日本拟将核废物后处理经费移交新机构管理

【日本原子能产业协会网站2004年3月报道】 美国核电厂运营业绩的不断提高主要得益于美国核管理委员会(NRC)不断改进其管理方式。传统的核电厂管理方式是根据20世纪60年代的设计与审批理念来进行的。三里岛事故暴露的问题促使NRC改进了管理规则,制定了大量公告和信息传递政策。1991年,NRC制定了维护管理规则,实施了概率风险评估(PRA)。为了加强成本管理并降低成本,NRC重新分析了可靠性与收益性的平衡问题。1995年,NRC推出了政策声明(PRA),用反应堆监测程序(ROP)替代了传统的运行性能的系统性评价(SALP),以便在严重风险来临之前,…     

法国称其新型反应堆属世界最安全的反应堆之例

【美国《核子周刊》1990年5月24日第11页报道】法国国营电力公司及其核安全机构上周透露,对法国压水堆(PWR)所作的概率风险评价(PRA)表明,法国的新型反应堆属经PRA的最安全的反应堆之列,比美国核管理委员会(NRC)对美郇山核电厂所作的PRA值小13倍(假设研究范围相同的     

美国核电厂风险评估的安全效益（三）

【美国《核新闻》2003年1月刊报道】 委托监管应用 美国核管会(NRC)在监管过程中积累了大量风险知识,并根据从实施概率风险分析(PRA)中获得的这些知识对监管作出了诸多改进。本章将对一些比较重要的风险通报应用进行概要介绍。 ATWS(未能紧急停堆的预期瞬态)规则 ATWS是反应堆事故保护停堆作用失败后的停堆事件。这个不太可能发生的事件将引起反应堆系统的高压,同时产生远远超出反应堆停堆散热能力的衰变热,因此反应堆必须停堆并保持在次临界状态。NRC在1983年发布了ATWS规则(10 CFR 50.62),通过以下措施降低ATWS风险: 降低预…     

美国核管会建议简化许可证税收程序

根据美国核管理委员会(NRC)税收计划的修改建议,许可证持有者向NRC支付的年度税款将减少。     

美国采用热中子活化法甄别行李

【美国《核新闻》1990年第5期第66页报道】美国核管理委员会(NRC)正在考虑修订它给联邦航空局(FAA)颁发的许可证,以便FAA可授权使用热中子活化方法(TNA)去甄别机场中央大厅(或门厅)范围内的已检查过的行李(不是只在行李装卸区或存放区进行甄别)。NRC已发现,在中央大厅正常使用TNA系统不会对环境有多大影响。     

国外核电站安全的审批机构及审批程序简介

1.审批机构目前,美国核电站和核材料的安全审批和颁发许可证的工作,是由美国核管理委员会(NRC)负责的。NRC 是美国政府的一个独立机构,它主要根据两个法律文件来行使其管理权力:一是根据1974年能源改组法修正案,NRC 负责履行1954年原子能法修正案中规定的所有管理职能。这些法律条款要求 NRC 负责确保公众在放射性方面的健康和安全,确保公共治安保卫,确保给核设施颁发许可证的决定不违反国家反托拉     

美国核管理委员会简介

美国核管理委员会(Nuclear Regulatory Commission,以下简称NRC)建立于1974年,它是由美国国会授权,按"原子能法"、"防止核扩散法"及"能源再组织法"等法律规定对核能安全实施管理的国家机构.NRC的前身是原子能委员会(AEC),它创立于1954年,解体于1974年,解体后的管理机能移交给NRC.     

美进一步严格干法贮存设施的申请书标准

[美国《核燃料》1996年5月6日刊第4页报道] 美国核管理委员会(NRC)已经告知国际霍尔泰克公司和整个核工业界,NRC新的成立乏燃料项目局(SFPO)将进一步严格干法贮存设施的申请书标准。     

美国核管会制订改革新方案

【欧洲核学会《核新闻网》 1998年 9月4日报道】　美国核管理委员会 (NRC)主席Shiriey Jackson向 NRC雇员简要介绍了一系列新的改革方案 ,目的在于使该组织更有效和更高效。NRC主席是在全体雇员会议上宣布的这一动议的。此行动在 NRC执行工作中的近几个月里遭到了猛烈的批评。Jackson博士在这次会议上说 ,国会委员会和由一些 NRC要求苛刻的批评家参加的今年 7月举行的圆桌讨论会最近所作的外部评论 ,为 NRC提供了有价值的见识。她说 ,NRC应该着重于“抓重点”。这并不意味着采取守势 ,而是在“通过改革提高效率的同时千万不要忘记…     

美国核管理委员会从严控制辐照剂量限值

【英国《国际核工程》1991年2月号第6页报道】美国核管理委员会(NRC)1990年12月13日宣称,他们对核电厂的工人和生活在核设施附近的居民的辐照剂量标准作了一些修改。在过去的30年中,虽然NRC     

Preparation of Zn/TiO2 powder and its photocatalytic performance for oxidation of P-nitrophenol

Zn-doped TiO2 catalysts were prepared using a sol-gel method and characterized by XPS,UV-Vis, BET, XRD in this study. Under the irradiation of simulant sunlight, the photocatalytic activity for the degradation of p-nitrophenol was studied too. After irradiation for 2.5 h, the degradation percentage of p-nitrophenol could rise to more than 80 %. The results showed that the spectrum absorption band edge of Zn/TiO2 powder does not broaden obviously comparing with pure TiO2 powder. Zinc exists as Zn （11）. When calcined at 973 K, there is a new phase as ZnTiO3 in Zn/TiO2 catalyst. The order of photocatalytic activity of Zn/TiO2 catalysts calcined at different temperatures for p-nitrophenol is 773 K 〉 673 K 〉 873 K 〉 573 K 〉 973 K and the photocatalytic activity of Zn/TiO2 catalyst calcined at 773 K is better than TiO2 catalysts heated at the same temperature, and outclasses that of commercial TiO2 catalyst. It also showed that the photocatalytic degradation of p-nitrophenol follows first-order kinetics under the irradiation of simulant sunlight.     

Current status of radiation therapy for prostate cancer

Radiotherapy for the treatment of prostate cancer has been extensively explored in the past. Along with the comprehensive understanding of the biology of prostate cancer and rapid advances in terms of technology, the out- come of treatment for the patients with prostate cancer has improved. The authors review radiotherapy as the primary treatment for the disease, with particular emphasis on the technological advances from both the radiobiological and radiophysics aspects. Nonconventional fractionated irradiation like hyper- or hypo-fractionation has been imple- mented in the clinic, the final results still need to be confirmed in the future. Technological advances like IMRT, IGRT, in the last two decades have significantly improved the delivery of external radiotherapy to the prostate. This has re- sulted in an overall increase in the total dose that can be safely delivered to the prostate, which has led to modest im- provements in the biochemical outcome. However, establishing the standard therapy for prostate cancer remains con- troversial. It is hoped that the next decades will bring continued advances in the development of biologicals that will further improve current clinical outcomes.     

水平管内含空气蒸汽强制对流冷凝换热模型研究

为研究含空气蒸汽在水平管内强制对流冷凝换热特性,基于对传热传质过程的分析,建立了管内为环状流与波状流条件下的流动冷凝换热模型。从潜热、显热和液膜3个环节对整个换热过程进行建模,最终得到计算局部冷凝换热系数的理论关系式。模型预测结果与实验数据的对比表明,二者相对偏差在±20%以内,验证了该换热模型的准确性与适用性。通过进一步的研究发现：从换热管入口至出口,随着冷凝的进行,管内换热主要热阻由液膜热阻向气液界面的凝结热阻转变;主流气体对流换热过程基本可忽略。     

Investigations on landmine detection by BF3 detector

Experiments were carried out to investigate the possible use of neutron backscattering for the detection of polyethylene (PE) sample buried in the soil. In detection of landmine by neutrons, the neutron detector and its shield play an important role. In this paper, the effects of graphite, heavy water, polyethylene and boric acid moderators on the flux of back scattered neutrons were investigated. We have also experimentally verified the effect of BF3 detector shield and obtained good agreement with theory.     

Web Services interface of SSRF archive data analysis system

Accelerator database stores various static parameters and real-time data of accelerator. SSRF (Shanghai Synchrotron Radiation Facility) adopts relational database to save the data. We developed a data retrieval system based on XML Web Services for accessing the archive data. It includes a bottom layer interface and an interface applicable for accelerator physics. Client samples exemplifying how to consume the interface are given. The users can browse, retrieve and plot data by the client samples. Also, we give a method to test its stability. The test result and performance are described.     

Assessment of radioactivity levels in some oil samples from the western desert, Egypt

Distributions of natural gamma-emitting radionuclides were determined in 93 oil samples collected from some petroleum fields in the western desert of Egypt. The radioisotope activities in the area under investigation lay in the range of (21 ± 4) to (38 ± 13) Bq?L-1 for 226Ra, (9 ± 2) to (15 ± 5) Bq?L-1 for 232Th, and (154 ± 28) to (303 ± 54) Bq?L-1 for 40K. The mean values were 27, 12, and 201 Bq?L-1, respectively. Among oils, variations in radionuclide ac- tivities could be on account of differences in TDS, HCO3, and Ba, with high or low pH. In this environment, oil prop- erties differently affected the mobilization of natural radionuclides. The range of 226Ra variation had been compared with available data from other countries. The calculated absorbed dose rate ranged from 22.33 to 32.66 nGy?h-1 in lo- cation (B) and (E) respectively, which was less than the accepted value.     

Preparation and properties of 117m Sn(IV)-TTHMP in in-vitro and in small animals

In this work,TTHMP was synthesized and labelled with 117m Sn.The preparation conditions,stability and lipophilicity of 117m Sn(IV)-TTHMP were investigated.Biodistribution of the complex in rabbits and mice was studied.It was found that the quantity of TTHMP and pH value of the prepararion solution had vital effects on the labeling yield of 117m Sn(IV)-TTHMP.It was also found that 117m Sn(IV)-TTHMP was hydrophilic and stable at room temperature and 37℃ in open air 117m Sn(IV)-TTHMP showed unexpectedly high bone uptake and bone-to-blood ratio in the animals.This made it potentially useful as an reagent for skeletal scintigraphy and radiotherapy of bone tumors.     

The role of AGFA high-energy CR in the calibration and quality control of multileaf collimators （MLC）

Linear accelerators equipped with multileaf collimators （MLC） are becoming more common and are widely used in the intensity-modulated radiotherapy （IMRT）. There is an imperative need to ensure the commissioning specification of the linear accelerators for the sake of quality assurance （QA） and quality control （QC）. This paper is aimed to investigate the role of AGFA high-energy CR （Computed Radiography） in calibrating dynamic multileaf collimators and evaluating the accuracy of the leaf position. The result shows that AGFA high-energy CR can easily and conveniently be used to calibrate MLC and verify its position. Hence, the application of AGFA high-energy CR is proved to be an accurate and time-saving method for routine MLC QC, especially when MLC calibration adjustments are required.     

微型X射线管空气比释动能和能谱的测量

为研究微型X射线管的特性,通过电离室测量光管出射口30 cm远处的空气比释动能,使用高纯锗探测器分别测量了Ag过滤和Cu过滤下的X射线能谱。结果表明,空气比释动能随电流的增加有线性增加的趋势,能谱图明显的观察到银的两个特征X射线。完成了微型X射线管空气比释动能和能谱的测量方法以及实验测量的工作,为微型x射线管下辐射质的建立提够了条件基础。     

Gamma-ray attenuation technique for measuring void fraction in horizontal gas-liquid two-phase flow

The measurement of void fraction is of importance to the oil industry and chemical industry. In this article, the principle and mathematical method of determining the void fraction of horizontal gas-liquid flow by using a single-energy γ-ray system is described. The γ-ray source is the radioactive isotope of 241Am with γ-ray energy of 59.5 keV. The time-averaged value of the void fraction in a 50.0-mm i.d. transparent horizontal pipeline is measured under various combinations of the liquid flow and gas flow. It is found that increasing the gas flow rate at a fixed liquid flow rate would increase the void fraction. Test data are compared with the predictions of the correlations and a good agreement is found. The result shows that the designed γ-ray system can be used for measuring the void fraction in a horizontal gas-liquid two-phase flow with high accuracy.