基于两级钯膜反应器的氚水处理技术

为了处理高浓氚水,搭建了一台氢-水同位素交换串联水汽变换的两级钯膜反应器装置,可以实现级联处理工艺.以天然水代替氚水为源项,以D2代替H2开展了除氢实验,最高获得了207.4的除氢因子,验证了两级钯膜反应器用于处理氚水的可行性.通常情况下,水汽变换反应的除氢因子大于氢-水同位素交换反应.其中,氢-水同位素交换中D2/H...     

Optimization for the tritium isotope separation factor and permeation by selecting temperature and thickness of the diffusion Pd-Ag alloy cathode

Large quantities of tritiated water will be produced in the controlled fusion reactors for power generation. To eliminate the concentrated tritiated water and for recycling tritium, an industrial electrolyzer was developed. The aim of this paper is to give the design of this electrolyzer and the results for optimization in diffusion and in isotopic exchange by selecting thickness of a thimble-shaped Pd-25%Ag cathode working at high temperature and current. In this process, the tritium recovery system is based on the principle of the tritium diffusion Pd-Ag cathode which produces very pure hydrogen isotopes from enriched tritiated water.     

Tritium: its generation and pathways to the environment at CANDU 6 generating stations

Tritium production rates and its pathways in CANDU 6 generating stations are studied in this paper. Tritium is generated primarily by the D(n, γ)T reaction in the reactor core. The major sources of tritium are moderator and coolant heavy water which are exposed to high neutron flux levels during reactor operation. A small amount of tritiated heavy water escape from heavy water filled systems is inevitable. Most of the tritiated heavy water which escapes is recovered through well-equipped heavy water recovery and collection systems. The vaporized tritiated heavy water is controlled by the D₂0 vapour recovery and ventilation systems. Similarly, the liquid tritiated heavy water is collected by portable D₂0 recovery tools and by an active drainage system. The remaining small amount escapes as tritiated heavy water and is lost to the environment in airborne and/or waterborne form.     

Adsorption and Desorption Behavior of Tritiated Water on the Piping Materials

The behavior of tritium on the surface of various piping materials must be investigated for establishment of the safety confinement technology of tritium or for development of the effective fuel handling technology in a D-T fusion reactor, because tritiated water or gaseous tritium is captured on the piping surface through adsorption or isotope exchange reaction. The present authors carried out the water adsorption and desorption experiments on 304 stainless steel, copper, and aluminum in the temperature range from 5 to 100°C and in the partial pressure range of water vapor between 11.8 and 198Pa using a breakthrough method and quantified the amount of water adsorbed and the overall mass transfer coefficients in adsorption and desorption of water. It was observed in this study that aluminum adsorbed more water than stainless steel or copper. It was also observed that the adsorption and desorption rates of water for three materials showed almost the same values. The breakthrough behavior of tritiated water in a 100 m pipe of stainless steel was also evaluated applying the results of this work. It is concluded that water adsorption and desorption reactions influence the behavior of tritiated water in the piping system under the condition where the partial pressure of tritiated water vapor is lower than several pascals.     

Simulation results of the online tritiated water measurement system

Currently,the liquid scintillation method is widely used to measure the activity of tritiated water in the primary circuit of nuclear power plants,which leads to the continuous production of radioactive waste during mea-surement.In addition,the real-time activity information of tritiated water cannot be obtained.To solve this problem,herein we present an online tritiated water measurement method based on plastic scintillators that used the optical transport process in the Geant 4 software toolkit to build a model of plastic scintillation detection for tritiated water.Through simulation,the basic geometric dimensions of the detector were determined.In this dimension,using one detector to measure for 3 h,when the tritiated water activity was 100 Bq/L,its resolution was 16％(16 Bq/L).In addition,calculations were performed for the presence of other background signals to obtain the minimum detectable concentration.     

The Second International Symposium on Advanced Nuclear Energy Research

The diffusion of tritiated water vapor into concrete walls of a fusion reactor building is studied to evaluate the capability of the tritium containment of concrete materials.

First, depth profiles of tritiated water in concrete are calculated to evaluate the capacity of the tritium containment by the sound concrete without cracks, and a 0.5-m-thick concrete wall is sufficient to prevent tritiated water releases to the environment in a normal operation of a fusion reactor over 50 yr. Second, simulations of the cleanup of tritiated water in the concrete reactor hall atmosphere taking into account the soaking are performed. Concrete porosity should be decreased to shorten the cleanup time of the reactor hall atmosphere. Surface coatings on the concrete, which apparently decrease the surface porosity, are effective measures to prevent the diffusion of tritiated water vapor into concrete during accidental releases.     

Desorption Rate of Adsorbed Tritiated Water from Molecular Sieve 5A by Exchange with Environmental Water Vapor

The desorption rate of tritiated water from molecular sieve adsorbed HTO, by exchange with the environmental water vapor, was measured. The molecular sieve, packed in a column, was initially changed with tritiated water and then humidified Ar gas was made to flow through it and the tritium concentration of effluent gas was measured. The desorption rate of tritiated water increased linearly with the water vapor pressure in the gas at constant flow rate. In the case where both the flow rate and the vapor pressure were kept constant, the amount of tritium left adsorbed on the molecular sieve decreased exponentially with time. It should be noted that the desorption rate was rather rapid even at room temperature and nearly all the tritiated water adsorbed on the molecular sieve was recovered by the flowing humidified gas at room temperature within several hours.     

氚化水放射性活度的绝对测量

液体闪烁计数器具有无自吸收、制源简单、操作简便等特点,测量氚化水具有一定优势。利用液闪CIEMAT/NIST方法和三双符合比(TDCR)方法校准氚化水的比活度,旨在为氚化水标准物质的研制提供定值手段。以54 Mn作为示踪核素应用CIEMAT/NIST方法标准化氚化水比活度,合成标准不确定度为0.80%。液闪TDCR方法应用装配有3个光电倍增管的计数器,根据测量的符合信息直接计算得到探测效率,绝对测量氚化水比活度,合成标准不确定度为0.66%。应用这两种方法测量了同一组氚化水淬灭系列源,测量结果 En数检验满意。     

Characteristic of Two-phase Slanting Flow in Rod Bundle

Palladium membrane has been studied for sepration and purification of hydrogen isotopes because of its large permeability. In order to consider permeation of mixture of hydrogen isotopes, solubilities of protium and deuterium in palladium were studied in the temperature range of room temperature to 500°C using breakthrough method. It was observed that solubilities were represented by Sieverts' law and that the separation factor of protium-deuterium binary system was different from the isotope effect ratio. The ideal adsorbed solution theory by Myers and Prausnitz can be applied to estimate the separation factor of protium-deuterium binary system in palladium using the isotope effect ratio observed when protium and deuterium are handled independently. The permeation behavior of multi component hydrogen isotopes through palladium membrane is discussed applying observation on solubilities of this work.     

低放废水处理系统的恢复改造与运行

本文简述了对某停运多年的低放废水处理系统进行恢复与改造的基本原则、主要内容以及系统经恢复改造后的工艺流程和主要优点。在恢复与改造过程中,保留原有的混凝沉降、蛭石吸附、离子交换等处理工艺,采用膜反应器技术进行固液分离及泥浆浓缩。系统经恢复与改造后,系统运行稳定、流程通畅、性能可靠,操作安全便捷、生产能力为0.74～0.8m³/h,达到恢复改造要求。低放废水经系统处理后,总α及总β的去除率分别为99.65%和98.20%,达标排放。     

PET核孔膜制备纳米钯及其形貌观测

采用径迹蚀刻的聚酯（PET）膜制作核孔膜模板,辅助电化学沉积法制备了纳米钯。利用扫描电子显微镜（SEM）和能量色散X射线光谱仪（EDX）对纳米钯的形貌和成分进行了表征。结果显示,在沉积电位为-0.65 V时,此法制备的纳米钯颗粒均匀,且呈阵列分布,长径比分布范围为5～70。     

Enrichment and Volume Reduction of Tritiated Water Using Electrolysis Cell Having Hydrogen Permeable Cathode

The electrolysis rate and the separation factor for hydrogen isotopes are measured using the electrolysis cell having the hydrogen permeable cathode. As the hydrogen gas without the vapor of electrolyte is obtained by this method, decrease of the apparent separation factor by mixing with vapor can be avoided. It is also observed in this study that enrichment and volume reduction of tritiated water using the bipolar electrode electrolysis cell is effective because it gives small loss of tritium from the cell during volume reduction. The separation factor obtained in this study indicates that attachment of two or three sub-cells is enough for volume reduction of tritiated water.     

中药制剂促排体内氚的研究进展

氚是氢的同位素,主要存在形式是氚化水,氚化水类似于水,进入人体后可以通过血液循环系统在人体内均匀分布,使身体所有器官受到均匀内照射,诱发机体辐射损伤。本文介绍了中药制剂促排体内氚的研究进展。     

Possibility of a high degree of removal of silver from fission palladium by petroleum sulfides

In order to use low-level fission palladium in technology, the paladium must be purified to a high degree with respect to foreign radionuclides with close chemical properties—ruthenium, antimony, and silver. The results of a simulation of an optimized two-cycle extraction scheme for extracting and refining palladium on the basis of one extractant—an aromatic solution of petroleum sulfides: first cycle with nitrate and second cycle with chloride system—are examined. The behavior of trace concentrations of silver is investigated and it is shown that total deep removal of silver from palladium of not less than 4.10⁷–40 in the first cycle and 10⁶ in the second cycle with a small number of extraction, washing, and reextraction steps can be attained. 2 figures, 3 tables, 6 references. Translated from Atomnaya énergiya, Vol. 88, No. 5, pp. 358–362, May, 2000.     

Fractional Treatment of Spent Scintillation Cocktail with Low Level Tritium by Azeotropic Distillation

Among various waste from RI laboratories, one of the most troublesome wastes is the spent liquid scintillation cocktail, because there are no good disposal way but to store in each laboratories.

The fractionation of tritiated water, solvent and alkyl detergent from the spent scintillation cocktail by the azeotropic distillation method is examined in this study, and it has been concluded that this method is applicable. It is also found in this study that removal of tritiated water from distilled solvent can be conducted by using adsorption tower with Molecular sieve 3A. Treatment of the spent scintillation cocktail within 3 months after use is recomended because no isotope exchange reaction with solvent or detergent is observed within 3 months after use in this study.

No isotope effects are observed in the azeotropic distillation process.     

氚水内照射对小鼠脾脏空斑形成细胞的影响

本文用单层液相溶血空斑技术研究了氚水内照射对 BALB/c 小鼠脾脏空斑形成细胞(PFC)的影响。结果表明,在本实验剂量范围内(0.047—1.270 Gy),氚水对小鼠脾脏 PFC 有抑制作用,并且随剂量增加,抑制作用更加明显,呈指数性抑制反应。当剂量为1.270 Gy 时,约98.5%的 PFC 受抑制。氚水对脾脏重量和脾细胞数也有类似的影响。     

Processing highly tritiated water desorbed from molecular sieve bed using PERMCAT

Tritium handling facilities use molecular sieve beds (MSB) to collect and recover tritiated water. After reaching the capacity limit of the MSB, the water is desorbed and decontaminated in a water detritiation system (WDS). In the case of highly tritiated water (HTW) absorbed into a MSB, an inherent safe option for processing is necessary due to the HTW specific properties. Ideally, HTW should be processed immediately in a continuous mode. With this in consideration, the water desorption process from a zeolite bed was developed and optimized in a dedicated non active facility. The results of this experiments were applied into the regeneration of a MSB previously loaded with HTW containing an activity of 1.9 × 10¹⁴ Bq kg^?1. The water was desorbed, by step increasing the temperature bed and fed by helium carrier gas into the PERMCAT for detritiation and tritium recovery. The processed water was collected in a dry MSB downstream of the PERMCAT. These initial studies successfully demonstrate the viability of the process. The obtained results of the preliminary study and the subsequent tests with tritium, will provide useful information for the design of tritium processes relying on MSB, such as the water processing foreseen for the test blanket modules in ITER.     

Development of a technical scale PERMCAT reactor for processing of highly tritiated water

In view of future fusion rectors fueled by deuterium–tritium mixtures, highly tritiated water (HTW) of up to 5.2·10¹⁶ Bq kg^?1 will be produced, during routine operation and scenarios as an accidental release of tritium into a glove box. Also in the solid breeder blanket concept, a non-negligible fraction of the tritium produced will be in the tritiated water fraction. To decontaminate HTW the PERMCAT using isotope swamping in a Pd/Ag membrane reactor has been identified as a robust and reliable solution. In order to investigate the decontamination of HTW at flow rates relevant for future fusion power plants, a technical scale, fully tritium compatible PERMCAT consisting of a bundle of finger-type membranes inserted in a single catalyst bed was developed. Nevertheless, it represents only one part of a PERMCAT cascade necessary to achieve the required performance to process HTW on technical scale. By improving the existing PERMCAT geometry using experimental data obtained from isotopic exchange between D₂O and H₂, the performance of the existing PERMCAT reactor was optimised. Based on the optimised geometry a new fully tritium compatible technical scale PERMCAT cascade comprising of two PERMCAT reactors in series was designed, manufactured and commissioned as presented in this paper.     

含氚废水的处理与处置

本文叙述了氚的特性,含氚废水的处理与处置方法以及我国高通量工程试验堆(HFETR)含氚废水的处置。     

Verification of hydrogen isotope separation by pressure swing adsorption process: Successive volume reduction of isotopic gas mixture using SZ-5A column

For the purpose of verifying the applicability of pressure swing adsorption (PSA) process to such as volume reduction of tritiated waste storage, an experimental series was carried out by a PSA apparatus having a zeolite packed column operated at the liquefied nitrogen temperature, where synthetic zeolite 5A was used as a candidate of adsorbents. Experimental results are shown here which were obtained from cyclic operation of isolating a volume of hydrogen decontaminated with its heaver isotope from a mixture of H₂ and D₂ while reducing a volume of this mixture storage. Successive reduction during six cycles is observed in the inventory of this hydrogen mixture in a gas holder. Experimental data are analyzed in order to evaluate the performance of this PSA process operating the hydrogen isotope separation, where several factors are introduced defining efficiencies of decontamination, volumetric reduction, and so on. These factors suggest that the PSA process is available for successive reduction of a tritiated hydrogen storage inventory. A tritium waste management system of PSA process combined with electrolysis is considerable which is aiming at reducing the inventory of tritiated water in storage.