氧化硼对铁磷酸盐玻璃陶瓷固化体的影响

研究了不同B₂O₃掺量对铁磷酸盐玻璃陶瓷高放废物固化体结构和性能的影响。应用溶出速率法（DR）对固化体进行了化学稳定性测试,使用傅里叶变换红外光谱（FTIR）和X射线衍射（XRD）方法研究了样品的结构。研究结果表明：玻璃陶瓷固化体的主晶相为独居石;B₂O₃的引入对玻璃陶瓷固化体的化学稳定性影响较大,以10%（摩尔分数）的B₂O₃代替Fe₂O₃制得的固化体化学稳定性最佳,其28d的质量浸出率约为7.81×10^-9g•cm^-2•min^-1;试样中存在大量正磷酸基团［PO₄］^3-和少量焦磷酸基团［P₂O₇］^4-,无偏磷酸基团［PO₃］^-存在,固化体中的B主要以［BO₄］四面体基团形式存在。     

模拟含锶废物铁磷酸盐玻璃固化体的化学稳定性

针对我国高放废液全分离流程中产出的锶废物组成特点,设计了用铁磷酸盐玻璃固化锶废物的配方。用红外光谱（IR）研究了玻璃固化体的结构,用Product Consistency Test(PCT）试验方法研究了玻璃固化体的化学稳定性。研究表明,在所选的配方组成范围内,所熔制的玻璃固化体均有较好的化学稳定性。当配料中模拟含锶废物的含量为24～28%(wt)、FeO3的含量大于24%(wt)、O/P（氧磷摩尔比）为3.5～3.6时,玻璃固化体的化学稳定性最好。     

含Pu废物的玻璃和玻璃陶瓷固化基材研究进展

对于239Pu含量较高且很难回收利用的含Pu废物,在安全处置前须进行妥善的固化处理。玻璃和玻璃陶瓷因在制备方面具有较陶瓷简单的工艺、低廉的成本和高效的产出被认为是目前处理含Pu废物综合优势明显的固化基材,因而得到了广泛和深入的研究。本文对碱硼硅酸盐玻璃、镧硼硅酸盐玻璃、铁磷酸盐玻璃以及含钙钛锆石、烧绿石或独居石结晶相的玻璃陶瓷等在含Pu废物固化方面的研究进展进行了综述,包括其组分、Pu包容量和化学稳定性,并进行了对比分析,认为在对玻璃固化基材继续研究与应用的基础上,玻璃陶瓷有望成为固化绝大多数含Pu废物的较佳选择。     

多组元烧绿石陶瓷固化体的制备及其抗浸出性能

烧绿石具有优异的理化稳定性和耐辐照稳定性,被认为是理想的放射性核素固化基材。然而,人造烧绿石在烧结过程中对核素的选择性高,从而限制了其固化核素的种类和数量。针对上述问题,本工作以镧系元素铕（Eu）、钐（Sm）、钕（Nd）模拟放射性的锕系核素,成功制备得到了2、3、4组元的烧绿石结构陶瓷固化体。结果表明,目标核素均匀地固溶在烧绿石的晶格结构中形成了单相均一的多组元烧绿石陶瓷固化体。化学浸出实验表明,多组元烧绿石结构具有优异的抗浸出性能,是一种具有应用前景的高放废物陶瓷固化体候选材料。     

国外高放废液玻璃固化体浸出行为的研究及发展

本文介绍了高放废液玻璃固化体的一般浸出过程，对高放废液玻璃固化体与模拟高放废液玻璃固化体的浸出情况进行了比较；探讨了在高放废液玻璃固化体浸出行为研究中的几个主要的发展方向，包括新的浸泡方法的建立，研究溶液中胶体及微生物对固化体浸出的影响及其它的一些发展动向。     

用钛酸盐陶瓷固化含铯亚铁氰化钛钾无机离子交换剂的初步研究

本文对在我国高放废液全分离流程中产生的含铯亚铁氰化钛钾无机离子交换剂的固化进行了初步研究。结果表明,对于含铯亚铁氰化钛钾无机离子交换剂,可先用热分解－催化氧化法除去其中的氰并将其转变为各种固体氧化物,然后用由碱硬锰矿（ＢａＡｌ２Ｔｉ６Ｏ１６）、假板钛矿（ＦｅＴｉ２Ｏ５）及金红石（ＴｉＯ２）三种矿相组成的钛酸盐陶瓷固化体对其进行固化包容。制备出的陶瓷固化体性能稳定,物理稳定性和化学稳定性与硼硅酸盐玻     

高放废物玻璃固化与人造岩石固化技术的研究进展

高放废物的处理和处置是世界各核能国家面临的重大挑战。高放废物处理和处置的技术路线是先将其固化,再将其深埋。高放废物的固化有玻璃固化及人造岩石固化两种。玻璃固化已发展成一项成熟的技术,人造岩石固化尚在研发中。由于人造岩石固化工艺更简单,固化体抗浸出性能更优,稳定性更好,已引起世界各核能国家的关注,有可能取代玻璃固化而成为新一代固化技术。本文对玻璃固化和人造岩石固化的类型、机理和优缺点进行了系统的分析,对人造岩石固化的发展方向提出了建议。     

Al2O3对独居石玻璃陶瓷固化体的影响

本文研究了Al₂O₃掺量对独居石玻璃陶瓷固化体结构和化学稳定性的影响。用傅里叶变换红外光谱（FTIR）和X射线衍射（XRD）方法表征样品结构,用溶解速率法和全谱直读等离子体发射光谱（ICP-OES）分别测定样品在浸出液中浸泡后的失重速率及各元素的浸出浓度,以研究固化体的化学稳定性。研究结果表明：当Al₂O₃掺量为4%（摩尔分数）时,在980 ℃下保温3 h得到的独居石玻璃陶瓷固化体具有较高的化学稳定性,浸泡14 d时其质量浸出率最低,约为8.1 ng/(cm²•min),其中Ce、La元素在浸出液中均未检出;固化体的主晶相为独居石,结构中含有大量稳定的正磷酸基团［PO₄］^3-和少量的焦磷酸基团［P₂O₇］^4-,不存在偏磷酸基团［PO₃］^-。     

高硅玻璃陶瓷对模拟高放废液中锕系核素的固化性能测试

为了提高玻璃固化体性能,将玻璃质的Si O2在1 200℃条件下烧结制备成高硅玻璃陶瓷固化体。测试结果表明:高硅玻璃陶瓷固化体的密度、包容量及浸出率等性能均优于硼硅酸盐玻璃固化体。     

玻璃-陶瓷固化工艺研究

随着核能的发展，乏燃料日益增多；核燃料燃耗逐渐增加，锕系核素的量会逐渐增大。锕系核素在玻璃中的溶解度很低，将锕系核素从高放废液中分离出来再进行人造岩石固化技术难度大，有必要开发高放废液和长寿命核素的处理新技术。本研究的目的是利用玻璃固化工艺制备玻璃一陶瓷，用结晶相固定锕系核素，玻璃相固定裂片核素。当高温玻璃熔融体被浇注到玻璃产品罐时，由于玻璃量大，降温速度很慢，这为晶核的形成、晶胞的生长提供了条件。     

Vitrification of high chrome oxide nuclear waste in iron phosphate glasses

A simulated high level waste (HLW) containing 4 mass% chrome oxide, whose overall composition is representative of the high chrome oxide wastes at Hanford WA USA, was easily vitrified in a phosphate glass at temperatures ranging from 1150 °C, for waste loadings of 55 mass%, to 1250 °C for waste loadings of 75 mass%. Even at these high waste loadings, these wasteforms had an excellent chemical durability. The best chemical durability was achieved when the O/(Si + P) atomic ratio was between 3.5 and 3.8. These wasteforms were also resistant to crystallization although trace amounts of crystalline Cr₂O₃ were present in wasteforms containing more than 70 mass% HLW. It is concluded that up to 45 mass% of the total HLW at Hanford, especially that containing as high as 4.5 mass% chrome oxide, could be directly vitrified into an iron phosphate glass, that meets all of the current chemical durability requirements by simply adding 25-35 mass% P₂O₅ to the waste and melting the mixture at 1150-1250 °C for a few (<6) hours.     

Stainless steel/glass-ceramic interactions under hot isostatic pressing (HIPing) conditions

The interactions between stainless steel (SS) and a glass-ceramic designed for immobilisation of the high-level nuclear waste generated at the Idaho chemical processing plant (ICPP) under hot isostatic pressing (HIPing) conditions (100 MPa in argon at 1200 °C) have been studied and subsequently the effect of such interactions on the chemical durability of the glass-ceramic waste form has been examined. The diffusion of Cr from SS (Cr depletion in SS) through the interaction layer and formation of crystalline Cr/Al oxides in glass dominate the overall interaction process. It appears that the depletion of Cr in SS may reduce the potential of SS as a barrier. However, such interactions have no significant impact on the glass-ceramic and the presence of the interaction layer does not seem to have any detrimental effect on the chemical durability of the glass-ceramic as a waste form.     

Characterisation of Al corrosion and its impact on the mechanical performance of composite cement wasteforms by the acoustic emission technique

In this study acoustic emission (AE) non-destructive method was used to evaluate the mechanical performance of cementitious wasteforms with encapsulated Al waste. AE waves generated as a result of Al corrosion in small-size blast furnace slag/ordinary Portland cement wasteforms were recorded and analysed. The basic principles of the conventional parameter-based AE approach and signal-based analysis were combined to establish a relationship between recorded AE signals and different interactions between the Al and the encapsulating cement matrix. The AE technique was shown as a potential and valuable tool for a new area of application related to monitoring and inspection of the mechanical stability of cementitious wasteforms with encapsulated metallic wastes such as Al.     

Properties of phosphate glass waste forms containing fluorides from a molten salt reactor

Radioactive fluoride wastes are generated during the operation of molten salt reactors(MSRs) and reprocessing of their spent fuel.Immobilization of these wastes in borosilicate glass is not feasible because of the very low solubility of fluorides in this host.Alternative candidates are thus an active topic of research including phosphatebased glasses,crystalline ceramics,and hybrid glass-ceramic systems.In this study,mixed fluorides were employed as simulated MSRs waste and incorporated into sodium aluminophosphate glass to obtain phosphate-based waste form.These waste forms were characterized by X-ray diffraction,Raman spectroscopy,and scanning electron microscopy.Leaching tests were performed in deionized water using the product consistency test A method.This study demonstrates that up to 20 mol%of simulated radioactive waste can be introduced into the NaA1 P glass matrix,and the chemical durability is much better than that of borosilicate.The addition of Fe_2O_3 in the NaAlP glass matrix results in increases of the chemical durability at the expense of fluoride loading(to 6.4 mol%).Phosphate glass vitrification of radioactive waste containing fluorides is a potential method to treat and dispose of MSR wastes.     

Reactive spark plasma sintering of Cs-exchanged chabazite: characterisation and durability assessment for Fukushima Daiichi NPP clean-up

ABSTRACT

Ion-specific media (ISM) have played an integral role in the clean-up and remediation efforts at the Fukushima Dai-ichi disaster site, through the processing of contaminated wastewaters. The use of these materials generates a secondary nuclear waste stream, presenting its own series of engineering problems arising from stringent handling and long-term storage requirements. A reactive spark plasma sintering (SPS) method was investigated for conditioning of the spent cesium exchanged zeolite, chabazite. A natural form of the zeolite was used as an analogue to the engineered ISM used at the Fukushima NPP site. Simulant wasteforms were sintered using different temperature and pressure parameters followed by analysis of phase assemblage, density, and durability (using the product consistency test (PCT)). The results indicated that zeolite structure had collapsed completely, with the exchanged cesium partitioned primarily into a durable feldspar to assure stability of the sintered material for passively safe storage or geological disposal.     

Characterization of monazite glass-ceramics as wasteform for simulated α-HLLW

Two monazite glass-ceramic wasteforms were sintered by mixing the lanthanum metaphosphate glass powder with the oxide powder of the components in simulated α-HLWs. The co-existence of components Al and Mo in an iron phosphate melt separated the melt into two immiscible glass melts, namely aluminum iron phosphate glass (Gb) and molybdenum iron phosphate glass (Gg). 24 wt% of ZrO₂, together with P₂O₅ and proper amounts of Fe and Mo formed a zirconium pyrophosphate glass (Gg1), which was immiscible with the phase Gg. The iron ions in the wasteforms were all in Fe³⁺, 1/3 of which was in 4-fold coordination. The O/P and O/(P + 1/3Fe³⁺) ratios for the glass phases were Gg1 3.70, Gb 3.89-3.98, Gg 4.23-4.25, and Gg1 3.58, Gb 3.47-3.42, Gg 3.74-3.69, respectively. The dissolution rates of two wasteforms were 0.3008 and 0.2598 g/m²d, respectively.