Deuterium trapping by irradiation damage in tungsten induced by different displacement processes

The deuterium trapping behaviors in tungsten damaged by light ions with lower energy (10 keV C⁺ and 3 keV He⁺) or a heavy ion with higher energy (2.8 MeV Fe²⁺) were compared by means of TDS to understand the effects of cascade collisions on deuterium retention in tungsten. By light ion irradiation, most of deuterium was trapped by vacancies, whose retention was almost saturated at the damage level of 0.2 dpa. For the heavy ion irradiation, the deuterium trapping by voids was found, indicating that cascade collisions by the heavy ion irradiation would create the voids in tungsten. Most of deuterium trapped by the voids was desorbed in higher temperature region compared to that trapped by vacancies. It was also found that deuterium could accumulate in the voids, resulting in the formation of blisters in tungsten.     

Void swelling in ion-bombarded molybdenum

Heavy ion bombardment of molybdenum single crystal has produced calculated swelling values of 2.5 to 3% in the temperature range 900°C to 1000°C. The swelling values are somewhat higher than those reported by Evans for 900°C bombardment. The differences in the swelling are believed to be due to the absence of helium or the slightly higher temperatures used in this work.     

Deuterium trapping in deep traps of differently oriented pyrolytic graphite exposed to D2 gas at 1473 K

Due to their importance for tritium inventories in future DT fueled fusion machines, experimental data on H isotope diffusion, absorption and retention in deep traps (E_b ≅ 4.3 eV) of graphites exposed to hydrogen at elevated temperatures have been reviewed. Deuterium retention was studied in edge- and basal-oriented pyrolytic graphite (PG) and polycrystalline RG-Ti-91 damaged by irradiation with 200 keV carbon ions. Deuterium loading was done by soaking in D₂ gas at 1473 K, and the resulting D retention was measured by nuclear reaction analysis. The microstructure was studied by cross-sectional TEM, SEM and microprofilometry. The concentration of strong traps created by irradiation and estimated by the amount of accumulated deuterium was shown to saturate with the damage above ≈1 dpa at about 1000 appm. In non-damaged and damaged graphites deuterium diffuses via porous grain boundaries and along basal planes within crystallites, while its migration through the graphite lattice along the c direction was found to be negligible. Radiation modifications of PG retard deuterium diffusion and decrease the rate of its chemical erosion by a factor of five. The amount of deuterium accumulated in strong traps in graphites is mainly influenced by their macro- and microstructure, while the degree of graphitization seems to be less important. Derivations are made of the susceptibility of damaged graphites, in particular, CFCs to the retention of hydrogen isotopes in deep traps.     

Ultradense Deuterium

An attempt is made to explain the recently reported occurrence of ultradense deuterium as an isothermal transition of Rydberg matter into a high density phase by quantum mechanical exchange forces. It is conjectured that the transition is made possible by the formation of vortices in a Cooper pair electron fluid, separating the electrons from the deuterons, with the deuterons undergoing Bose–Einstein condensation in the core of the vortices. If such a state of deuterium should exist at the reported density of about 130,000 g/cm³, it would greatly facility the ignition of a thermonuclear detonation wave in pure deuterium, by placing the deuterium in a thin disc, to be ignited by a pulsed ultrafast laser or particle beam of modest energy.     

Deuterium implantation in graphite

A study has been made of deuterium ion implantation in polycrystalline graphite over the temperature range 100 K to 450 K. Deuterium depth profiles are obtained using a method based on observing the energy spectra of the tritons and protons from D-D reactions initiated with a 200 keV probing deuteron beam. In marked contrast to the low adsorption for gaseous hydrogen previously reported, graphite is found here to retain large concentrations of implanted deuterium with atomic loadings exceeding unity in the deeper regions of a cold target. The amount of deuterium retained continues to decrease with increasing temperature until at 150°C the retention has fallen to approximately half that at −160°C. No evidence is found for a layer of surface deuterium of the type seen in metals such as copper. Scanning electron micrographs of irradiated areas show no observable surface deformation for doses of up to 2.4 × 10¹⁹ deuterons/cm².     

Be in commercial beryllium

¹⁰Be has been observed at a level of about 10⁻¹⁴ in four commercially available beryllium compounds. The possibility that this ¹⁰Be arises from cross-talk in the ion source has been eliminated. On the other hand, beryllium oxide extracted from beryl crystals found at a depth of 30–40 feet in a lithium mine in South Dakota shows no indication of containing ¹⁰Be. An upper limit on its ¹⁰Be:⁹Be ratio is 1.7 × 10⁻¹⁵ at the 95% confidence level.     

超轻水中氘含量的气相色谱分析

通过实验研究建立了测定超轻水中氘含量的气相色谱分析方法。用金属镁在500℃高温下将超轻水分解为气体,然后在常温下以高纯H2为载气,5A分子筛作为色谱柱,进行超轻水中氘含量的检测。用金属镁法分解水样,避免了传统铀法可能带来的放射性危害,且同位素效应远小于金属锌法。采用色谱在常温下检测氢气中氘的含量,也克服了普遍采用液氮低温法操作复杂,且H2、HD和D2的校正因子难以测定的缺点。研究结果表明,以极低重水标准样绘制的HD峰面积与对应氘含量的标准曲线能反向延长到天然丰度以下,能用于不同氘含量的超轻水样品检测。该分析方法精密度高,同一样品经多次分解进样,检测的相对标准偏差5%,在3个添加水平下的回收率为96.6%～99.9%,合成相对不确定度为0.166。测量结果精密度和准确度较高,完全能满足超轻水生产过程中氘含量定量分析的要求。     

10 Be in commercial beryllium

¹⁰Be has been observed at a level of about 10^?14 in four commercially available beryllium compounds. The possibility that this ¹⁰Be arises from cross-talk in the ion source has been eliminated. On the other hand, beryllium oxide extracted from beryl crystals found at a depth of 30–40 feet in a lithium mine in South Dakota shows no indication of containing ¹⁰Be. An upper limit on its ${}^{10}\text{Be}\text{:}{}^9\text{Be}$ ratio is 1.7 × 10^?15 at the 95% confidence level.     

IRMS定量分析超轻水中氘同位素

超轻水氘同位素定量分析结果误差的主要来源是记忆效应和仪器的精确性等方面。为了探讨更准确快速的超轻水中氢同位素比值检测分析方法,采用疏水铂催化H2-H2O平衡法以及稳定同位素质谱仪来作为定量检测方法。分析标准水样、超轻水和蒸馏水样品的测试结果显示:多次分析标准水样,测量值均在推荐值的误差允许范围内;测试超轻水及蒸馏水相对标准偏差在1%以内(n≥5)。结果初步证明该分析方法减少了记忆效应和仪器精确性带来的误差,提高了超轻水检测的可靠性和稳定性。     

Aging of beryllium

A survey of studies devoted to the possibility of increasing the plasticity of technical-purity beryllium within the temperature region 400–600°C is given. It is shown that the heat treatment of beryllium at 600–800°C leads to the deposition of the superfluous phases from the supersaturated solution. This is accompanied by a substantial change in the properties of the metal, in particular, the plastic and strength characteristics, hardness, creep, and electric resistance. The results of metallographic, electron microscopic, electron diffraction, x-ray diffraction, and other investigations of the microstructure of beryllium in various states are cited. The mechanism of the aging of beryllium is described on the basis of the available data, and practical conclusions are drawn on the possibilities of increasing the plasticity of beryllium at high temperatures.Translated from Atomnaya Énergiya, Vol. 19, No. 2, pp. 144–153, August, 1965     

State of helium in irradiated beryllium

Experimental data are presented on the change of the pycnometric density and unit-cell volume of beryllium irradiated in an SM reactor to neutron fluence 14·10²² cm^–2. The behavior of the unit-cell volume as a function of the neutron fluence is similar to the data for other metals. This and data on the volume change in beryllium oxide, where a large amount of gas is also formed during irradiation, make it possible to evaluate critically the assertion that helium forms a solid substitution solution. It is proposed that helium is confined in small accumulations.     

Migration of helium in irradiated beryllium

Kurchatovskii Institute, Russian Scientific Center. Siberian Branch, Scientific Research and Design Institute for Power Technology. Translated from Atomnaya Énergiya, Vol. 73, No. 2, pp. 157-158, August 1992.     

Deuteron trapping in titanium

A tensimetric technique has been developed for measuring 15 keV D⁺ trapping in Ti metal. The formation of the TiD₂ phase in the surface and near-surface regions was monitored by decoupling the θ–2θ scan of an X-ray diffractometer as well as by scanning electron microscope studies. Micron-sized ‘reaction zones’ appear to serve as nucleation centers for the TiD₂ phase. Insight into the mechanism of chemical trapping is obtained by correlating the results from the three types of measurements used in the present work.