Measurement Of Radon In Water Research Articles

Utilization of novel bubbling device for continuous measurement of radon in water

Utilization of novel bubbling device for continuous measurement of radon in water

A new-designed system for continuous measurement of radon in water

On-line continuous monitoring of radon concentration in water is of great significance for its environmental application as a radioactive tracer, for example, as a potential precursor for earthquake forecast and volcanic eruption. To realize on-line continuous measurement on radon in complex water body, a compact measurement system mainly consisted of a simple degassing device and an electrostatic radon monitor is newly developed. The sensitivity of the measurement system is 73 ± 5 cph/(Bq/L), and the detection limit is 0.04 Bq/L with a 60-min cycle at 25 °C water temperature. Intercomparison measurements with RAD H2O were performed both in laboratory condition and in field, and consistent results within the error range were achieved. To test the developed measurement system, a continuous monitoring of radon concentration in water in the drainage tunnel of Mount Jinping was performed for 3 months. The arithmetic mean of radon concentration in water is 0.34 ± 0.09 Bq/L, varying in the range of 0.04–0.60 Bq/L during the period. Several rapid decreases of radon concentration in water were observed, which might be attributed to the increase of rainwater mixing in the drainage tunnel caused by heavy rainfall. The stability of long-term operation of the system enables it to be widely used in the field of radon in water as a tracer.

Radium interference during radon measurements in water: comparison of one- and two-phase liquid scintillation counting.

Assessment of radiation exposure to drinking, surface, and groundwater and of the associated health risks calls for accurate and precise 226Ra and 222Rn measurements. One method that fits the bill is liquid scintillation counting (LSC), which allows measurements in one-phase (homogenous) or two-phase samples. The aim of our study was to compare the measurement efficiency with both variations in Niška Banja spa water, known for its elevated 222Rn content to get a better insight into the stability and behaviour of the samples and 226Ra interference in samples spiked with 226Ra with 222Rn measurement. 226Ra interference was more evident in homogenous, one-phase and much lower in two-phase samples. However, one-phase samples offer more accurate indirect 226Ra measurements. Water-immiscible cocktails (in two-phase samples) have shown a limited capacity for receiving 222Rn generated by Ra decay from the aqueous to organic phase when 222Rn/226Ra equilibrium is reached. We have also learned that samples with naturally high 222Rn content should not be spiked with 226Ra activities higher than the ones found in native samples and that calibration of two-phase samples can be rather challenging if measurements span over longer time. Further research would require much lower 226Ra activities for spiking to provide more practical answers to questions arising from the demonstrated phenomena.

Radon transfer velocity at the water–air interface

Radon is a radionuclide that is one of the most commonly used natural tracers, for example in groundwater. The transport of radon at the water–air interface is investigated in this work at very low turbulence such as when water samples are taken for radon measurements. This very important process for the accurate measurement of radon in water has, surprisingly, not been investigated very often. By using a mathematical model and an experiment the radon transfer velocity coefficient (k) from the water–air interface was found to be (1.4±0.2)×10−6ms−1. This radon transfer velocity indicates that the escape is a relatively slow process which justifies the use of radon in water measurements.

Effects of tetrachloroethene on the measurement of radon in water with liquid scintillation counting method

This study investigated the effects of tetrachloroethene (PCE) on radon measurements that employed the liquid scintillation counting (LSC) method referring to 7500-Rn B of Standard Methods for the Examination of Water and Wastewater. Laboratory-produced radon-enriched water was used to compare the counting rates of the radon water with and without PCE addition, and groundwater samples from a site contaminated by chlorinated solvents were used to investigate the application of the laboratory experiments. The results showed that the major factor reducing counting efficiency was resulted from the interaction between PCE and a cocktail through the quench effect. The counting rate showed an exponentially decreasing trend when PCE addition was increased. The results indicated that a small addition of PCE reduced the counting rate considerably. An alternative energy channel 500–1000 to the optimal channel was suggested to attenuate the quench effect on radon measurement. The quench effect was also observed on samples from a site contaminated by chlorinated solvents. The concepts and procedures presented in this study are a reference for future research on the topic of chlorinated solvents or other quench chemicals involving in radon measurement.

Studying the response of CR-39 to radon in non-polar liquids above water by Monte Carlo simulation and measurement

The application of CR-39 has been extensive for measurement of radon and progeny in air of dwellings, but limited as regards to measurements of radon in water. In this paper, a new method is introduced for efficient measurement of radon in water by registering alpha particle tracks in a CR-39 detector placed in a non-polar medium such as cyclohexane, hexane and olive oil when each mixed with water, then separated and fixed above water, as a two-phase media. The method introduced here is however different from the widely used liquid - liquid extraction technique by liquid scintillation spectrometry since it is a passive detection method (CR-39) in a non-polar liquid with enhanced absorption of radon in the liquid, it has a capability for long sample counting to decrease the minimum detection limit (MDL), it does not require sophisticated low light counting systems, and it has the potential for simultaneous measurements of large number of samples for large-scale applications. It also has a low cost and is readily available. A new Monte Carlo calculation of energy-distance travelled by alphas from radon and progeny in a medium was also investigated. The sensitivity of CR-39 detector to radon and progeny in water was determined under two conditions; in a single-phase and two-phase media. In a single-phase medium, CR-39 is directly placed either in air, water, cyclohexane, hexane or olive oil. When CR-39 is placed directly in water, its sensitivity is (2.4 ± 0.1) × 10 −4 (track/cm 2 )/(Bq.d/m 3 ). In the two-phase media, CR-39 is placed either in cyclohexane, hexane or olive oil when each is fixed above water. The sensitivities in the two-phase media are significantly enhanced and are respectively (1.98 ± 0.10) × 10 −2 , (2.8 ± 0.15) × 10 −2 and (2.86 ± 0.15) × 10 −2 (track/cm 2 )/(Bq.d/m 3 ). The sensitivies are about 76, 82 and 110 times more than that of when CR-39 is directly placed in water. The new method is a novel alternative for radon measurements in water with a lower MDL than that of for example liquid scintillation method with a number of advantages. The results are presented and discussed. ► A new passive detection method is introduced for efficient radon measurements in water. ► Method is based on alpha tracks of radon/progeny in CR-39 in a non-polar medium above water. ► Sensitivity was enhanced (>80 times) relative to water by radon/progeny detected in hexane. ► Monte Carlo simulation was applied to determine CR-39 sensitivity to radon/progeny in water. ► The method has a number of advantages with MDL lower than alternative wide-scale methods.

γ-Ray spectrometry of radon in water and the role of radon to representatively sample aquifers

Measurement of radon in water by γ-ray spectrometry using a HPGe detector has been investigated to determine aquifer characteristics. The radon activity concentration is determined by taking the weighted average of the concentrations derived from γ-ray lines associated with 214Pb and 214Bi decay. The role of accurate radon data to representatively sample aquifers was also investigated by studying a semi-cased borehole. A simplified physical model describing the change of radon concentration with the pumping time, reproduces the data and predicts the time for representative sampling of the aquifer.

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%.

Advantages of low-background liquid scintillation alpha-spectrometry and pulse shape analysis in measuring222Rn, uranium and226Ra in groundwater samples

Liquid scintillation counting (LSC) and pulse shape analysis (PSA) was used in measuring radon and gross alpha- and beta-activities in groundwater. We used conventional LSC counters for the measurement of radon in water, but low-background LSC spectrometers for the gross activity measurements. The lower limit of detection (LLD) for radon in water is 0.6 Bq/l for a 60 min count with a conventional counter, but 0.1 or 0.2 Bq/l, with the two types of low-background LSC spectrometers equipped with a pulse shape analyser (PSA). The gross alpha and beta activity measurements are made using a simple sample preparation method, PSA of a low background LSC and spectrum analysis. The LLD recorded for gross alpha and beta with the two spectrometers are 0.02 and 0.03 Bq/l and 0.2 and 0.4 Bq/l, respectively, for a 180 minutes count and a 38 ml sample volume. The method also enable the calculation of the U and226Ra contents in water and indicates the presence of some other long-lived radionuclides (210Pb,228Ra or40K). The LLD for U recorded with both spectrometers is 0.02 Bq−1 and for226Ra 0.01 Bq·1−1. The LLDs attained by this LSC method are two orders of magnitude lower than the maximum permissible concentrations set for U and226Ra.

A method for continuous measurement of radon in water of springs for earthquake prediction

A method for the continuous measurement of radon in water, which uses a ionisation chamber, is described. The ionisation current (in the range of 10−11 A) is strictly proportional to the radon content in the water. It is supposed that there is a connection between the radon concentration in groundwater and springs and earthquakes. We therefore think that this connection might be used for earthquake prediction. A research project for that purpose had been started in Austria.