铀钼合金中钼的测定——EDTA容量法

介绍了采用EDTA返滴定法测定铀钼合金中钼的质量分数的方法。该方法以盐酸、硝酸溶样,磷酸三丁酯萃取分离铀,盐酸羟胺将钼(Ⅵ)还原为钼(Ⅴ),EDTA络合钼(Ⅴ),然后用硝酸铋返滴过量的EDTA来确定铀钼合金中钼的质量分数并对萃取酸度、萃取剂用量、盐酸羟胺用量、还原时间、滴定酸度、铀对钼的干扰等进行了条件实验,结果令人满意。当取样量在0.1~0.25 g时,方法精密度优于1%,回收率在99.2%~101.0%之间。     

铀钼合金燃料组件初步设计研究

作为低浓化计划（RERTR）正在研究和开发的一新燃料,高密度铀钼合金弥散体燃料是未来替代现有研究堆燃料的候选燃料。与现有U3Si2弥散体燃料相比,铀钼合金燃料具有燃料铀密度高,及后处理性能良好的特点,因此,其应用前景良好。     

铀钼合金燃料合格性鉴定试验的现状及发展前景

美国、法国、阿根廷和俄罗斯正就铀钼（U-Mo）合金燃料的开发、合格性鉴定和商业应用的许可证问题进行国际合作。进行合格性鉴定试验的样品分别是小板、全尺寸板和组件。美国、法国和阿根廷采用的是轧制工艺，铀密度为6～8g·cm^-3；俄罗斯采用的是挤压工艺，挤压工艺对于提高铀密度比较困难。铀密度为5～6g·c^-3。根据合格性鉴定计划，每个合作国家都根据本国的辐照试验给出了综合性的辐照结果。结果表明，铀钼合金燃料在低燃耗时具有很好的辐照性能，但最近发现，在高温高能耗辐照条件下，铀钼合金弥散型燃料出现了严重的肿胀。即所谓的枕头效应，这主要是由于铀燃料与铝基体发生了过度反应引起的。解决办法有两个，一个是在铝基体材料中添加硅，以减少U～Mo与Al基的反应；另一个办法是采用U-Mo片状合金燃料。     

钼精矿中铀的测定

酸法溶矿,加入氨水,钼形成(NH4)2MoO4、铜形成络离子:[Cu(NH4)4]2+留在溶液里,过滤除去钼、铜。滤渣经2%盐酸溶解,铅与残渣留在滤纸上,铁等金属元素与铀以离子形式存在滤液中。在滤液中加入EDTA,用氨水调节溶液的酸度,控制溶液的pH=7±0.5,铀以(NH4)2U2O7形式沉淀,铁形成Fe(OH)Y络离子,过滤分离。该方法的加入标准回收率为98.8%～101.4%。     

锆铀合金铸造工艺研究

本文叙述了用感应炉熔炼及铸造锆-8.5wt％铀合金棒的工艺。铸棒的成份均匀,上下端面铀含量偏差不大于0.1％,因涂层坩埚带入的杂质含量均在允许范围,铸棒质量良好,合金的收得率为90％,用该工艺生产脉冲堆燃料棒要比电弧熔炼、挤压成型工艺简单,经济效益显著。     

光纤光度计测定铀及铀铌合金中氮含量

以光纤光度计为检测仪,百里酚为显色剂,用分光光度法测定了铀及铀铌合金中的氮含量。在次氯酸钠溶液中w(Cl)=0.1%～0.14%的条件下,氨与酚形成的络合物最大吸收波长为660nm,方法检测限为20μg/g,测量相对标准偏差小于15%,方法回收率为88%～106%。经比对,该法测定结果与传统分光光度法基本一致。     

预热退火对铀和铀铌合金氢化动力学的影响

用压力-体积-温度(P—V—T)法研究了铀和铀铌合金与氢气反应的动力学过程。研究结果表明，加热预处理可以缩短铀和铀铌合金试样与氢气反应的孕育期；加热预处理温度(600-700℃)对铀和铀铌合金与氢气反应的影响不同。加热预处理温度为600℃、反应温度为200℃时，低碳铀、高碳铀、铀-7％铌合金和铀-3．5％铌合金与氢气反应的活性依次增强。因此，高碳铀和铀铌合金比低碳铀更易于与氢气反应。     

铀铌合金中铌的测定

本文介绍了氯代磺酚Ｓ直接分光光度法测定铀铌合金中的铌．方法具有简便、快速、灵敏度高等优点。可测铀铌合金中１％～１０％的铌．回收率为９９％～１０２％。     

辐照铀元件溶解液中钼的放化分离

研究了草酸对α－安息香肟－ＣＨＣｌ３萃取＾９９Ｍｏ和＾９５Ｚｒ－＾９５Ｎｂ的影响，寻找了最佳Ｍｏ萃取率和＾９５Ｚｒ－＾９５Ｎｂ去污因数的实验条件。提出了在ＨＮＯ３介质中使用α－安息香肟萃取Ｍｏ的分离程序，可从辐照铀元件溶解液中分离Ｍｏ。     

锆铀合金氢化研究

锆铀合金通过氢化可制得U-ZrH_x燃料。合金中加入0.2—0.4wt%碳,有效地防止了燃料棒氢化过程中出现开裂的现象。氢化系统采用常压、高温、小流量的通氢方式,分级保温保压慢速冷却的氢化工艺及调整最终的氢化温度和压力,能够控制U-ZrH_x燃料的氢锆原子比H/Zr,以满足使用要求。     

锆、锆-4合金及新锆合金的热膨胀

用示差式石英膨胀仪在室温至800℃范围内测量了Zr、Zr-4合金、N18新锆合金、N36新锆合金的热膨胀行为．给出了测量结果的经验公式,并对这些材料的热膨胀行为进行了比较,测量结果表明．Zr-4合金、N18新锆合金、N36新锆合金棒材试样的热膨胀基本相同,金属Zr、Zr-4合金和新锆合金板材试样的热膨胀都存在各向异性。     

压应力对各向同性细颗粒石墨热膨胀系数的影响

采用应变电测法测定了IG-11石墨在不同压应力下的热膨胀系数,研究了压应力对石墨热膨胀系数的影响.不同压缩载荷下的实验结果表明,压应力增大了平行于加载方向的热膨胀系数,并减小了垂直于加载方向的热膨胀系数.同时,随着载荷的不断增加,热膨胀系数的绝对变化量不断增大.此外,卸载后残余应变的存在也对热膨胀系数产生了类似的影响.     

Effect of Neutron-Irradiation on Thermal Conductivity,Electric Resistivity and Thermal Expansion of Boron Carbide

Boron carbide possessing porosities of 91 and 77%T.D. were irradiated at about 300°C to 6.0x10¹⁸～ 3.3×10¹⁹ n/cm² in helium atmosphere. The thermal conductivity, the electric resistivity and the linear thermal expansion were determined. Upon irradiation to 3.3×10¹⁹ n/cm², cracking occurred in all of the 91%T.D. specimens and in two of the five 77%T.D. specimens. The thermal conductivity changed with irradiation more markedly in the case of the 77%T.D. specimen, which also increased its specific electric resistivity by a factor of 10⁴, while that of the 91%T.D. specimen increased by less than 10-fold. This significant difference in thermal and electric conductivity change by irradiation is attributed to the difference in microstructure. It was observed that the recovery of radiation damage began at about 300°C when the specimens were subjected to heating and the changes observed in respect of thermal conductivity, electric resistivity and linear thermal expansion.     

压缩应力下石墨IG-110热膨胀系数的测量及验证

采用应变电测法测量压缩应力状态下石墨IG-110的热膨胀系数,分析不同压缩应力对IG-110热膨胀系数的影响.结果表明,压缩应力对IG-110的热膨胀系数影响显著.与未加载时相比,分别加载20、30、40 MPa压缩应力石墨试样平行加载方向的平均热膨胀系数由3.71×10~(-6) K~(-1)逐渐增大至4.20×10~(-6)、4.41×10~(-6)、4.78×10~(-6) K~(-1),分别提高约13.2%、18.9%和28.8%;而垂直加载方向的平均热膨胀系数则由4.03×10~(-6)K~(-1)逐渐减小至3.80×10~(-6)、3.79×10~(-6)、3.75×10~(-6)K~(-1),分别降低约5.7%、6.0%和6.9%.压缩应力状态下石墨热膨胀系数的变化可能与应力导致石墨内部微裂纹的张开和闭合有关.     

Thermal Expansion and Thermal Conductivity of Cesium Uranates

Two kinds of cesium uranates, which are often predicted by thermochemical calculations to be formed in irradiated oxide fuels with high oxygen potentials, were prepared from U₃O₈ and Cs₂CO₃ to determine the thermal expansions and the thermal conductivities. The lattice parameters of tetragonal Cs₂UO₄ and monoclinic Cs₂U₂O₇ were measured by the high-temperature X-ray diffraction method as a function of temperature. The linear thermal expansions of Cs₂UO₄ and Cs₂U₂O₇ obtained from the temperature dependencies of the lattice parameters were 1.2% and 1.1% from room temperature to 973 and 1,073K, respectively. The thermal diffusivities of Cs₂UO₄ and Cs₂U₂O₇ were measured on the disk-shaped samples by the laser flash method as a function of temperature. The thermal conductivities were evaluated from the measured thermal diffusivities and the bulk densities, and the specific heat capacity available in literature. The thermal conductivity of Cs₂UO₄ corrected for 100%TD was 1.2W/m·K at 980K and that of Cs₂U₂O₇ was 0.94W/m·K at 1,093K, which are about 30% and 27% of that of UO₂, respectively.     

核电厂SCIENCE程序包反射层功能扩展研究

文章根据实际工作需要,阐述了基于来自法国的SCIENCE V1程序包进行反射层计算的功能扩展开发;深入研究部分功能的实现细节,按需增加部分代码,扩展开发出反射层计算功能。应用扩展后的SCIENCE程序包研究秦山二期堆型反射层参数,并与1、2号机组共19个循环堆芯的实测值进行比较,结果符合良好,满足工程精度要求。通过对SCIENCE V1程序包的功能扩展研究,扩大了SCIENCE V1程序包的适用范围,同时积累了大型程序的研发经验。     

石墨导瓦热胀差对主泵电机低速启动的影响分析

通过主泵电机热备用状态下温度场计算、导轴承石墨导瓦热胀性能试验、发生故障电机的拆检情况的验证以及故障重现试验,对主泵电机热备用状态下低速启动不成功问题进行了分析和验证,并得出了结论.     

Approximate Treatment of Thermal Expansion Effect in Lattice Transport Calculations

In this paper, thermal expansion effect on neutronics characteristics is approximately taken into account by a correction on cross sections. Dimensions of reactor core components depend on their temperatures due to the thermal expansion phenomena. However, the variation of calculation geometry requires considerable computational load for trajectory based lattice transport calculations such as the characteristics method since ray tracing must be re-executed. Therefore, if a correction on cross sections can accurately capture the effect of geometrical variation due to the thermal expansion, computation time of a lattice transport calculation that treat temperature variation can be reduced. Three different corrections on cross sections were tested in PWR fuel assembly geometry using UO₂ and MOX fuels. It was found that the correction of cross sections that preserves neutron attenuation in a region almost reproduce the reference calculation that explicitly considers geometrical variation due to the thermal expansion. The result of this paper will be useful for lattice calculations in production analysis since material temperatures are frequently changed in such analysis to cover various reactor conditions.     

Linear Coefficient of Thermal Expansion and Mechanical Property of Pb/B4C/BPR Composite

Lead/boron carbide/boron phenolic resin (Pb/B₄C/BPR) is a new kind of shielding composite with high temperature resistance and high shielding performance for radiations. In this paper, the effects of lead powder content, particle size and surface treatment (SiO₂ coating) on the linear coefficient of thermal expansion (CTE) and mechanical properties of the composites were systematically studied. The results show that the composites have the smallest linear CTE and excellent comprehensive mechanical properties when the lead powder content is 36% (volume fraction) and the particle size is 38 μm. Proper coating of SiO₂ on the surface of lead powder effectively reduces the density difference between lead powder and B₄C powder, which not only significantly reduces the linear CTE of the composites, but also improves the tensile, flexural strength and impact toughness. However, too much SiO₂ coating content will result in the linear CTE of the composites increasing and the tensile, flexural strength and impact toughness reducing.     

一种节块展开法

采用分离热中子方程的技巧 ,节块展开法解中子扩散方程 ,可提高计算速度 ,节省计算时间约 40 %。