液体闪烁计数法测定共沸蒸馏生物样品气氚活度

本文介绍液体闪烁计数测定有机溶剂共沸蒸馏生物样品组织自由水氚的方法。实验测得甲苯共沸蒸馏新鲜松针、青菜、萝卜、、牛奶、猪肉（精）和大米组织自由水的回收率，分别为０．９０、０．９５、０．９５、０．８５、０．５２和０．９０以及组织自由水氚活度．每升样品水中分别为１．８、３．２、１．８、４．０、３．３和２．７Ｂｑ。     

流体闪烁计数法测定共沸蒸馏生物样品氚活度

本文介绍液体闪烁计数测定有机溶剂共沸蒸馏生物样品组织自由水氚的方法。实验测得甲苯共沸蒸馏新鲜松针、青菜、萝卜、牛奶、猪肉（精）和大米组织自由水的回收率，分别为０．９０、０．９５、０．９５、０．８５、０．５２和０．９０以及组织自由水氚活度，每升样品水中分别为１．８、３．２、１．８、４．０、３．３和２．７Ｂｑ。     

液体闪烁计数法测定生物样品中组织自由水氚

本文介绍生的样品有机溶剂共沸蒸馏－－液体闪烁计数测定组织自由水氚法，组织自由水回收率松针，大米为９０％；青菜，萝卜为９５％；牛奶为８５％；猪肉（精）为５２％。松针（鲜），青菜，萝卜，大米，猪肉（精）与牛奶组织自由水氚活度为分别为１．８，３．２，１．８，２．７，３．３，４．０Ｂｑ／Ｌ－Ｈ２Ｏ。     

尿中氚水和总氚的分析测定

用蒸馏 液闪法和氧化蒸馏 液闪法分别测量了氚污染人员尿中的氚水和总氚(氚水和有机氚)的浓度。根据72个高于本底水平的尿中氚水和总氚浓度分析结果比较,认为在氚内污染工作人员的尿中,有机氚与氚水的浓度比值为(5.4±3.7)%。     

氚水在模拟水稻田中的动力学行为

研究了氚水在模拟水稻田中迁移、输运的动态过程。结果表明,由田水引入的氚水,不仅在系统各组分中转移和分配,而且也向系统外迅速地散逸;氚水的氚以自由水氚和结合态氚形式存在于水稻和土壤中;早稻和晚稻田水中的氚浓度皆随时间单调减少;早稻地上部中自由水氚浓度开始增大,至第8天达最大值后便下降,而结合态氚基本上呈增加趋势,并在第22天高于自由水氚,早稻根氚浓度基本上皆低于地上部;至于晚稻,其地上部及根中的自由水氚及结合氚浓度在采样期间基本上随时间降低;早稻土中的总氚在1天达到最大值后便下降,晚稻土中的总氚浓度则始终随时间单调地降低。     

新型氚蒸馏装置的研制及性能验证

为提高硅胶吸附法监测环境空气中氚的样品前处理效率,采用铸铝加热方式结合温度自动控制技术,研制了一种用于环境硅胶样品自动化氚水蒸馏的装置。经实验验证,该装置选择250℃的加热温度,15 min的蒸馏冷凝收集时间为硅胶吸附氚化水的最佳解析条件,此时对硅胶中氚化水的平均回收率大于99%,氚记忆效应小于0.2‰,100 g饱和硅胶样品能解析水7～10 ml,满足液闪测量要求,研制的氚水蒸馏装置较以往装置蒸馏效率提高了近3倍,能耗减少约77%。     

101重水研究堆含氚轻水脱氚方案研究

101重水研究堆(HWRR)是中国第一座核反应堆,现已停堆进入退役准备期。其乏燃料水池和废水贮存罐中存有一定量的含氚轻水,含氚浓度较高,需进行脱氚处理。本文针对HWRR含氚轻水的处理量和含氚浓度,分别评价了3种含氚水脱氚方案:两种联合电解催化交换(CECE1和CECE2)工艺和水蒸馏(WD)工艺。结果表明,与WD相比,CECE工艺的塔径和塔高更小,CECE电解槽的能耗也较WD工艺的蒸发器稍低;两种CECE工艺相比,顶部进天然水的CECE2工艺更适合处理HWRR的含氚轻水。     

监测环境空气中氚(HTO)的简便方法

本文介绍了一种测定环境空气中氚(HTO)浓度的方法。本方法以变色硅胶作为干燥剂,置于环境空气中自行吸收空气中的氚化水蒸汽,用加热蒸馏法将硅胶吸附的水蒸汽解析制备成水样品,在液体闪烁计数器上测定其氚的活性,根据采样时的温度和相对湿度估算空气中氚(HTO)的浓度。本方法的探测下限不仅与所用的液体闪烁计数器的灵敏度、本底有关,而且与环境温度和相对湿度密切相关。现场实验表明,本方法灵敏度高,简单易行,且不受样品数量限制,特别适用于较大范围内环境空气中氚浓度监测工作。     

秦山核电基地外围环境氚水平分析

本文分析了自秦山三期两台70万千瓦重水堆机组运行以来秦山核电基地外围环境空气、水体、陆生和水生动植物食品中氚活度浓度的历年变化趋势。结果表明,自秦山三期重水核电机组相继投入运行后,在气载放射性流出物排放的主导方位,距核电基地8km范围内空气中氚活度浓度逐年升高,浅井水和湖塘水中的氚活度浓度也有逐年升高的趋势;陆生食物中组织自由水氚略有增高。随着与秦山三期的距离增加,空气中氚活度浓度呈明显下降趋势。秦山三期排放口的海水氚活度浓度高于附近海域,但在5～7km外的附近海域海水中氚活度浓度为本底水平,低于探测限值(1.3Bq/L)。秦山核电基地外围环境中氚水平虽然较本底水平升高,但是对周围居民的健康影响很小,经各种途径摄入的氚产生的年待积有效剂量仅占公众年剂量限值的1%左右。     

植物中组织自由水氚的测量方法

为评价核设施退役中氚对环境的影响,可监测退役前后植物中氚的活度变化来反映.文章设计加工1套用于植物组织自由水解析的低温真空解析系统,该系统对云南杉树叶样品的最佳解析时间定为5～6 h,此时20 g样品至少能解析水4～5 mL用于液闪测量,对树叶中组织自由水的平均回收率为61%.     

人工模拟降雨装置的研制与应用

本文介绍为现场核素迁移试验而研制的人工模拟降雨装置 ,着重介绍了设计参数的选择和性能测试的方法及其结果。该装置采用医用注射针头在一圆圈内振动洒落水滴模拟降雨。经过两年多现场试验中的使用 ,证明它具有降雨强度可变范围宽 (小降雨器 2～ 10 0 mm/h、大降雨器 4～ 10 0 mm/h) ,降雨强度下限低 (小降雨器 2 mm/h、大降雨器 4 mm/h)和性能稳定等特点。与采用喷嘴喷淋的装置相比较 ,便于控制降雨面积、降雨量和总给水量。该装置能满足现场核素迁移试验使用要求 ,也可用于其它需要模拟降雨的试验研究中     

Experiences from sensor tests and evaluation of sensor performance

Sensors are part of the protection system in a nuclear power plant. They are the first link in the chain with influence to the protection system. It is therefore important that the sensors fulfil the demands of reliability and response time. Dynamic investigations of the sensor systems are possible to perform during operation of the plant with the aid of advanced signal analysis. Correctly performed, such an investigation indicates if any sensor with attached sensing lines deviates from the expected dynamic behaviour. The paper presents results from Ringhals 1 in Sweden where snubbers (pulsations dampers with exchangeable needles) were used in the sensing lines to differential pressure sensors. The dynamic influence of the needles was equivalent to a time constant = 0.55 s. It was clear that the response time was longer than the demanded response time with respect to the sensors task in the safety system. By eliminating the needles the demand on the response time was fulfilled. The deviation lead to a report to the Swedish Nuclear Power Inspectorate (equivalent to a Licensee Event Report) with INES level 1. The title of the report is “Too long response time caused by not correct installed pulsation dampers in swelling transmitters”. The paper proves convincingly that signal analysis of multiple sensor signals is a fruitful way to observe dynamic deviations in measurement systems in nuclear power plants.     

秦山核电基地外围植被中14C水平分布研究

为了解秦山核电基地外围¹⁴C的水平分布与规律,本文采用加速器质谱法（AMS）对秦山核电基地外围6.5 km以内的植物样品（苔藓、松针）与食物样品中的¹⁴C比活度进行测量。测量结果显示：苔藓样品的¹⁴C比活度范围为223.0～265.6 Bq/kg C（本底为223.8 Bq/kg C）,¹⁴C比活度随距排放点距离的增加呈降低的趋势,在距排放源6.5 km处达到了本底水平。与松针相比,苔藓更适合做核设施¹⁴C排放的指示植物。苔藓样品的¹⁴C比活度分布规律表明,¹⁴C气态污染物在大气中的扩散受地形和风向因素的影响。食物样品的¹⁴C比活度比参照样品高8.5～13.0 Bq/kg C（大米样品除外）,给当地公众带来的附加剂量为0.5 μSv /a。     

An in-situ study of the dissolution of γ-zirconium hydride in zirconium

The dissolution of γ-zirconium hydride has been examined in single crystal specimens of zirconium using a hot stage in a high voltage electron microscope. It was found that a significant proportion of the dislocations generated by the hydride needles during growth were not annihilated when dissolution occurred on heating to well above the solvus temperature. This is contrary to earlier work where similar experiments were carried out with thinner specimens at conventional accelerating voltages. Electron irradiation completely prevented annihilation of the hydride dislocations during dissolution. The results are discussed in relation to (a) repeated nucleation at the same sites during thermal cycling, (b) external shape changes (growth), (c) strain steps observed during thermal cycling under creep conditions, (d) positron annihilation experiments, and (e) the terminal solid solubility of hydrogen in zirconium.     

Determination of Cr(VI) in wood specimen: A XANES study at the Cr K edge

The content of chromium in different oxidation states in chromium-treated wood was studied with XANES (X-ray absorption near-edge structure) measurements at the Cr K absorption edge. It could be shown that wood samples treated with Cr(VI) (pine and beech) did still contain a measurable content of Cr(VI) after four weeks conditioning. If such wood samples were heat exposed for 2 h with 135 °C prior conditioning, Cr(VI) was no longer detected by XANES, indicating a complete reduction to chromium (III).     

一个在堆中子活化分析测量中多用途的自动换样器

用缓发中子计数法测铀时,每隔90秒左右就要换一次样品,用堆中子短照作纯仪器多元素活化分析时每隔5—6分钟也要更换一次样品,即使在测量长半衰期核素时,每天也要更换几十次样品。显然,靠人工换样,对工作人员不仅劳动强度大而且还要受到较强     

草酸甲基肼应用于污溶剂洗涤的研究

在无水乙醇溶液中制得了白色针状草酸甲基肼晶体。经过分析，其分子式为（CH3N2H4）2C2O4，100g水中的溶解度为241g(25℃）。研究了草酸甲基肼洗涤含少量铀的TBP的性能，考察了一些因素对单级洗涤实验的影响。在未经辐照情况下，草酸甲基肼对含铀TBP的洗涤效果略差于碳酸钠，对含钚TBP的洗涤效果略好于碳酸钠；在一定辐照剂量下，对钚的洗涤效果明显优于碳酸钠。草酸甲基肼洗涤CMP体系中钚的效果略好于碳酸钠；洗涤镅的效果优于碳酸钠。草酸甲基肼四级逆流串级洗涤含铀TBP可获得良好的洗涤效果，洗涤后的有机相铀浓度约为1mg/L。     

Etude de la précipitation isotherme dans un alliage uranium—titane à 2,5% at de titane

Isothermal precipitation between 500 and 650°C in a U-2.5 at % Ti alloy was studied by various methods. To establish precipitation kinetics, the electrical resistance of samples was continuously measured at the ageing temperature or, at intervals, at 300 K and 77 K. A deviation from Matthieson's law, already established for uranium-aluminium alloys, was found here also. The several stages seen in the ageing curves are explained; in particular the influence of the high resistivity of U₂Ti on the high-temperature resistivity values is shown. The apparent activation energy for precipitation is $\text{1.1 ± 0.1 eV}$. Micrographie observations have demonstrated the existence of three different forms of precipitate: cellular precipitation at the old γ grain boundaries, precipitates at the junctions of α needles and oriented rods following a single direction in the needles. These rods form the major part of the precipitate, and their orientation relationships with the matrix were determined. The results are compared with those obtained for a U-2.7 at % Mo alloy of similar structure and supersaturation.     

我国部分地区植物样品中放射性核素水平监测

本文报道1995—2006年我国部分地区的粮食、蔬菜、水果等主要陆生食用植物和部分指示植物样品中放射性核素水平的监测结果。监测结果表明：各植物样品中天然放射性核素238U2、32Th2、26Ra4、0K比活度均在正常范围内。大米、小麦和玉米3大种类主要粮食样品中90Sr平均比活度分别为0.17、0.33、0.36 Bq/kg（鲜）,137Cs平均比活度分别为0.24、0.130、.08 Bq/kg（鲜）;青菜、白菜和萝卜3类主要蔬菜样品中的90Sr平均比活度分别为0.18、0.10、0.17 Bq/kg（鲜）,137Cs平均比活度分别为0.02、0.03、0.03 Bq/kg（鲜）;苹果样品中90Sr平均比活度为0.05 Bq/kg（鲜）,137Cs平均比活度为0.02 Bq/kg（鲜）;海洋植物马尾藻样品中90Sr平均比活度为0.08 Bq/kg（鲜）,137Cs平均比活度为0.06 Bq/kg（鲜）;指示植物松针样品中90Sr平均比活度为4.29 Bq/kg（鲜）,137Cs平均比活度为0.08 Bq/kg（鲜）。此外,还报道了茄子、柿子、山楂、荔枝、牧草和茶叶等样品中放射性核素水平的监测结果。