Actinides in metallic waste from electrometallurgical treatment of spent nuclear fuel

Argonne National Laboratory has developed a pyroprocessing-based technique for conditioning spent sodium-bonded nuclear-reactor fuel in preparation for long-term disposal. The technique produces a metallic waste form whose nominal composition is stainless steel with 15 wt.% Zr (SS-15Zr), up to ∼ 11 wt.% actinide elements (primarily uranium), and a few percent metallic fission products. Actual and simulated waste forms show similar eutectic microstructures with approximately equal proportions of iron solid solution phases and Fe-Zr intermetallics. This article reports on an analysis of simulated waste forms containing uranium, neptunium, and plutonium. For more information, contact Dawn Janney, Argonne National Laboratory-West, P.O. Box 2528, Idaho Falls, ID 83403-2528; (208) 533-7478; fax: (208) 533-7863; e-mail dawn.janney@anlw.anl.gov.     

Uranium processing during the treatment of sodium-bonded spent nuclear fuel

Several key technical areas have been developed during a demonstration program at Argonne National Laboratory to advance the electrometallurgical treatment of spent nuclear fuel, including equipment operating conditions, uranium-product purity and recovery, and processing rates. Operating conditions for three integral processing steps were optimized based on minimizing the impurities to the final uranium product while meeting program goals for processing rates. The overall recovery of uranium during the process steps was influenced by process conditions as well as the production rates set forth for the demonstration program. For more information, contact B.R. Westphal, Argonne National Laboratory, Nuclear Technology Department, P.O. Box 2528, Idaho Falls, Idaho 83403-2528; (208) 533-7398; fax (208) 533-7735; e-mail brian.westphal@anl.gov.     

Using a plasma-fired cyclone reactor for calcining and vitrifying radioactive wastes

A plasma-fired closed-top cyclone reactor for the direct treatment of simulated radioactive waste slurries to produce a final vitreous waste form has been engineered and operated. A nontransferred arc plasma torch was attached tangentially to the cyclone and utilized as both an enthalpy source and to provide the gas velocities required to generate the cyclonic gas-flow patterns. Various injection points for waste slurries and vitrifying media were studied to determine optimal positions for each. The feasibility of simulant injection directly into the flame zone and its effect on electrode lifetimes was studied. For more information, contact P.R. Taylor, University of Idaho, Metallurgical and Mining Engineering Department, McClure Hall, Moscow, Idaho 93944-3024; (208) 885-6769; fax (208) 885-2855; e-mail prtaylor@uidaho.edu.     

Fabricating sports equipment components via powder metallurgy

Powder metallurgy (P/M) offers a viable, cost-effective approach to fabricating sports and leisure equipment components. Both complex, monolithic parts and parts produced from materials of quite different densities can be manufactured by this technique. In the latter category, lightweight titanium and heavyweight tungsten can be used in combination to optimally distribute mass, such as in golf club heads. Examples of P/M components used in golfing, skating, baseball, and even darts are presented. For more information, contact F.H. Fores, University of Idaho, Institute for Materials and Advanced Processes, Mines Building Room 321, Moscow, Idaho, 83844-3026; telephone (208) 885-7989; fax (208) 885-4009; e-mail imap@uidaho.edu.     

Structure and thermal creep of the oxide-dispersion-strengthened EP-450 reactor steel

Production of initial and mechanically alloyed powders of oxide-dispersion-strengthened (ODS) 12Kh13M2FBR (EP-450) reactor stainless steel are considered. Structures of powders and compacted materials have been studied. The rate of thermal creep of the mechanically alloyed EP-450 ODS steel in comparison with the conventional EP-450 steel was estimated.     

Rapid plasma quenching for the production of ultrafine metal and ceramic powders

The rapid plasma quench concept used to produce ultrafine titanium hydride, magnesium, and aluminum powders involves the thermal dissociation of liquid reactants into gaseous components followed by rapid quenching of the products of the subject reaction to prevent back reactions. For example, in the case of titanium hydride powder production, titanium tetrachloride dissociates into titanium and chlorine atoms at 5,000 K. Expansion through a Delaval nozzle accelerates the gas to supersonic speed, cooling it very rapidly at rates as high as 7¹⁰ K/s. Injected hydrogen reacts with condensed titanium particles to form titanium hydride and with the chlorine to form hydrogen chloride. Titanium powder has been produced at 20 kg/h in a continuous reactor. Costs are projected to be lower than the Kroll process at a sufficiently large scale. Magnesium and aluminum production based upon the rapid plasma quench concept are also discussed. For more information, contact Alan Donaldson, Idaho Titanium Technologies, Inc., 101 Technology Drive, Idaho Falls, ID 83401; (208) 522-9909; fax (208) 523-6685; e-mail al@aljeanie226.myrf.net.     

Innovations in titanium powder processing

One way of reducing the cost of titanium components is to use near-net shape powder-metallurgy techniques. This article describes a number of new approaches to producing components using the powder-metallurgy method for the aerospace, industrial, and consumer marketplaces. For more information, contact F.H. Froes, Institute for Materials and Advanced Processes, University of Idaho, Mines Building, Room 321, Moscow, Idaho 83844-3026; (208) 885-7989; fax (208) 885-4009; e-mail imap@uidaho.edu.     

Creep rupture of alloy 718 after thermal aging

Alloy 718 given the conventional 718/621°C age-hardening treatment was thermally aged at 593°C, 621°C, and 649°C for up to 50,000 h. These temperatures bracket the lowest of the duplex age-hardening temperatures. Subsequent creep-rupture tests conducted at the same temperature of thermal aging show no detrimental effects of 593°C aging after 50,000 h. Material aged for 50,000 h and tested at 621°C shows the rupture life to be approximately 60–65% of the unaged material, but at 649°C, the aged-material rupture life is on the order of 15% of the unaged material. For more information, contact G.E. Korth, Bechtel BWXT Idaho, LLC, Idaho National Engineering and Environmental Laboratory, Idaho Falls, Idaho 83415-2218; (208) 526-0348; fax (208) 526-0690; e-mail gok2@inel.gov.     

Will the titanium golf club be tomorrow’s mashy niblick?

In the sporting goods industry, the application of game-improving advanced materials has resulted in titanium golfclubs attaining near-mythical status. These improvements have not come cheaply, however, and titanium clubs are losing ground to creative designs that employ combinations of lower cost materials. As a result, unless the cost of titanium can be lowered, the metal will see its share of the market become significantly reduced by the judicious use of lower-cost materials. For more information, contact F.H. Froes, Institute for Materials and Advanced Processes, University of Idaho, Moscow, Idaho 83844; (208) 885-7989; fax (208) 88504009; e-mail imap@uidaho.edu. Author’s Note: Do not expect good club design and advanced materials to cure all golfing woes. They can help, but they are not a panacea for a bad swing and/or lack of strength. For these problems, see your local, friendly Professional Golfers’ Association professional.     

CPR1000核电站核岛主管道预制焊接变形研究及应用

针对CPR1000核电站核岛主管道用厚壁不镑铜核岛主管道预制焊接中的焊接变形问题,采用理论分析与模拟试验相结合的研究方法,系统地研究了核电站核岛主管道预制焊接不同装配结构的焊接变形特点,确立了主管道预制焊接的反变形措施,保证了主管道预制焊接质量.     

Treating waste with PAM

The plasma-arc melter system can be designed for essentially all solid waste, depending on the economics and the waste to be treated. The capital costs as well as the operating costs and revenues of these systems are equivalent to waste-to-energy plants. As a paradigm shift of conventional technology, however, the first commercial plant has yet to be built. For more information, contact T.L. Eddy, MeltTran Incorporated, 1293 East 65th, North, Idaho Falls, Idaho 83401; (208) 524-6358; fax (208) 523-1049.     

核电用316H不锈钢的蠕变性能评估

通过对核电用316H不锈钢的蠕变数据分析,利用速率温度参数模型拟合得出材料蠕变本构方程。根据相关统计检验方法,确定了材料的蠕变可靠度函数。结合Z’参数的数据分布,分别得出316H不锈钢蠕变应力-RTP参数-可靠度曲线和温度-容许应力-可靠度曲线。结合ASME的评价规范,确定了316H不锈钢在550~700℃下的容许应力。结果表明,基于RMB’模型的蠕变本构方程在拟合精度方面优于其他传统模型。实测数据均位于蠕变可靠性模型预测结果的99.7%置信区间内。该模型可以较好地评估316H不锈钢的稳态蠕变性能及容许应力。     

Superior Slurry Erosion Behavior of a Casting NiCoCrFeNb_(0.45) Eutectic High Entropy Alloy

The flow passage components in hydraulic machinery will be eroded rapidly when running in sand water.The wear resistance of materials commonly used in hydraulic machinery needs to be improved to prevent the failure of hydraulic machinery.New wear-resistant materials are urgently needed to improve the service life of hydraulic machinery.Eutectic high entropy alloy(EHEA) is a new kind of alloys with in situ lamellar structure.NiCoCrFeNb_(0.45) EHEA has combined excellent strength and toughness.In this study,slurry erosion tests of NiCoCrFeNb_(0.45) EHEA were carried out with different impact angles and impact velocities using a rotary jet erosion test apparatus.The NiCoCrFeNb_(0.45)EHEA exhibited significant slurry erosion resistance compared with medium carbon steel 1045 and stainless steel 04 Cr13 Ni5 Mo.The erosion rate of EHEA is much slower.Compared with medium carbon steel and stainless steel,the erosion of EHEA is completed via the accumulation and removal of platelets after plowing and work hardening,accompanied by partial micro-cutting.     

Örtliche Korrosion von Komponenten aus Messing MS 58 in der Trinkwasser-Installation

Localized corrosion of yellow brass 58 in tap water installation Yellow brass material with 58 wt.-% Cu is subjected to dezincation and cracking in tap water. Both kinds of corrosion are enhanced by tensile stresses and by anodic polarisation resp. oxygen content of the water. Furthermore, the water type has an effect, where - according to this investigation – the chloride content is of interest. The presence of critical components for SCC (such as NH₃) are not necessary. In the case of mixed installation with tubing of inert material (such as stainless steel or plastics) the corrosion likelihood is increased in comparison to galvanised steel or copper because of oxygen consumption by corrosion of the latter materials. Bimetallic corrosion in mixed installation with stainless steel does not take place. Failures of components of domestic installations by corrosion should be prevented by using a material having a higher resistance to dezincation.     

堆内构件304L焊接件在除氧和氯离子环境中的应力腐蚀开裂研究

采用高温高压慢应变速率拉伸试验方法(SSRT),研究了在除氧环境下不同浓度氯离子对304L焊接件在模拟一回路高温高压硼锂水介质中氯致应力腐蚀开裂的影响。结果表明:当氯离子浓度为1 mg/L时,其各项力学性能指标与惰性氮气空白样一致,表明在低浓度氯离子除氧条件下,304L焊接件没有应力腐蚀敏感性。随着氯离子含量(1~50mg/L)的增加,304L焊接件应力腐蚀敏感指数变化呈增加趋势。断口侧面没有观察到明显的裂纹,氯离子浓度越低,断口缩颈现象越明显,表明主要是机械断裂。氯离子浓度较高时,棱角部分出现微裂纹源,可能与棱角部分应力更为集中相关。所有样品的断裂位置都在焊缝和热影响区,在焊缝和热影响区发生了巨大的形变,离断口越近,变形越严重。焊接部位是304L堆内构件中薄弱环节,应该成为应力腐蚀开裂和其他性能检测的重点部位。     

Joining stainless steel metal foams

Abstract

Metallic foams produced from stainless steel are one of the most recently developed ultralightweight materials. These foams have very low densities and high energy absorption capacities and are therefore expected to have widespread applications in the manufacture of ultralightweight structural components. The fabrication of load bearing structural components such as implants, and high temperature air or fluid filters, are potential application areas depending on the form of the cell structure of the foam. Closed cell metal foams are typically suitable for structural uses whereas open cell foams tend to be preferred for functional applications. Development of adequate joining technologies for these materials is an essential step for their widespread industrial utilisation. The present paper describes a brazing method that is capable of providing excellent joints between 316 stainless steel foams and a conventional 316 stainless steel bulk alloy. Having optimised the bonding conditions and using a Cu–Ti alloy as the filler metal, bonds between a foam and a bulk alloy were produced. No apparent plastic deformation of the metal foam occurred in the course of the 10 min length brazing process, and the resulting bonds had tensile strengths higher than that of the stainless steel foam.     

Corrosion behaviour of reactor coolant system materials in nuclear power plants

The materials used for the pressure‐retaining parts of reactor coolant system components in light water reactor nuclear power plants have to meet special requirements in terms of their mechanical properties, workability and in‐service performance. Corrosion issues play an important role in connection with plant operating conditions. While giving consideration to the specific service environment of the reactor whether a pressurized or boiling water reactor – the materials used for the individual components and the water chemistries employed in the various systems are selected such that metal loss due to general corrosion will remain very low. Thus the materials used in light water reactor plants exhibit a high general resistance to corrosion for their specified service conditions, material conditions and mechanical loads. However, under certain operating conditions other corrosion mechanisms may be found to induce damage. This paper uses data from the literature, published results of national and international research programs, information on damage which has actually occurred world‐wide and experience gained by Framatome ANP GmbH (former Siemens/KWU) in this field as a basis for discussing these mostly localised corrosion phenomena in terms of “classical” corrosion systems. Aspects associated with irradiation and its effects are not considered. Suitable remedial actions are, however, addressed wherever these are of relevance. The materials considered comprise unalloyed and low‐alloy steels, austenitic chromium‐nickel steels as well as high‐nickel steels and nickel‐base alloys which are exposed to the reactor coolant environment of boiling water reactor or pressurized water reactor plants, including materials investigated in corresponding water environments simulated in the laboratory.     

Microstructure and Mechanical Properties of B-Bearing Austenitic Stainless Steel Fabricated by Laser Metal Deposition In-Situ Alloying

In the field repair application of laser metal deposition (LMD), the kinds of powder materials that can be used are limited, while the equipment components are made of various materials. Hence many components have to be repaired with heterogeneous materials. However, it is difficult to match the mechanical properties between the repaired layer and the substrate due to the different materials. Based on the high flexibility of raw materials and processes in LMD, an in-situ alloying method is proposed herein for tailoring the mechanical properties of LMDed alloy. Using different mixing ratios of Fe314 and 316L stainless steel powders as the control parameter, the microstructure and mechanical properties of B-bearing austenitic stainless steel fabricated by LMD in-situ alloying with different proportions of Fe314 and 316L particles were studied. With the increase in the concentration of 316L steel, the volume fraction of the eutectic phase in deposited B-bearing austenitic stainless steel reduced, the size of the austenite dendrite increased, the yield strength and ultimate tensile strength decreased monotonically, while the elongation increased monotonically. Moreover, the fracture mode changed from quasi-cleavage fracture to ductile fracture. By adding 316L powder, the yield strength, tensile strength, and elongation of deposited B-bearing austenitic stainless steel could be adjusted within the range of 712 MPa-257 MPa, 1325 MPa-509 MPa, and 8.7%-59.3%, respectively. Therefore, this work provides a new method and idea for solving the performance matching problem of equipment components in the field repair.     

等离子弧异质异构增材制造构件的组织与力学性能分析

采用等离子弧增材系统实现了不锈钢/高强钢异质异构增材构件制备，等离子弧增材构件具有良好的沉积形貌及优异的力学性能.为揭示叠合方式对等离子弧异质增材构件的宏微观组织和力学性能特征影响，研究采用了体视显微镜、金相显微镜、拉伸及硬度等测试方法.结果表明，不锈钢/高强钢异质异构增材构件中存在两种过渡形式，即以奥氏体枝晶过渡和马氏体组织过渡.增材构件横截面硬度波动较大，主要是混合过渡区域的高合金元素导致的组织变化引起的.叠合方式的改变能够显著影响材料性能，在强度下降不多的情况下，提高材料的冲击韧性.