Radon Leakage Research Articles

Contribution of Lab Radon Flux Measurements for Evaluating Submarine Groundwater Discharge in Coastal Areas

Laboratory-scale experiments were conducted on Carboniferous Limestone gravels from the Mendip Hills area, England; sandstones from the Pirambóia and Botucatu formations, Paraná sedimentary basin, Brazil; samples of schist and quartzite from Caldas Novas Hydrothermal Complex, Brazil; and the minerals tantalite, cassiterite, and columbite from mining areas at Rio Grande do Norte State, Brazil, with the purpose of evaluating the release of 222Rn to the water phase. The specific surface area of the samples corresponded to 1.69–81.36 cm2g−1, which provided values of 0.001–1.68 dpm/g and 3.18 × 10−6 to 0.59 for the radon released and radon emanation coefficient, respectively. These results allowed us to calculate the radon flux with respect to the radon leakage, which corresponded to values of 0.00016–0.00158 Bq/m2/d for the denser materials and 0.018–0.43 Bq/m2/d for limestones and sandstones. They also permitted us to find an inverse, significant relationship between the radon generated by the minerals/rocks and the radon flux into the water phase, which was tested for sediments in coastal and inland Brazilian areas, demonstrating utility for evaluating the diffusive radon flux from the sediments, which is an important parameter to monitor submarine groundwater discharge (SGD) by means of radon as a natural tracer.

Radon leakage in LSC vials: Material-dependent analysis for utilization and reutilization

Liquid scintillation counting (LSC) is a method commonly used for natural occurring radionuclides measurements in water, in which radon concentration is measured after placing water samples in LSC vials that contain scintillation cocktails. Due to the low levels of activity that are involved in natural environments, it is required to characterize any radon loss during the measuring process in order to minimize errors and uncertainties. Hence, radon leakage in different types of vials (plastic and plastic lined with Teflon) is studied. This analysis reported that, after one and a half radon half-lifes, plastic and Teflon lined vials, compared with the values expected for no radon leakage, presented deviations in radon concentration over the 7% and 3%, respectively. Additionally, the diffusion of radon through the vials' wall is checked, as well as if it remains embedded in the polymeric matrix. This study confirmed that radon remains embedded in the polymeric matrix and can diffuse back to the vial, having the plastic vials a greater contribution. The possibility to re-utilize single-use vials is also studied from characterizing the presence of radon depending on the vial's material.

Quantification of the dependence of the emanation of radon from water on the pH and temperature of water

Uranium- and thorium-series isotopes are able to dissolve in hot spring waters and decay into radon, which could potentially cause health risk of the public. Besides, several environmental investigations can be carried out by measuring radon concentrations in hot spring waters. Accordingly, the measurement of radon in hot spring water is a significant issue.A practical method for measuring radon in hot spring water was developed by using a silicon semiconductor detector, RAD-7. The overall effect of detection efficiency and radon leakage of the measuring system were examined to calibrate the measured concentration of radon in hot spring waters. In addition, the effect of water temperature and pH on emanation of radon from standard 226Ra solutions as well as that of the measuring time on precision of the measurement were investigated. The correlation among temperature, pH and emanation of radon was then obtained. Further, the established method was applied to in-situ measurement to investigate the concentration of radon in hot spring waters from different geological areas in Taiwan.According to the percent error of the measurement, the measuring time for environmental samples was set as 50 min. The overall effect of radon leakage and detection efficiency of the measuring system was estimated to be 99.19 ± 7.47% with a standard rock source of 222Rn from NIST. Standard sources of 222Rn were prepared from 226Ra standard solutions with different pH values. The 226Ra standard solutions were sealed and stand for 38 days in a 250 mL vial specific for the RAD-7. After measured by the WAT250 mode of the RAD-7, the data were measured as (52.5 ± 8.9)%∼(83.6 ± 11.0)% of the prepared concentration of 222Rn (from 226Ra). The emanation rate of 222Rn from standard solution under pH 1.44–9.07 was (53.2 ± 6.9)% ∼(84.3 ± 11.1)% and decreased with pH to a minimum value at 7.00. Moreover, the effect of temperature increases with pH. High correlated trend curves (r2 = 0.9829–0.9999) for 222Rn emanation rate versus pH under different temperature were obtained. A smooth curved surface fitted by the MATLAB for emanation rate of 222Rn was accordingly derived. The 222Rn concentrations in waters of the Beitou Hot Spring (acid-digestion sulfate spring on sedimentary rock strata), Wulai Hot Spring (sodium bicarbonate spring on metamorphic rock strata), Choshuitan (sodium bicarbonate spring on mudstone strata) and Zhaori Hot Spring (acid-digestion sulfate spring on andesite strata) were measured with RAD-7 by WAT250 for 50 min and then calibrated by 222Rn emanation rate estimated above, which were 215 ± 37 (Bq/m3), 6797 ± 1073 (Bq/m3), 2124 ± 577 (Bq/m3) and 26644 ± 2768 (Bq/m3).

Determination of 226Ra in TENORM Sample Considering Radon Leakage Correction

Background: Phosphogypsum is material produced as a byproduct in fertilizer industry and is generally used for building materials. This material may contain enhanced radium-226 (226Ra) activity concentration compared to its natural concentration that may lead to indoor radon accumulation. Therefore, an accurate measurement method is proposed in this study to determine 226Ra activity concentration in phosphogypsum sample, considering the potential radon leakage from the sample container.Materials and Methods: The International Atomic Energy Agency (IAEA) phosphogypsum reference material was used as a sample in this study. High-purity germanium (HPGe) gamma spectrometry was used to measure the activity concentration of the 226Ra decay products, i.e., 214Bi and 214Pb. Marinelli beakers sealed with three different sealing methods were used as sample containers. Due to the potential leakage of radon from the Marinelli beaker (MB), correction to the activity concentration resulted in gamma spectrometry is needed. Therefore, the leaked fraction of radon escaped from the sample container was calculated and added to the gamma spectrometry measured values.Results and Discussion: Total activity concentration of 226Ra was determined by summing up the activity concentration from gamma spectrometry measurement and calculated concentration from radon leakage correction method. The results obtained from 214Bi peak were 723.4 ± 4.0 Bq· kg-1 in MB1 and 719.2 ± 3.5 Bq· kg-1 in MB2 that showed about 5% discrepancy compared to the certified activity. Besides, results obtained from 214Pb peak were 741.9 ± 3.6 Bq· kg-1 in MB1 and 740.1 ± 3.4 Bq· kg-1 in MB2 that showed about 2% difference compared to the certified activity measurement of 226Ra concentration activity.Conclusion: The results show that radon leakage correction was calculated with insignificant discrepancy to the certified values and provided improvement to the gamma spectrometry. Therefore, measuring 226Ra activity concentration in TENORM (technologically enhanced naturally occurring radioactive material) sample using radon leakage correction can be concluded as a convenient and accurate method that can be easily conducted with simple calculation.

Annual effective dose from radon-222 concentration levels in underground water in bungoma south sub - county, Kenya

This research measured the concentration levels of radon in groundwater and determined the ingestion and inhalation dose. The study used RAD7 detector with RAD7-H2O accessory from Durridge Company to determine the radon levels. Thirty water samples in granitic dominated regions were collected from various areas of Bungoma County: ten from boreholes (BH), ten from hand dug wells (WL) and ten from springs (SP). The water samples were collected in 250 ml bottles which were tightly covered with lid to avoid radon leakage. The highest value was 303±4.00 KBq/m3 recorded in Kanduyi well and the lowest was 126±11.4kBq/m3 from where most of the samples recorded a high radon concentration with a mean of 269±5.25 KBq/m3 in wells, 213±7.96 KBq/m3 in boreholes and 290±7.70 KBq/m3 in springs. The average ingestion dose was found to be 1.5±0.07mSv/yr, 1.9±0.09 mSv/yr and 2.1±0.1 mSv/yr. The average annual effective dose rate for the samples collected were 2±0.1 mSv/yr for boreholes, 2.6±0.13 mSv/yr for wells and 2.7±0.14 mSv/yr for springs. The samples reported an average value of AED higher than the world average of 1.15 mSv/yr but below the exception limit of recommended action level of 10 mSv/yr hence the radon concentration levels in underground water in the study area has minimal health implications to the population.

Determination of radon leakage from sample container for gamma spectrometry measurement of 226Ra

Gamma spectrometry is widely used for radionuclide activity measurement of environmental sample including 226Ra in soil because it is versatile, easy to implement, non-destructive, and relatively cheap compared to other methods. By gamma spectrometry, 226Ra can be determined directly using its energy peak of 186.2 keV or indirectly by its decay products which are in secular equilibrium with 226Ra, i.e. 214Bi and 214Pb. However, both methods have challenges where for direct measurement, interfering from 235U energy peak of 185.7 keV can add significant contribution to the 186.2 keV of 226Ra gamma peak while for indirect measurement using energy peaks of 214Bi and 214Pb, decay products of 222Rn gas, longer time (at least 21 days) for their equilibrium ingrowth is needed and radon tightness of sample container must be ensured. In some measurements, the equilibrium could not be reached due to radon leakage from sample container. Therefore, in this paper, the radon leakage fraction from three different sealing methods of Marinelli beaker used in soil activity measurement were studied using HPGe detector and radon accumulation chamber with RAD7. The three sealing methods were only lid without sealing (MB1), sealed with paraffin film (MB2), sealed with silicone glue and vacuumed plastic bag (MB3) and their leakage fractions were 53%, 30%, and negligible leakage, respectively. Significant radon leakage from MB1 and MB2 have caused underestimation of 226Ra activity concentration measured by indirect gamma spectrometry. The study result recommends using MB3 sealing method for gamma spectrometry measurement because it is simple and cheap and has negligible leakage, moreover, its vacuumed plastic bag facilitates visual inspection to possible radon leakage.

Methods of kernel parameter calculation for stabilization technology of radon concentration in a closed radon chamber

A radon chamber is a standard apparatus for experimental research of radon that can simulate ambient conditions such as atmosphere, ground surface and subsurface, and the dynamic stabilization technology of radon concentration in a radon chamber is the core technology of radon chamber research. In this paper, an attenuation method was proposed based on a radon leakage attenuation model for calculation of leak rate, a kernel parameter of the stabilization technology of radon concentration in a closed radon chamber, as well as a bench method based on a radon replenishment model for calculation of the effective generation rate at radon source, another kernel parameter of stabilization technology. In this study, the present methods were applied to parameter calculation in an HD-6-type small/medium-sized radon chamber, achieving an excellent application effect.

Control of radon emanation at determination of activity concentration index for building materials

Radon emanation is a well-known source of uncertainty at determination of activity concentration index for building materials and NORM. To reduce this uncertainty both radon emanation coefficient of the sample material and radon leakage from the measuring container should be considered. Two different methods (the rapid method and precise method, which requires to keep the sample sealed for at least three weeks), which are based on the use of only gamma-ray spectrometer, are proposed for testing radon emanation. Both methods also allow simultaneous determination of the specific activity of radium and an assessment of radon exhalation rate from the surface of the finished building products. In addition, the method for determination of radon leakage from the container is proposed. The reliability of the sealing methods of containers is compared and standard PET-flasks with a high radon-tightness are offered. The criteria to control radon leakage and radon emanation coefficient are given for three types of test samples: (a) building materials, (b) natural materials of mineral origin (sands, clays, rocks etc.), and (c) artificial materials, such as absorbents, filters, radioactive wastes. A simplified screening test to control activity concentration index for building materials without a need to keep the sample sealed before the measurement is proposed.

Radon leakage as a source of additional uncertainty in simultaneous determination of 226Ra and 228Ra by gamma spectrometry—Validation of analysis procedure

A series of validation experiments was carried out to assess robustness, repeatability, and trueness of an analysis procedure for simultaneous determination of 226Ra and 228Ra in water samples. The study revealed instabilities in the radon holding capacity of the sample matrix (epoxy resin). The discovered effect is a new additional component in the uncertainty budget which should be considered when 226Ra is measured via its progeny in similar sample matrices.

Determination of the radon emanation fraction from phosphogypsum using LSC

A simple method for the determination of the radon emanation fraction was studied using a liquid scintillation counter. The radon activity of the gaseous phase in a closed container was measured 1 day and 35 days after sealing and used to calculate the radon emanation fraction. Radon leakage from the container was investigated using a 226Ra radioactive standard solution (SRM4967, NIST) to plot a radon growth curve. The method was applied to materials that typically contain a high level of radium, such as phosphogypsum, phosphate fertilizer and a rock sample. The effect of temperature on the radon emanation fraction from the materials was investigated at 0, 10, 20, 30 and 40 °C. It was found that there is a linear correlation (R2 = 0.746 − 0.946) between temperature and the emanation fraction. Within the temperature range, the radon emanation fractions were 0.241–0.466 for phosphogypsum, 0.225–0.351 for phosphate fertilizer and 0.154–0.351 for the rock sample.

A modified Lucas cell for leakage measurement from encapsulated radium sources

A new method to determine the leakage rate from encapsulated radium sources is proposed. The method is based on the principle of enclosing the source to be tested in a hermetically sealed container and measuring the radon radioactivity growth in the container as a function of time. A cylindrical modified Lucas cell, designed and built in our laboratory, is used for measuring the radon which are done by ZnS(Ag) alpha scintillation counting and can be easily compared with existing standard for leak tests. Results obtained show the applicability of the method for leak testing for radon leakage from sealed radium sources.

Emanation of radon-222 from marine sediments

Abstract The behavior of radon in the sea-floor region provides a useful test of theories which describe mass transport in sediments. We have made measurements of Rn-222 and Ra-226 in near-bottom waters and near-surface sediments at the same location. The distribution of radon in sediments can be described by a simplified diagenetic equation when advection, adsorption, and bioturbation are ignored. Sediment measurements show a radon deficit relative to radium emanation. A reasonable balance is found between integrated radon deficit in sediment and radon surplus in the overlying water. In most cores radium increased with depth in the top 10 cm of sediment. This implies that bioturbation and other mixing processes do not homogenize the radium concentration in the zone of diffusive radon loss, and that radium is diffusing out of the sediments. Radon leakage is less than that predicted by previous authors. Radon leakage depends upon the physical distribution of radium in marine sediments. We present a model that predicts leakage of 30–40% for normal deep-sea sediments, in agreement with measured values. Radon surplus in near-bottom waters depends upon the radium distribution, radon leakage, and effective diffusion coefficients. These in turn depend on the properties of the sediment, such as composition, accumulation rate, and porosity. As we learn how these factors interact we may be able to infer sedimentary features from measurements of radon in overlying waters.

Radon leakage from radium sources

Radon leakage from radium sources

Radon leakage from sealed radium sources in medical use.

Medical Journal of AustraliaVolume 1, Issue 10 p. 496-498 Original Article RADON LEAKAGE FROM SEALED RADIUM SOURCES IN MEDICAL USE Roger J. Bayliss B.Sc., Roger J. Bayliss B.Sc. Department of Public Health, N.S.W.Search for more papers by this author Roger J. Bayliss B.Sc., Roger J. Bayliss B.Sc. Department of Public Health, N.S.W.Search for more papers by this author First published: 01 March 1967 https://doi.org/10.5694/j.1326-5377.1967.tb21411.xAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume1, Issue10March 1967Pages 496-498 RelatedInformation

Isotopic geochemistry of uranium and lead in the Swedish kolm and its associated shale

The uranium and lead concentration and isotopic composition in a variety of samples of kolm and associated black shale from the Peltura beds (Franconian stage) of the Upper Cambrian of Sweden have been determined by isotope dilution techniques. In addition Th 230, Ra 226, Pb 210 and radon leakage values have been determined on certain samples. All samples show discordant U-Pb isotopic ages. It appears that two processes have been at work; selective removal of Pb 206, resulting from the movement of an intermediate member of the U 238-Pb 206 series, and removal of bulk radiogenic lead. The absolute age of the formation is concluded to be greater than 500 million years with the most probable age near this lower limit. This is in good agreement with the latest results on the absolute geologic time scale. The stratigraphically well-dated kolm cannot, however, be considered a calibration point in the absolute time scale. It does show that uranium-lead dating on bituminous shales will lead to minimum ages for these formations.

A Method for Testing Radium Containers for Leakage Using the Well-Type Scintillation Counter

A new method for testing for leakage of radon from clinical radium containers has been developed. Preliminary tests show the method to be reproducible and highly sensitive. It is based on trapping the radon which escapes from faulty radium containers in a mixture of water and activated charcoal and subsequently measuring the radon in a well-type scintillation counter. Method: Mix 5 ml. of tap water with 0.37 gm. (1 level 1/4 teaspoonful) of activated charcoal in a test tube suitable for well-type scintillation counter use. Place the radium container to be tested in the test tube. Stopper test tube. Leave radium in place for twenty-four hours. Remove radium. Replace stopper. Wait twenty-four hours and count in a well-type scintillation counter. Theory: If it is assumed that radon leaks from a faulty radium container at a constant rate, the rate of leakage, Rn, is related to the count rate, C, by: where K (IJ-c/count per min.) is the counter calibration factor; t is the time the radium container was left in the test tube; T is the time interval between removal of radium and counting; A is the radon decay constant; and f is the fraction of radon lost when the radium is removed from the test tube. Experimental: To establish the values of the constants involved in the equation, preliminary tests were made on 5–0.5-mg. radium cells previously known to be leaking. The half-life of the radioactivity within the test tube was observed to be 3.9 ± 0.1 days, confirming that the radioisotope was radon in equilibrium with its decay products. Leakage through the stopper was less than 1 per cent per day. Additional tests showed that f was less than 1/50. Repetitive tests on the same radium containers showed that the method was reproducible to about ± 7 per cent. The counting sensitivity for a conventional well-type scintillation counter was found to be 1.2 × 106 counts per minute per µg. by comparison with radium standards. Under the conditions given above, and for a standard error of 50 per cent of net count rate with a one-minute sample count and a ten-minute background count, the minimum detectable leak was 2.5 × 10−8 mc for the twenty-four hours of the test. This corresponds to 1.4 × 10−7 mg. of completely de-emanated radium. Conclusions: The method appears to have the following advantages: 1. With proper planning of operations, a large number of radium containers can be tested easily. 2. Handling procedures are simple, so that exposure to the operator is minimal. 3. The method is quantitative. 4. The method is quite sensitive, ample to detect significant radon leakage from clinical sources. 5. Previous methods used for testing clinical radium containers have been based on the measurement of alpha particles from Ra A-B-C (effective half-life about twenty minutes), so that counting had to be done immediately. The measurement of radon, to the contrary, allows counting to be done several days after testing. This makes it possible to use a central counting facility for radiation safety survey work, since the radium can be tested in its normal storage place and only the test tubes transported to the counting facility.

Isotopic study of some Colorado Plateau ores

A number of selected uranium ore specimens from several localities have been analyzed for uranium and lead in both pitchblende and galena phases by isotope dilution techniques and the lead isotopic abundance determined. It is shown that the hypothesis of hydrothermal deposition of uranium accompanied by old radiogenic lead from the basement at one time about 60 m.y. ago does not satisfy the isotopic data. A new hypothesis is presented which requires local sources with high U/Th and U/Pb ratios, variable radon leakage, suitable ground water movement, and deposition at the site of H 2 S production at low temperature. This hypothesis can explain the age discordances and the lead isotope abundances in galena. It is possible from the isotopic data to have all deposition occurring within the last five million years but it does not preclude other periods of deposition such as in Laramide time. The isotopic ages are apparent ages only and bear no direct relation to the time of deposition. The isotopic ratios, however, provide information which may be used to restrict theories of origin.

URANIUM-LEAD METHOD OF AGE DETERMINATION

Many new isotopic age determinations by the uranium-lead method were made on most of the important North American localities from which primary uranium minerals were reported. With the aid of other published isotopic U-Pb age measurements, it was attempted to interpret the most probable age for each locality and to assign a reasonable uncertainty to that age. The recognition of differential lead loss, the relation of alteration to mineral type, the importance of radon leakage for young samples, and the potential analytical errors make it timely to conduct such a re-evaluation. Among the well established ages are: Spruce Pine district, North Carolina, 360 plus or minus 20 m.y.; Portland, Connecticut, 265 plus or minus 10 m.y.,; Front Range, Colorado, 59 plus or minus 5 m.y.; Black Hills, South Dakota, 1620 plus or minus 20 m.y.; southeast Manitoba, 2650 plus or minus 100 m.y.; Lake Athabasca, Saskatchewan, 1900 plus or minus 50 m.y.; and the Wilber-force area, 1050 plus or minus 20 m.y. Other probable ages are Bedford, New York, 350 m.y.; Colorado Plateau, 60 m.y.; Coeur d'Alene, 1200 m.y.; and Great Bear Lake, Northwest Territories, 1500 m.y. Although there may have been several regional metamorphic events in the Appalachian Provincemore » in the Precambrian, the post-Cambrian effects appear at only two periods centering on 260 and 360 m.y. The Grenville metamorphism appears limited to a narrow time interval about 1050 m.y. ago. The Front Range and Colorado Plateau uranium mineralization may have been one event occurring about 60 m.y. ago.« less

URANIUM-LEAD METHOD OF AGE DETERMINATION

A suite of samples of pitchblende, clausthalite, and galena from various mines in the Lake Athabasca uranium province was subjected to isotopic and chemical analyses as well as radon-leakage measurements in order to obtain apparent ages from the isotopic ratios Pb/sup 2-6//U/sup 238/, /pb/sup 206, Pb/ sup 210/pb/sup 206/ measurements were made to check equilibrium in the decay series. The apparent isotopic ages range from 220 to 1860 m.y. Aiteration effects which might explain these anomalies are considered. Uranium leaching and radon leakage are inadequate to explain these anomalies. The diverse ages can be calculated on the hypothesis of a single period of pitchblende deposition at 1.90 plus or minus 0.04 b.y. ago followed by two periods of exsolution of lead at about 1.2 and 0.15 b.y. This is consistent with the 207/206 ratio of the radiogenic lead in the clausthalite and galena which apparently formed at the times of recrystallization. However, the existing data do not preclude more than two periods of lead exsolution. An alternative hypothesis involving successive epochs of pitchblende deposition is more complex geologically and, without contemporaneous lead exsolution, cannot account for the observed isotopic relations. The recrystallization presumably requires only the elevation of the regionalmore » temperature to 150 to 300 deg C in the presence of water. The variable fractions of lead removed during the periods of recrystallization can be ascribed to variations in temperature and water content throughout the district. it is quite certain that (1) the initial uranium deposition occurred about 1.9 b.y. ago, (2) there have been at least two periods of lead exsolution, (3) one period of lead exsolution must have occurred subsequent to 0.22 b.y. ago; (4) another period of lead exsolution probably occurred about 1 ago. (5) alteration of subsurface pitchblende has been negligible during the last million years. These conclusions resulting from an intensive study of an important uranium province suggest some general principles which may be applied to other areas. If samples are chosen to avoid recent weathering effects and if the radon leakage is measured, the remaining anomalies in the isotopic ages are probably due to partial lead removal at some time or times during the geologic history of the mineral. In all cases the 207/206 age will be closest to the true age but will be minimal. The true age can be approximated if a large number of samples from a given locality are studied with their associated common leads. Uranium minerals that give accordant isotopic ages have a known age and indicate the absence of significant regional thermal metamorphism following formation.« less

ANOMALOUS URANIUM-LEAD AGES

The ages from the isotopic ratios Pb206U238, Pb207U2 and Pb207/Pb206 do not agree with each other for a large fraction of the minerals studied. Many of these anomalous ages cannot be explained by radon leakage or errors in lead isotopic composition, and one possible cause may be removal of Pb from U minerals during recrystallization. Analysis of age data for several specimens of pitchblende and Pb minerals from the Lake Athabasca U district indicates that the true age is 1900 plus or minus 40 million years and that there must have been more than one period of Pb removal. it is concluded that detailed study of the U and Pb isotopic content of a district can be used to evaluate the times of deposition and Pb removal. (D.L.C.)