Byung-Hwan Rho

Rapid determination of 99Tc in environmental samples by high resolution ICP-MS coupled with on-line flow injection system

High resolution inductively coupled plasma mass spectrometry coupled with an on-line flow injection system (FI-HR-ICP-MS) was applied to determine the ultra-trace level 99Tc in soil. The flow injection system (PrepLab™) was composed of two TEVA-SpecÒresins, reduced remarkably the sample amounts and the analysis time, compared to the conventional analytical methods. In the flow injection system, Mo and Ru were sufficiently eliminated by using the flow injection system, with the decontamination factors of 1.6.104 and 9.9.105, respectively. With the present method, it was possible to determine ultra-low level of 99Tc in 3-6 g soil at 3–5 hours of analysis time per sample. The relative standard deviation for each sample was less than 4%. The detection limits for 99Tc was 85 fg.ml–1 (0.05 mBq.ml–1), which was calculated from the three times standard deviation of the count rate of the blank.

Determination of226Ra in environmental samples using high-resolution inductively coupled plasma mass spectrometry

A time-saving and accurate technique for determining226Ra in groundwater and soil was examined, using high-resolution inductively coupled plasma-mass spectrometry (HR-ICP-MS). The technique was applied to the determination of226Ra in groundwater and soil samples and compared with the conventional liquid scintillation counting method. This technique was capable of completing226Ra counting within 3 minutes, without the in-growth period to allow radon and its progeny to achieve secular equilibrium with the parent226Ra. The detection limits of HR-ICP-MS for226Ra in groundwater and soil were 0.19 mBq·1−1 and 0.75 Bq·kg−1, respectively, which were about 10 times lower than that of the liquid scintillation counter. The results obtained from HR-ICP-MS in groundwater and soil were in accordance with those of LSC within a relative error of about 13%.

Nationwide survey of radon levels in Korea

Abstract— A nationwide radon survey was conducted to provide data on the annual average indoor radon concentration in Korean homes. This survey also provided data on the variation of radon concentration with season, house type, and building age. The arithmetic mean (AM) of annual radon concentration in Korean homes was 53.4 ± 57.5 Bq m−3. The indoor radon concentration showed a lognormal distribution with a geometric mean (GM) and its standard deviation (GSD) of 43.3 ± 1.8 Bq m−3. The radon concentrations in the traditional Korean- style houses were about two times higher than those in apartments and row houses. The average annual outdoor radon concentration was 23.3 Bq m−3. The average annual effective dose to the general public from radon was 1.63 mSv y−1.

Environmental distribution and behavior of 3H and 14C around Wolsong Nuclear Power Plants.

Abstract—To estimate of the dispersion trend of 3H and 14C discharged from the Wolsung Nuclear Power Plants, the present level of 3H and 14C in environmental samples in the vicinity of the Wolsong site was studied. Tree-ring cellulose analyses were carried out for retrospective evaluation of 3H and 14C in the environment around the Wolsong Nuclear Power Plants. 3H released from the Wolsong Nuclear Power Plants has affected an area up to a 25-km radius from the site, while almost all 14C was deposited within a 2-km radius, reaching to a natural level over 2 km. Organically bound tritium concentrations in tree rings were strongly correlated with the gaseous tritium discharge rate, while &dgr;14C (excess) in tree rings ranged from 204‰ to 460‰, which did not significantly vary with year.

Environmental radiation monitoring in Korea

Environmental radiation monitoring in Korea can be categorized as (1) nationwide monitoring program and (2) monitoring program for nuclear facilities. The former is designed to quickly detect any abnormal situation in environmental radioactivity levels. The latter has the objective of evaluating environmental radioactivity levels resulting from the operation of nuclear facilities. This paper describes the two monitoring programs, how they are implemented, items of being measured, analytical techniques, quality control programs and R&D activities associated with the monitoring. Also, some of the latest data obtained by the monitoring programs are introduced.

Fluctuations of exposure rate at regional radiation monitoring stations in Korea

Based on hourly means of exposure rate between August 2000 and July 2001 at nine Regional Radiation Monitoring Stations (RRMS) in Korea, we analyzed spatio-temporal characteristics of exposure rate. The mean and fluctuations of exposure rates were 99 and 3.8 nGy h(-1), respectively. The hourly exposure rate over 9 RRMS indicated a diurnal pattern with the exposure rates reaching a maximum between 5:00 and 8:00 a.m. in the early morning and a broad minimum between 4:00 and 10:00 p.m. in the afternoon. The fluctuations of exposure rate in the inland areas were less than 3.2 nGy h(-1), and those of exposure rate in coastal areas were larger than 3.9 nGy h(-1). The frequency distribution of exposure rates had one peak around the mean and was to be skewed to the right or positively skewed and its tails were fatter than those of a normal distribution. The interrelations of exposure rates at each station generally decreased with the distance between the stations. Empirical orthogonal function (EOF) analysis showed that almost all (99.9%) of exposure rate fluctuations were described by simultaneous variations. The spatial distribution of the first EOF modes of actual, low-pass (periods longer than one month) and high-pass (periods shorter than one month) exposure rate series were similar to each other.