Tritium concentrations in precipitation in Shanghai

Tritium concentrations in precipitation can be used as a criterion to evaluate the tritium baseline of the environment. The tritium concentration in precipitation in Shanghai during 2014-2015 was determined. Values ranged from 0.68 ± 0.04 to 4.11 ± 0.39 Bq/L, and it showed a decreasing trend compared with historical data; however,the values were slightly higher than the natural background tritium level. Additionally, the tritium concentration shows a seasonal variation: It was higher in autumn and winter and lower in summer and spring. A comparison of concentrations in precipitation in Shanghai and around the Qinshan Nuclear Power Plant reveals no correlation,implying that the nuclear power plant operations may not affect the environment of Shanghai. Thus, the raised tritium concentrations in Shanghai might be due to the effects of monsoons, spring leak, raindrop, or other activities that generate tritium there. Those activities may include chemistry research that uses tritium as a tracer.     

量热法测量贮氚容器中的氚

设计建造了 1台样品池容积为1 95mm× 42 0mm的大型氚量热计。该量热计测量样品热功率下限为 6mW。样品热功率在 1 60～ 3 5 0 0mW范围内时 ,信号输出与样品热功率的线性相关系数大于0 9999。当样品热功率不低于 1 60mW时 ,精密度好于 0 2 %。它适用于非对称置样方式的样品中氚的测量。对大容积铀化学床中氚的实测结果表明 :该量热计具有较好的准确性。     

Behavior of Tritium in Aluminum-Lithium Alloys

The hehavior of radiation induced gas bubbles in Al-Li alloys was observed by means of ³H autoradiography. The autoradiographs were compared with photomicrographs of the corresponding areas. Autoradiography proved to reveal the gas bubbles in the alloys more distinctly than photomicrography.

It was found that the bubbles first appeared at the grain boundaries and subgrain boundaries, and there also appeared depleted zones along the grain boundaries. This was followed by crystallographic alignment of the bubbles when heated to higher temperatures. In the case of large gas concentrations, bubbles as large as 5 μ in diameter were observed in specimens heated for 1 hr at 500°C. Bubbles precipitated along the boundaries of recrystallized grains in a specimen of irradiated Al-2.7 w/0 Li when it was tension stretched and then heated for 1 hr at 300°C.     

混合堆产氚演示回路及其氚释放实验

本文介绍了我国第一条混合堆产氚演示回路，阐述了该回路的主要组成部分，如辐照盒、固体增殖剂、分析和监控系统等。     

Tritium in the DIII-D carbon tiles

The amount of tritium in the carbon tiles used as a first wall in the DIII-D tokamak was measured recently when the tiles were removed and cleaned. The measurements were made as part of the task of developing the appropriate safety procedures for processing of the tiles. The surface tritium concentration on the carbon tiles was surveyed and the total tritium released from tiles samples was measured in test bakes. The total tritium in all the carbon tiles at the time the tiles were removed for cleaning is estimated to be 15 mCi and the fraction of tritium retained in the tiles from DIII-D operations has a lower bound of 10%. The tritium was found to be concentrated in a narrow surface layer on the plasma facing side of the tile, was fully released when baked to 1000°C, and was released in the form of tritiated gas (DT) as opposed to tritiated water (DTO) when baked.     

Computed Tritium Concentration in a Heavy-Water Reactor

The solutions of a system of equations governing the accumulation of tritium and helium in the heavy water of a reactor are presented for arbitrary initial conditions. The solutions are presented as functions of heavy-water exchange and helium extraction. The concentration change is illustrated for typical values of the thermal-neutron flux density. __________ Translated from Atomnaya Energiya, Vol. 99, No. 3, pp. 210–214, September, 2005.     

Catalytic Oxidation of Tritium in Wet Gas

Use of precious metal catalyst is recommended in the tritium recovery system because it can oxidize tritium at ambient temperature. The ability to operate at the ambient temperature without preheating and past cooling is a large advantage in the ease of system operation. It is observed in this study, however, that the catalytic oxidation characteristics of the precious metal catalysts are largely affected by the water vapor to such extent that almost no oxidation rate of tritium is expected in the wet gas. Effect of the water vapor on the oxidation rate is quantitatively discussed based on data obtained in this study and an emergency cleanup system from the room air with pre-adsorption bed is proposed.     

Tritium solubility in SUS-316 stainless steel

Tritium solubility in SUS-316 stainless steel was determined with a gas absorption method, in which tritium gas diluted by protium was used. The tritium absorption experiments were carried out at temperatures of 703, 804 and 903 K under pressures of 10, 30, 50 and 100 torr of tritiated hydrogen gas. The radioactivity of tritium dissolved in the specimen was measured by the method of liquid scintillation counting.The tritium solubility was derived from the experimental data by taking into consideration of isotopic equilibrium among H₂, T₂ and HT molecules. The determined tritium solubility can be expressed by the equation:

     

用液体闪烁法测电解重水中的氚

本文简介了用双道液体闪烁计数器测量电解重水中氚的β活性。测量结果表明产生了异常效应的重水中含有氚。     

我国核电厂运行中的氚排放

对2005年底以前我国已运行核电厂的气载和液态氚排放状况进行了总结,并对不同堆型电厂的氚排放差异进行了分析。结果表明,我国压水堆核电厂,氚的排放得到了有效的管理和控制,均在国家规定的限值之内。我国重水堆核电厂,在运行初期的氚的归一化排放量平均值在全球平均值的10%以下。压水堆核电厂氚的排放水平以液态排放途径为主,而重水堆核电厂液态氚与气载氚的排放水平相当。重水堆核电厂气载氚的排放水平明显高于压水堆核电厂。     

Tritium environmental transport studies at TFTR

Environmental tritium concentrations will be measured near the Tokamak Fusion Test Reactor (TFTR) to help validate dynamic models of tritium transport in the environment. For model validation the database must contain sequential measurements of tritium concentrations in key environmental compartments. Since complete containment of tritium is an operational goal, the supplementary monitoring program should be able to glean useful data from an unscheduled acute release. Portable air samplers will be used to take samples automatically every 4 hours for a week after an acute release, thus obtaining the time resolution needed for code validation. Samples of soil, vegetation, and foodstuffs will be gathered daily at the same locations as the active air monitors. The database may help validate the plant/soil/air part of tritium transport models and enhance environmental tritium transport understanding for the International Thermonuclear Experimental Reactor (ITER).     

氘-氚分馏系数法确定氚的电解回收率

天然水中氚含量很低,一般采用电解浓缩-液闪计数法进行测量。电解水样时,氚的电解回收率可由水样的浓缩倍数和氚分馏系数来确定。而电解过程的氚分馏系数和氘分馏系数存在一个近似的关系,即lnβ=ηlnα。采用氚标准水进行电解实验,可得到氚分馏系数,采用光腔衰荡激光同位素法测量电解前后的氘含量可以获得氘的分馏系数。电解条件为低碳钢-镍电极装置,以Na2O2为电解质,电解过程温度为0.5℃。实验得到η为1.27。在电解水样时,可根据lnβ=1.27 lnα可得到氚分馏系数,从而获得本批次每个水样的电解回收率。     

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%.     

氚污染监测中的异常现象研究

由于在实验过程中频繁操作氚钛源(TiT源),造成了实验室氚污染.专门的氚污染监测机构用氚表面污染测量仪进行监测,发现有遮挡物遮挡、不容易污染到的地方污染水平比容易污染到的地方还高,这是不合常理的一种异常现象.经过分析发现,污染异常的地方常年受氢(氘)气放电源照射,这种异常很可能与气体放电有关,论文给出了假设性解释.