Thermochemical and Experimental Considerations of NOx Composition and Iodine Species in the Dissolution of Spent PWR-Fuel Specimens

Abstract

The NO_x composition and iodine species in the dissolution of spent fuels are discussed on the basis of thermochemical calculations and experimental results. The influence of N0_x sparging on the expulsion of iodine is also discussed. The dissolution of a spent PWR-fuel specimen (–3g) in 30 ml of 3.5_MHNO₃ at 100°C is calculated to yield a concentration of 7×10^?2atm of N0₂, which is 80% of the total NO_X in the dissolver. This N0₂ fraction is much higher than experimental values of 15% or less that were reported for dissolver off-gas cooled near to room temperature. The high N0₂ fraction suppresses the formation of iodate (IO₃ ^?) in the dissolution. The calculations predict that IO₃ ^?) is not formed in 3.5 M HNO₃ at 100°C at an NO₂ pressure ≥3×10^?2 atm (3kPa). Attempts to expel iodine from the fuel solution indicated that the main iodine species in the solution was colloidal iodine and not iodate (I0₃ ^?) which earlier workers postulated. The obtained experimental results are consistent with the thermochemical predictions. For the decomposition of the colloidal iodine in the expulsion process, NO₂ sparging has a negative effect. This is because an increase in NO₂ pressure promotes the formation of colloidal Agl.     

Formation of Analcime Film under Hydrothermal Conditions

Polycrystalline analcime film was prepared from hydrogels under hydrothermal conditions. The analcime film of about 200 pm thickness built up on a porous alumina support at temperatures above 160°C, and the size and crystallinity of analcime increased with temperature. The thickness of analcime film increased with incubation time, and the growth rate at 180°C was faster than that at 160°C. The analcime film obtained was thermally stable at temperatures up to 700°C, and no structural changes were observed after treatment in nitric acid solutions below 0.01M. Analcime had an ion-sieve ability to large sized Cs⁺ ion, and Ag⁺ and Rb⁺ ions of small sizes were incorporated in analcime.     

河北某难选银矿选冶工艺试验研究

河北省某难选银矿中银矿物种类多且嵌布特征复杂,在工艺矿物学研究基础上,通过选矿方案对比,采用浮选—浮选尾矿氰化联合工艺流程。浮选试验研究了磨矿细度、矿浆PH值、组合捕收剂丁基黄药和FZ-9538用量等条件对银回收率的影响,确定了最佳工艺条件,闭路试验可获得银品位3145g/t、回收率82.52%的银精矿;浮选尾矿含银42g/t,经氰化浸出24小时后,银浸出率为65.48%,对原矿回收率11.45%,浮选加氰化总回收率93.97%。     

银纳米线-聚对苯二甲酸乙二醇酯透明导电胶膜

以银纳米线作为导电填料,以聚对苯二甲酸乙二醇酯(PET)为柔性衬底,采用平板热压机通过热压方式制备了银纳米线-PET透明导电胶膜。研究了银纳米线-PET导电胶膜的耐弯曲性能、电学性能以及透光性。结果表明,所制备的银纳米线-PET导电胶膜透光率达到80%以上,表面电阻率达到1×10^-3Ω·cm。银纳米线-PET导电胶膜经过500次的弯曲循环后电阻率未下降。随着银纳米线溶液浓度的增加,银纳米线-PET导电胶膜透光性下降,表面电阻率增加。     

Green Synthesis of Silver Nanoparticles Using an Otherwise Worthless Weed Mimosa (Mimosa pudica): Feasibility and Process Development Toward Shape/Size Control

A bioinspired method of silver nanoparticle (AgNP) synthesis using the highly invasive terrestrial weed mimosa (Mimosa pudica) is presented. An aqueous extract of the leaves of the weed that served as a reducing and stabiliaing agent was employed in various proportions with Ag (I) solution for this synthesis. The effect of several key variables that influence the shape/size of the AgNPs—concentrations of the extract relative to Ag (I), temperature, interaction time, stirring, and pH—was studied employing UV-visible spectrophotometry, scanning electron microscopy (SEM), transmission electron microscopy (TEM), dynamic light scattering (DLS), and x-ray diffraction (XRD). The study provides the basis for selecting processes for synthesizing AgNPs of desired shapes and sizes that can be developed using mimosa as the bioagent. All processes in this synthesis, being simple, nonpolluting, inexpensive, and nonhazardous, raise the possibility of large-scale utilization of mimosa, thereby offering a means to reduce ecological degradation that is caused by mimosa.     

三氯乙酸在活性银阴极上的电还原脱氯

采用循环伏安法和恒电流电解法研究了碱性水溶液中三氯乙酸在活性银阴极上的电化学还原脱氯反应。实验结果表明：活性银阴极对三氯乙酸的还原脱氯反应具有很高的电催化活性,三氯乙酸在银电极上的还原反应是个分步脱氯过程,主要的路径为三氯乙酸--二氯乙酸--氯乙酸--乙酸。     

AAO模板中AgBr的显影过程探讨

在AAO(Anodic Aluminum Oxide)模板中生长AgBr纳米线,并对其进行化学显影.显影结果表明,D-72显影液和D-76显影液显影后得到的银大部分都在模板的表面,分别呈丝状和颗粒状;而原位显影液得到的银则在孔隙中呈线状分布.文章认为,3种显影液中物质传质过程及显影剂活性的不同造成了显影银存在位置和形貌的差异,并提出用直接电子转移和间接电子转移机理解释银的形貌差异.     

添加剂对水性喷墨墨水性能的影响

为了研究添加剂对水性喷墨墨水性能的影响,选择几种水性喷墨墨水的常用添加剂,测试了不同添加剂对墨水黏度、表面张力、pH值和电导率的影响。结果表明,不同有机溶剂对喷墨墨水黏度的影响不同,表面活性剂是影响表面张力的主要因素,pH调节剂和螯合剂会同时对墨水的pH值和电导率有影响。最终通过选用合适量的添加剂配制的墨水符合喷墨打印用墨水的性能指标。     

电子辐射对渗透性材料上书写墨水信息记录的影响

本文介绍电子辐射对不同墨水书写信息的影响。2001年10月当发现炭疽病毒感染邮寄的信件时,美国政府开始利用电子辐射杀死邮件上的病毒,并在全国推广这项技术。可是过了一段时间发现,这项技术对某些邮寄物品是有害的。数据表明电子辐射可能对邮品上存在的时间特征有损害,尤其是邮寄通过常规船运的美术和历史资料,时间特征是非常重要的。     

硅系喷墨打印纸获得高光泽度的方法研究

本文主要介绍间隙型硅系喷墨打印纸的涂层结构,并制备不同涂层结构的3种喷墨打印纸,对3种喷墨打印纸的光泽度、吸墨性、固墨性、化工成本以及制造工艺进行讨论和比较。研究表明:铸涂纸有最低的化工成本,生产工艺也相对简单,但打印性能欠缺,只适用作低档喷墨打印纸。多层涂布硅系喷墨打印纸打印性能优良,化工成本较高,适用作高档喷墨打印纸。