用LiF-TLD测量氚表面污染及刻度技术

本文介绍用LiF(Mg,Ti)热释光探测器(TLD)的异常发光曲线测冠氚气瓶螺母上的氚表面污染结果,讨论了用氚钛靶源刻度氚β射线的IL响应的技术。在样品照射30h情况下,此方法的探测下限为400 Bq/cm~2。     

气相色谱仪的氚污染调查

随着分析技术的提高,近年来操作气相色谱仪的单位日益增多。气相色谱仪内有一氚一钪源,在操作时有氚气逸出。为了解上述特定场所氚的污染情况,最近我们对上海市部份气相色谱操作场所氚污染水平作了初步调查。发现空气含氚浓度与本底值比较有明显增高。     

氚监测方法现状及其进展

随着动力堆的发展,氚对环境的可能污染已经引起人们的重视。由于氚在工农业,医学和水文方面的广泛应用,特别是聚变堆的研究和进展,氚的产量、利用及释放量增加很快,氚的监测和防护就成为一个突出的问题。目前,有关氚的文献和监测数据,国外每年发表很多。氚的现场防护技术日趋完善,已出现由计算机控制的氚研究实验室监测系统。环境中的氚,从高空的大气到地表     

熔盐堆中氚的控制和监测

熔盐堆中氚除了从废气中排出,还能经熔盐管道渗透进入环境.氚在管道中的渗透严重影响熔盐堆结构材料的力学性质和使用寿命,同时对环境造成污染.为了减少氚对材料和环境的危害,必须对熔盐堆中的氚进行严格控制.控制氚产生和渗透的主要方法包括提高7Li的浓度、向熔盐中补充Li或Be等.对氚进行监测是氚控制的基础,能及时反映熔盐堆的运...     

车载式大气氚取样系统设计

介绍了车载式大气氚取样系统,该系统由大气氚累积取样器、气体冷阱、车载电源、中心控制器等分系统组成,具有实时、机动、地理位置信息自定位、取样快速等特点,可用于核设施周围环境大气氚浓度异常变化监测、核设施突发事件应急监测、环境辐射调查监测等工作的大气氚取样。     

阳江核电站的排放物及环境样品中氚的放射性水平

主要介绍了2014—2018年,广东省阳江核电站周围空气、雨水、地表水、饮用水、地下水、海水、生物样品中氚的放射性活度水平及阳江核电站流出物中氚排放的抽样监测情况。结果表明,液态流出物排放口附近海域监测到高于本底水平的氚,海水中氚的年均值范围为:0.95～2.87 Bq·L~(-1),单点最高值为35.9 Bq·L~(-1);核电站附近空气中,个别月份可监测到高于探测限值的氚;核电站附近雨水、地表水、饮用水、地下水和生物样品中氚均未发现异常。     

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)%。     

氚污染手套箱内壁及金属去污实验

对氚污染手套箱内壁及金属采用擦拭去污和可剥离膜去污。擦拭去污后,手套箱内壁残留氚污染水平降低到20Bq/cm2以下。对氚污染水平高处采用SO42－/TiO2固体超强酸掺杂可剥离膜或聚乙烯醇（PVA）可剥离膜去污,去污因子高,而氚污染水平低的金属通过可剥离膜去污后残留氚为20Bq/cm2。     

一个值得注意的辐射防护问题——氚-钛靶使用的安全问题

一、引言 在一些研究单位中,对安全使用氚钛靶缺乏足够的认识和重视,没有采取必要的防护措施。前不久,在使用氚钛靶的过程中,一个同志由于误打磨氚钛靶造成了一次比较严重的污染事故。在处理这次事故的过程中,我们发现有些污染和这次事故毫无关系。经各方面的调查和论证,发现以往在氚钛靶的使用过程中,也存在着较严重的污染问题。我们认为,这种     

美国西屋3400 MW_(th)压水堆氚排放研究

本研究较为系统地分析了美国3 400MW_(th)压水堆的运行数据,为AP1000氚源项的研究提供了重要的技术支持。通过统计分析得到现实和保守的AP1000机组氚排放量推荐值分别为25.1TBq/a和44.4TBq/a,气氚和液氚的平均释放比例为12%和88%,发现美国压水堆机组的液氚排放量的极大值集中出现在大修所在季度。另外,本研究初步分析了同一厂址规划6台AP1000机组的可行性。本研究为传统的基于理论模型计算的AP1000机组的氚源项设计方法提供了新思路,同时也为AP1000工程项目的源项评审提供了重要依据。     

Analysis of the SEAFP Reactor Fuel Cycle

The safety aspects of a fusion reactor fuel cycle, which handles substantial quantities of tritium, have been assessed in the framework of the European Programme on Safety and Environmental Assessment of Fusion Power Long Term (SEAL). This study focused on the assessment of the tritium inventory that could be released from interlinked systems in accidental scenarios. A systematic review of the fuel cycle systems was performed by focusing attention on the main interfaces and to the possible propagation of accident sequences through these interfaces. For the bounding accident sequences identified, deterministic analyses were carried out to determine the accident consequences. Both process source terms (PST) and environmental source terms (EST) were estimated. Simultaneous failure of the primary and secondary containment was considered to be beyond the design basis, nevertheless a preliminary analysis has been carried out; a bounding accident sequence related to a double failure, involving a hydrogen fire, has led to a tritium environmental release of 5.3 g and the wall mechanical load deriving from the maximum hypoth-esizable hydrogen detonation has been defined. Tritium releases into the secondary containment are treated by the appropriate detritiation and by the vent detritiation system. The related EST has been estimated based on an overall tritium cleanup efficiency of 99%, deliberately chosen low to cause the EST to be overestimated. The maximum tritium environmental release is less than 11 g and corresponds to an in-vessel LOCA. For accidents initiating in the fuel cycle only, the maximum tritium release is at most 3.1 g.     

氟盐冷却高温堆主冷却剂放射性源项研究

针对氟盐冷却高温堆(FHR)正常运行时主冷却剂放射性源项进行了研究。对主回路源项主要贡献来源及产生原理进行了分析,基于三维蒙特卡罗输运程序KENOⅥ、燃耗分析模块ORIGEN-S及Mathematica程序,对堆芯中子能谱、堆芯源项及主回路源项扩散及活化进行了分析。应用该方法对FHR的一种设计堆型进行了定量分析,结果表明:主回路氚源项相对其他堆的较高,其产生率为5.16×1014 Bq·GWth~(-1)·d~(-1),应采取有效措施限制其向环境的释放。本文结果可为FHR的工程设计、辐射防护设计、氚源项控制、三废处理系统设计等提供参考。     

Discharge Characteristics of Large-Area High-Power RF Ion Source for Positive and Negative Neutral Beam Injectors

A large-area high-power radio-frequency(RF) driven ion source was developed for positive and negative neutral beam injectors at the Korea Atomic Energy Research Institute(KAERI). The RF ion source consists of a driver region, including a helical antenna and a discharge chamber, and an expansion region. RF power can be transferred at up to 10 kW with a fixed frequency of 2 MHz through an optimized RF matching system. An actively water-cooled Faraday shield is located inside the driver region of the ion source for the stable and steady-state operations of high-power RF discharge. Plasma ignition of the ion source is initiated by the injection of argongas without a starter-filament heating, and the argon-gas is then slowly exchanged by the injection of hydrogen-gas to produce pure hydrogen plasmas. The uniformities of the plasma parameter,such as a plasma density and an electron temperature, are measured at the lowest area of the driver region using two RF-compensated electrostatic probes along the direction of the shortand long-dimensions of the driver region. The plasma parameters will be compared with those obtained at the lowest area of the expansion bucket to analyze the plasma expansion properties from the driver region to the expansion region.     

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.     

Study on oxidation of hydrogen over commercial catalyst for tritium recovery system

For the establishment of the D-T fusion reactor technology, recovery of tritium released into the working area of fusion power plants is quite important. When tritium leaks to working areas, the last barrier is the wall of the building. Due to higher diffusion coefficient of tritium, it diffuses through the wall and would be readily liberated to the environment. Thus, the tritium recovery system is indispensable for the D-T fusion reactor. The objective of the present study is to develop the advanced technology of the tritium recovery system.In the near future, deuterium plasma discharge experiments scheduled be conducted with Large Helical Device (LHD) in National Institute for Fusion Science. A small amount of tritium is produced by D-D reaction in LHD. Tritium in plasma exhaust gases and process gas during discharge needs to be recovered, and thus the design and construction of the tritium recovery system used for that purpose is a matter of considerable urgency.The tritium recovery system usually consists of catalysts and adsorbents, which is the most conventional and reliable method for removing tritium that is accidentally released into the working area of these facilities. However, more recent and advanced type of catalysts on the market cannot be directly applied to the design of tritium recovery system, because of paucity of design data for tritium recovery system. In this study, the authors performed oxidation experiments of hydrogen over a catalyst. The experiments were performed by changing various experimental parameters.     

氢气放电源打靶谱的分析

在以氢气放电源打钆靶为例,分析氢气放电源打靶谱时,发现有以下几类谱线:源谱、靶材料的特征X射线、衍射谱线和一些未知谱线。根据打靶的初级谱可以分辨出源谱;根据靶材料的成分可将特征线区分出来;用改变靶面和入射角、固定测量角的方法及打多晶体靶和非晶体靶的方法可以分辨出X射线衍射谱线;剩下的无法辨识的那些谱线是一种未知谱线,对它的认识还在深入中。     

氚污染金属手套箱退役技术研究

为减少氚污染金属手套箱退役解体过程中氚的二次释放,降低工作人员的辐射危害,减少退役中产生的氚污染废物量,本文针对退役氚污染金属手套箱的解体,设计了氚污染金属手套箱退役解体技术方案,即解体前对氚污染金属手套箱进行初步去污,解体中采用合适的切割技术和相应的防护措施。利用氚污染金属手套箱对该解体方案进行了验证,结果表明,设计的解体方案满足氚污染金属手套箱退役需要。     

Studies on the permeation of hydrogen and tritium in nuclear process heat installations

To realistically evaluate the important problems of hydrogen and tritium permeation in nuclear heated high temperature systems, estimates are made, among others, on the basis of the authors preliminary experimental data. Steam-methane reforming is used as the key process. The results show that oxide layers can decrease the hydrogen permeation rate by more than two orders of magnitude and that not only the oxidation potential and temperature but also the water partial pressure may be essential for the formation and possibly the structure of oxide layers, and consequently for the permeation rate. The consequences of the experimental data for the permeation of tritium are also discussed. The available empirical data and results of the measurements discussed here still contain large uncertainties. It will therefore be necessary to carry out, under as realistic conditions as possible, a broad parameter study of heat exchanger materials which are seriously considered for use in nuclear process heat installations.     

Release behavior of tritium from graphite heavily irradiated by neutrons

The release behavior of tritium formed in graphite has been investigated as a function of radiation damage by means of isochronal annealing of samples heavily irradiated by neutrons. The lithium impurities in graphite were estimated as the source of tritium formation. The main chemical form of released tritium was hydrogen accompanied by a small quantity of methane. No other hydrocarbons could be detected. Tritiated water was always measured, but the formation mechanism was experimentally confirmed as the secondary oxidation of released HT molecule. The release spectrum of tritium in isochronal annealing was shifted to a higher heating temperature with the increase of the neutron fluence received by the graphite crystal. A relationship was established between the amount of tritium released up to a certain temperature and the degree of graphitization of the sample.     

Fuel hydrogen retention of tungsten and the reduction by inert gas glow discharges

Polycrystalline tungsten was exposed to deuterium glow discharge followed by He, Ne or Ar glow discharge. The amount of retained deuterium in the tungsten was measured using residual gas analysis. The amount of desorbed deuterium during the inert gas glow discharge was also measured. The amount of retained deuterium was 2–3 times larger compared with a case of stainless steel. The ratios of desorbed amount of deuterium by He, Ne and Ar glow discharges were 4.6, 3.1 and 2.9%, respectively. These values were one order of magnitude smaller compared with the case of stainless steel. The inert gas glow discharge is not suitable to reduce the fuel hydrogen retention for tungsten walls. However, the wall baking with a temperature higher than 700 K is suitable to reduce the fuel hydrogen retention. It is also shown that the use of deuterium glow discharge is effective to reduce the in-vessel tritium inventory in fusion reactors through the hydrogen isotope exchange.