环境生物有机氚分析方法的研究与应用

本文通过大量的实验,对所购买的Carbolite生物氚碳燃烧装置进行了局部改良,优化了环境生物有机氚分析方法的设置条件。优化后,样品的生成水回收率可达到80%以上,Carbolite生物氚碳燃烧装置氧化燃烧更充分,制样过程更安全;相同环境样品不同实验人员的测量结果相对偏差小于30%。结果表明,本文的分析方法具有重现性。     

尿氚制样系统的研制

为改善尿氚制样过程中自动控制差、制样效率低、操作流程复杂、耗能高等问题,研制了一套用于尿中氚分析的快速、批量尿氚制样系统,并通过相关实验对系统性能进行了测试。结果表明,系统制样的最佳制样条件是加热温度为200℃,蒸馏冷凝时间为10 min;系统制样稳定度高,重现性好,较以往的尿氚蒸馏装置制样效率提高了5倍,能耗降低了1/3,操作流程实现自动化。     

燃烧制样法测定牛奶中的氚

本文用燃烧法研究了牛奶中氚的测量方法,使用自制的简单石英燃烧装置和HR-1型蜂窝状燃烧催化剂。用低本底液体闪烁仪进行测量。以水和氚放射性回收率验证该燃烧器的性能。牛奶中水回收率为98.6±1.5％。氚水和有机氚的回收率相一致,都在97％左右。     

植物样全氚制样装置的研制与验证

介绍了一种自行研制的用于进行植物样品全氚测量的制样装置,该装置将传统的高温氧化方式与明火燃烧的方式相结合,一次能够处理10.00～15.00g植物鲜样,处理时间为2～3h,与传统的高温氧化法相比,处理时间短,与国外同类装置相比,样品处理量大。经过实验验证,收集的冷凝水不需要再进行后续处理,可以直接进行液闪测量。     

有机氚氧化燃烧制样装置的研制及应用

研制了有机氚(OBT)氧化燃烧制样装置,该装置主要由石英管、固定和移动式管式电炉及冷凝收集器3部分组成。1次可处理环境样品40～100 g,对有机氚的氧化燃烧效率高达97.4%,生成水的回收率达94.4%,氧化燃烧过程直观可视。利用该装置对四川某设施外环境采集的动植物样品中的有机氚进行了测定,其活度水平在0.16～2.71 Bq/kg之间,肉类有机氚活度较高,植物类较低。     

植物样品中有机氚测量方法的初步研究

为研究植物样品中有机氚（OBT）浓度相关测量的最佳方法,以秦山核电基地所采植物和人为氚污染的植物样品为研究对象,对去除交换性有机氚(E-OBT)所需的最合适浸泡水用量和浸泡时间及样品氧化燃烧和收集过程中氚的残留效应进行了研究。结果表明：用30倍于干物质质量的低氚水浸泡24 h,可有效去除植物样品中的E-OBT;用50 mL低氚水冲洗氧化燃烧炉1次,即可将残留在其中的氚冲洗干净;经3次大量低氚水冲洗后OBT水样收集瓶与石英舟中无氚残留。     

核设施氚气态释放后植物中有机氚的研究进展

从核设施释放到大气中的氚主要以氚化水（HTO）和氚化氢（HT）两种形式存在,最终以HTO的形式进入植物体。植物体中的氚有两种化学形态：自由水氚（TFWT）和有机氚（OBT）,其中OBT又被细分为交换性OBT和非交换性OBT。与TFWT相比,OBT在植物体内有较长的滞留时间和较大的剂量转换因子,在氚的食入剂量中OBT占主要份额,因此有必要对植物中的OBT展开全面研究。本文就植物中OBT的定义、交换性OBT和非交换性OBT的确定、OBT的形成过程及其影响因子、OBT预测模型的研究进行综述,同时对今后植物中OBT应重点研究的内容进行了简单分析,以期为植物中OBT的研究提供一定的参考。为准确评价OBT造成的辐射剂量,今后对OBT的研究中应着重从测量、夜间形成机理和环境中的行为等方面进行。     

环境样品中自由氚和组织结合氚的收集

本文介绍了所建立的环境样品中的自由氚和组织结合氚的分别采样装置和方法。对于样品中的自由氚,用低真空干燥回收法,回收率可达98%;对于样品中的组织结合氚,用连续加样催化氧化冷凝收集法,回收率为93%。两法都能一次收集足够制两个并行测量样的水量。     

焚烧处理有机废液中氚对大气环境的影响评价

中国原子能科学研究院有机废液焚烧装置于1986年建成,并于1989年8—9月焚烧处理了1.7 t 含氚(10~8Bq/L)废机油。监测结果表明,这次焚烧排放造成的空气中氚浓度最高值为13.3Bq/m~3,估算结果与监测结果相一致;对周围居民产生的最大个人年有效剂量当量为0.32 μSv。     

碳酸盐中碳、氧同位素快速制样装置研制

介绍一种碳酸盐中碳、氧同位素快速制样装置。实验证明,该装置具有真空度好、使用方便、无污染、制样效率高、成本低的优点,所生成的二氧化碳具有高纯、分析结果准确、可靠等特点,完全能满足碳酸盐中碳、氧同位素分析的制样要求。     

茯苓聚糖的氚离子束标记及其在小鼠体内的药物动力学研究

本文采用氚离子束标记法,对茯苓聚糖进行了标记,放射性比活性达1.81—2.07TBq/mmol。药物动力学研究证明~3H-茯苓聚糖尿素液口服灌喂小白鼠,按一定时间在尾部静脉取血样作放射性分析。得到的药-时曲线适合于双定模型。     

被动式氚取样器性能的实验研究

介绍了核设施工作场所和环境空气中氚化水蒸气HTO的监测,被动式氚取样器在国外已经得到非常广泛的应用,所研制的被动式氚取样器,特别适用于7－30d的长期取样,给出该取样周期内空气中HTO浓度的平均值。     

土壤-植物系统中氚迁移研究现状与展望

对土壤-植物系统中氚迁移研究的意义、国内外研究进展作了概括性的介绍与展望,包括氚在不同土壤和植物中的时空分布、迁移规律及其影响因素、氚的化学形态和氚迁移数学模型研究等。总结了已取得的研究成果,并分析、讨论了研究中存在的问题。     

Numerical simulation of tritium behavior under a postulated accident condition for CFETRTEP system

China Fusion Engineering Test Reactor(CFETR)is China's self-designed and ongoing next-generation fusion reactor project.Tritium confinement systems in CFETR guarantee that the radiation level remains below the safety limit during tritium handling and operation in the fuel cycle system.Our tritium technology team is responsible for studying tritium transport behavior in the CFETR tritium safety confinement systems of the National Key R&D Program of China launched in 2017,and we are conducting CFETR tritium plant safety analysis by using CFD software.In this paper,the tritium migration and removal behavior were studied under a postulated accident condition for the Tokamak Exhaust Processing system of CFETR.The quantitative results of the transport behavior of tritium in the process room and glove box during the whole accident sequence(e.g.,tritium release,alarm,isolation,and tritium removal)have been presented.The results support the detailed design and engineering demonstration-related research of CFETR tritium plant.     

Numerical simulation of tritium migration in groundwater at Wolsong Plant 1 site

On-site groundwater has been reported to be contaminated by the unplanned release of liquid radioactive material at some nuclear power plants. Thus, it is of utmost importance to implement a timely and effective groundwater protection program at a site based on a good understanding of groundwater flow and a reasonable prediction for the potential impact of the unplanned release. In this study, the tritium migration has been simulated based on the modeling result of groundwater at Wolsong Plant 1 site to assess the potential impact of an unplanned release in the form of a leak. The results indicate that the groundwater eventually flowed into the sea, leaving marine activities as the only possible exposure pathway for receptors. Furthermore, the tritium concentrations in groundwater were simulated to be lowered very quickly with groundwater approaching the sea. Therefore, an additional radiation dose contribution due to the discharge of the contaminated groundwater was estimated to be negligible. Particularly, the draining effect of the dewatering sumps was shown to have a strong influence on the groundwater flow characteristics and the simulation of tritium migration, mainly decreasing the spread rate of the contaminated groundwater, which is advantageous to the protection of groundwater.     

Experimental study on the adsorption and desorption of tritium in the graphite materials for HTR-PM

Tritium behavior in the reactor such as production, diffusion and release are accompanied by their adsorption and desorption in graphite materials, which are essential to the safety of high temperature gas cooled reactor (HTGR). In order to study this important issue, hydrogen instead of tritium is experimentally used in this work and justified viable by theory. By performing multiple sets of comparative experiments, the features of hydrogen adsorption and desorption behavior changing by adsorption temperature and time in typical graphites used in HTR-PM (High Temperature Gas Cooled Reactor – Pebble Bed Module), i.e. reflective layer, fuel element and boron carbon bricks, have been observed and analyzed. Furthermore, the adsorption rates of hydrogen in the three materials as above at different conditions are also given. Based on the experimental results, tritium behavior in the HTR-PM was inferred and estimated, which is significant for the further study on the mechanism of tritium transport.     

18F标记的脑受体PET显像剂的制备研究进展

脑受体的PET显像剂制备研究具有重要意义 ,其中以18F标记的药物研究最多。介绍了18F标记的脑受体PET显像剂制备的一般方法 ,对亲核取代法进行了较为详细的讨论 ,分析了主要影响因素 ;按照脑受体功能进行分类 ,回顾了近年来脑受体的PET显像剂制备研究的一些进展。     

Enhanced tritium production for fusion reactors via3He(n,p)3 H in the heavy water moderator of a CANDU reactor

There is an increasing requirement for tritium to supply the fuel needs of current experimental fusion devices and in the initial startup of future power generating reactors. Tritium is produced in heavy water reactors through deuterium activation, but the total production capacity of Canadian operated CANDUs will fall short of future demands, during the period before and for some time after self-sufficient reactors become available. Consequently, methods of enhancing tritium generating rates warrant investigation. Herein we provide the results of an inquiry into the feasibility of enhancing tritium production levels through the activation of helium-3 following its external addition to the heavy water moderator system of a hypothetical 500–600 MWe CANDU reactor. The approach adopted involves simulation of the temporal evolution of the tritium activities, originating from²H(n,)³H and³He(n, p)³H, as described by a simple first order kinetic model. The results suggest that the frequent addition of helium-3 to the moderator water will enhance tritium production inventories. The enhancement factor is highly dependent upon the rate at which helium-3 irretrievably escapes to the moderator cover gas. However, the direct activation of helium-3, contained in a closed loop such as the annulus gas system, for example, would be essentially complete within a few weeks without any significant loss.     

低流速自然循环过冷沸腾汽泡脱离点实验研究

针对低流速环形通道中自然循环过冷沸腾汽泡脱离点特性进行了实验研究,运用Saha-Zuber模型、Bowring模型、Forster模型和Levy模型测算汽泡脱离点的位置,与实验值进行比较,发现由于流速较低,上述模型不适用于计算本实验条件下的汽泡脱离点。以Levy模型为基础,修正了浮力项的影响系数,修正后的模型与实验结果符合良好。     

BIXS技术测量氚化钛膜氚活度实验方法研究

完成了BIXS能谱测量系统的组建及调试,对BIXS技术测量氚化钛膜氚活度的实验方法进行了研究。实验获得了空气和Ar气介质中的X射线能谱,与空气介质相比,除有两个相同峰位能量为4.5 keV和5.0 keV的谱峰和峰强度(或峰面积)分别减弱至约为0.4%、1%外,还增加了3.0 keV、9.0keV的两个谱峰;同时获得了不同氚活度氚化钛膜的X射线能谱,结果表明氚活度决定着X射线能谱的峰面积,具有良好的线性关系。