美国低中放废物陆地浅埋处置模拟试验简介

美国是世界上从事放射性废物处置活动最早、废物处置量最大、处置研究最为活跃的国家。截止1984年,美国六个商用场共处置了1,097,700m~3的废物;能源部所属处置场截止1986年1月共处置了2,276,000m~3的低放废物,并以每年100,000m~3的速度增长。迄今为止,世界上所有大规模的废物处置活动虽然没有造成影响人们健康的环境污染,但是放射性核素的泄漏和迁移曾多次发生。在美国东部,有五个处置场曾发生过不同程度的氚和其它活泼放射性核素的迁移。造成这些核素浸出和迁移的直接原因有如下几点。     

低放固体废物核素活度浓度上限值的推导

介绍了近地表处置设施在300 a监护期前及其以后的任何时间,公众个人及闯入者通过各种途径的受照剂量分别小于剂量限值时所要求的低放固体废物核素活度浓度上限值的推导方法及过程。以我国放射性废物近地表处置的基本安全要求为前提,并以遥田处置场和北龙处置场为对象,分析处置设施关闭后各景象的核素迁移过程和照射途径,建立各景象核素迁移的概念模型、数学模型,并计算各景象对人类产生的照射剂量。假设核素活度浓度与剂量之间呈线性关系,推导满足剂量准则下各景象各放射性核素的活度浓度上限值,选择最小的上限值,从而确定出低放固体废物各核素活度浓度上限值的量级。     

中低放废物的安全处置与评价

本文综述了中低放废物安全处置技术的新近发展；结合我国中低放废处置前期工作的需要，着重讨论了有关含长寿命核素的固体废物分类，在处置场选址和设计中灵活应用多重屏障原理，安全评价模式和计算机程序的选择，以及废物包质量跟踪系统的建立等问题，并提出了相应的建议。     

低中放固体废物处置场关闭后的景象分析

在低中放固体废物处置场关闭后的一定时期内仍将继续监护。当监护期结束以后,处置场场址实现无限制或有限制开放,公众可能通过某种途径与处置场填埋废物近距离接触,从而受到填埋废物中的放射性核素的辐射影响。为估算处置场关闭后对环境造成的影响,需对处置场关闭后影响核素释放和迁移的特征、事件以及过程进行分析和筛选。本文依据IAEA研究成果,对国内某低中放固体废物处置场关闭后的景象进行了分析和筛选。分析和筛选结果表明,处置场关闭后景象的选择应在充分调查的基础上,合理确定评价场景。     

浅谈实验室短寿命放射性废物的管理

１　引言放射性废物管理依赖于专门为其制订的管理细则。对研究人员来说,最基本、有效的放射性废物分类原则是以废物中所含核素的半衰期来分类。短寿命废物为只含有半衰期小于９０ｄ的废物,长寿命废物为含有半衰期超过９０ｄ的任何放射性物质的废物。短寿命放射性废物经过几个月或几年后,基本上衰变得没有放射性了,对人类或环境呈无辐射危害状态。它可保存在产生废物的实验室的共用贮存间或辐射安全部门的贮存场,最少应保存１０个半衰期。长寿命废物将被保存在永久性废物处置场。这些处置场可将放射性物质与环境隔离几百年甚至几千年。…     

西北处置场废物处置信息管理系统的建立

根据西北处置场运行管理要求建立西北处置场废物处置信息管理系统,该系统由一个允许废物产生单位录入废物数据的申报登记用户端和废物管理主系统组成。主系统分为基础资料库、基础数据库、废物申报与核实子系统、处置运行子系统、辐射环境监测子系统、维修维护和培训记录子系统等6个模块。该系统实现了西北处置场废物处置全部信息的电子化管理,利用该系统可及时查询统计在西北处置场处置的废物情况,其功能基本满足西北处置场运行管理的要求。     

中低放废物近地表处置安全评价中关键核素的筛选计算

１前言中低放废物近地表处置要涉及几十种核素，其中短寿命核素较多，长寿命核素较少。过去，国内外针对９０Ｓｒ、１３７Ｃｓ、６０Ｃｏ等短寿命核素在放射性废物的固化体、处置库的回填材料和混凝土容器中的行为做了许多研究工作，似乎认为它们是安全处置的关键核素。近...     

广东低、中水平放射性废物处置经济分析(英文)

根据工程经济学的基本原理,参照我国有关废物处置的法律法规,通过与废物处置管理有关部门的协商讨论,结合广东北龙废物处置场建设运营的特点,采用废物处置完全成本法,将废物处置总成本划分为首期投资成本,运行维护成本,处置场关闭成本和关闭的处置场监护成本四部分。为了遵守废物产生者公平承担废物处置费用的原则,文章通过三种初始投资筹资方式的比较,建议采用废物产生者预付处置库容建造款,并根据我们提出的后续投资和更新投资的原则解决废物处置初始投资和更新投资来源问题。为保证处置场具有一定的抗风险和自我发展能力,同时考虑我国核电发展的龙头作用,本研究提出了废物处置利润的确定原则,避免废物处置业主追求最大利润。在引进了动态经济分析原则的前提下,使处置总成本各部分在现在的成本计算中保持一致,并研究和提出了北龙处置场废物处置总成本、收入、还款、利润和税收的计算方法和计算程序。     

低中放固体废物处置场选址规划环境影响评价方法研究

建造低、中水平放射性固体废物处置场,对低中放废物进行安全处置是降低低中放废物管理的环境风险、减少对环境和公众影响的必要途径。而对全国低中固体废物处置场进行选址规划有利于合理布置处置场、合理利用资源以及减少对公众和环境的影响。为了减少规划实施后可能对环境产生的影响,需要对《我国低中水平放射性固体废物处置场所选址规划》进行环境影响评价。本文对如何开展这类规划的环境影响评价进行了探讨。     

加速器驱动洁净核能系统物理及技术基础研究：1“加速器驱动洁净核能系统的物理及技术基础研究”项目总结报告

人们在享受核电带来的巨大好处时，也不得不面对核电产生的核废料，尤其是长寿命核废料的最终处理处置难题。根据对核电站废物的潜在生物危害性分析，核电站废物的远期风险决定于长寿命高放废物，其中，主要是Np，Am，Cm等被称为次量锕系核素（MA）的核素和长寿命裂变产物（LLFP）。MA和LLFP要衰变数十万年才能达到天然铀的毒性水平。大量的如此长寿命高放废物进行地质深埋处置是有环境风险的。     

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.     

The control system for SSRF injection and extraction

This paper introduces the injection and extraction control system design for SSRF,which is a distributed control system aimed at stability and reliability of the pulse power supplies,PPS(Personnel Protection System)and MPS(Machine Protection System).The hardware environment is mainly based on PLC(Programmable Logic Con- troller),and ARM(Advanced RISC Machine)is also applied for studying stability of the power supplies.WinCC and EPICS(Experimental Physics and Industrial Control System)have been selected as the platforms of SCADA(Super- visory Control and Data Acquisition).For unifying the interfacing to the control computer,all front-end equipments are connected via Industrial Ethemet.     

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.     

Gamma radiation levels in the ambient environment of the QNPP Base

Monitoring results of gamma dose rate level in 1992～2004 in the ambient environment of the Qinshan Nuclear Power Plants(QNPP)Base,the northeast of Zhejiang Province,are reported in this paper.It is shown that the gamma dose rate of five monitoring sites of 2.5 km to QNPP Base is 84～113 nGy/h,with an average of 96 nGy/h in the 13 years.The average value is close to the background level of 93 nGy/h prior to operation of the QNPP Base,and is lower than the monitoring result of 101 nGy/h at the reference site in Hangzhou City.Within 50 km from the QNPP Base,the cumulative dose rate of the thermoluminescent dosimeter(TLD)is 90 nGy/h,which is lower than the back- ground level of 111 nGy/h.     

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.