不锈钢放射性模拟样片在空气中的激光去污技术

采用APEX放电型准分子激光器作为激光光源,用低放废液制备不锈钢放射性模拟样片,在激光去污装置上开展激光去污工艺参数的研究。通过考察不同的辐照强度、脉冲频率、辐照角度及扫描速率参数对不锈钢放射性模拟样片表面去污因子DF的影响,获得了激光去污工艺参数。在此参数下对模拟样片表面的去污因子大于200,剥离厚度小于20μm。     

干冰喷射去除带有油漆涂层金属表面污染实验

采用干冰喷射去污技术去除金属表面油漆涂层,实验显示,随着喷嘴行走速度的增加,油漆涂层的去除重量及去除宽度均呈下降趋势;最佳靶距为25 mm,最佳入射角度为63°,压缩空气压力为0.6–0.7 MPa时,对金属表面油漆涂层的去除效果较好;空气净化装置净化效果>99%;去除油漆涂层时生成的气溶胶集中在5.8–9.0μm。结果表明,干冰喷射去污技术可将137Cs表面污染水平降至仪器探测限以下;对于235U污染样品,可达到清洁解控水平。     

电化学去污工程应用的现场验证试验

采用电化学去污技术对放射性污染金属进行了现场验证试验.结果表明:在前期研究得出的电解液及工艺参数下,电化学去污技术与去污剂擦洗、酸液循环两种常用去污方法相比,可快速、高效地对放射性污染金属表面进行去污;电化学去污技术对于不同污染类型、不同污染程度的金属设备均能有效去污,在电解5 min内,放射性水平可降至仪器探测限以下;在电化学去污过程中,金属的污染水平随电解时间增加呈对数下降趋势,去污系数DF值成线性变化.     

干冰喷射去除表面放射性污染技术研究

为有效去除需复用部件表面放射性污染,开发了一种去污效率高、对基材损伤小且二次废物产生量小或二次废物易于处理的去污装置和方法。将干冰清洗技术移植用于放射性表面污染的去除,对干冰去污技术从喷射去污到去污后二次废物收集、处理进行闭环设计,形成了一整套干冰去污—气体净化的系统装置。采用该系统装置开展了去污条件实验,获得了既可实现高效去污又不损伤基材的去污参数,通过测量被去污物件表面温度、压力变化,干冰喷射后表面形貌表征等方法验证了去污过程对基体材料损伤轻微。将干冰喷射+尾气净化这一新型去污技术应用于现场复用金属部件去污,验证了该技术既具有高效的去污及气溶胶净化效果,同时又具有二次废物产生量小的特点。     

面向强放热室退役的高效复合去污技术研究

强放热室作为反应堆材料辐照检验的配套设施,其辐射水平高、结构复杂、去污难度较大。针对强放热室退役不锈钢壳体去污的特殊性和复杂性,开展了高压水射流去污、可剥离膜去污和机械打磨去污3个单项去污试验和去污工艺试验研究,并创新性的提出了一种强放热室不锈钢壳体高效复合去污工艺。经工程去污实践验证,去污后热室不锈钢覆面表面污染水平均低于40 Bq/cm2,去污因子最高达110以上,达到了国内先进水平。热室高效复合去污技术的研发解决了强放热室不锈钢壳体表面去污的技术难题,降低了退役阶段工作人员的受照剂量,保护了工作人员和环境的安全,具有显著的经济、社会效益。      

核电站放射性污染液压扭力扳手的去污实践

核电站在日常生产及大修过程中,放射性污染设备和场地的检修作业会产生一定量的污染检修工具,其中包含价值高、体积大、去污难度大的液压扭力扳手。因液压扭力扳手结构复杂、主子部件较多、且热点多淤积在死角位置,导致其放射性去污难度较大,国内核电站多作放射性固体废物处理为主。液压扭力扳手作为高价值专用工具,大量放射性污染检修工具报废给核电站成本管控、放射性废物最小化管理和电站辐射防护最优化带来了较大的压力。针对此问题, 电站开展了多项放射性污染液压扭力扳手深度去污试验,采用化学去污、机械去污、泡沫去污、超声波去污等多种组合工艺,经过四个阶段的深度去污试验,最终将多台放射性污染液压扭力扳手全部去污合格,并全部实现现场复用。此次深度去污试验研究总结的“放射性污染液压扭力扳手深度去污方法”,去污因子超过10³,去污试验各项指标效果良好,方法可行、有效、实用,可为业内同行提供参考。     

板式换热器放射性去污实践探索

核电站反应堆和乏燃料水池冷却处理系统(PTR)及设备冷却水系统(RRI)中使用的板式换热器,结构复杂,运行过程中放射性热点易淤积在导流函道及沟槽等死角位置,放射性去污难度较大,业内以作为放射性固体废物处理为主。板式换热器作为高价值专用设备,大量污染报废给成本管控和放射性废物最小化管理带来了较大的压力。针对上述问题,红沿河核电厂实践探索了“放射性污染板式换热器去污方法”,采用“化学去污+泡沫去污+可剥离膜去污”分段去污方法开展试验,经去污后的换热器表面污染水平均小于0.4 Bq/cm²,4个阶段累计去污率约为99.80%,193片放射性污染板式换热器全部实现复用。     

针对不锈钢表面60Co污染的电化学去污研究

核设施退役与三废治理过程中会产生大量表面被沾污的不锈钢金属部件,作业环境和人员将面临潜在的放射性污染和受照剂量问题。针对不锈钢金属表面的60Co污染问题,设计了手持式电化学试验装置对不锈钢表面污染进行合理有效的原位去污;采用正交实验法优化电解液浓度、电流密度和电极间距等电化学工艺参数,并对不锈钢表面60Co污染进行去污验证。研究结果表明,本文建立的电化学原位去污方法具有去污时间短、效率高等优点;在电解时间为30 s、电解液为10 mol/L硝酸、电流密度为0.3 A/cm2、电极间距为0.4 cm的条件下,此方法对不锈钢表面60Co污染的去污效率可达99.9%以上,腐蚀深度大于10 μm,可使污染降低至环境本底辐射水平。      

西南某火警源生产线退役中~(241)Am污染金属部件去污

依据241Am火警源生产线污染金属特点和验证实验结果选择了针对金属部件表面去污方案。实施过程中按照初步去污、化学去污、机械去污的顺序对火警源生产线中金属污染物实施分类去污处理,去污面积共计2584.3m2,解控效率达86.6%,较好地达到了退役目标。     

近年来日本对几项去污技术的研究及启示

介绍了2000～2004年日本超临界CO2去污、等离子体去污和激光-凝胶去污等放射性去污技术的部分试验研究成果,并尝试从中总结出一些有益于我们的启示.     

酸性泡沫对放射性模拟污染样的去污研究

为使化学泡沫去污工艺达到后处理厂工程应用水平,进行了酸性泡沫对后处理厂模拟样品的去污实验研究。结果表明,在室温条件下,酸性草酸泡沫对模拟污染样品的志污效果较好,不锈钢去污系数８．８７￣１４．３４,漆钢为６．５７￣８．４０;酸性硫酸高铈泡沫对模拟污染样品有很好的去法效果,不锈钢去污系数为１２．３９￣２４．０８,漆钢为３．６２￣５．１４。这两种酸性泡沫适合对后处理厂大体积、复杂形状和多锈的放射性污染主     

Application of physicomechanical methods of separation to the decontamination of contaminated soils

The physicomechanical methods of separation of conventional mineral raw materials, including uranium-containing stock, can be used successfully to decontaminate soils and remediate territories contaminated by mining companies. Using its many years of scientific and applied experience in the development and commercial adoption of technology for reprocessing uranium-containing raw materials, the All-Russia Research Institute of Heat Sources is restoring radioactively contaminated territories within the Russian Federation and the Commonwealth of Independent States. The results of investigations of the decontamination of contaminated soils and territories, including radiometric separation, fine classification in hydrocyclones, and magnetic separation, are described. Effective technological schemes and their hardware implementation have been developed. __________ Translated from Atomnaya énergiya, Vol. 101, No. 4, pp. 296–301, October, 2006.     

Demonstration test on purification systems of contaminated water using liquid–solid settling technology by flocculants (decontamination technology using high-pressure water)

For the purpose of decontaminating residential buildings, roads, rubble, and so on, the high-pressure water washing decontamination system had been developed, which are composed of a recovery system for contaminated washing water and mobile purification system of liquid–solid settling technology by flocculants. The high-pressure washing technology applied in this demonstration test can be used for both high- and ultrahigh-pressure washing decontamination and water surface chipping, by changing pumps and attachments. These systems were applied to decontaminate pools, concrete floor and side ditch around the pool in an elementary school located at Motomiya, Fukushima Prefecture as a demonstration test. Additionally, to compare decontamination effects, the tests, to chip and decontaminate surfaces of outer concrete and asphalt pavement had been conducted. From the results, high-pressure water jet decontamination systems have been practically proven.     

Removal of Metal Oxide Layers as a Dry Decontamination Technique Utilizing Bead Reaction and Thermal Quenching by Dry Ice Blasting

A new removal method for metal oxide layers formed on steel surfaces was developed as a dry decontamination technique for radioactively contaminated metal waste. In this method, surface oxide layers formed on metal wastes are fused with glass flux and the resulting hot glass layers are removed by thermal quenching using dry ice blasting. After optimization of operating conditions in each process, removal tests were carried out using oxidized stainless and carbon steel samples, which were prepared in boiling water reactor conditions. The experimental results indicated that the surface oxide layers were fused into the glass flux such as borax by a bead reaction and successfully removed by dry ice blasting. Energy dispersive X-ray analysis confirmed that no oxide layer remained on the oxidized steel samples after treatment by the present method.     

Simulation of Safe Methods for Performing Decontamination Work

Devices for obtaining gamma images have undergone extensive development in the last few years. Using such devices for examining radioactively contaminated equipment and enclosures makes it possible to develop maps of the distribution of the radioactive contamination. Knowing the radioactivity distribution it is possible to calculate the exposure dose rate at any point of the enclosure and therefore to simulate the safest methods for performing decontamination work. In the present paper, decontamination work is simulated for an enclosure of a nonoperating research reactor at the Russian Science Center Kurchatov Institute. This reactor was shutdown for decontamination and disassembly. It is shown that the worker dose loads can be substantially decreased by performing the decontamination work in the correct sequence.     

氚污染金属手套箱退役技术研究

为减少氚污染金属手套箱退役解体过程中氚的二次释放,降低工作人员的辐射危害,减少退役中产生的氚污染废物量,本文针对退役氚污染金属手套箱的解体,设计了氚污染金属手套箱退役解体技术方案,即解体前对氚污染金属手套箱进行初步去污,解体中采用合适的切割技术和相应的防护措施。利用氚污染金属手套箱对该解体方案进行了验证,结果表明,设计的解体方案满足氚污染金属手套箱退役需要。     

Decontamination and decommissioning of radioactively contaminated rooms and equipment at the Bochvar All-Russia Research Institute of Standardization in Machine Engineering

Work on decontaminating and decommissioning radioactively contaminated rooms and equipment has been conducted at the All-Russia Research Institute of Standardization in Machine Engineering since 1999. Organizational and technical measures to consolidate the material and human resources and centralized planning of all work on decontamination, rehabilitation, and waste handling have been developed at the Institute. A scientific and industrial division whose main purpose is to provide comprehensive solutions to all ecological problems of the Institute has been created. Because of the large scale of the problems, special attention is being devoted to the economics of the technical solutions adopted and to minimizing the handling of wastes with definite priority given to the safety. Experience shows that several effective, low-waste technologies must be used in each specific case for decontaminating and localizing radioactive contamination taking account of the specific nature of the object. Performing decontamination work to meet Institute's needs has fostered the development of new, effective technical means for decontamination, specifically, the development of bench facilities for laser, electrochemical, and foam decontamination and facilities for soil decontaminations, and other means. __________ Translated from Atomnaya énergiya, Vol. 105, No. 1, pp. 44–48, July, 2008.     

Consideration of decontamination model for severe accident consequence assessment

Cost per severe accident, which can cover various kinds of consequences, namely health effects, economic, social and environmental impacts, has been used as an index for severe accident consequence assessment in the authors' previous studies. Decontamination of the contaminated area was concluded influential to the cost per severe accident, though it employed simple and conservative assumptions, which made further discussion difficult. A new decontamination model is formed to address this issue. A sensitivity analysis using the elementary effects method is performed to identify parameters which have large influence on the cost per severe accident. We identify 25 important parameters, and fix most negligible parameters to their medians to form a simplified decontamination model. Calculations of the cost per severe accident with the simplified model and the full model are performed and compared. The differences of the results of the two model are not significant, which ensure the validity of the simplified model. The cost per severe accident calculated by the simplified model is compared with the previous study. The decontamination cost increases its importance significantly. It is therefore necessary to pay attention to decontamination-related issues, e.g., determination of decontamination target area and decontamination waste management scheme.