Activities of Pu radionuclides and 241Am in soil samples from an alpine pasture in Romania

Activity concentrations of Pu radioisotopes and ²⁴¹Am were determined in the organic and mineral layers of four soil sections collected in 1996, providing for the first time information on the levels of these radionuclides in soil samples from Romania. The investigated site was an alpine pasture located in the Charpathian Mountains, in an area found as one of the most affected in Romania after the Chernobyl accident. In the examined soil sections radioactive inventories were estimated to be 500 Bq/m² for ²⁴¹Pu, 115 Bq/m² for ^239+240Pu, 8 Bq/m² for ²³⁸Pu and 50 Bq/m² for ²⁴¹Am. On the basis of activity ratios in the soil profile, the source of the radioactive release is discussed.     

On variations of volumetric activity of 90Sr and 137Cs in the Baltic Sea coastal waters near the shore of Lithuania in 2005–2009

The article presents the measurement results of the volumetric activity (VA) of artificial radionuclides ⁹⁰Sr and ¹³⁷Cs in the coastal waters of the Baltic Sea near the Curonian Peninsula in 2005–2009. The annual average values for this period of time were 12 Bq/m³ (⁹⁰Sr) and 40 Bq/m³ (¹³⁷Cs). Considerable variations in the VA of the radionuclide in individual measurements compared to the average results were observed. The extreme values were 6 and 16 Bq/m³ for ⁹⁰Sr and for ¹³⁷Cs—27 and 75 Bq/m³. It is proposed to allow such variations under the influence of a variety of external factors such as hydro meteorological situations, inflowing rivers and bays, storm activity and etc. Besides, a possibility of penetration of radionuclides into the sea waters from the additional radioactive sources is not excluded.     

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.     

Pu isotopes and137Cs in the surrounding areas of the former Soviet Union's Semipalatinsk nuclear test site

Field missions were sent to Semipalatinsk City and several settlements near the former Semipalatinsk nuclear test site to investigate the current radioactive contamination levels of the land coming from long-lived radionuclides. The soil was sampled at about 20 sites, including some settlements such as Mostik, Dolon and Chagan, forest and pasture areas, along the roads from Semipalatinsk City to Kurchatov City and to Korosteli settlement in the direction of the Altai District. The radioactivities of¹³⁷Cs,²³⁸Pu and^239,240Pu as well as²⁴⁰Pu/²³⁹Pu atomic ratios in the soil were determined by non-destructive γ-ray spectrometry and radiochemical separation followed by α-ray spectrometry and/or ICP-MS, respectively. The results showed a distinction of¹³⁷Cs and^239,240Pu inventories in soil depending on the site where we visited. While the overall¹³⁷Cs levels were as same as or slightly lower than the domestic global fallout level (3·10³–7·10³ Bq/m²),^239,240Pu levels at some sites were several to a few ten times higher than the domestic level (40–120 Bq/m²). The atomic ratios of²⁴⁰Pu/²³⁹Pu in the soil were in the range of 0.024–0.125, which were significantly lower than the value of 0.18 commonly accepted for global fallout Pu.     

An unusual case of indoor air radon contamination: An unusual method for effective mitigation

In the course of routine surveillance for indoor radon in Austria, concentrations above 10,000 Bq/m³ were found in a house in the province of Carinthia, Austria. Multiple 3-day-measurements in all the rooms of the house were carried out for the next 21 months. All rooms of the house had elevated radon concentrations but radon levels decreased systematically from east to west within the house. Moreover, radon concentrations in one room of the building were found to be below 300 Bq/m³ in winter but above 12,000 Bq/m³ in summer. After installing a medium sized fan, operated only during the summer season, the semiannual summer radon levels dropped from approximately 8,000 Bq/m³ to 250 Bq/m³ at ground floor level. Note: The paper reflects the personal opinions of the authors.     

Outdoor 222Radon concentrations monitoring in relation with particulate matter levels and possible health effects

Air quality monitoring could potentially improve exposure estimates for use in epidemiological studies. We investigated air quality by monitoring concentrations of ²²²Rn near the ground and particulate matter (PM) with an aerodynamic diameter less than or equal to 10 μm (PM10) and 2.5 μm (PM2.5) for Bucharest-Magurele periurban area. Atmospheric radon concentrations have been continuously monitored near the ground at 1 m height as well as at 10 m height. This paper presents time-series of radon concentrations monitoring in air near the ground measured during 1 January 2011–1 January 2012 by use of solid state nuclear track detectors SSNTD CR-39, exposed for 10 days periods. The daily average atmospheric radon concentration near the ground registered at 1 m height was found to be in range of 40.25 ± 7.53 Bq/m³, which was comparable with the daily average radon concentration of 44.92 ± 9.94 Bq/m³ recorded for period 1 August 2011–20 December 2011 at 10 m height by AlphaGUARD Radon monitor. Also, was done a comparative analysis of spatio-temporal variations in time series of outdoor radon concentration and PM in two size fractions (PM10 and PM2.5) in Bucharest Magurele area for 2011 year. The predominant recorded component in PM10 was PM2.5. Observational results show that recorded yearly average PM2.5 and PM10 concentrations were 35.96 μg/m³ and 40.91 μg/m³, respectively. The average ratio of PM2.5/PM10 was 87.9 % at this sampling site. However, in densely populated Bucharest urban and suburban areas the mean daily EC limit values for PM10, PM2.5 and attached ²²²Rn are frequently exceeded leading to serious public concern during the last years. The ambient air pollution measurements like as PM10 and PM2.5 levels are used as a proxy for personal exposure levels. Have been investigated also meteorological effects on the temporal patterns of atmospheric radon and particle matter.     

Ground based radon (222Rn) observations in Bucharest, Romania and their application to geophysics

Atmospheric radon concentration was continuously monitored in Bucharest-Magurele area both near the ground at 1 m height as well as at 10 m height. This paper presents the results of radon in air near the ground concentrations obtained during the 1 July 2010 to 1 February 2012 period by use of solid state nuclear track detectors SSNTD CR-39. The mean atmospheric radon concentration near the ground at 1 m height was found to be 360.91 ± 66.49 Bq/m³, which was about more than an order of magnitude lower than average radon concentration in range of 44.92 ± 9.94 Bq/m³ recorded for period 1 August 2011 to 20 December 2011 at 10 m height by AlphaGUARD Radon monitor. The meteorological effects on the variation of atmospheric radon concentration were discussed. The analysis of spatio-temporal variations in time series radon concentration in air near the ground is a useful tool to study geo-dynamical processes associated with seismic activity in active Vrancea zone in Romania. Taking off the variations induced by external variables, such as temperature, barometric pressure, rainfall, and other meteorological parameters, can be assessed radon anomalies due to possible tectonic movements and also can be surveyed radioactivity background in relation with nuclear emergencies.     

Exposure to underground radon in and around Kolkata Municipal Corporation area: an exhaustive study

Air radon survey was carried out at different underground locations at Kolkata using radon monitor. Average radon concentration for basements was found to be 22.70 ± 1.12 Bq/m³ with maximum 59.00 ± 7.18 Bq/m³ and minimum 8.50 ± 3.14 Bq/m³. Average level for sub-ways was 23.05 ± 2.59 Bq/m³ fluctuating between maximum 39.00 ± 1.24 Bq/m³ and minimum 13.50 ± 1.78 Bq/m³. In comparison, open air background at basement entrance was 19.44 ± 1.06 Bq/m³ and subway entrance was 18.58 ± 1.14 Bq/m³. Annual effective dose was calculated to assess probable health risk. Radon concentration level and annual effective dose were found well below safe levels recommended by International Agencies WHO and UNSCEAR.

     

Comparison of analytical methods used to determine <Superscript>235</Superscript>U, <Superscript>238</Superscript>U and <Superscript>210</Superscript>Pb from sediment samples by alpha,beta and gamma spectrometry

An intercomparison of the methodology (alpha, beta and gamma spectrometry) used for ²³⁸U, ²³⁵U and ²¹⁰Pb determination was carried out based on 38 sediment samples. The activity range of the samples varied from 10–700 Bq/kg for ²¹⁰Pb, 1–35 Bq/kg for ²³⁵U and 10–800 Bq/kg for ²³⁸U. Results obtained using the three methods were not statistically different at high activity levels, but agreement between the results decreased at lower sample activity levels. For ²¹⁰Pb, the smallest difference was found between alpha and gamma spectrometry. A good correlation between results from alpha and gamma spectrometry was observed over the whole activity range. In beta spectrometry, the results were slightly higher than those obtained by alpha or gamma spectrometry due to the impurity of ²²⁸Ra. In ²³⁸U analysis, good correspondence was observed between ²³⁸U determined by gamma and alpha spectrometry, particularly at higher ²³⁸U activity concentrations over 100 Bq/kg. In ²³⁵U analysis, attention needs to be paid to interference from ²²⁶Ra and its reduction.     

Radon survey in office room and effective dose estimation for staff

This study aims to: (1) Acquire the radon level in closed office rooms, providing radon exposure data for preliminary health risk assessment of office-working population. (2) Pre-analyze the relationship between radon concentration and indoor temperature, relative humidity. (3) Estimate seasonal, annual and total radon effective dose for ordinary office-working population. The results show that the 24-h or 8-h average radon concentrations in closed office rooms were about 32.0 Bq/m³ and 29.5 Bq/m³ during detection period, and the estimated effective doses in office rooms calculated by using 24-h and 8-h average radon concentrations were all far below that in residential environment.

     

Assessment of Summer Trends of Tropospheric Radon Isotopes in a Coastal Antarctic Station (Terra Nova Bay)

This work reports the first results of atmospheric radon measurements performed at the Italian Antarctic station located at Terra Nova Bay (74.69°S; 164.12°E) during summer campaigns of 1995-96, 1996-97 and 1997-98. Mean²²²Rn concentrations was 0.51 - 0.43 Bq m^m3 (median = 0.37 Bq m^m3), and ranged from 0.01 to 2.74 Bq m^m3 . On the average, these values were considered high, in comparison to results reported for other sites in Antarctica at equivalent latitudes. This could be explained by two causes: radon data for Terra Nova Bay were only for the summer period, when the ice-free area is at its maximum and thus the radon emission to the atmosphere; and by the larger ice-free area at Terra Nova Bay compared, for example, to measurements taken at another Antarctic site by the same technique (Ferraz station - 62°05'S; 058°23.5'W). The mean ²²²Rn to ²²⁰Rn activity ratio was 4.4 - 4.2, ranging between 0.1 and 45.3. The highest ratios indicated that some of observed surges of concentration of ²²²Rn could be attributed to not local sources. Lower radon concentrations were observed during katabatic wind events. The diurnal radon variation followed the general trend observed for continental areas located at lower latitudes.     

Development of an environmental atmospheric tritium monitoring system at the Toki site

n this study, the application for monitoring atmospheric tritium at the site of nuclear fusion facility is presented. Construction and examination of the tritium sampler and its arrangement at the site are mainly discussed. Atmospheric tritium concentrations at Toki site were determined in the sampling period from September 2000 to June 2001. Although the data for HTO were low because of their low specific activity (0.62 Bq/l), our average HT and CH₃T data were 9.1 and 3.3 mBq/m³, respectively, and systematically lower than the previously reported values at the same site, even if the considerable decay correction was carried out. Suitable monitoring points are discussed by considering the local meteorological features at the Toki site. Since the wind conditions at this site were governed by diurnal and nocturnal wind blowing to the contrary directions, it is concluded that the monitoring points should be placed at the site boundary of downwind direction of these winds. Considering that the expected levels of effluent tritium in the D-D experiment at the National Institute for Fusion Science are competitive with those in the environment, the detailed variations of the environmental tritium should be comprehended to detect minute amounts of the artificial tritium.     

A one-year study of the total air-borne14C effluents from two Swedish light-water reactors,one boiling water- and one pressurized water reactor

The results of a one-year study of the total air-borne¹⁴C effluents from two Swedish light-water reactors, one boiling water reactor (BWR) at Forsmark and one pressurized water reactor (PWR) at Ringhals, are presented. Air emitted from the stacks has been collected continuously over two-week periods and the¹⁴C content in the samples has been analysed using accelerator mass spectrometry (AMS). The¹⁴C activity concentration in the air issuing from the stack of the PWR varied between 2 and 1132 Bq/m³ with a mean value of 200 Bq/m³, while from the BWR the activity concentration varied between 4 and 146 Bq/m³, with a mean value of 95 Bq/m³. The corresponding¹⁴C release rate was 0.27 TBq/GW_el·year for the PWR and 0.48 TBq/GW_el·year for the BWR. During the same period of time, for comparison, the¹⁴C activity in continuously collected air from the stack of the PWR was also measured by liquid scintillation counting. In most cases the results of these measurements were in fair agreement with the corresponding AMS results.     

Calibration technique for a CR-39 detector for soil and water radon exhalation rate measurements

The calibration factor of 0.029 ± 0.0002 track cm^?2 per Bq d m^?3 for radon concentration measurements was determined using CR-39 and RAD7 detectors. The ²²²Rn concentration varied from 2,225 to 9,950 and 12 to 1,002 Bq m^?3 in soil and water, respectively. The highest radon exhalation and gamma dose rates were found in Acid and undifferentiated granitic rocks and Miscellaneous soils.     

Determination of a strong organic ligand dissolved in seawater: Thorium-complexing capacity of oceanic dissolved organic matter

Studies have been made of loose water tritium (LWT) distribution and behavior in the soil samples taken from the region within a radius of 2 km to the HWRR stack of CIAE. The analytical results show that the LWT concentrations in most soil samples of the region are in the range from 24.8 Bq/l (3.6 Bq/kg) to 116 Bq/l (16.0 Bq/kg) with an average value of 58.1±24.8 Bq/l (10.3±4.5 Bq/kg). There are two areas with a higher LWT content; the first one (4.61 · 10⁴ m²) is located near HWRR with ahighest LWT concentration of 287 Bq/l (55.8 Bq/kg) and the second one (3.27 ·10⁵ m²) is located near Lab. A with a highest LWT concentration of 2.35 · 10⁴ Bq/l (2.56 · 10³ Bq/kg). It is estimated that the LWT inventories deposited in soil of the two areas are about 1.52 · 10⁹ Bq and 1.42 · 10¹⁰ Bq, respectively. The analytical results have been evaluated by comparing the possible tritium intake of the human body with the annual limit of intake recommended by ICRP, it can be concluded that the operations of all the nuclear facilities releasing tritium in CIAE are safe without causing any notable tritium contamination.     

Determination of137Cs and134Cs in air samples collected near Belgrade /Yugoslavia/ following the Chernobyl accident

This paper presents the results of measurements of¹³⁷Cs and¹³⁴Cs content in air sampled during May 1986. Maximum concentrations:¹³⁷Cs 2.94±0.01 Bq m^–3 and¹³⁴Cs 1.38±0.01 Bq m^–3 were registered on May 3. Several other long lived radionuclides having -energies in the region 33 keV to 1365 keV were registered in the same samples two years later. The results of measurements of the total -activity in air for the same period are also presented.     

Variations in the <Superscript>7</Superscript>Be content in the ground layer of the atmosphere at middle latitudes

Data from measurements of the volume activity ⁷Be in the ground layer of the atmosphere, taken at the middle latitudes over a period of five and a half years, are discussed. The studies allowed us to determine that the course of changes in the volumetric activity (VA) of ⁷Be over time is a superposition and interaction of three kinds of fluctuations: short-period irregular, caused by meteorological factors; seasonal, associated with ⁷Be entering the troposphere from the stratosphere; and long-term, determined by changes in the Galaxy’s cosmic ray flux.     

Monitoring of tropospheric ozone in the ambient air with passive samplers

Two sampling campaigns in suburban places in the north zone of Santa Clara city, Cuba, have been carried out on a weekly base with the use of Radiello passive diffusion tubes in order to monitor the tropospheric ozone (O₃) levels in 2010. The first campaign was scheduled from February to April (cold season) and the second one in August and October (warm season), both of them at two sampling sites, i.e., Farm and School of Art Instructors. After aqueous extraction, the samples were analyzed by UV–VIS spectrophotometry.A seasonal trend was observed with the maximum O₃ concentrations in the cold season and the minimum levels in the warm season. Samples collected during the cold season showed the highest O₃ levels. Higher levels were reached at the Farm site with average values of about 58 ± 12 μg/m³, which exceeded the limit of the Cuban Standard 99:1999. In the warm season, the O₃ concentrations were similar for both sites, but lower than those observed in the cold season. The overall, seasonal average value was found to be 24 μg/m³. Despite the higher weekly average temperatures in August, the O₃ concentrations during this month showed the lowest values of the whole sampling period, which finding is in agreement with that reported by the Meteorological Institute of Cuba.Mathematical models, based on the Cochrane-Orcutt algorithm, were fitted to the acquired data set to explain the change in the tropospheric ozone concentrations under various meteorological conditions during the two campaigns. The correlation coefficients for both the cold and the warm seasons demonstrated a strong correlation, i.e., 0.779 and 0.951, respectively. The high correlation of wind speed in the model from the first sampling campaign explains the sharp decrease in O₃ concentrations at the SAI sampling site from the sixth week of sampling.     

Plutonium Isotopes in Ground-Level Air in Northern Germany Since 1990

The activity concentrations, ratios and seasonal fluctuations of plutonium isotopes in ground-level air in Northern Germany are reported for the years 1990 to 1997. The ^239+240Pu activity concentrations (a) measured on quarterly samples lie in a range 0.4 nBq/m³<a<4 nBq/m³. The ²³⁸Pu activity concentrations are lesser by up to a factor of 0.1 (0.1 nBq/m³<a<0.8 nBq/m³). The total activity concentration shows a typical seasonal fluctuation in the time period under review. In a few quarterly samples the activity ratio of a(²³⁸Pu)/a(^239+240Pu) is significantly increased.