The activity concentration of natural and fallout radionuclides in the soil at some selected Thanas around the TRIGA Mark-II Research Reactor at Atomic Energy Research Establishment (AERE), Savar, Dhaka were measured ...The activity concentration of natural and fallout radionuclides in the soil at some selected Thanas around the TRIGA Mark-II Research Reactor at Atomic Energy Research Establishment (AERE), Savar, Dhaka were measured by using a high purity germanium detector (HPGe). The study revealed that only natural radionuclides were present in the samples and no trace of any artificial radionuclide was found. The average activity concentration of 238U, 232Th and 40K were found to be 37.8 ± 5.6 Bq.kg-1, 58.2 ± 11.0 Bq.kg-1 and 790.8 ± 153.4 Bq.kg-1 respectively. The radium equivalent activity (Req), absorbed dose rate (D), external radiation hazard index (Hex) and internal radiation hazard index (Hin) were also calculated to find out the probable radiological hazard of the natural radioactivity.展开更多
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
目的:比较和分析Vita Mark II与2种全瓷系统饰瓷的结合强度。方法:将Vita Mark II瓷块切割成8 mm×6 mm×2 mm试件20个,随机分成2组(n=10),分别在其表面烧结饰瓷VM9和Titankeramik,用万能试验机测定剪切强度,扫描电镜(SEM)观察...目的:比较和分析Vita Mark II与2种全瓷系统饰瓷的结合强度。方法:将Vita Mark II瓷块切割成8 mm×6 mm×2 mm试件20个,随机分成2组(n=10),分别在其表面烧结饰瓷VM9和Titankeramik,用万能试验机测定剪切强度,扫描电镜(SEM)观察结合界面的形貌和构象,热场发射扫描电镜(FE-SEM)对结合界面进行元素定性分析。结果:VM9组和Titankeramik组剪切强度(MPa)分别为:36.92±7.6和41.02±9.40(P>0.05);各组试件破坏模式均以基底瓷破坏为主,SEM观察显示2种饰瓷材料在界面区与Mark II瓷块镶嵌融合,结合紧密无间隙。FE-SEM分析表明界面区Al元素质量分数呈梯度变化,由基底瓷向饰面瓷Al的质量分数逐渐下降,提示基底瓷中Al有越过界面相互渗透的现象。结论:VM9和Titankeramik饰瓷与Vita mark II的结合强度均能满足临床需要。展开更多
针对坐落于意大利帕维亚大学的TRIGA Mark Ⅱ反应堆热柱结构进行优化设计,从而满足面向硼中子俘获治疗(BNCT)的单光子发射计算机断层成像(SPECT)研究要求。为提高计算效率并减小统计误差,对比分析使用SSW/SSR方法与直接使用反应堆为源...针对坐落于意大利帕维亚大学的TRIGA Mark Ⅱ反应堆热柱结构进行优化设计,从而满足面向硼中子俘获治疗(BNCT)的单光子发射计算机断层成像(SPECT)研究要求。为提高计算效率并减小统计误差,对比分析使用SSW/SSR方法与直接使用反应堆为源项时热柱内照射位置处中子能谱,其结果基本一致,从而验证了SSW/SSR方法的可靠性。为在该反应堆开展BNCT中SPECT实验,热柱中子束需准直为笔形束。对比分析四种热柱优化方案下束流口处及探测器处热中子和光子通量:40cm长石墨(射束口5cm×3cm);0.5cm厚硼包裹40cm长石墨(射束口5cm×3cm);30cm长天然锂聚乙烯(射束口直径4cm);30cm长天然锂聚乙烯(20cm长射束口直径5cm,5cm长射束口直径4cm,5cm长射束口直径2cm)。结果显示,射束口处热中子通量分别为1.05×108,2.52×107,6.08×107和5.10×107#/(cm2·s)。综合考虑中子准直效果及光子污染,方案三具有最优性能。为后续进行BNCT-SPECT理论和实验研究提供了基础,从而有效促进BNCT剂量准确评估方法的研究进程。展开更多
The COOLOD-N2 and PARET computer codes were used for a steady-state thermal hydraulic and safety analysis of the 3 MW TRIGA Mark-II research reactor located at Atomic Energy Research Establishment (AERE), Savar, Dhaka...The COOLOD-N2 and PARET computer codes were used for a steady-state thermal hydraulic and safety analysis of the 3 MW TRIGA Mark-II research reactor located at Atomic Energy Research Establishment (AERE), Savar, Dhaka, Bangladesh. The objective of the present study is to ensure that all important safety related thermal hydraulic parameters uphold margins far below the safety limits by steady-state calculations at full power. We, therefore, have calculated the hot channel fuel centreline temperature, fuel surface temperature, cladding surface temperature, the departure from nucleate boiling (DNB) heat flux and DNB ratio, axial fuel centreline temperature and compared. The comparison indicates that the calculated values are in satisfactory agreement between the codes. The data obtained in this investigation are largely far to compromise safety of the reactor. The results can also be used to upgrade the current core configuration of the TRIGA reactor.展开更多
The assessment of the radiological concentration of <sup>134</sup>Cs and <sup>137</sup>Cs owing to hypothetical accident of TRIGA Mark-II research Reactor at AERE, Savar, Bangladesh is presente...The assessment of the radiological concentration of <sup>134</sup>Cs and <sup>137</sup>Cs owing to hypothetical accident of TRIGA Mark-II research Reactor at AERE, Savar, Bangladesh is presented here in this work. The concentration of <sup>134</sup>Cs and <sup>137</sup>Cs was estimated in different pathways consisting of the ingestion of plants, milk, and meat. The highest air concentration has been determined at 65 m distance from the core of the reactor. The maximum concentration passed off without delay simply after the accident in various directions. Local meteorological information such as average wind velocity and wind frequency were analyzed. Considering all directions, the highest concentration has been observed in the “S” direction. The concentrations of <sup>134</sup>Cs and <sup>137</sup>Cs were determined in ground, vegetation, milk and meat. The concentration of <sup>137</sup>Cs is investigated to be higher than the <sup>134</sup>Cs. The concentration of <sup>134</sup>Cs and <sup>137</sup>Cs was found to be lower in vegetation, milk, and meat than that of ground concentration. Overall, in this study, the concentration in meat has been investigated to be lower. In case of a reactor accident, the concentration assessment due to the ingestion of vegetables, milk, and meat will be a valuable guide for insuring radiological protection across the research reactor at AERE, Savar, Bangladesh.展开更多
由于HVAC系统噪声的特性不同于其他噪声,其能量常集中在人们不敏感的频域内,因此在评价方法上要和常规的噪声评价方法有所区别,剧院环境中的背景噪声往往属于此类噪声,它可能会影响某些观众的听闻质量。自从倍频带被提出以后,对这种噪...由于HVAC系统噪声的特性不同于其他噪声,其能量常集中在人们不敏感的频域内,因此在评价方法上要和常规的噪声评价方法有所区别,剧院环境中的背景噪声往往属于此类噪声,它可能会影响某些观众的听闻质量。自从倍频带被提出以后,对这种噪声的评价变得可能。本文利用国际上常采用的NC、NCB、RC、RC Mark Ⅱ四种基于倍频带的噪声评价方法,分别对国内某大型剧院的HVAC系统噪声进行评价,结果表明RC Mark Ⅱ评价方法对于评价此类噪声具有一定优势。展开更多
文摘The activity concentration of natural and fallout radionuclides in the soil at some selected Thanas around the TRIGA Mark-II Research Reactor at Atomic Energy Research Establishment (AERE), Savar, Dhaka were measured by using a high purity germanium detector (HPGe). The study revealed that only natural radionuclides were present in the samples and no trace of any artificial radionuclide was found. The average activity concentration of 238U, 232Th and 40K were found to be 37.8 ± 5.6 Bq.kg-1, 58.2 ± 11.0 Bq.kg-1 and 790.8 ± 153.4 Bq.kg-1 respectively. The radium equivalent activity (Req), absorbed dose rate (D), external radiation hazard index (Hex) and internal radiation hazard index (Hin) were also calculated to find out the probable radiological hazard of the natural radioactivity.
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.
文摘目的:比较和分析Vita Mark II与2种全瓷系统饰瓷的结合强度。方法:将Vita Mark II瓷块切割成8 mm×6 mm×2 mm试件20个,随机分成2组(n=10),分别在其表面烧结饰瓷VM9和Titankeramik,用万能试验机测定剪切强度,扫描电镜(SEM)观察结合界面的形貌和构象,热场发射扫描电镜(FE-SEM)对结合界面进行元素定性分析。结果:VM9组和Titankeramik组剪切强度(MPa)分别为:36.92±7.6和41.02±9.40(P>0.05);各组试件破坏模式均以基底瓷破坏为主,SEM观察显示2种饰瓷材料在界面区与Mark II瓷块镶嵌融合,结合紧密无间隙。FE-SEM分析表明界面区Al元素质量分数呈梯度变化,由基底瓷向饰面瓷Al的质量分数逐渐下降,提示基底瓷中Al有越过界面相互渗透的现象。结论:VM9和Titankeramik饰瓷与Vita mark II的结合强度均能满足临床需要。
文摘针对坐落于意大利帕维亚大学的TRIGA Mark Ⅱ反应堆热柱结构进行优化设计,从而满足面向硼中子俘获治疗(BNCT)的单光子发射计算机断层成像(SPECT)研究要求。为提高计算效率并减小统计误差,对比分析使用SSW/SSR方法与直接使用反应堆为源项时热柱内照射位置处中子能谱,其结果基本一致,从而验证了SSW/SSR方法的可靠性。为在该反应堆开展BNCT中SPECT实验,热柱中子束需准直为笔形束。对比分析四种热柱优化方案下束流口处及探测器处热中子和光子通量:40cm长石墨(射束口5cm×3cm);0.5cm厚硼包裹40cm长石墨(射束口5cm×3cm);30cm长天然锂聚乙烯(射束口直径4cm);30cm长天然锂聚乙烯(20cm长射束口直径5cm,5cm长射束口直径4cm,5cm长射束口直径2cm)。结果显示,射束口处热中子通量分别为1.05×108,2.52×107,6.08×107和5.10×107#/(cm2·s)。综合考虑中子准直效果及光子污染,方案三具有最优性能。为后续进行BNCT-SPECT理论和实验研究提供了基础,从而有效促进BNCT剂量准确评估方法的研究进程。
文摘The COOLOD-N2 and PARET computer codes were used for a steady-state thermal hydraulic and safety analysis of the 3 MW TRIGA Mark-II research reactor located at Atomic Energy Research Establishment (AERE), Savar, Dhaka, Bangladesh. The objective of the present study is to ensure that all important safety related thermal hydraulic parameters uphold margins far below the safety limits by steady-state calculations at full power. We, therefore, have calculated the hot channel fuel centreline temperature, fuel surface temperature, cladding surface temperature, the departure from nucleate boiling (DNB) heat flux and DNB ratio, axial fuel centreline temperature and compared. The comparison indicates that the calculated values are in satisfactory agreement between the codes. The data obtained in this investigation are largely far to compromise safety of the reactor. The results can also be used to upgrade the current core configuration of the TRIGA reactor.
文摘The assessment of the radiological concentration of <sup>134</sup>Cs and <sup>137</sup>Cs owing to hypothetical accident of TRIGA Mark-II research Reactor at AERE, Savar, Bangladesh is presented here in this work. The concentration of <sup>134</sup>Cs and <sup>137</sup>Cs was estimated in different pathways consisting of the ingestion of plants, milk, and meat. The highest air concentration has been determined at 65 m distance from the core of the reactor. The maximum concentration passed off without delay simply after the accident in various directions. Local meteorological information such as average wind velocity and wind frequency were analyzed. Considering all directions, the highest concentration has been observed in the “S” direction. The concentrations of <sup>134</sup>Cs and <sup>137</sup>Cs were determined in ground, vegetation, milk and meat. The concentration of <sup>137</sup>Cs is investigated to be higher than the <sup>134</sup>Cs. The concentration of <sup>134</sup>Cs and <sup>137</sup>Cs was found to be lower in vegetation, milk, and meat than that of ground concentration. Overall, in this study, the concentration in meat has been investigated to be lower. In case of a reactor accident, the concentration assessment due to the ingestion of vegetables, milk, and meat will be a valuable guide for insuring radiological protection across the research reactor at AERE, Savar, Bangladesh.
文摘由于HVAC系统噪声的特性不同于其他噪声,其能量常集中在人们不敏感的频域内,因此在评价方法上要和常规的噪声评价方法有所区别,剧院环境中的背景噪声往往属于此类噪声,它可能会影响某些观众的听闻质量。自从倍频带被提出以后,对这种噪声的评价变得可能。本文利用国际上常采用的NC、NCB、RC、RC Mark Ⅱ四种基于倍频带的噪声评价方法,分别对国内某大型剧院的HVAC系统噪声进行评价,结果表明RC Mark Ⅱ评价方法对于评价此类噪声具有一定优势。
