 2002

1 Introduction With the rapid development of radiation process- ing by electron beam irradiation in China, it is more Ever since 1962, alanine/EPR dosimetry system and more needed to establish a transfer dosimetryhas been used to measure the absorbed dose.[1] Its ad- system with high accuracy to assure the quality of thevantages over othe…     

环境γ辐射剂量率仪现场校准用辐照装置的研制

为开展环境γ辐射剂量仪的现场校准,研制了一套辐照装置,其辐射场空气比释动能率可在0.27-34.86μGy·h~(-1)范围内通过距离与减弱器来调节。基于大量Geant4蒙特卡罗模拟设计了一种轻便型辐射准直器,在保证辐射场品质的前提下,大大降低了准直器重量,更适用于现场校准。此外,还研制了一套自动化支撑平台与三片曲面辐射减弱器,可远程实现辐射装置空间定位以及辐射场强度和空间的调节,曲面辐射减弱器有利于保证辐射场均匀性。测试实验及蒙特卡罗模拟结果显示,该辐射装置辐射场再现性、自散射、均匀性等性能良好,通过系统地计算地面散射对辐射场的影响,可为现场校准提供指导。     

Analysis of fuel management in the KIPT neutron source facility

Argonne National Laboratory (ANL) of USA and Kharkov Institute of Physics and Technology (KIPT) of Ukraine have been collaborating on the conceptual design development of an experimental neutron source facility consisting of an electron accelerator driven sub-critical assembly. The neutron source driving the sub-critical assembly is generated from the interaction of 100 KW electron beam with a natural uranium target. The sub-critical assembly surrounding the target is fueled with low enriched WWR-M2 type hexagonal fuel assemblies. The U-235 enrichment of the fuel material is <20%. The facility will be utilized for basic and applied research, producing medical isotopes, and training young specialists. With the 100 KW electron beam power, the total thermal power of the facility is ∼360 kW including the fission power of ∼260 kW. The burnup of the fissile materials and the buildup of fission products continuously reduce the system reactivity during the operation, decrease the neutron flux level, and consequently impact the facility performance. To preserve the neutron flux level during the operation, the fuel assemblies should be added and shuffled for compensating the lost reactivity caused by burnup. Beryllium reflector could also be utilized to increase the fuel life time in the sub-critical core. This paper studies the fuel cycles and shuffling schemes of the fuel assemblies of the sub-critical assembly to preserve the system reactivity and the neutron flux level during the operation.     

60 Co单源照射装置的蒙特卡罗方法优化设计

参考辐射是辐射剂量监测仪器校准工作必备的条件, 60 Co单源照射装置是产生参考辐射场的重要设备。本文利用蒙特卡罗方法对 60 Co单源照射装置产生的辐射场的均匀性和散射辐射进行模拟计算,完成照射装置中散射腔、准直光阑和快门体等部分的设计并利用PTW电离室对辐射场进行测量。结果表明,辐射场中散射辐射和均匀性与模拟结果符合较好,满足设计要求。     

Plasma grid design for optimized filter field configuration for the NBI test facility ELISE

Maintenance-free RF sources for negative hydrogen ions with moderate extraction areas (100-200 cm²) have been successfully developed in the last years at IPP Garching in the test facilities BATMAN and MANITU. A facility with larger extraction area (1000 cm²), ELISE, is being designed with a “half-size” ITER-like extraction system, pulsed ion acceleration up to 60 kV for 10 s and plasma generation up to 1 h. Due to the large size of the source, the magnetic filter field (FF) cannot be produced solely by permanent magnets. Therefore, an additional magnetic field produced by current flowing through the plasma grid (PG current) is required. The filter field homogeneity and the interaction with the electron suppression magnetic field have been studied in detail by finite element method (FEM) during the ELISE design phase. Significant improvements regarding the field homogeneity have been introduced compared to the ITER reference design. Also, for the same PG current a 50% higher field in front of the grid has been achieved by optimizing the plasma grid geometry. Hollow spaces have been introduced in the plasma grid for a more homogeneous PG current distribution. The introduction of hollow spaces also allows the insertion of permanent magnets in the plasma grid.