Natural radioactivity distribution in geological matrices around Kaiga environment

Summary The activity and absorbed dose rate of the naturally occurring radionuclides, viz. ²³⁸U, ²³² Th and ⁴⁰K were determined in soil and rock samples collected around Kaiga site. The mean activity levels (Kaiga soil) of naturally occurring ²³² Th are comparable with that in worldwide soil, while concentrations of ²³⁸U and ⁴⁰K are lower than those in worldwide soil. The absorbed dose rate in outdoor air ranged 20-58 nGy ^. h^-1 with a mean of 33.3 nGy ^. h^-1, which is below the world average of 60 nGy ^. h^-1. The total effective dose rate in outdoor air for soils ranged 25.6-74.4 mSv ^. y^-1 with a mean of 43.0 mSv ^. y^-1. The estimated dose rate at Kaiga is comparable with that estimated at Kakrapar and Rawatbhata and much less than that estimated at coastal sites of India.     

Nature of percolation phase transition in hydration water films around immersed bodies

The phenomenological vector model of water is used to clarify the nature of the percolation phase transition in hydration water films around the surface of immersed bodies, which is found in molecular dynamic calculations. The transition is explained by the emergence of ordering in the directions of projections of water dipole moments on the body surface at the lower critical temperature, i.e. by the formation of ferroelectric water film. The evaluation of this temperature is given, which is consistent with numerical calculations.     

Tritium activity levels in drinking water of Adana,Turkey

Tritium activity in potable drinking water samples from Adana city were measured using liquid scintillation counting after distillation procedure. The results exposed that the activity concentrations of the tritium measured in one-third of these samples were lower than minimum detectable activity which has a value of 2 Bq/L for counting time of 1,500 min. However, the maximum and mean value of the tritium activity was found to be 9.1 Bq/L (77.3 TU) and 7.0 Bq/l (59.4 TU), respectively. These values were substantially below the 100 Bq/L which is normative limit in Turkey for waters intended for human consumption. The highest values of annual effective dose received by infants, children and adults due to measured tritium activity were estimated as 0.041, 0.057 and 0.120 μSv/y, respectively.     

Tritium and carbon-14 concentrations around an incinerator for radioactive liquid scintillator waste

Activity measurements of 3H and 14C in several environmental samples around the incinerator for radioactive liquid scintillator waste at the Radioisotope Center, Kyushu University were carried out to estimate their levels. It was indicated that 3H and 14C concentrations in the atmosphere at 1 m from the outlet were about 0.2% of those estimated at the outlet, respectively. At 6 m away from the outlet, 3H concentration decreased to about one twentieth of that at 1 m and 14C concentration to background level. For soils and plants, 14C concentrations showed negligibly low values. The existence of these nuclides in particle form was not confirmed. It is considered that the result of the higher 3H concentrations as compared to 14C concentrations reflects not only the difference of the waste amounts of their nuclides, but also the discharge of 3H as moisture as well as water vapor.     

Tritium in Lebensmitteln

Zusammenfassung Zur Ermittlung des natürlichen Tritiumgehaltes von Lebensmitteln wurde eine Verbrennungsanlage entwickelt, in der aus Lebensmitteln beliebiger Zusammensetzung in einem Arbeitsvorgang etwa 100 ml Wasser gewonnen werden. Zur Messung der Tritiumaktivität dieses Verbrennungswassers im Flüssigkeitsszintillationsspektrometer wird das Wasser von störenden Verbrennungsprodukten durch Destillation gereinigt. Aufbau und Arbeitsweise der Verbrennungsanlage und des Wasserreinigungssystems werden beschrieben.Die Teilnahme von S. Mlinko an diesen Untersuchungen wurden durch ein Stipendium der Alexander von Humboldt-Stiftung ermöglicht, wofür wir hier unseren herzlichen Dank sagen wollen.Frl. I. Kuschel wird für die wertvolle Mitarbeit bei den Untersuchungen gedankt.     

Tritium in Lebensmitteln

To investigate the natural tritium content of foods a combustion apparatus was developed, in which nearly 100 ml of water are obtained in one operation from foods of any composition. To measure the tritium activity of this combustion water in the liquid scintillation spectrometer, the interfering combustion products are removed by distillation. The construction and operation of the combustion apparatus and of the water purification system are described.     

Tritium in Lebensmitteln

In order to test the method of tritium determination and to determine the tritium activity, foods of known origin were investigated. The accuracy of the method over a prolonged period of time is confirmed by the statistical evaluation of the background values and of the counting efficiency. An average value of 600–800 pCi of tritium in one litre of water was found in milk, potatoes and apples. Drinking water contained very different activities of tritium, depending on its origin as ground or surface water. Food samples from the environment of nuclear reactors were not different in their tritium content when compared to those of other origin.     

Isotope quantum effects in water around the freezing point

We have measured the difference in electronic structure factors between liquid H(2)O and D(2)O at temperatures of 268 and 273 K with high energy x-ray diffraction. These are compared to our previously published data measured from 279 to 318 K. We find that the total structural isotope effect increases by a factor of 3.5 over the entire range, as the temperature is decreased. Structural isochoric temperature differential and isothermal density differential functions have been used to compare these data to a thermodynamic model based upon a simple offset in the state function. The model works well in describing the magnitude of the structural differences above approximately 310 K, but fails at lower temperatures. The experimental results are discussed in light of several quantum molecular dynamics simulations and are in good qualitative agreement with recent temperature dependent, rotationally quantized rigid molecule simulations.     

Tritium measurement in the Western Caucasus

Measurement of tritium in water of rains, springs, wells, mud volcanoes and rivers, lakes of the Western Caucasus (Krasnodar region) has been carried out since 1997 for hydrogeology, engineering geology, ecology and seismology. Electrolytic cells with spiral electrodes and the big multiwire proportional chamber were used for low tritium concentration measurements on expeditions. With the new design of the cell the enrichment factor of 64.0 ± 1.5 % was obtained during the electrolytic process. Correlation of tritium concentration is observed in mud volcanoes and spring water with regional seismicity. The long-term tritium data are shown in natural waters in South Russia.     

氚核磁共振波谱在氚标记甾族化合物制备中的应用

本文介绍了十一种氚化甾族化合物的氚核磁共振谱。我们依照英国放化中心和英国萨里大学报道数据,(甾体骨架上的CH及CH_2各位置的谱线归属,应用了定位标记化合物作为对照)归属了其氚在化合物中标记的位置,根据其积分曲线定出了各位氚的相对百分含量。同时图谱中又提供了立体构型的信息,为氚化甾族化合物制备过程中,催化剂的选择,实验条件的控制及反应机理等研究提供了理论依据。     

Tritium in foods

The qualities of selected scintillation systems for the measurement of very low tritium content in water samples from foods were investigated in the liquid scintillation spectrometer. The influence of the parameters of the measuring method on the detection limit was defined by figures of merit. Optimum values were obtained with an emulsion system, which consists of PPO, bis-MSB, p-xylene and Triton N-101, and which takes up 40% water. 0.16 to 0.18 pCi/ml water are detectable with this system. Reference water, which is poor in tritium, was produced by combustion of propane.     

Tritium in foods

Zusammenfassung Es wurden die Eigenschaften ausgewählter Szintillationssysteme für die Messung sehr niedriger Tritiumgehalte in aus Lebensmitteln gewonnenen Wasserproben im Flüssigkeitsszintillationsspektrometer untersucht. Der Einfluß der Parameter der Meßmethode auf die Nachweisgrenze wurde über Wertziffern definiert. Optimale Werte wurden mit einem aus PPO, bis-MSB, p-Xylol und Triton N-101 bestehenden Emulsionssystem erhalten, das 40% Wasser aufnimmt. 0,16–0,18 pCi/ml Wasser sind mit diesem System noch nachweisbar. Tritium-armes Vergleichswasser wurde durch Verbrennung von Propan hergestellt.Die Teilnahme von S. Mlinko an diesen Untersuchungen wurde durch ein Stipendium der Alexander von Humboldt-Stiftung ermöglicht, wofür besonders gedankt wird. — Frl. I. Kuschel wird für die wertvolle Mitarbeit bei den Untersuchungen gedankt.     

Tritium separation from heavy water by electrolysis with solid polymer electrolyte

A tritium separation from heavy water by electrolysis using a solid polymer electrode layer was specified. The cathode was made of stainless steel or nickel. The electrolysis was performed for 1 hour at 5, 10, 20, and 30 °C. Using a palladium catalyst, generated hydrogen and oxygen gases were recombined, which was collected with a cold trap. The activities of the samples were measured by a liquid scintillation counter. The apparent tritium separation factors of the heavy and light water at 20 °C were 2 and 12, respectively.     

Tritium concentration in ocean

Surface seawater and water vapor about 10 m above the sea level were collected in the Pacific and Indian Oceans during the expedition of KH-96-5 to examine tritium concentrations in open sea. The tritium concentration in the water vapor was one order of magnitude higher than that in the surface seawater, attributed to downward movement of naturally occurring tritium from stratosphere to troposphere.     

Tritium concentrations of river water on northern and southern islands of Japan

Tritium concentrations were measured for river waters on two islands in Japan. Significant difference was observed on the distribution of tritium concentrations on both islands, the river water samples from the northern island had higher concentrations and the average was about twice compared to that from the southern island. Higher tritium concentration in precipitation and the larger area of the northern island would be responsible for higher tritium concentrations in river waters.     

Novel electrocatalysts for generating oxygen from alkaline water electrolysis

We have obtained spinel-type Co₃O₄ and La-doped Co₃O₄ in the form of thin film on Ni, using microwave-assisted synthesis, which dramatically exhibit very low overpotentials for the oxygen evolution reaction (OER). Investigations have shown that at the apparent current density of 100 mA cm⁻² in 1 mol dm⁻³ KOH at 25 °C, the new electrodes, Co₃O₄ (oxide loading = 3.4 ± 0.3 mg cm⁻²) and La-doped Co₃O₄ (oxide loading = 2.8 ± 0.4 mg cm⁻²), produce overpotentials, 235 ± 7 and 224 ± 8 mV, respectively. Such low overpotentials for the OER, to our knowledge, have not been found on any mixed oxide electrode material reported in literature till today. Small La addition improved the BET surface area and porosity of the oxide catalyst powder and reduced the charge transfer resistance for the OER on the electrode made of oxide powder.     

Molecular cobalt pentapyridine catalysts for generating hydrogen from water

A set of robust molecular cobalt catalysts for the generation of hydrogen from water is reported. The cobalt complex supported by the parent pentadentate polypyridyl ligand PY5Me(2) features high stability and activity and 100% Faradaic efficiency for the electrocatalytic production of hydrogen from neutral water, with a turnover number reaching 5.5 × 10(4) mol of H(2) per mole of catalyst with no loss in activity over 60 h. Control experiments establish that simple Co(II) salts, the free PY5Me(2) ligand, and an isostructural PY5Me(2) complex containing redox-inactive Zn(II) are all ineffective for this reaction. Further experiments demonstrate that the overpotential for H(2) evolution can be tuned by systematic substitutions on the ancillary PY5Me(2) scaffold, presaging opportunities to further optimize this first-generation platform by molecular design.