Tritium permeation in EUROFER in EXOTIC and LIBRETTO irradiation experiments

The reduced activation martensitic steel (RAFM) EUROFER is foreseen as a structural material in test breeder module (TBM) in ITER and breeder blanket in DEMO design. In a number of irradiation experiments conducted in high flux reactor (HFR) in Petten EUROFER was used as a containment wall of the breeder material, through which tritium permeation was monitored on line. Thus in EXOTIC-9/1 (EXtraction Of Tritium In Ceramics) experiment where Li₂TiO₃ pebbles were the breeder material, EUROFER was irradiated up to 1.3 dpa at 340–580 °C. In LIBRETTO experiments (LIBRETTO-4/1, -4/2 and -5) the breeder material was lead lithium eutectic which was in direct contact with the EUROFER containment wall. The neutron damage in steel achieved in the LIBRETTO experiments varied from 2 to 3.5 dpa. The irradiation temperature was 350 °C (LIBRETTO-4/1), 550 °C (LIBRETTO-4/2), and 300–500 °C (LIBRETTO-5).Tritium permeability was studied by varying the irradiation temperature and hydrogen concentration in the purge gas. From the analysis of the temperature transients performed in all four experiments yielded the tritium diffusion coefficients were derived, which appear to be factor ten lower than the literature data obtained in the gas driven permeation experiments.     

Thermal stability of hydrostatically extruded EUROFER 97 steel

EUROFER 97 steel is a candidate structural material for the future fusion power reactors, as well as for the European Test Blanket Modules (TBMs) to be tested in ITER. In the reported study, the microstructure of EUROFER 97 was modified by hydrostatic extrusion (HE) which reduced the grain size from 400 to 86 nm and that of the carbide particles from 111 to 75 nm. The changes in the microstructure significantly improved the strength of the extruded samples. However, it is important that the enhanced properties of nanostructured materials are stable over the required range of intended service temperature. The thermal stability of the nanostructured EUROFER steel was evaluated by subjecting the hydrostatically extruded samples to annealing at temperatures ranging from 473 to 1073 K (200–800 °C) for 1 h. Tensile tests and microhardness measurements with a 200 g load were carried out on the annealed samples to determine the effect of the heat treatment. The results show that the highest microhardness (403 HV_0.2) was achieved for samples annealed at 673 K. However, the tensile and yield strength decreased at the higher temperature of 873 K and the total elongation increased to 15%, compared to only 3% for as-extruded samples. The changes in the mechanical properties were rationalized by the examination of the microstructural changes. During heating the initial grain size remains virtually unchanged below a temperature of 873 K. However, above 873 K the grain size increased and it is very likely that growth will be very rapid at higher temperatures.     

CLAM钢、EUROFER97钢与钨在HT-7托卡马克中辐照后的表面分析

两种低活化马氏体钢(CLAM、EUROFER97)以及钨被放入HT-7托卡马克的刮削层中,以研究托卡马克装置中高温等离子体与低活化马氏体钢和钨表面的相互作用。通过SEM装置观察,发现某些样品的表面形貌发生了很大变化。低活化马氏体钢的表面起泡比较密集,钨的表面起泡比较稀少,且直径较大。在一些样品的表面,还观察到了等离子体灰尘以及明显的被等离子体冲击后的痕迹。另外,XPS分析发现样品表面的某些元素成分也发生了变化,而且处在托卡马克装置中不同位置处的样品,其表面硅的含量呈现出明显的规律性。     

中子对氟聚合物力学性能的影响

对中子辐照前后氟聚合物 F2311和 F2314的静态力学性能、动态力学性能以及分子量进行了考察。结果表明,经注量为 1.5×1013/ cm2的中子辐照后,F2311和 F2314的静态力学性能稍有增强,分子量变化不大;F2311的动态力学性能基本不变,F2314的储存模量和损耗模量却有所降低,经注量为 2.5×1013/ cm2的中子辐照后,F2311的静态力学性能和 F2314的拉伸性能明显增强,F2314的压缩性能反而降低;F2311的动态力学性能基本不变,F2314的储存模量和损耗模量却明显减小。     

TIG焊对工业纯锆R60702接头腐蚀性能的影响

通过对工业纯锆(R60702)钨极惰性气体保护焊(TIG)保护效果和不平衡条件结晶的运用,制备焊接接头的显微组织试样及其焊接接头的腐蚀电位测定试样。观察接头在高倍金相显微镜下的显微组织特征,测定焊接接头极化曲线,研究R60702的显微第二相的分布及对接头组织腐蚀性能的影响。研究表明热影响区的耐腐蚀效果最差。     

国产快堆燃料元件包壳材料316不锈钢的中子辐照效应

介绍国产六种不同成分与工艺的快堆燃料元件包壳材料316不锈钢(316SS)经650℃高温、积分中子注量3.1×1021n/cm2(En>0.1MeV)的辐照概况,以及辐照后在650℃与室温下的拉伸力学性能试验和金相检查的结果及评述。     

Studies on mechanical, thermal and morphological properties of irradiated recycled polyamide and waste rubber powder blends

The aim of this article was to show the effect of gamma irradiation on mechanical and thermal properties of recycled polyamide (rPA) copolymer blended with different content of waste rubber powder (WRP). In order to study the structural modifications of prepared blends have been subjected to irradiation doses up to 200 kGy were applied to all samples. Non-irradiated blends were used as control samples. Mechanical properties, namely, tensile strength (TS), elastic modulus, elongation at break and hardness have been followed up as a function of irradiation dose and degree of loading with rubber content. Furthermore, the influence of radiation dose in the thermal parameters, melting temperature, heat of fusion, ΔH_f of the recycled PA and its blend with waste rubber powder (WRP) was also investigated.     

尼龙66/紫外辐照线性低密度聚乙烯共混物的力学性能

通过紫外辐照实现了高密度聚乙烯(HDPE)的官能化，改善了HDPE复合材料的性能。本工作采用傅立叶红外(FT-IR)、X射线光电子能谱(XPS)、凝胶、熔融指数和水接触角测试等研究了紫外辐照对线性低密度聚乙烯(LLDPE)化学结构和性能的影响。紫外辐照后，在LLDPE的分子链上引入了C=O、C-O和C(=O)O等含氧基团，其含量随辐照时间延长而增加。凝胶分析结果表明，紫外辐照过程中，LLDPE产生凝胶，     

Mechanical properties of irradiated spinel ceramics

The effects of grain size on the nanomechanical properties of Ar-irradiated magnesium-aluminate spinels was studied. Spinel single crystals and ceramics of different grain size varying from ∼1 μm up to few tens of micrometers were used in the experiments. The measurements were performed in both grain centers and grain boundaries and point to rapidly disappearing differences between bulk and boundaries in irradiated ceramics. The stress-induced hardening has been observed as well. This last effect depends on the grain size of the irradiated material and may serve as an indicator of the stress evolution in the irradiated samples.     

Influence of various catalysts on the radiation resistance and the mechanical properties of cyanate ester/epoxy insulation systems

Fiber reinforced composites impregnated with mixtures of various cyanate ester and epoxy resins demonstrated their excellent performance at the ITER design fluence and beyond. The insulation systems consist of a wrapped R-glass/Kapton reinforcement, vacuum impregnated with a cyanate ester/epoxy blend. For the fabrication of the insulation a long pot-life of the resin is of great importance, which is mainly determined by the amount and the composition of the catalyst needed for curing the resin. However, the catalyst, which amounts to 1–2% of the resin, may also affect the mechanical properties as well as the radiation hardness of the material. In order to investigate these effects, two different composites were fabricated using a Mn- and a Co-catalyst, respectively.The mechanical properties are characterized prior to and after irradiation to a fast neutron fluence of 1 × 10²² m⁻² (E > 0.1 MeV) in tension and interlaminar shear at 77 K.     

伽玛射线辐照接枝对杨树木材力学性能的影响

摘要常温常压下用甲基丙烯酸甲酯（MMA）对速生杨树木材进行浸渍处理,采用^60Coγ射线对其进行辐照接枝改性,考察浸渍时间和吸收剂量对杨树木材主要力学性能的影响,并采用扫描电镜观察接枝前后试材切面的变化。试验结果表明：当浸渍时间为48h,吸收剂量为20kCy时,其顺纹抗压强度、抗弯强度和抗弯弹性模量较素材分别提高了72．3％、72％和42．5％。经过辐照处理后的杨树木材细胞壁被大量聚合物填充,并形成了明显的颗粒状聚合物,其力学性能有较大程度提高。     

Characterization and qualification of advanced insulators for fusion magnets

Intensive research over the past decades demonstrated that the mechanical material performance of epoxy based glass fiber reinforced plastics, which are normally used by industry as insulating materials in magnet technology, degrades dramatically upon irradiation to fast neutron fluences above 1 × 10²² m^?2 (E > 0.1 MeV). which have to be expected in large fusion devices like ITER. This triggered an insulation development program based on cyanate ester (CE) and blends of CE and epoxies, which are not affected up to twice this fluence level, and therefore appropriate for large fusion magnets like the ITER TF coils. Together with several suppliers resin mixtures with very low viscosity over many hours were developed, which renders them suitable for the impregnation of very large volumes. This paper reports on a qualification program carried out during the past few years to characterize suitable materials, i.e. various boron-free R-glass fiber reinforcements interleaved with polyimide foils embedded in CE/epoxy blends containing 40% of CE, a repair resin, a conductor insulation, and various polyimide/glass fiber bonded tapes. The mechanical properties were assessed at 77 K in tension and in the interlaminar shear mode under static and dynamic load conditions prior to and after reactor irradiation at ~340 K to neutron fluences of up to 2 × 10²² m^?2 (E > 0.1 MeV). i.e. twice the ITER design fluence. The results confirmed that a sustainable solution has become available for this critical magnet component of ITER.     

Study on thermal and mechanical properties of cis- and trans-polyisoprene blends implanted by carbon ions

In the present work, elastomeric blends of cis- and trans-polyisoprene prepared by solution casting have been implanted by carbon ions (C⁶⁺) at three different fluencies with 87 MeV energy. The implanted samples were characterized through X-ray diffraction. The thermal transport and mechanical properties of implanted samples have been investigated using transient plane source and dynamic mechanical analyzer respectively. It was found that both thermal transport and mechanical properties show increasing trend up to certain fluence and beyond this fluence a decrease is observed. The variations in these properties have been discussed in terms of crosslink density and crystallinity.     

Mechanical properties and microstructural investigations of TIG welded 40 mm and 60 mm thick SS 316L samples for fusion reactor vacuum vessel applications

The development of advanced fusion reactors like DEMO will have various challenges in materials and fabrication. The vacuum vessel is important part of the fusion reactor. The double walled design for vacuum vessel with thicker stainless steel material (40–60 mm) has been proposed in the advanced fusion reactors like ITER. Different welding techniques will have to be used for such vacuum vessel development. The required mechanical, structural and other properties of stainless steels have to be maintained in these joining processes of components of various shapes and sizes in the form of plates, ribs, shells, etc. The present paper reports characterization of welding joints of SS316L plates with higher thicknesses like 40 mm and 60 mm, prepared using multi-pass Tungsten Inert Gas (TIG) welding process. The weld quality has been evaluated with non-destructive tests by X-ray radiography and ultrasonic methods. The mechanical properties like tensile, bend tests, Vickers hardness and impact fracture tests have been carried out for the weld samples. Tensile property test results indicate sound weld joints with efficiencies over 100%. Hardening was observed in the weld zone in non-uniform manner. Macro and microstructure studies have been carried out for Base Metal (BM), Heat Affected Zone (HAZ) and Weld Zone (WZ). Scanning Electron Microscopy (SEM) analysis carried out for the impact fractured specimens show ductile fracture. The microstructural study and ferrite number data indicate the presence of high content of delta ferrite in the weld zone as compared to the delta ferrite in base metal.     

一种Zr基非晶/晶体复合型核材料的力学性能与耐腐蚀性能的研究

采用Zr65Cu35和Nb双靶直流共溅射方法,通过调节Nb靶的溅射功率,制备了不同Nb含量的Zr Cu Nb非晶薄膜。分别使用能谱仪、X射线衍射仪、高分辨透射电子显微镜观察Zr Cu Nb非晶薄膜的成分与结构,最终选择具有优异非晶形成能力的Zr53Cu38Nb9成分溅射到纯Zr基片上,以制备锆基非晶复合材料。研究测试Zr53Cu38Nb9非晶复合材料的力学性能与耐腐蚀性能。结果表明:与纯Zr基片相比,复合材料在弹性阶段力学性能无明显差异;而在塑性变形阶段,由于非晶薄膜与纯Zr基片的变形与断裂机制不同,该复合材料具有更好的拉伸塑性,其表现为非晶膜厚为280 nm、640 nm和960 nm的复合材料的最大拉伸塑性形变较纯Zr基片分别提高了2.72%、5.22%、4.27%;在耐腐蚀性能方面,非晶膜厚为640 nm的复合材料与纯Zr基片相比,具有较小的自腐蚀电流密度icorr、较正的腐蚀电位Ecorr以及较大的容抗弧半径,表现出更优异的耐腐蚀能力。因此,该新型Zr基复合材料在核材料领域具有潜在的应用。     

Modifications in structural, cation distribution and magnetic properties of Co gamma irradiated Li-ferrite

Polycrystalline samples of Li_0.5Fe_2.5O₄ ferrite precursor were prepared by conventional standard double sintering ceramic technique and then irradiated with three different doses of ⁶⁰Co gamma rays. The crystal structure and phase orientation of the irradiated and unirradiated samples of Li_0.5Fe_2.5O₄ ferrite was done by using X-ray diffraction technique at room temperature. The lattice parameter of the studied samples increased due to the formation of Fe²⁺ ions under the ionizing effect of gamma radiation. The strain in the materials due to the irradiation was calculated from XRD data. Scanning electron microscope (SEM) studies indicate that the irradiation causes amorphization, especially at the grain boundaries. The cation distribution was calculated from XRD data analysis. By using cation distribution structural parameters such as theoretical lattice constant, ionic radii of available sites and the oxygen parameter ‘u’ have been calculated. The estimated cation distribution and other structural parameters shows strong influence of gamma rays on polycrystalline Li-ferrite. The magnetic properties of irradiated and unirradiated lithium ferrite were performed by using pulse field hysteresis loop technique at room temperature. Electrical properties such as diffusion coefficient and dielectric properties were carried out with the influence of gamma irradiation. Activation energy of diffusion process decreased after irradiation. The increase of diffusion coefficient with increasing dose rate of gamma irradiation was reinforced by the increase of Fe²⁺ ions and the displacement of metal ions from its original sites under the effect of gamma irradiation.     

Radiation synthesis of polymer/clay nanocomposite hydrogels with high mechanical strength

Poor mechanical properties of PNIPAAm hydrogels have limited their applications. Nanocomposite hydrogels(NC gels) which incorporate inorganic clay possess high mechanical strength and other desirable properties.In this paper, we report a facile approach to synthesize NC gels using radiation technique. With exfoliated clay sheets acting as crosslinkers, N-isopropylacrylamide monomers are polymerized and crosslinked to form NC gels under γ-irradiation at room temperature. Apart from regular swelling behavior and interesting performance in thermo sensitivity, the radiation synthesized NC gel(RNC gel) has good optical transparency, high strength and flexibility. Through Micro-FTIR, XPS and TG analyses, a particular chemically crosslinked organic/inorganic network was identified in the RNC gel.     

辐射硫化对三元乙丙橡胶力学性能的影响

以三元乙丙橡胶(Ethylene propylene dine terpolymer rubber,EPDM)为基材,三羟甲基丙烷三甲基丙烯酸酯(Trimethylopropane trimethylacrylate,TMPTMA)为交联敏化剂,采用60Co对其进行辐射硫化。研究了不同吸收剂量、不同TMPTMA用量对EPDM的凝胶分数和力学性能的影响,并通过热空气老化测试和热重分析,研究了辐射硫化橡胶与化学硫化橡胶耐老化性和热稳定性。结果表明:随着TMPTMA用量的增加,EPDM的凝胶分数增加,适宜用量为EPDM质量的8%。吸收剂量在120 kGy以下时,拉伸强度、伸长率为100%时的弹性模量及邵氏A硬度随着剂量的增加而增加,而断裂伸长率减小,合适的吸收剂量为约80 kGy。热空气老化后,化学硫化橡胶的拉伸强度及断裂伸长率迅速下降,而辐射硫化橡胶的拉伸强度先增加后减小,断裂伸长率缓慢降低。热重分析结果显示,化学交联的EPDM在430℃-480℃发生热分解,辐射硫化交联的EPDM的热分解温度为480℃-530℃。这些结果表明辐射硫化橡胶比化学硫化橡胶的耐老化性能和热稳定性好。     

Effects of ion irradiation on the mechanical properties of SiNawOxCyHz sol-gel derived thin films

A study of the effects of ion irradiation of hybrid organic/inorganic modified silicate thin films on their mechanical properties is presented. NaOH catalyzed SiNa_wO_xC_yH_z thin films were synthesized by sol-gel processing from tetraethylorthosilicate (TEOS) and methyltriethoxysilane (MTES) precursors and spin-coated onto Si substrates. After drying at 300 °C, the films were irradiated with 125 keV H⁺ or 250 keV N²⁺ at fluences ranging from 1 × 10¹⁴ to 2.5 × 10¹⁶ ions/cm². Nanoindentation was used to characterize the films. Changes in hardness and reduced elastic modulus were examined as a function of ion fluence and irradiating species. The resulting increases in hardness and reduced elastic modulus are compared to similarly processed acid catalyzed silicate thin films.