• Nuclear Engineering and Technology
• /
• 제56권4호
• /
• pp.1538-1543
• /
• 2024

The importance of determining the radon exhalation rate from water surface is emphasized by the increased use of radon and its daughter products as tracers in large-scale circulation studies of the atmosphere. There were many methods to measure radon exhalation from water surface. With the development of radon exhalation rate measurement methods and instruments on the surface of the soil, the rock and building materials, so the radon exhalation rate from water surface can be more accurately measured by applying these improved methods and instruments. In this paper, a cuboid accumulation chamber surrounded by foam boards and a RAD7 were used to measure the radon exhalation rate on the water surface at three different positions by Yixin lake. Each measurement was performed 2 h. The radon exhalation rate from the water surface was about 6 × 10^-3 Bq m^-2s^-1. The thoron exhalation rate from the water surface also can be estimated, it is about 0.16 Bq m^-2s^-1. These results hint that the radon transmission from the lake bottom soil to water and then into the atmosphere.

• Nuclear Engineering and Technology
• /
• 제52권6호
• /
• pp.1289-1296
• /
• 2020

The estimation of radioactivity level is vital for population health risk assessment and geological point of view and can be evaluated as rate of exhalation and source concentration (²²⁶Ra, ²³²Th and ⁴⁰K). The present study deals with the soil samples for investigation of radionuclides content and exhalation rates of radon -thoron gas from different sites in northern Haryana, India. Absorbed dose and associated index estimated in the present study are the measures of environmental radioactivity to inhalation dose. Effective doses received by different tissues and organs by considering different occupancy and conditions are also measured. Exhalation rates of radon and thoron are measured with active scintillation monitors based on alpha spectroscopy namely scintillation radon (SRM) and thoron (STM) monitors respectively. Sample height was optimized before measurement of thoron exhalation rate using STM. Average values of radon and thoron exhalation are found 16.6 ± 0.7 mBqkg^-1h^-1 and 132.1 ± 2.6 mBqm^-2s^-1 respectively. Also, a simple approach was also adopted, to evaluate the thoron exhalation which accomplished a lot of challenges, the results are compared with the data obtained experimentally. The study is useful in the nationwide mapping of radon and thoron exhalation rates for understanding the environmental radioactivity status.

• Journal of the Korean Wood Science and Technology
• /
• 제46권6호
• /
• pp.735-747
• /
• 2018

Radon radiation exposures in home have been posed as a potential cancer hazard. This research aims to present the basic data of the indoor radon concentration level by examining the radon exhalation rates of wood species. Radon exhalation rates from five commonly used wood species in Korean wood building construction were measured with Continuous Radon Monitor (CRM), Model 1028 (Sun Nuclear Co., USA) using the Closed Chamber Method (CCM). The mass exhalation rate was observed to vary from $0.00089Bq{\cdot}kg^{-1}{\cdot}h^{-1}$ to $0.00181Bq{\cdot}kg^{-1}{\cdot}h^{-1}$, whereas the surface exhalation rate was observed to be $0.00677-0.01517Bq{\cdot}m^{-2}{\cdot}h^{-1}$. The radon exhalation rate of Quercus accutissima Carruth (white oak) which has the highest density showed the highest figure among the five wood species, on the other hand, the rest of four species showed similar results which were similar to the radon exhalation rates of wood in the U.S.A. and Canada. The average of the concentration measured by the CCM represented well up to the second half-life period (7.7 days). Because result of these small quantities seems to indicate that radon exhalation from the tested wood species has almost negligible impact, the main culprit of the high indoor radon concentration is clearly derived from the background of surrounding wood house. Therefore, as a safety precaution, infrastructures made of wood materials should be designed with the consideration of influx of radon and built accordingly. Furthermore, it is highly desirable that wood will be needed to use for furniture and interior finishing material in indoor environment.

• 한국환경보건학회지
• /
• 제47권5호
• /
• pp.425-431
• /
• 2021

Background: This study evaluated the radon contribution rate through an evaluation of the exhalation rate of radon from building materials. Objectives: This study compared and evaluated the computation of the radon contribution rate based on each different exhalation rate in a building. Methods: The six demonstration houses that are the subject of this study are wall structures or Rahmen structures, and include demonstration houses similar to general residential environments and non-finishing houses with some walls exposed. Results: The highest exhalation rate was found at 62.98 Bq/m² per day from the non-finishing floor, and the second highest exhalation rate was from stone materials at 58.76 Bq/m² per day. Based on this result, investigating the contribution rate of building materials derived from building materials among indoor radon concentrations, house three was the highest at 81.7%, and house one was confirmed to be 33.96%. Conclusions: It can be judged that the effect of exposed concrete and stone is high, and that it is possible to reduce radon emitted from indoor building structures by controlling the indoor materials.

• Journal of Radiation Protection and Research
• /
• 제43권1호
• /
• pp.29-38
• /
• 2018

Background: Radon contributing about 42% of annual average dose, mainly comes from soil. In this paper, standard measurement procedures for soil radon exhalation rate are suggested and their measurement uncertainties are analyzed. Materials and Methods: We used accumulation method for estimating surface exhalation rate. The closed-loop measurement system was made up with a RAD7 detector and a surface chamber. Radon activity concentrations in the system were observed as a function of time, with data collection of 5 and 15-minute and the measurement time of 4 hours. Linear and exponential fittings were used to obtain radon exhalation rates from observed data. Standard deviations of measurement uncertainties for two approaches were estimated using usual propagation rules. Results and Discussion: The exhalation rates (E) from linear approach, with 30 minutes measurement time were $44.8-48.6mBq{\cdot}m^{-2} {\cdot}s^{-1}$ or $2.14-2.32atom{\cdot}cm^{-2}{\cdot}s^{-1}$ with relative measurement uncertainty of about 10%. The contributions of fitting parameter A, volume (V) and surface (S) to the estimated measurement uncertainty of E were 59.8%, 30.1% and 10.1%, in average respectively. In exponential fitting, at 3-hour measurement we had E ranged of $51.6-69.2mBq{\cdot}m^{-2} {\cdot}s^{-1}$ or $2.46-3.30atom{\cdot}cm^{-2}{\cdot}s^{-1}$ with about 15% relative uncertainty. Fitting with 4-hour measurement resulted E about $51.3-68.2mBq{\cdot}m^{-2} {\cdot}s^{-1}$ or $2.45-3.25atom{\cdot}cm^{-2}{\cdot}s^{-1}$ with 10% relative uncertainty. The uncertainty contributions in exponential approach were 75.1%, 13.4%, 8.7%, and 2.9% for total decay constant k, fitting parameter B, V, and S, respectively. Conclusion: In obtaining exhalation rates, the linear approach is easy to apply, but by saturation feature of radon concentrations, the slope tends to decrease away from the expected slope for extended measurement time. For linear approach, measurement time of 1-hour or less was suggested. For exponential approach, the obtained exhalation rates showed similar values for any measurement time, but measurement time of 3-hour or more was suggested for about 10% relative uncertainty.

• Nuclear Engineering and Technology
• /
• 제55권6호
• /
• pp.2222-2229
• /
• 2023

Radon and radon progeny being natural radioactive pollutants, seriously affect the health of uranium miners. Radon reduction by ventilation is an essential means to improve the working environment. Firstly, the relational model is built between the radon exhalation rate of the loose body and the ventilation parameters in the stope with radon percolation-diffusion migration dynamics. Secondly, the model parameters of radon exhalation dynamics are uncertain and described by triangular membership functions. The objective functions of the left and right equations of the radon exhalation model are constructed according to different possibility levels, and their extreme value intervals are obtained by the immune particle swarm optimization algorithm (IPSO). The fuzzy target and fuzzy constraint models of radon exhalation are constructed, respectively. Lastly, the fuzzy aggregation function is reconstructed according to the importance of the fuzzy target and fuzzy constraint models. The optimal control decision with different possibility levels and importance can be obtained using the swarm intelligence algorithm. The case study indicates that the fuzzy aggregation function of radon exhalation has an upward trend with the increase of the cut set, and fuzzy optimization provides the optimal decision-making database of radon treatment and prevention under different decision-making criteria.

• Asian-Australasian Journal of Animal Sciences
• /
• 제7권1호
• /
• pp.97-101
• /
• 1994

Two experiments were conducted to study the effect of ambient temperature and nicarbazin on SCWL adult roosters. In Experiment 1, the effects of nicarbazin supplementation (125 ppm) on the water metabolism, blood acid-base balance; and rectal temperature of 16 birds in normal ($21^{\circ}C$) and hot ($35-36^{\circ}C$) temperature were investigated. In Experiment 2, the evaporative water loss and $CO_2$ exhalation from 8 birds were measured individually with an open-circuit gravimetric respiration apparatus in normal ($21^{\circ}C$) and hot ($33.5-34^{\circ}C$) temperature. The amount of water intake and evaporative water loss increased in birds under heat stress (HS). Nicarbazin exacerbated these effect in hot temperature. Also, nicarbazin decreased the blood $pCO_2$ and increased pH of HS birds. The rectal temperature of birds increased in hot temperature, and nicarbazin worsened this effect. The evaporative water loss, measured directly with respiration apparatus (Experiment 2), was increased in hot temperature. HS decreased the amount of $CO_2$ exhalation. Nicarbazin did not exert ant effect on either of these measurements, probably due to the limited duration (2 h) of the trial. The decrease in $CO_2$ exhalation by HS birds could be explained by reduced metabolic rate, which helps homeothermy of birds in hot temperature.

• 한국환경과학회지
• /
• 제24권9호
• /
• pp.1131-1138
• /
• 2015

Radon exhalation rates have been determined for samples of concrete, gypsum board, marble, and tile among building materials that are used in domestic construction environment. Radon emanation was measured using the closed chamber method based on CR-39 nuclear track detectors. The radon concentrations in apartments of 100 households in Seoul, Busan and Gyeonggi Provinces were measured to verify the prediction model of indoor radon concentration. The results obtained by the four samples showed the largest radon exhalation rate of $0.34314Bq/m^2{\cdot}h$ for sample concrete. The radon concentration contribution to indoor radon in the house due to exhalation from the concrete was $31.006{\pm}7.529Bq/m^3$. The difference between the prediction concentration and actual measured concentration was believed to be due to the uncertainty resulting from the model implementation.

• Journal of the Korean Wood Science and Technology
• /
• 제49권2호
• /
• pp.122-133
• /
• 2021

The radon gas from nature mainly considers a cause of radon problems, and it is closely affect human life cycle. Korean yellow residual soil, Hwangtoh, widely used as a building material, is considered to be one of major sources of indoor radon. However, there have, as yet, been no studies about radon from Hwangtoh in mass market brands. Here, we investigated the indoor radon concentrations and exhalation rates in four Hwangtohs from different brand names and regional features. The Closed Chamber Method (CCM) conducted by a Continuous Radon Monitor (CRM) has been used for the rates of radon exhalation. Based on equations of previous references, the indoor radon concentrations were deducted. As a result, the radon surface exhalation rates resulted in the 1.4208 to 3.0293 Bq·㎡·h-1 range. Significant differences were found among Hwangtohs according to production regions. Materials with higher radon concentration required a longer time to reach a quasi-steady state in a given environment, in other words, the number of half-life cycles increased from a set starting point. The experimentally identified Hwangtohs demonstrated its safety for construction purposes. There exists, so far, a possibility to exert influence radon emanation due to unidentified factors. Therefore, it is necessary to corroborate with more research by increasing the number of Hwangtohs, considering the other references reported high radon exhalation rates. In addition, it is highly recommended that the radon exhalation rates should be measured for all building materials for preventing human health before the material usage.

• 사상체질의학회지
• /
• 제28권1호
• /
• pp.40-50
• /
• 2016

Objectives We observed what effects both ratio of inhalation and exhalation(I/E) and posture have on heart rate variability(HRV) according to Sasang Constitution(SC).Methods HRV of 73 healthy participants who filled in self-questionnaires was recorded while they carried out 0.1Hz paced breathing(PB) with sitting, usual breathing(UB) with standing, and 0.1Hz PB with standing. PB was conducted to 4:6 or 6:4 of I/E and UB with sitting was executed before and after each breathing. Finally, HRV indices were analyzed of 60 participants(Soeum: 24, Soyang: 18, Taeeum: 18).Results & Conclusions In both self-questionnaires and HRV indices, there are not statistically significant between SC about the posture and I/E. SOEUM preferred 4:6 of I/E and showed lower mean RR and SDNN. SOYANG preferred 6:4 of I/E and showed higher mean RR and lower mean heart rate. TAEUM did not prefer I/E and showed the highest SDNN.