Development and validation of Ni–Ni electrolytic enrichment method for tritium determination in samples of underground waters of Jeju Island

A method of tritium electrolytic enrichment was developed, optimized and validated. The enrichment parameters were compared with different current and total current charge variation and tritium separation factor was from 8 to 36 with a current density variation. The detection limit of tritium measurement is about 0.5 TU using 1,000 mL sample and 600 min counting time. Several samples of groundwaters were processed in our and another laboratory with good agreement of results within 15% deviation. Developed and validated method of tritium determination was applied groundwaters in Jeju Island with a liquid scintillation counter (LSC) and electrolytic enrichment method using Ni–Ni electrodes. The tritium concentrations in fifty eight groundwaters in Jeju Island were ranged <0.5 TU-3.9 TU and averaged value was 2.12 TU.     

Tritium activity concentration along the Western shore of the Black Sea

The Black Sea tritium level was investigated in 33 places southward the Danube Delta covering about 360 km of the Black Sea Western Shore. Both surface (10 cm depth) and bottom (up to 20 m depth) water samples were collected. In the close vicinity of Danube Delta, the tritium activity concentration in the surface water was around 28 TU, which is almost the same as that of the Danube River waters, but it decreased to about 5 TU in the bottom water. This discrepancy slowly diminished wherein at about 120 km southward, the tritium content in both surface and bottom water reached almost the same constant value of 6.5 ± 2.3 TU. This value, about two and a half times smaller than that reported 17 years ago, remained almost unchanged for the last 240 km of shore up to the Turkish border.     

Proportional counting of tritium gas generated by polymer electrolyte membrane (PEM) electrolysis

The combination of an Ir/Pt PEM electrolyzer with a 1 L flow-through gas proportional counter was characterized for the quantification of tritium in water. The goal of the detection system is to quantify at concentrations below the Environmental Protection Agency (EPA) primary drinking water standard (740 Bq/L) with minimal expendables. The detector operating voltage, efficiency, background count rate of the passively shielded counter were measured in order to calculate the minimum detectable concentration of the detection system. The electrolyzer fractionation factor β _e value deduced from the measurement of gas phase activity concentrations generated from tritium aqueous standards was found in good agreement with literature values.     

Determination of gross alpha and beta activities in seawater and plankton from the Upper Gulf of Thailand

Gross alpha and beta activities were determined in seawater and plankton samples collected during the wet and dry seasons from 10 different sampling stations in Chonburi, the Upper Gulf of Thailand. Seawater samples were sampling, 1 km from the coastal and 2 m below the water surface, during July 2008 to July 2009. Seawater samples were prepared by coprecipitation technique. Plankton samples were prepared by filtration and dryness on filter paper. Both types of samples were counted using a low background alpha/beta proportional counter with multiple detector type (Berthold LB770). The results showed that gross alpha activities in seawater and plankton sample are in the range of 0.0591 ± 0.0209–0.3914 ± 0.0606 Bq/l and 0.0029 ± 0.0020–0.0294 ± 0.0043 Bq/l, respectively and also showed the lowest and highest activity level in the same sampling time. The activities of gross beta in seawater and plankton sample are in the range of 0.2803 ± 0.0177–1.3064 ± 0.0319 Bq/l and 0.0208 ± 0.0123–0.9151 ± 0.0262 Bq/l, respectively. Minimum detectable activity (MDA) had been observed in the measurements. The MDA of seawater sample were estimated to be 0.0832 Bq/l for alpha and 0.0577 Bq/l for beta at counting time of 100 and 200 min, respectively. In plankton samples, the MDA were estimated to be 0.0053 Bq/l for alpha and 0.0409 Bq/l for beta at the same counting time of 250 min.     

Radon measurement in carbonated water with the Lucas cell and charcoal adsorption methods

There have been developed several different methods for measuring radon concentration in water which are now widely used, such as: liquid scintillation counting, Lucas cell counting, gamma and alpha spectroscopy. However, as far as the radon measurements in carbonated water are concerned, there are some issues caused by the gas excess. The aim of our work was to develop a simple method for measuring radon concentration in carbonated water that can be used for in situ measurements. Nevertheless, we propose not one, but two methods for measuring radon concentration in carbonated water. Thus, the first one is based on Lucas scintillation cells, and can be used for on-site measurements, while the second one utilizes activated charcoal adsorption, and needs a setup laboratory for gamma spectrometry measurements. For the evaluation of the methods, we compared the results of the Lucas cell-Luk3C method and of the activated charcoal method, both for non-carbonated and carbonated water. The simplest method for radon concentration determination—Lucas cell method—was successfully applied to fourteen natural carbonated water samples from Borsec to Bilbor area. The radon concentrations obtained ranged from 5.6 ± 0.5 to 39.6 ± 4.0 Bq/L, with a mean of 15.9 ± 2.6 Bq/L, these values are lower than 100 Bq/L, the maximum value recommended by the World Health Organization.     

Variation of atmospheric tritium concentrations in three different chemical forms in Fukuoka, Japan

Atmospheric tritium concentrations of tritiated water vapor (HTO), tritiated hydrogen (HT) and tritiated hydrocarbons (primarily tritiated methane, CH₃T) have been measured in Fukuoka prefecture, Japan from 1984 to the present to establish a general database on the behavior of atmospheric tritium. HTO concentrations expressed in Bq/l-H₂O vary within a range of 1.19 to 2.45, giving an overall average value of 1.86±0.077. HTO concentrations expressed in-mBq/m³-air vary within a range of 7.8 to 46.1 and have a strong correlation with the atmospheric humidity, being high in the summer and low in winter. In the case of HT and CH₃T, no seasonal variations were observed with average monthly values of 23.1 to 61.0 mBq/m³-air and 8.3 to 23.9 mBq/m³-air, respectively. The present HTO concentrations are already close to the tritium level before nuclear testings. However, the present HT and CH₃T concentrations are still higher by a factor of about 140 and 30, respectively, than those before the testings. Specific activities are estimated to be 14.6–16.7 TU for HTO, 5.5·10⁵–1.0·10⁶ TU for HT and 3.2·10⁴–4·10⁴ TU for CH₃T. The apparent difference in the specific activities suggests a very slow transformation of these species in the atmosphere or a continuous supply of HT and CH₃T with high specific activity. Residence time for atmospheric HT was found to be 6.5 years over the period 1988–92 and 10 years for 1988–95. These times are longer than 4.8 years given by Mason and Östlund in the 1970s, and thus indicate a supply to the atmosphere of HT from various tritium sources.     

Radon concentration in air, hot spring water, and bottled mineral water in one hot spring area in Thailand

Hot springs are famous as spa resorts throughout the world. However, these areas usually have high natural radioactivity from radon gas. In this study radon concentrations in air, hot spring water, and bottled mineral water produced in a spa area of Suan Phueng district, Ratchaburi province, Thailand were measured. Radon concentrations in air were in the range of 10–17 and 11–147 Bq/m³ for outdoor and indoor, respectively. Committed effective dose from inhale of radon were assessed and found to be in the range of 0.004–0.025, 0.25–0.6, and 1.134 mSv/y for visitor, local people and resort workers, respectively. These doses were in the range of 1.2 mSv/y regulated by UNSCEAR for the general public. Radon in hot spring water ranged from 2–154 Bq/L. Radon in bottled mineral water produced from the hot spring water were in the range of 17–22 and 0.2–0.3 Bq/L for those that stored for 7 and 90 days, respectively, after production. Radon concentration levels were in the range of the US Environmental Protection Agency reference level for radon in air which is 148 Bq/m³ and alternative maximum concentration limit (AMCL) for raw water which is 150 Bq/L. However, when considering the USEPA (Maximum concentration limit), 11 Bq/L, for radon in drinking water, the mineral water should be stored for at least 8–9 days after bottling before selling to the market.     

Detection of tritium and alpha decaying radionuclides in L/ILW by measurements of helium isotopes

As decay products, helium isotopes can clearly indicate the presence of tritium and alpha decaying isotopes in a closed system. This study presents the helium and neon measurements and their interpretation of long-term headspace gas investigations in L/ILW waste drums from Paks Nuclear Power Plant and closed vaults of the Radioactive Waste Treatment and Disposal Facility, Püspökszilágy, Hungary. Development of special sampling methods and preparation lines as well as isotope-analytical measurements of the headspace gas samples were done in the Hertelendi Laboratory of Environmental Studies in the ATOMKI. In the gas samples helium isotopes as well as neon isotopes have been determined mass spectrometrically. While neon content can be of atmospheric origin only, helium can be produced either by alpha decay (⁴He) or decay of tritium (³He). ³H/⁴He and He/Ne ratios have been used to determine the different origin of the helium isotopes. Helium isotope ratios always represented ³He enrichment in the headspace gases produced by the decay of the tritium in the waste. Using the recent ³He concentration in headspace gas the total amount of ³H restored in L/ILW vaults was estimated. The investigated seven different vaults were closed between 1979 and 1995 when they had been full with L/ILW. The calculated tritium activities based on the He measurements showed good agreement with the documented isotope inventory of the vaults. Typical tritium activity concentrations were between 0.1 and 10 Bq/L gas in the drums and between 10 and 1000 Bq/L gas in the vaults. Additionally, one drum showed a higher He/Ne ratio compared to air, which clearly indicates ⁴He excess, thus the presence an alpha source in the waste.     

Evaluation of 222Rn and 226Ra concentrations in cement and limestone of Sheikh Buddin Hill,Pezu, Pakistan using different techniques

Lucky Cement Factory, Pezu is using limestone of Sheikh Buddin Hills as a raw material in cement. Workers of the factory have direct and general public have indirect exposure to radiological hazard due to natural radionuclides present in limestone. To address the radiological hazards, limestone, mixed (limestone+clay) and cement samples were evaluate for concentrations of ²²²Rn and ²²⁶Ra using CR-39, RAD7 and HPGe detectors. Maximum mean values of ²²²Rn using CR-39 and RAD7 detectors were found 1447 ± 198 and 1416 ± 74 Bq.m^?3 in cement samples and minimum were found in 536 ± 122 and 525 ± 45 Bq.m^?3 limestone samples, respectively. Maximum mean value of radon exhalation rate of 12.28 ± 1.68 Bq.m^?2 h^?1 in cement samples was found below the world average value of 57.6 Bq.m^?2 h^?1. Maximum mean values of ²²⁶Ra measured by CR-39 and HPGe detectors were found 24.25 ± 3.35 and 23.6 ± 0.70 Bq.kg^?1 in cement samples and minimum were found in 8.98 ± 2.02 and 9.19 ± 0.40 Bq.kg^?1 limestone samples, respectively. A positive correlations (R² = 0.9714) using CR-39 and RAD7 detectors and (R² = 0.9573) using CR-39 and HPGe detectors were obtained for the concentrations of ²²²Rn and ²²⁶Ra, respectively. Maximum mean value of annual effective dose of 347.78 ± 47.58 µSv.y^?1 in cement samples was found below the world average value of 1100 µSv.y^?1.     

Leaching dynamics of uranium in a contaminated soil site

Samples from a potentially contaminated industrial area were analyzed for uranium using neutron activation analysis (NAA). Uranium concentration values had a typical uncertainty of 2 % and a detection limit of 1 Bq/kg. To investigate the potential leaching dynamics into ground water two techniques were employed. The US EPA Toxicity Characterization Leaching Procedure (TCLP) and the Sequential Extraction Procedure (SEP) were used to determine the concentration of uranium in the leachates. TCLP and SEP showed that very little of the uranium leached into solution under different chemical conditions. Values of uranium leachates ranged from 0.05 to 3.5 Bq/L; a concentration much lower than the results found in the soil concentrations which ranged from 29 to 155 Bq/kg. NAA showed an 8 % uncertainty for leachates with a detection limit of 0.13 Bq/L. To mimic environmental conditions and acid rain, pH 4.3 water was used as the extraction solvent instead of the acetic acid routinely used in TCLP. Results confirmed that very low amounts of uranium leached with values ranging from 0.0002 to 0.0122 Bq/L. These values represent 0.01–1 % of the uranium in the soil samples. The distribution of uranium in soil according to particle size was also investigated to evaluate its potential movement and possible contamination of the water table. Particles below 250 μm in diameter showed a linear increase in uranium concentration whereas those with a larger diameter had constant uranium content.     

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     

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.     

Tissue free water tritium in pine needles around a nuclear power plant

The elevation of the concentration of tissue free water tritium (TFWT) in pine needles was discernible in trees growing around a nuclear power plant. The values varied from 2.6 Bq/l to 6.1 Bq/l with a mean value of 3.8 Bq/l. Analysis of pine needles collected at Fukui City as control samples was done. The values averaged 1.7 Bq/l and fell within 1.5 B/l-1.8 Bq/l which was obtained nation-wide survey of TFWT in pine needles in Japan. The present study also revealed that reactor tritium incorporated into pine needles decreased rapidly with a half time of 6 days and then tissue free water tritium has a short retention time.     

Determination of tritium enrichment parameters of a commercially available PEM electrolyzer: a comparison with conventional enrichment electrolysis

The combination of an Ir/Pt PEM electrolyzer with a 1 L flow-through gas proportional counter was characterized for the quantification of tritium in water. The goal of the detection system is to quantify at concentrations below the Environmental Protection Agency (EPA) primary drinking water standard (740 Bq/L) with minimal expendables. The detector operating voltage, efficiency, background count rate of the passively shielded counter were measured in order to calculate the minimum detectable concentration of the detection system. The electrolyzer fractionation factor β _e value deduced from the measurement of gas phase activity concentrations generated from tritium aqueous standards was found in good agreement with literature values.     

Levels of tritium concentration in the environmental samples around JAERI TOKAI

By the operation of research reactors, tritium-handling facilities, nuclear power plants, and a reprocessing facility around JAERI TOKAI, tritium is released into the environment in compliance with the regulatory standards.To investigate the levels of tritium concentration in environmental samples around JAERI, rain, air (vapor and hydrogen gas), and tissue-free water of pine needles were measured and analyzed from 1984 to 1993. Sampling locations were determined by taking into consideration wind direction, distance from nuclear facilities, and population distribution. The NAKA site (about 6 km west-northwest from the TOKAI site) was also selected as a reference point.Rain and tissue-free water of pine needles were sampled monthly. For air samples, sampling was carried out for two weeks by using the continuous tritium sampler. After the pretreatment of samples, tritium concentrations were measured by a low background liquid scintillation counter (detection limit is 0.8 Bq/l).Annual mean tritium concentrations in rain observed at six points for 10 years was 0.8 to 8.9 Bq/l, which decreased with distance from the nuclear facilities. Tritium concentrations in rain obtained at Chiba City were around 0.8 Bq/l (1987–1988) and those at the NAKA site were 0.8 to 3.8 Bq/l.Annual mean HTO concentrations in air at three points for 10 years were 9.2×10^–2 to 1.1 Bq/m³, although HT concentrations in air, ranging from 1.7×10^–2 to 5.8×10^–2 Bq/m³, were not influenced by the operation of the nuclear facilities.Annual mean tritium concentrations in tissue-free water of pine needles at four points for 10 years were 1.4 to 31 Bq/l. Those at the NAKA site ranging from 1.4 to 6.2 Bq/l were in good agreement with the reported value by Takashima of 0.78 to 3.0 Bq/l at twenty-one locations in Japan.Monthly mean HTO concentrations in air for 10 years showed a good correlation with absolute humidity, while other samples showed no seasonal variation.Higher level tritium concentrations in rain, in air (vapor), and in tissue-free water of pine needles at the TOKAI site were caused by the tritium released from the nuclear facilities.The committed effective dose equivalent to the member of general public, estimated using the maximum tritium concentration in air (1.1 Bq/m³), was 0.23 Sv, which was about 1/4000 of dose limit for general public.     

Radon (222Rn) in underground drinking water supplies of the Southern Greater Poland Region

Activity concentration of the ²²²Rn radionuclide was determined in drinking water samples from the Sothern Greater Poland region by liquid scintillation technique. The measured values ranged from 0.42 to 10.52 Bq/dm³ with the geometric mean value of 1.92 Bq/dm³. The calculated average annual effective doses from ingestion with water and inhalation of this radionuclide escaping from water were 1.15 and 11.8 μSv, respectively. Therefore, it should be underlined that, generally, it’s not the ingestion of natural radionuclides with water but inhalation of the radon escaping from water which is a substantial part of the radiological hazard due to the presence of the natural radionuclides from the uranium and thorium series in the drinking water.     

Spatial distribution and risk assessment of radioactivity and heavy metal levels of sediment,surface water and fish samples from Lake Van,Turkey

In this study, radioactivity levels of 228 lake water samples, 63 upper and depth sediment samples and 12 fish samples from Lake Van were investigated from 2005 to 2008 and the distribution patterns of the radionuclides were presented. Analysis included gross alpha–beta and total radium isotopes activities and uranium concentrations of the water, and gross alpha and gross beta activities and relevant ²³⁸U, ²³²Th and ⁴⁰K activity of the sediment and fish samples of the lake. Mean gross alpha, gross beta and radium isotopes activities of lake water were found 0.74 ± 0.46, 0.02 ± 0.01 and 0.06 ± 0.04 Bq/L, respectively. Mean gross alpha and beta activities in upper and depth sediments were found to be 41 ± 6 and 1,514 ± 74 Bq/kg; 77 ± 5 and 394 ± 24 Bq/kg at a 95 % confidence level, respectively. Mean activities of ²³⁸U, ²³²Th and ⁴⁰K activity concentrations in upper and depth sediments were determined to be 225 ± 22, 70 ± 7 and 486 ± 39 Bq/kg; 174 ± 4, 63 ± 3 and 263 ± 25 Bq/kg, respectively. The mean gross alpha and beta, ²³⁸U, ²³²Th and ⁴⁰K aktivities in fish samples were established as 47 ± 18, 470 ± 12, 0.57 ± 0.220, 0.022 ± 0.006, 319 ± 11 Bq/kg, respectively. The transfer factor from lake water to fish tissues, annual intake by humans consuming fish, and annual committed effective doses were estimated and evaluated.     

Study of radon in ground water and physicochemical parameters in Khartoum state

This study was conducted primarily to measure and map radon activity concentration in wells within water supply network of Khartoum State. Ground water samples were collected before and after autumn and analysed using low level γ-spectrometry equipped with HPGe-detector. Radon activity concentration was found in the range of 1.58–345.10 Bq/L with an average value of 59.20 ± 6.60 Bq/L. Upon comparing the radon concentration values obtained with EPA it was found they were far below the maximum contaminant level of EPA with the exception five samples. Physicochemical water parameters were measured and no correlation was noted between radon concentration and these parameters. The overall annual effective dose for adults due to radon ingestion is less than WHO recommended reference dose level for most except 14 samples.     

A simple correction method for isobaric interferences induced by lead during uranium isotope analysis using secondary ion mass spectrometry

The present study is to determine the activity concentration of radioactive nuclide in plant fertilizers used in agriculture in Iraqi Kurdistan region using high- purity germanium detector (HPGe) gamma spectrometer. The results showed that the range of activity concentrations for ²²⁶Ra, ²³²Th, ⁴⁰K and ¹³⁷Cs in chemicals and organic fertilizers are (0.1–134), (0.1–74), (1–12,000) and (0–1) Bq/kg respectively, based on the measured activities that were used to assess the radiological hazards. Radium equivalent activity in some samples exceeds the value (370 Bq/kg) which recommended by the OECD.     

Evaluation of radon concentration and heavy metals in drinking water and their health implications to the population of Quetta,Balochistan, Pakistan

ABSTRACT

The purpose of this study is to estimate the concentrations of radon and heavy metals in drinking water and assess their health implications to the population of Quetta, Pakistan. The concentration of radon and heavy metals was measured in drinking water collected from tube wells of different depths of the Quetta, Balochistan, Pakistan, using RAD7 detector and Atomic Absorption Spectrometer, respectively. The results show that the concentration of radon ranged from 3.56 ± 0.98 to 8.56 ± 1.32Bq/L with an average of 5.67 ± 1.34Bq/L. The average value of contribution of radon in water to indoor air was found 2.02 ± 0.47mBq/L. In addition to concentration of radon in drinking water, physiochemical parameters like pH and electrical conductivity (EC), and annual effective doses for different age groups were also estimated. Positive correlation of (R² = 0.8471) was observed between depth of well and concentration of radon, however no such relations were found among pH and EC with concentration of radon. Average values of annual effective doses due to intake of radon for age groups 0–1 years (infants), 2–16 years (Children) and ≥17 years (adults) were found (3.00 ± 0.71)×10^?2, (1.1 ± 0.26)×10^?2 and (1.45 ± 0.34)×10^?2 mSv/y, respectively. Average values of heavy metals concentrations were found 1.85 ± 0.64, 3.21 ± 0.75, 5.06 ± 1.19, and 2.47 ± 0.77 and 5.58 ± 1.23 µg/L for As, Cr, Ni, Cd and Pb, respectively. The values of radon concentration and heavy metals in drinking water were found below the USEPA permissible limits, Thus we conclude that, the investigated waters are safe.