低氚压气-液交换法标记强效镇痛剂

本文报道使用氧化钯作催化剂、二氧六环作溶剂,在氚气压力为13.3kPa下,催化氚化强效镇痛剂,制得氚标记强效镇痛剂放射性比度为51.8—242.OGBq/mmol。该法与常用的高氚压气-液交换法相比,只有用氚量少、污染小、经济等优点。     

Hydrogen incorporation in tungsten deposits growing by deuterium plasma sputtering

Tungsten deposits were produced by sputtering method using hydrogen isotope RF plasma, and the density and the incorporated components in the deposits were investigated. The density changed in the range from 14.2 g/cm³ to 6.1 g/cm³, and hydrogen isotope retention changed in the range from 0.25 to 0.05 as (H + D)/W by the difference of deposition conditions. Both the density and hydrogen isotope retention tended to decrease with an increase of pressure. Even though a deuterium gas was used for producing tungsten deposits, not only deuterium but also hydrogen, oxygen and water vapor were incorporated in the deposits. It is considered that the incorporation of these components originated in water vapor unintentionally existing in the vacuum chamber.     

Radiometric method of determining tritium activity in experiments

Moscow Physics Research Institute. Translated from Atomnaya Énergiya, Vol. 70, No. 6, pp. 394–396, June, 1991.     

Hydrogen and helium trapping in tungsten under single and sequential irradiations

The trapping of hydrogen and helium in polycrystalline tungsten irradiated with 500 eV He⁺, H⁺ and D⁺ ions, individually or sequentially, has been measured by thermal desorption spectroscopy. Specimens irradiated with 500 eV He⁺ at 300 K show three He release peaks in the vicinity of ∼500, ∼1000, and ∼1200 K. The helium is thought to form He vacancy complexes or bubbles. Increasing the specimen temperature to 700 K does not significantly affect the trapping behavior of He. Sequential He⁺-D⁺ irradiation at 300 K results in the elimination of He release above 800 K. Instead, both D and He were released in the range 400-800 K. This is interpreted as interstitial D and He released from the near surface. Sequential He⁺-D⁺ irradiation at 700 K resulted in a reduced single He peak at ∼1000 K with very little release observed below 800 K; no D was trapped for irradiations at 700 K. Sequential D⁺-He⁺ irradiations at 300 K show that He trapping occurs in much the same manner as for the He⁺-only case while D retention is reduced at the near surface. Sequential D⁺-He⁺ irradiations at 700 K indicate that pre-irradiation with D⁺ has little or no effect on the subsequent trapping behavior of He.     

Hydrogen isotope retention and recycling in fusion reactor plasma-facing components

The proper design of a fusion reactor is not possible unless there is an understanding of the hydrogen isotope retention and recycling for the plasma-facing components. From the tritium inventory point of view, it is absolutely necessary to understand the short-term and long-term hydrogen isotopes retention characteristics of the individual materials used for the first wall and divertor. From the plasma density and fueling point of view, it is necessary to understand the recycling characteristics of these materials. This report is an overview of the available data on hydrogen isotope retention and recycling for beryllium, tungsten, carbon, and selected liquid metals. For each material discussed, recommendations are made as to the most appropriate values to use for parameters such as diffusivity, solubility, recombination rate coefficient, and trapping.     

Deactivation of hydrophobic catalysts for a hydrogen isotope exchange: Application of the time-on-stream theory

A recycle reactor was built for the purpose of characterizing newly developed hydrophobic catalysts for a hydrogen isotope exchange. The catalytic rate constants of two types of hydrophobic catalysts were measured at a 100% relative humidity. The catalytic rate constants were measured at 60 °C for 28 days and both the catalysts showed very high initial catalytic rate constants. The measured deactivation profile showed that the catalytic rate constants of both the catalysts were almost identical for 28 days. The deactivation of the catalysts was modelled based upon the time-on-stream theory. The deactivation profiles of the catalysts were estimated by using the model for a period of three years. The results showed that both the catalysts had a good exchange capacity for hydrogen isotopes and they could be applicable to a tritium removal facility that will be built at the Wolsong nuclear power plants in the near future.     

High enrichment of N isotope by ion exchange for nitride fuel development

Two kinds of nitrogen-isotope enrichment experiments were conducted for the purpose of developing a process to obtain highly enriched ¹⁵N by ion-exchange chromatography. As the first stage experiments, high enrichment of ¹⁴N was carried out by displacement chromatography using columns packed with cation-exchange resin and feed ammonium ion of which ¹⁵N abundance is natural namely 0.36%. In the second stage, high enrichment of ¹⁵N was studied starting from ca. 80% enriched ¹⁵N feed material; after 30 m migration 99.67% ¹⁵N was obtained. The height equivalent to a theoretical plate (HETP) of ion-exchange separation is usually very small, but the results clearly indicate that the HETP is enlarged when the high enrichment zone of ¹⁴N or ¹⁵N is developed at the front or the rear band boundary, respectively. The information obtained is very important and should be useful for designing when the plant for the high enrichment isotope separation is designed.     

Enhancement of hydrogen isotope retention capacity for the impurity deposited tungsten by long-term plasma exposure in LHD

The stress relieved tungsten samples were placed at three positions, PI (sputtering erosion dominated area), DP (deposition dominated area) and HL (Higher heat load area) during 15th plasma experiment campaign in Large Helical Device (LHD) at National Institute for Fusion Science (NIFS), Japan and were exposed to ～ 6700 shots of hydrogen plasma in a 15th long-term experiment campaign in LHD. Thereafter, the additional deuterium ion implantation to these tungsten samples was performed to evaluate the change of hydrogen isotope retention capacity in the samples by long-term plasma exposure. It was found that the carbon-dominant mixed-material layer with more than 100 nm thickness was formed on a wide area of the tungsten surface. The thicker mixed-material layer was formed on the DP sample, where the deuterium retention was about 21 times as high as that for pure W. The major desorption temperature of deuterium was shifted toward higher temperature side, which was comparable to the trapping characteristic of carbon or irradiation damages.     

Advances in boron-10 isotope separation by chemical exchange distillation

Advances in boron-10 isotope separation by chemical exchange distillation are reviewed in this article. With a brief introduction of the principle of the separation, the progress on the research of this method and the problems relating to the separation coefficient are discussed. Several new donors, including nitromethane, acetone, methyl isobutyl ketone (MIBK) and diisobutyl ketone (DIBK), which have large separation factors are introduced. The complexes of these new donors and boron trifluoride (BF₃) are more stable than those of using the donors examined before. Among these new donors nitromethane could be a promising substitute for donors in present use to develop new technology of separating boron-10.     

Nitrogen isotope enrichment for nitride fuel by using hybrid chemical exchange process

In order to develop a feasible process for production of enriched nitrogen, chromatography operation was carried out to study the nitrogen isotope separation by using a high porous cation ion exchange resin(SQS-6). The ammonium ion adsorption band initially charged in the resin bed using 0.5 mol·dm⁻³ NH₄OH solution and was eluted in a reverse breakthrough manner. The temperature of column was kept constant at 308K by temperature-controlled water through a jacket. A constant length of adsorbed bands were maintained throughout the elution. The enrichment of ¹⁴N at the front boundary region and ¹⁵N at the rear boundary region were confirmed. The attention was placed on enrichment high purity of ¹⁴N (99.99%). An enrichment factor of ¹⁴N was determined to be 0.026±0.001 and HETP was evaluated 0.18 cm. HETP of front boundary region is obviously lager than that of the rear part.     

Setup for isotope separation by the ICR-heating method

A design of a setup for performing ICR isotope separation is examined. Its main components are based on new physical concepts. It is proposed that ionization of matter will occur in a discharge with crossed electric and magnetic fields. New hf antennas are proposed for ICR heating, making the heating process highly selective. The possibility of heating on the second harmonic of the ion cyclotron frequency is discussed. It is suggested that a curvilinear magnetic field be used for, separating the heated isotope, 6 figures, 24 references. Translated from Atomnaya énergiya, Vol. 88, No. 5, pp. 370–378, May, 2000.     

用氢同位素估算氚在熔盐堆结构材料中的渗透

熔盐堆产生的氚在高温下透过结构材料管壁进入大气环境。为降低此危害,研究氚在堆结构材料中的渗透过程十分必要。针对熔盐堆常用的结构材料Hastelloy N、GH3535、Hastelloy C230、Hastelloy C276,本研究采用压力差驱动法,在400-700 oC和5-40 k Pa的试验条件下,获得了氕、氘的渗透系数,并初步估算氚在该结构材料中的渗透。结果表明:氕、氘在镍基合金中的渗透通量与气体压力的平方根成正比,渗透系数随温度增大,与温度倒数的关系符合阿伦尼乌斯公式;氕、氘在成分相似的GH3535和Hastelloy N中渗透系数接近,与其它两种合金材料中渗透系数都在一个数量级内,在相同温度下两者渗透系数比值接近1.4,符合经典扩散理论;在400-700 oC内,氚在4种镍金合金中渗透过程的指前因子为1.1×10-7-1.6×10-7 mol·m-1·s-1·Pa-1/2,活化能为59-62 k J·mol-1。     

Modelling of hydrogen isotope retention in the tungsten divertor of EAST during ELMy H-mode

In this work, we study hydrogen isotopes (HI) inventory inside tungsten plasma-facing materials during high confinement mode discharges with repetitive edge localized modes (ELMy H-mode) based on the operating parameters of the EAST device, since tungsten is considered as the primary plasma-facing material and the ELMy H-mode is an important operation regime for EAST and future devices. The upgraded Hydrogen Isotope Inventory Processes Code (HIIPC) is applied with the incident depth profile provided by SRIM-2013 to make the study. The code is first verified by comparison with experimental measurements. The effects of the incident ion energy and ion flux on the retention are then studied. Finally, using the parameters obtained from EAST diagnostics, the HI retention inside the W divertor during ELMy H-mode is studied, which indicates the retained HI can be increased dramatically mainly due to ion-induced trap sites by ELMs.