Alpha Scintillation Cells Research Articles

Radon measurement of natural gas using alpha scintillation cells

Due to their sensitivity and ease of use, alpha-scintillation cells are being increasingly utilized for measurements of radon (222Rn) in natural gas. Laboratory studies showed an average increase of 7.3% in the measurement efficiency of alpha-scintillation cells when filled with less-dense natural gas rather than regular air. A theoretical calculation comparing the atomic weight and density of air to that of natural gas suggests a 6–7% increase in the detection efficiency when measuring radon in the cells. A correction is also applicable when the sampling location and measurement laboratory are at different elevations. These corrections to the measurement efficiency need to be considered in order to derive accurate concentrations of radon in natural gas.

Radon levels and doses in dwellings in two villages in Kosovo, affected by depleted uranium

The radon ((222)Rn) activity concentration in 15 dwellings in the Planej village and 10 dwellings in the Gorozhup village has been measured with the aim to complement the national radon survey and to compare the results of two different measurement techniques. The radon concentration has been measured in winter and spring using alpha scintillation cells and in winter, spring and summer by exposing solid-state nuclear track detectors. Both methods gave similar results. Radon concentrations in both villages were similar, ranging from 82 to 432 Bq m(-3); the value of 400 Bq m(-3) was exceeded only in two dwellings. The resulting annual effective doses ranged from 1.78 to 6.40 mSv, with the average values of 3.28 mSv in the Planej village and 3.87 mSv in the Gorozhup village.

EMANATION OF RADON FROM HOUSEHOLD GRANITE

Emanation of radon (222Rn) from granite used for countertops and mantels was measured with continuous and integrating radon monitors. Each of the 24 granite samples emitted a measurable amount of radon. Of the two analytical methods that utilized electret-based detectors, one measured the flux of radon from the granite surfaces, and the other one measured radon levels in a glass jar containing granite cores. Additional methods that were applied utilized alpha-scintillation cells and a continuous radon monitor. Measured radon flux from the granites ranged from 2 to 310 mBq m-2 s-1, with most granites emitting <20 mBq m-2 s-1. Emanation of radon from granites encapsulated in airtight containers produced equilibrium concentrations ranging from <0.01 to 11 Bq kg-1 when alpha-scintillation cells were used, and from <0.01 to 4.0 Bq kg-1 when the continuous radon monitor was used.

Comparison of various methods of estimating radon dose at underground workplaces in wineries

Levels of radon were surveyed in the air at underground workplaces of eight major Slovenian wineries. Geometric mean and geometric standard deviation values, respectively, obtained with different devices were 81 Bq m(-3) and 2.3 with alpha scintillation cells, 114 Bq m(-3) and 2.0 by exposing etched track detectors for 1-5 months, and 183 Bq m(-3) and 2.6 from 1-4-weeks continuous measurements. The equilibrium factor was 0.25-0.67, and the unattached fraction of radon short-lived decay products was in the range 0.09-0.20. Effective doses were calculated and compared based on radon data obtained with different techniques.

Performance of a commercial radon-in-water measurement kit

Methods currently approved for the measurement of radon ( 222Rn) in water in New York State are liquid scintillation counting and emanation into alpha-scintillation cells. A passive system using an electret ion chamber (EIC) was evaluated as an alternative for the measurement of radon in water. Over 130 water samples from a community water supply containing 32 Bq L −1 and 30 standards containing 686 Bq L −1 were measured using the EIC method over 1- to 4-day exposure times. For comparison, identical samples were measured using liquid scintillation counting. Results of duplicate samples were typically within 5% for liquid scintillation counting and within 10% for the EIC. With respect to accuracy, the EIC produced results that were consistently low by 11–15%.

Exposure to radon in the Gadime Cave, Kosovo

Air radon concentration was measured in summer and winter at 11 points along the tourist guided route in the Gadime Cave in Kosovo using alpha scintillation cells and etched track detectors. At two points in summer, values higher than 1700 Bq m −3 were observed; they otherwise were in the range 400–1000 Bq m −3. Values were lower in winter. The effective dose received by a person during a 90 min visit is 3.7 μSv in summer and 2.5 μSv in winter. For a tourist guide the annual effective dose is less than 3.5 mSv.

Seasonal variation of indoor air radon concentration in schools in Kosovo

Indoor air radon ( Rn 222 ) concentrations were measured in March, May, August and December in 15 rooms of five elementary and in six rooms of one high school in Sharr, Kosovo, using alpha scintillation cells. Only in one room did the value exceed 200 Bq m - 3 . Values decreased from December to August, and from basement to first floor.

Indoor air radon concentration in schools in Prizren, Kosovo

Indoor air radon ((222)Rn) concentrations were measured in spring and winter in 30 rooms of 9 elementary schools and 19 rooms of 6 high schools in Prizren, Kosovo, using alpha scintillation cells. Only in three rooms of elementary schools and four rooms of high schools did winter concentrations exceed 400 Bq m(-3).

Radon survey and exposure assessment in hospitals

In this study radon (222Rn) in indoor air was surveyed in 201 rooms of 26 major hospitals in Slovenia and annual effective doses for 1025 persons working in the rooms surveyed were estimated. Instantaneous radon concentrations were measured with alpha scintillation cells, long-term average concentrations with etched track detectors and electret detectors, and radon, its progeny and equilibrium factor were continuously recorded with portable devices. Effective doses were estimated by using ICRP Publication 65 methodology. Only in seven rooms did the average radon concentration, obtained by 1 month exposing etched track detectors, exceed the national limit of 400 Bq m-3; and these places will be mitigated; elsewhere it was lower. Annual effective doses for 966 persons (94.2%) were estimated as <1 mSv, but for 10 persons they were between 2.1 and 7.3 mSv. The results warn that in an environment with generally low radon levels, 'hot' points may be found, and therefore radon surveys should be carefully designed and performed in order not to miss them.

A simple and rapid method for analyzing radon in coastal and ground waters using a radon-in-air monitor

We have developed a simple and portable technique for measuring moderately high levels of 222Rn ( t 1/2 = 3.8 d) in natural waters such as coastal water, groundwater, and river water. The water sample is carefully collected in a glass bottle, and the sample bottle is connected to a radon-in-air monitor in a closed air-loop mode. By purging air through the sample, radon is emanated from the water until a chemical equilibration is obtained between the two phases. The radon in the air loop is determined using the radon-in-air monitor. Then, the radon in water is calculated by a radon-partitioning factor between water and air for a measured water temperature. This technique is especially convenient for determination of 222Rn in natural waters on field sites, since it eliminates the preparation of He gas, cold traps, and alpha-scintillation cells and counter, which are required for traditional radon emanation methods.

Indoor radon in Slovenia

The Slovenian Radon Programme started in 1990. Since then, radon and radon short-lived decay products have been surveyed in 730 kindergartens, 890 schools, 1000 randomly selected homes, 5 major spas, 26 major hospitals, 10 major municipal water supply plants, and 8 major wineries. Alpha scintillation cells, etched track detectors, electret-based detectors and various continuously measuring devices have been used. On the basis of estimated effective doses, decisions were made on appropriate mitigation. In total, 35 buildings have been appropriately modified. The programme is displayed and results reviewed chronologically and discussed.

Identification of sources of high radon levels in Slovenian schools.

The sources of radon were investigated in twenty selected schools with high room levels of radiation. A combination of radon measuring techniques was applied: etched track and electret detectors to obtain average indoor air radon concentration. devices to record radon concentration continuously and thus characterise its diurnal variation, and alpha scintillation cells to analyse air from potential sources of radon entry. In some cases, a single strong source was identified (e.g. sinks, sub-floor channels), while in others the poor quality of the basic concrete slab was responsible for high indoor radon concentrations. The combination of etched track and electret detectors and alpha scintillation cells was essential for locating these sources.

Do long-term average radon concentrations in schools and kindergartens differ from the average during working hours?

Radon concentrations in air in schools and kindergartens were measured by alpha scintillation cells, electret and etched track detectors, and a continuous device. Values obtained by different devices under different conditions are compared and their correlation discussed. The radon concentration averaged over working hours may differ substantially from the whole-day average, although Pearson's correlation coefficients between the two averages of 0.83 and 0.82 were obtained for schools and kindergartens, respectively.

Search for radon sources in buildings — kindergartens

In ten high radon level kindergartens, radon sources were sought by applying a combination of several radon measuring techniques: etched track detectors to obtain average indoor air radon concentration, continuous devices to record radon concentration and see its diurnal variation, and alpha scintillation cells to determine radon concentration in the air entering a room from cracks, holes and sinks in the floor and from under-floor channels. In three cases, a strong local radon source was identified while, in the others, the bad quality of the basic concrete slab was responsible for the high indoor radon concentration.

Systematic indoor radon and gamma-ray measurements in Slovenian schools.

During the winter months of 1992/93 and 1993/94, instantaneous indoor radon concentrations and gamma dose rates were measured in 890 schools in Slovenia attended in total by about 280,000 pupils. Under "closed conditions," the room to be surveyed was closed for more than 12 h prior to sampling, the air was sampled into alpha scintillation cells with a volume of 700 cm3, and alpha activity was measured. An arithmetic mean of 168 Bq m(-3) and a geometric mean of 82 Bq m(-3) were obtained. In 67% of schools, indoor radon concentrations were below 100 Bq m(-3), and in 8.7% (77 schools with about 16,000 pupils) they exceeded 400 Bq m(-3), which is the proposed Slovene action level. In the majority of cases, radon concentrations were high due to the geological characteristics of the ground. Approximately 70% of schools with high radon levels were found in the Karst region. Gamma dose rates were measured using a portable scintillation counter. An arithmetic mean of 102 nGy h(-1) and a geometric mean of 95 nGy h(-1) were obtained. No extraordinarily high values were recorded.

Radon and Thoron Emanation from Uranium-Glazed Tableware

Radon and thoron gas emanation from tableware with ceramic glazes containing elevated uranium levels was determined using alpha-scintillation cells. Though gamma spectroscopy noted significant uranium concentrations in the glazed, no radioactive gas emanation was observed, contradicting a previous report.

Systematic indoor radon and gamma measurements in kindergartens and play schools in Slovenia.

Systematic measurements of indoor radon concentrations and gamma dose rates were carried out in the 730 kindergartens and play schools in Slovenia that, together, care for 65,600 children. The main method for indoor radon measurement was direct sampling in alpha scintillation cells, but in cases with an increased instantaneous radon concentration, the additional methods of track-etch detectors and alpha spectroscopy were applied. In 528 kindergartens and play schools (72%), radon concentrations were below 100 Bq m-3, with a geometric mean of 58 Bq m-3. In 16 kindergartens and play schools (2.2%), radon concentrations exceeded 800 Bq m-3. In all cases, the main reason for a high indoor radon concentration was the geological structure of the soil. Gamma dose rates were measured with a portable scintillation counter, but in the Ljubljana region thermoluminescence dosimeters were also exposed. The results ranged from 30 to 295 nGy h-1, with a geometric mean of 88 nGy h-1.

Preliminary Indoor Radon Investigations in Lublin Region, Poland

Indoor air radon concentrations in all kindergartens and play schools in Lublin, Poland, were determined in grab samples by using alpha scintillation cells. In addition, some public buildings and homes in Lublin and several places in Eastern Poland were surveyed for radon. For kindergartens and play schools, the geometric mean was 23 Bq m-3 with a standard deviation of 1.4 Bq m-3, while in public buildings and homes, these values were 26 and 1.6 Bq m-3, respectively.

Indoor radon concentrations in kindergartens

Indoor radon concentrations in the kindergartens of Osijek were measured with alpha-scintillation cells, LR-115 nuclear track detectors, as well as a Radhome semiconductor detector and average values of 50.2, 43.7 and 47 Bq m −3 were obtained respectively. Under the worst conditions, the annual radon effective dose equivalent was 10 mSv per year. Using the bare and filtered LR-115 detectors, the average equilibrium factor was assessed as 0.36 indoors. Measurements of the gamma dose rate in the kindergartens did not show any significant correlation with radon concentrations.

National survey on indoor radon in Spain

A national survey on indoor radon levels in Spain has been carried out by measuring the radon concentration in 1555 randomly chosen houses. Measurements were performed during the winter season of 1988 with complementary measurements in the winter of 1989. Radon in air was determined using modified alpha-scintillation cells under specified conditions in the sampling collection and nuclear track detectors in selected houses. The distribution of indoor radon levels has been found to be approximately log-normal with a geometric mean of 41.1 Bq·m −3 and a standard deviation of 3.0. The highest value of the radon concentration found was 15 400 Bq·m −3 In about 4% of the houses, the radon concentration was found to be in excess of the recently recommended value of 400 Bq·m −3, suggested by the Commission of the European Communities (CEC). Elevated indoor levels were found to be more prevalent in the west and northwest than in the rest of the country. Also shown in this paper is an evaluation of the median effective dose equivalent to the individual in Spanish houses for different regions.