The present work gives a methodology for assessing radiological concentration of 131I, 132I, 133I, 134I, and 135I due to a hypothetical accident of TRIGA Mark-II research Reactor at AERE, Savar, Bangladesh. The concen...The present work gives a methodology for assessing radiological concentration of 131I, 132I, 133I, 134I, and 135I due to a hypothetical accident of TRIGA Mark-II research Reactor at AERE, Savar, Bangladesh. The concentrations were estimated through different pathways like ingestion of vegetation, milk, and meat from air and ground deposition. The maximum air concentrations for all 16 directions were found at 110 m distance from the core of the reactor and it was found to be highest in the southern (S) direction. The maximum ground concentration occurred immediately just after the accident in different directions. In all pathways, the most concentration was found to be in S-direction. The concentrations in vegetation of 131I, 133I, 135I were significant, while no concentrations of 132I and 134I were observed. The concentration in vegetation for 131I was found to be highest than all other isotopes of iodine. The concentrations of 133I were found to be higher and concentrations of 134I were observed to be lower in both milk and meat compared to other radio isotopes of iodine. In the case of a radiological accident, the results of the present study will be a valuable guide for adopting radiological safety measures for radiation protection against the ingestion of vegetables, milk and meat from around the research reactor at AERE, Savar, Bangladesh.展开更多
文摘The present work gives a methodology for assessing radiological concentration of 131I, 132I, 133I, 134I, and 135I due to a hypothetical accident of TRIGA Mark-II research Reactor at AERE, Savar, Bangladesh. The concentrations were estimated through different pathways like ingestion of vegetation, milk, and meat from air and ground deposition. The maximum air concentrations for all 16 directions were found at 110 m distance from the core of the reactor and it was found to be highest in the southern (S) direction. The maximum ground concentration occurred immediately just after the accident in different directions. In all pathways, the most concentration was found to be in S-direction. The concentrations in vegetation of 131I, 133I, 135I were significant, while no concentrations of 132I and 134I were observed. The concentration in vegetation for 131I was found to be highest than all other isotopes of iodine. The concentrations of 133I were found to be higher and concentrations of 134I were observed to be lower in both milk and meat compared to other radio isotopes of iodine. In the case of a radiological accident, the results of the present study will be a valuable guide for adopting radiological safety measures for radiation protection against the ingestion of vegetables, milk and meat from around the research reactor at AERE, Savar, Bangladesh.
文摘晶片标识码的手写方式存在不美观、字体边缘玻璃蹦渣及划痕深等缺点。某些MEMS工艺玻璃-Si键合片需KOH腐蚀。采用手写,KOH通过玻璃片标码部位侵入晶片正面而腐蚀器件结构。因此,采用波长10640 nm CO2激光器针对玻璃晶片进行激光标识制作的打标工艺。研究中分别改变激光平均输出功率、脉冲频率及扫描速度,借助目视、金相显微镜及动态三维光学轮廓仪来观察标识码的清晰度、是否产生裂纹及字体凸起程度,了解它们与上述参数间相互对应关系。重点解决清晰度与凸起高度的矛盾,从而得到清晰、无裂纹且凸起高度满足后续半导体纳米级加工工艺要求的激光标码技术。结果表明:脉冲频率对清晰度、裂纹产生及凸起高度无显著影响;平均功率与清晰度及凸起程度呈正比例关系,与裂纹产生无相关性;扫描速度与清晰度、裂纹产生的可能性及凸起高度呈反比关系。采用40%平均功率,20 k Hz频率,150 mm/s扫描速度及单线字体(JCZ Single Line)进行标刻时,标识码在目视及镜检下清晰可视,无微细裂纹,轮廓仪测量结果显示字迹凸起高度为185 nm。应用上述条件标码的玻璃片与Si键合并在KOH中腐蚀5 h后无KOH进入晶片正面的现象发生。
