共查询到18条相似文献,搜索用时 53 毫秒
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本文简要介绍采用自制的几种疏水催化剂进行的室温H-T同位素交换实验,初步考察了氢气流速对催化活性的影响。实验表明,催化剂的催化活性较高,能够用于室温下从氚水中回收氚。 相似文献
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在研制粒径为6mm的多孔PTFE疏水担体基础上,采用浸渍法研制了可在工程上应用的Pt PTFE疏水催化剂。室温下,在并流催化床上考察了该疏水催化剂的催化活性、疏水性能和催化剂上活性粒子的稳定性。结果表明:当氚浓度为153Bq/mL,氢气线速度为5.31cm/s和15.93cm/s时,水中氚的催化转化率分别为73.7%和69.6%。在用普通水浸泡并淋洗145d后,该疏水催化剂的催化活性和活性粒子(Pt)的含量无明显变化。 相似文献
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在研制粒径为6mm的多孔PTFE疏水担体基础上,采用浸渍法研制了可在工程上应用的Pt—PTFE疏水催化剂。室温下,在并流催化床上考察了该疏水催化剂的催化活性、疏水性能和催化剂上活性粒子的稳定性。结果表明:当氚浓度为153Bq/mL,氢气线速度为5.31cm/s和15.93cm/s时,水中氚的催化转化率分别为73.7%和69.6%。在用普通水浸泡并淋洗145d后,该疏水催化剂的催化活性和活性粒子(Pt)的含量无明显变化。 相似文献
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三种疏水催化剂耐氚辐照稳定性初步研究 总被引:4,自引:1,他引:4
为考察3种疏水催化剂Pt-SDB(SDB为苯乙烯-二乙烯苯共聚物),Pt-PTFE(PTFE为聚四氟乙烯),Pt-C-PTFE 的耐氚辐照稳定性,将其置于1.26×1012Bq/L的氚水中静态辐照210 d后,对其催化交换性能及催化剂中残存氚进行分析。结果表明,3种催化剂在氚的β辐照下未发生裂解,催化剂中氚的残存量随催化剂比表面积的增加而增加,基本没有发生结构上的氚取代反应;但在氚水辐照后,3种疏水催化剂的交换性能出现了不同程度的变化,按单位质量Pt粒子计算,在测试不确定度范围内Pt-PTFE和Pt-C-PTFE的转化率没有发生明显变化,Pt-SDB(1)的转化率下降了11.2%,Pt-SDB(2)的转化率下降了16.9%。 相似文献
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用于水/氢同位素交换的P_t/SDB疏水性催化剂的研究 总被引:7,自引:1,他引:6
一、前言 随着核工业的发展,各种核设施不断产生大量的含氚轻水或重水。考虑到工作人员的安全和防止天然水源的污染,必须除去水中的氚。许多学者在这方面作了大量的工作。这里主要介绍铂/聚苯乙烯-二乙烯基苯(Pt/SDB)疏水性催化剂的制备及水/氢间T-H交换实验。 相似文献
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为提升疏水催化剂性能并扩展其应用范围,以柱状(ø=5 mm)多孔陶瓷为载体,在载体表层构筑氧化铈(CeO2)微纳结构为载体提供疏水环境,采用浸渍还原法制备用于氢同位素交换分离的新型Pt/疏水陶瓷催化剂。为验证新型疏水催化剂实用性,以X射线衍射(XRD)、扫描电镜(SEM)、X光电子能谱(XPS)、一氧化碳(CO)脉冲吸附、能谱(EDX)对催化剂性能进行综合表征,并采用气汽并流方式测试催化剂催化活性。结果表明,新型陶瓷载体疏水性优良,疏水结构对载体孔结构性能影响较小;疏水层使浸渍液对载体浸润能力下降,铂粒子分散度及零价铂含量降低;浸润能力下降使前驱体多沉积在载体表层而较难渗入载体内部,表层铂粒子含量高,使反应物的反应通道较短,相同时间内有更多的铂粒子参与反应。制得催化剂催化活性可达同种形状有机载体类催化剂催化活性的80%,冲淋12周后,催化活性下降比率小于5%,新型疏水催化剂催化活性及耐冲淋稳定性均较好,实用性佳,具有良好的应用前景。 相似文献
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S. Fukada Y. EdaoK. Sato T. TakeishiK. Katayama K. KobayashiT. Hayashi T. YamanishiY. Hatano A. TaguchiS. Akamaru 《Fusion Engineering and Design》2012,87(1):54-60
An experimental study on tritium (T) transfer in porous concrete for the tertiary T safety containment is performed to investigate (i) how fast HTO penetrates through concrete walls, (ii) how well concrete walls contaminated with water-soluble T are decontaminated by a solution-in-water technique, and (iii) how well hydrophobic paint coating works as a protecting film against HTO migrating through concrete walls. The experiment is comparatively carried out using disks of cement paste which W(water)/C(cement) weight ratio is 0.6:1 with or without hydrophobic paints, and mortar disks which W/C/sand ratio is 0.6:1:2 with or without the paints. The hydrophobic paints tested in the present study are an epoxy polymer resin paint and an acrylic-silicon polymer resin one. After T exposure during specified time under a constant HTO vapor pressure in an acrylic box, the amount of water-soluble HTO on/in the disks is determined using a technique of H2O dissolution during specified time. The results obtained here are summarized as follows: (1) HTO penetration in porous concrete can be correlated in terms of the effective diffusivity. (2) Its value in porous cement without coating is 1.2 × 10−11 m2/s at 25 °C. (3) HTO penetrates only through pores in cement, and there is no path for HTO transfer in non-porous sand. (4) Rates of sorption and dissolution of HTO in disks of cement and mortar coated with the epoxy resin paint are correlated in terms of the effective diffusivity through the paint film which value is DT = 1.0 × 10−16 m2/s. The rate-determining step is diffusion through the paint. (5) The epoxy resin paint works more effectively as an anti-HTO diffusion coating. (6) Another acrylic-silicon resin paint does not work well as anti-HTO diffusion coating. This may be because the hydrophobic property of the silicon resin paint is deteriorated with elongating the contact time with H2O vapor or liquid. (7) The HTO uptake inside the epoxy paint is greater than that of the silicon one. (8) The permeation reduction factor (PRF) of HTO for the epoxy paint at steady-state is expected large, if HTO vapor only contributes to diffusion. However, when concrete surfaces coated with the epoxy paint are under wet conditions, the PRF value becomes smaller. All those results can be used to estimate the effect of HTO soaking in concrete walls in case of accidental T release in a fusion reactor room and to decontaminate wastes of tritiated concrete. 相似文献
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以5—甲酰基尿嘧啶为起始原料,采用“二步法”:第一步合成了氚标记的5—羟甲基尿嘧啶,第二步合成了氚标记的胸腺嘧啶。放射性比活度分别达到1.6PBq/mol和2.2PBq/mol,再经酶促反应,生成氚标记胸腺嘧啶核苷,其比活度达2.2PBq/mol,放化纯度大于95% 相似文献
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利用氯化聚乙烯、聚偏二氯乙烯(Polyvinylidene chloride,PVDC)、高密度聚乙烯等高分子材料复合防氚材料。采用渗透实验测量氚气渗透率;通过测量断裂强力和剥离力测量力学性能;通过测量浸泡化学试剂前后的溶失率、断裂强力下降率、剥离力下降率等表征材料的耐化学性能。结果表明,氚气在防氚高分子复合材料中的渗透率为3.44×10-10 m3/(m2?s);与PVC相比,氚气渗透率降低约70倍。PVDC薄膜复合后断裂强力提高约20倍,经纬向断裂强力为721 N。防氚高分子复合材料浸泡5种化学试剂后,最大溶失率为0.29%、断裂强力最大下降率为5.1%,其力学性能、耐化学性能均满足《防护服装酸碱类化学品防护服》(GB24540-2009)等相关标准的要求。 相似文献
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Pt—C—PTFE疏水性催化剂的H2O—H2同位素交换研究 总被引:7,自引:4,他引:7
本文简要介绍了Pt-C-PTFE疏水性催化剂的制备方法,采用此种催化剂进行了T-H交换实验,得到催化活性与温度、氢气流速的关系。同时对气/液并流和气/汽并流交换实验作了比较,后者活性大大高于前者。此外,在疏水性催化济中加入适量亲水性载体,可以大大提高催化剂的交换效率。 相似文献
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在氘或氚化溶剂中,16-次甲基-17α-乙酰氧基-19-羧基-孕甾-4-烯-3、20-二酮(Ⅰ)通过脱羧反应制得[10-~2H]ST-1435或[10-~3H]ST-1435(Ⅱ)。氘标记ST-1435经质谱分析表明有1—3个氘原子掺入到ST-1435分子中去,其中m/e 371(M~+)的氘掺入率为22.6%。氚标记ST-1435的比活度为52.5TBq/mol,放化纯度>95%。 相似文献
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Among the recent design activities of the Ignitor program, the analysis of the tritium system has been carried out with the aim to describe the main equipments and the operations needed for supplying the deuterium–tritium mixtures and recovering the plasma exhaust.
In fact, the tritium system of Ignitor provides for injecting deuterium–tritium mixtures into the vacuum chamber in order to sustain the fusion reaction: furthermore, it generally manages and controls the tritium and the tritiated materials of the machine fuel cycle. Main functions consist of tritium storage and delivery, tritium injection, tritium recovery from plasma exhaust, treatment of the tritiated wastes, detritiation of the contaminated atmospheres, tritium analysis and accountability.
In this work an analysis of the designed tritium system of Ignitor is summarized. 相似文献
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The operation of the European Tritium Handling Experimental Laboratory (ETHEL) will require the implementation of means and procedures for allowing tritium control within the facility. For that purpose, account must be taken of the particular characteristics of tritium, such as its high mobility, capacity to dissolve in materials, often limited precision when performing inventory measurements. This paper estimates the influence of these effects on the overall tritium balance in ETHEL. By employing available models for predicting tritium hold-up, it is estimated that three to four grams of tritium may potentially remain irreversibly fixed in various plant items of the standard laboratory infrastructure (exclusive of experimental circuits). On the other hand, the highest overall precision that may be attained with the present plant regarding inventory measurements is estimated to be of the order of few percent. On the basis of the above estimates, the allowable limits for the Material Unaccounted For (MUF) are discussed. 相似文献