Evaluation of groundwater tritium content and mixing behavior of Tatapani geothermal systems,Chhattisgarh, India

Isotopic investigations were carried out on hot springs, groundwater and surface water to evaluate the mixing processes within the geothermal system. Physico-chemical parameter (EC, pH, Temp.) and tritium content of groundwater, hot springs and surface water were measured. The temperature of the hot springs were varied from 60 to 98.8 °C and EC from 674 to 728 μS/cm. The tritium content of groundwater varies from 1.5 to 5 TU whereas, geothermal water have slightly less tritium and their values ranges from 1.4 to 4.4 TU. Low tritium, higher EC and high temperature of a few hot springs indicate insignificant mixing whereas high tritium, lower EC and low temperature indicates significant mixing of thermal and non-thermal water. The degree of mixing for geothermal springs is estimated. It is found that the groundwater components present in the diluted thermal waters are about 25–80%. It is also observed that mixing process is prominent along the fault and in the area where groundwater exploitation is more. Extensive pumping of groundwater causes an increase in the rate of mixing of thermal and non-thermal water. The tritium content of groundwater, surface water and hot springs are indicating, it is of modern recharge.     

A semi-automatic combustion method for the simultaneous determination of3H and35S in doubly labelled organic materials by liquid scintillation counting

A sample preparation method developed for the simultaneous liquid scintillation assay of tritium and³⁵S in doubly labelled organic materials is described. The sample is burnt in a stream of oxygen and the radioactive isotope carriers formed are collected separately for individual counting.³⁵S content of the sample is measured as a dilute sulfuric acid solution, while the tritium is counted as water. The procedure is free of cross-contamination and memory effect, provides quantitative analytical recovery, and the final solutions ready for counting are obtained in twelve minutes.     

Method for rapid tritiated water extraction from environmental samples

We have developed a thermal vacuum desorption process to rapidly extract water from environmental samples for tritium analysis. Thermal vacuum desorption allows for extraction of the moisture from the sample within a few hours in a form and quantity suitable for liquid scintillation counting and allows detection of tritium at the levels of <2 Bq/l of milk, <0.5 Bq/g of vegetation, and <0.5 Bq/g of soil. We developed a prototype unit that can process batches of twenty or more samples within 24 hours. Early data shows that a high percentage of water is extracted reproducibly without enrichment or depletion of the tritium content. The quench coefficient of the extracted water is low allowing for accurate, direct liquid scintillation counting. In most samples, good comparison has been observed with results using freeze-dry lyophilization as the water extraction method     

Relative sensitivity of combined standard uncertainty to changes induced in uncertainty components

This work provides a straightforward and rigorous solution to the problem of evaluating and expressing relative changes in combined uncertainty resulting from relative changes in the uncertainty components. The acquired information is essential to optimize the measurement method, indicating the most significant components to work with. This approach works for any discrete relative change in the uncertainties of the inputs, whether positive or negative, and was developed for the cases of independent and correlated quantities. Examples of both cases are treated. The results agree with that provided by direct calculation and are consistent with the ideas in EA 4/16. We propose the use of the expression “sensitivity of combined standard uncertainty to changes in uncertainty components” as a uniform quantitative reference to the individual importance of the components that form the combined uncertainty. We also discuss the reason to avoid the use of the expression “contribution of an uncertainty component to the combined uncertainty.”     

Field deployable tritium analysis system for ground and surface water measurements

Researchers from the Savannah River Technology Center, the Center for Applied Isotope Studies (CAIS) and Sampling Systems have developed a prototype Field Deployable Tritium Analysis System (FDTAS) for near-real-time measurements of environmental levels of tritium in ground and surface water. The device consists of a modified liquid scintillation counter coupled to an automatic sampler which incorporates on-line water purification. The FDTAS has been field tested at several Savannah River Site locations and has produced results comparable to laboratory analyses for low concentrations of tritium. Figures of merit obtained in the field include an average tritium background count rate of 1.5 counts per minute (cpm), tritium detection efficiency of ≈25%, and a detection limit of <10 Bq/l for a 100 minute count.     

An uncertainty evaluation for multiple measurements by GUM

An approach for uncertainty evaluation is proposed to determine the overall uncertainty by combining the uncertainties of the individual results from multiple measurements. It is accomplished by the separate combinations of the individual random and systematic components of the uncertainties of the individual results. The approach is useful when the individual results are not statistically different. It is recognized that, owing to the correlation, the uncertainty resulting from systematic effects is not reduced by multiple measurements. On the contrary, the uncertainty resulting from random effects can be reduced. Received: 3 May 2002 Accepted: 16 July 2002     

Determination of tritium activity and chemical forms in the exhaust gas from a large fusion test device

A water bubbler system that can distinguish chemical forms of tritium was proposed for long-term tritium monitoring of the exhaust gas of a large fusion test device. The characteristics and performance of the water bubbler system were evaluated under operational conditions and confirmed to be suitable for tritium monitoring. For the tritium measurements, the water bubbler system determined the tritium activity and distinguished the chemical forms of tritium. The tritium activity and chemical forms in the exhaust gas provided helpful information to understand the tritium behavior in the large fusion test device.     

Carbon sorbents for immobilization of tritium-containing waste oils

Emission of tritium from the pump oil-carbon sorbent-cement compositions (where the carbon sorbent is thermally expanded graphite or charcoal fabricated by thermal or radiation evaporation of a cellulose material) was studied. The compositions are characterized by a high hold-up ability with respect to oil components, when the matrix is contacted with water. The apparent diffusion coefficients of tritium are equal to 10⁻¹⁵–10⁻¹⁶ m² s⁻¹. The compositions are found to be resistant to radiation and can be recommended for solidification of radioactive waste oils.     

A fundamental study on testing candidate tritium breeders for fusion reactiors

An apparatus was designed and constructed for investigation of the tritium release rate from neutron-irradiated materials for fusion reactors. The design principles, as well as safe handling of tritium and complete trapping of tritium components released, are described and the tritium release rates obtained with this apparatus are discussed for sintered lithium fluoride pellets.     

Concentrations of Tritium in Water Vapor and Precipitation on Mt. Hakkoda

A large reprocessing plant of spent nuclear fuel is now under construction in Rokkasho-village, Aomori Pref. Japan. We carried out the survey of tritium concentration in water vapor and precipitation on the top of Mt. Hakkoda, to grasp the behavior of tritium in the environment of Aomori Pref. The tritium concentration in water vapor and precipitation tended to increase from spring through summer. Deuterium concentration in water vapor is lower than precipitation and the effect of the isotope separation by evaporation was observed. The tritium concentration in water vapor, however, is a little bit higher than precipitation. The tritium concentration in water vapor showed the similar change on the top of Mt. Hakkoda and also the wide region covering Rokkasho-village from Aomori-City. Also, on the top of Mt. Hakkoda the correlation was observed between the tritium concentration in water vapor and ozone concentration.     

Tritium monitoring with a scintillation chamber

A tritium monitor based on plastic scintillation sheets is described. The sensitive volume of the scintillation chamber is 0.95 l. The chamber with coincidence electronics has a discrimination capability and permits to detect tritium in the presence of other radionuclides and external gamma-radiation. The monitor characteristics obtained with tritiated air are presented. The monitor sensitivity for tritium in air is 5.6 cpm for each kBq·m⁻³. The monitoring of tritium in air and water is possible using the instrument described.     

Tritium in a Pine Forest Ecosystem: Relation between Fresh Pine Needles, Organic Materials on a Forest Floor and Atmosphere

Tritium concentrations were analyzed in organic and water fractions of fresh pine needles, dead and degraded pine needles accumulating on a pine forest floor to examine tritium cycle in a forest ecosystem. Tritium concentration was higher in the organic fraction of dead and degraded pine needles compared to others, suggesting two tritium sources. Rain is responsible for water fractions in the samples, while atmospheric hydrogen and methane are speculated to be responsible for high tritium level in the organic fraction of dead and degraded pine needles.     

Mechanism of HTO formation in gaseous tritium mixtures

The mechanisms for the conversion of molecular tritium gas to tritiated water are examined for tritium mixtures with (1) oxygen and nitrogen, (2) oxygen and argon, and (3) water and helium, for which previous experimental data exist. By analyzing results of these experiments in light of the radiation chemistry involved in a mixture of tritium and other gases, an understanding of the conversion mechanisms is reached. The formation of H and/or OH free radicals as intermediate species is of particular significance in the formation of HTO in that these radicals initiate a number of reactions which lead to the formation of water. These reactions are analyzed in terms of steady-state kinetics to obtain predictive models which can be judged against the experimental observations. For the three experimentally observed mixtures, model agreement is found to be within a factor of 2–3.     

Determination of tritium in natural waters

A study of the tritium content of precipitation and of river water samples, collected during a seasonal maximum of tritium concentration in 1976 is given. The measurements were made for precipitation in Belgrade from April to December 1976, and for river water from the Sava (in Belgrade), the Tisa at 137 km, and the Danube at 1425 km, 1174 km, 861 km from the confluence. The maximum monthly value of the tritium content of precipitation is 135 TU, and the Danube at 1425 km has a maximum of 196 TU (627 pCi/l). In general, there is no correlation between the amount of precipitation and river water with tritium content.     

A mathematical model of measurement uncertainty of single substrate enzyme assays

Clinical laboratory tests provide critical information at every stage of the medical decision‐making process, and measurement of the activity levels of enzymes such as alkaline phosphatase, lactate dehydrogenase, etc. provide information regarding various body functions such as the liver and gastrointestinal tract. The uncertainty associated with these enzyme measurement processes describes the quality of the measurement process, and therefore methods to improve the quality of the measurement process require minimizing the measurement uncertainty of the enzyme assay. In this study, we develop a mathematical model of the lactate dehydrogenase measurement process, with uncertainty introduced into its parameters that represent the sources of variation in the different components and stages of the measurement process. The Monte Carlo method is then utilized to estimate the uncertainty associated with the model, and therefore the measurement process. An empirical function used to generate estimates of uncertainty for patient samples with unknown activity levels is constructed using the model. The model is then used to quantify the contributions of the individual sources of uncertainty to the net measurement uncertainty and also quantify the effect of uncertainty within the calibration process on the distribution of the measurement result. Copyright © 2014 John Wiley & Sons, Ltd.     

Tritium/Protium Fractionation Near and Inside DNA

The fractionation factor of tritium between water and DNA as well as between water and the first hydration shell of DNA is determined. For this purpose the sublimation kinetics of water from DNA dissolved in water were determined at -200 °C and tritium was measured in the remaining water free DNA. The last sublimating water fractions showed a tritium level of about 1.4, the residual water free DNA about 1.9 units above the bulk water. The tritium accumulation inside and near DNA is attributed to the thermodynamic triton-proton exchange isotope effect existing between the strong hydrogen bridges of water and weaker hydrogen bridges as well as inside DNA as between the first hydration shell and DNA.     

Tritium in surface waters, tap water and in precipitation in Poland during the 1994–1999 period

Concentrations of tritium in environmental waters (precipitation, rivers, lakes, tap water) have been determined using electrolytic enrichment and liquid scintillation counting. In waters of big rivers (the Vistula and the Odra rivers), lakes and tap water the annual average concentrations were similar to each other being from 1.4 to 1.9 Bq·dm^-3. These concentrations were similar to those in the precipitation in which they ranged from 1.7 to 2.2 Bq·dm^-3. The lowest tritium concentrations were found in waters of the Seashore Region rivers (average for 1994–1999 was 1.1 Bq·dm^-3). The tritium concentrations in surface waters and in precipitation are still higher than that of natural level. The data obtained show that tritium concentration in the water of rivers might depend on the size of drainage area. The observed seasonal variations of tritium concentration in the precipitation collected in Warsaw and at the Mount Sniezka indicate the stratospheric source of tritium. It was found that about 30% of tritium deposited with precipitation is removed to the Baltic Sea with river waters.     

Distribution of tritium between water and exchangeable hydrogen bridges of biomolecules

The fractionation factor of tritium between water and biomoleculeswhich are structured by hydrogen bridges, is found to be around 2. In additionto an intramolecular accumulation, an extra-molecular one is found to be about1.4 in the hydration sheets. During growth of plants (maize), the growth incrementof tritium in non-exchangeable organically bound tritium (OBT) is about 2.4times (140% larger than) the growth increment of hydrogen. The intrinsic growthrate of tritium is about 20 percent larger than that of hydrogen. Tritiumbound in water overtakes its kinetic delay in photosynthetic or metabolicreactions according to the larger mass by the fast established thermodynamicisotope effect of proton-triton exchange.     

Distribution and movement of tritium in an ion exchanger-water system

The study of the behavior of hydrogen in ion exchange columns is of theoretical and practical interest. This problem can be solved by using tritium as radioactive hydrogen tracer. The present paper describes the first results obtained in an experimental study of the statics and dynamics of the distribution and movement of tritium in an ion exchanger-water system.The materials studied were Ku-2 cation exchange resin in the H- and Sr-forms, and AN-2F and AV-17 anion exchange resins in the Cl-form. The isotopic effects in the distribution of tritium have been estimated. It has been shown that tritium is concentrated to a greater extent in the water than in the resin. Study of the filtration of water labeled with tritium in ion exchange columns has established that, as a result of isotopic exchange sorption, the rate of movement of the water front labeled with tritium is less than the rate of flow of water. The effluent curves have been interpreted theoretically on the basis of the general theory of the dynamics of sorption, and values for the constants of the dynamics of sorption have been estimated.     

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.