• Title, Summary, Keyword: HTO vapor

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TFWT and OBT Concentrations in Rice Plants Exposed to HTO Vapor during Daytime and Nighttime at Different Seed-Developing Stages (벼의 종실 발육단계에 따른 주간 및 야간 HTO 증기 피폭시 TFWT 및 OBT 농도)

  • Choi, Yong-Ho;Lim, Kwang-Muk;Lee, Won-Yun;Kang, Hee-Suk;Choi, Heui-Joo;Lee, Han-Soo;Diabate, Silvia;Strack, Siegfried
    • Journal of Radiation Protection and Research
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    • v.28 no.1
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    • pp.9-18
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    • 2003
  • Rice plants at different seed-developing stages were exposed to HTO vapor in an exposure box for 1 h during daytime and nighttime to investigate the levels of tissue free water $^3H$ (TFWT) and organically bound $^3H$ (OBT) in different plant parts. In the daytime experiment, TFWT concentrations in leaves at the end of exposure $(h_0)$ were around 100% of the 1 hour mean HTO concentrations in air moisture whereas in the nighttime experiment, they were as low as $30{\sim}40%$ of the air concentration. TFWT concentrations in both experiments decreased very rapidly in the beginning but much mote slowly later and those at harvest were hundreds to hundred thousands times lower than those at $h_0$. OBT concentrations varied with time in different manners depending on plant parts and exposure times and differed between at $h_0$ and at harvest by factors of less than 10 on the whole. Even during nighttime exposures, OBT was produced at about a third the rate for daytime exposures. The degree of the conversion of airborne HTO into OBT in mature rice seeds, being several times higher in the daytime experiment than in the nighttime experiment, was highest after the exposure peformed at the most actively seed-developing stage for both experiments. It is estimated that OBT would contribute much more to the ingestion radiation dose than TFWT if rice plants are exposed to HTO vapor for the seed-developing period.

TFWT and OBT Concentrations in Soybean Plants Exposed to HTO Vapor at Different Growth Stages (콩의 생육단계별 HTO 증기 피폭에 따른 작물체내 TFWT 및 OBT 농도)

  • Lim, K.M.;Choi, Y.H.;Lee, W.Y.;Park, H.G.;Kang, H.S.;Choi, H.J.;Lee, H.S.
    • Journal of Radiation Protection and Research
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    • v.29 no.4
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    • pp.213-219
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    • 2004
  • Soybean plants were exposed to HTO vapor in an exposure box for 1 hour at different growth stages. Relative concentrations of TFWT at the end of exposure (percent ratios of TFWT concentrations to mean HTO concentrations in air moisture in the box during exposure) decreased on the whole in the order of leaf > shell > seed > stem with the highest values of 40.2% and 6.4% for leaf and stem, respectively. TFWT concentrations reduced by factors of several thousands to several hundred-thousands from the end of exposure till the harvest. The reduction factor decreased in the order of leaf > shell > seed > stem. Relative OBT concentrations at harvest (ratios of the OBT concentration in the dry plant part at harvest to the initial leaf TFWT concentration, ml $g^{-1}$) were in the range of $2.2{\times}10^{-5}{\sim}9.5{\times}10^{-3}$ for seeds being the highest when the exposure was performed at the actively seed-developing stage. The exposure time-dependent variation in the OBT concentration was much greater in seeds and shells than in leaves and stems. It was indicated that OBT would contribute to almost all the radiation dose due to the consumption of soybean seeds in most cases after an acute exposure of growing plants to HTO vapor. Present results are applicable to establishing and validating soybean $^3H$ models for an acute accidental release of HTO.

Tritium Concentrations of Tritiated Water Vapor and Tritiated Hydrogen in the Atmosphere in Taejon (대전지역 대기중 수증기상태 (HTO) 및 가스상태 (HT) 삼중수소의 농도)

  • Kim, C.K.;Han, M.J.;Kim, K.H.
    • Journal of Radiation Protection and Research
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    • v.22 no.2
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    • pp.97-101
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    • 1997
  • During the period of March 1995 to December 1995, tritium concentrations of tritiated water vapor (HTO) and tritiated hydrogen (HT) in the atmosphere in Taejon were measured to evaluate present background levels of tritium in the atmosphere. Air samples were collected continuously for three weeks with a sampling system for tritium in the atmosphere and were analyzed by a liquid scintillation counting system. The range of the atmospheric HTO concentrations was 3.2-36 mBq $m^{-3}$ with a mean value of 16.2 mBq $m^{-3}$. The atmospheric HTO concentrations were the highest in summer and the lowest in winter. This trend was similar to the variation of atmospheric absolute humidity. The specific activities of tritium in atmospheric water vapor in Taejon ranged from 0.62 Bq $L^{-1}$ to 3.82 Bq $L^{-1}$ with a mean value of 2.04 Bq $L^{-1}$. The atmospheric HT concentrations were in the range of 35.7 mBq $m^{-3}$ to 48.9 mBq $m^{-3}$ with a mean value of 41.1 mBq $m^{-3}$.

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Verification of a Dynamic Compartment Model for the Tritium Behavior in the Plants After Short HTO Release Using a BIOMOVS II Scenario

  • Park, Heui-Joo;Kang, Hee-Suk;Lee, Hansoo
    • Nuclear Engineering and Technology
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    • v.35 no.2
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    • pp.171-177
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    • 2003
  • A dynamic compartment model was required for the prediction of radiological consequences of the tritiated vapor released from the nuclear facility after an accident. A computer code, ECOREA-T, was developed by incorporating the unit models for the evaluation of tritium behavior in the environment. Dry deposition of tritiated vapor from the atmosphere to the soil was calculated using a deposition velocity. Transport of tritium from the atmosphere to the plant was calculated using a specific activity model, and the result was compared with the Belot's analytic solution. Root uptake of tritiated water from the soil and formation of OBT from T were considered in the model. The ECOREA-T code was verified by comparing the results from the other computer codes using a scenario developed through BIOMOVS II study. The results showed good agreements.

A new method for measuring ultra-low water vapor permeation for OLED displays

  • Dunkel, Ralf;Bujas, Roko;Klein, Andre;Horndt, Volker;Wrosch, Matt
    • 한국정보디스플레이학회:학술대회논문집
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    • pp.589-593
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    • 2005
  • It is well known that proper encapsulation is crucial for the lifetime of organic light emitting diode (OLED) displays. With the development of increasingly better barrier coatings and perimeter seals, it has now become very desirable to be able to precisely measure the rate of water vapor and oxygen permeation through barrier coatings and perimeter sealing. This paper demonstrates a new permeation measurement method that uses tritium-containing water (HTO) as a tracer material. The theoretical detection limit of this direct method is $2.4{\times}10^{-8}g/(m^2day)$.

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Evaluation Model and Experimental Validation of Tritium in Agricultural Plant (농작물의 삼중수소 오염평가 모델 개발 및 실험검증)

  • Kang Hee Suk;Keum Dong-kwon;Lee Hansoo;In Jun;Choi Yong Ho;Lee Chang Woo
    • Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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    • v.3 no.4
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    • pp.319-328
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    • 2005
  • This paper describes a compartment dynamic model for evaluating the contamination level of kritium in agricultural plants exposed by accidentally released tritium. The present model uses a time-dependent growth equation of plant so that it can predict the effect of growth stage of plant during the exposure time. The model including atmosphere, soil and plant compartments is described by a set of nonlinear ordinary differential equations, and is able to predict time-dependent concentrations of tritium in the compartments. To validate the model, a series of exposure experiments of HTO vapor on Chinese cabbage and radish was carried out at the different growth stage of each plant. At the end of exposure, the tissue free water(TFWT) and the organically bound tritium(OBT) were measured. The measured concentrations were agreed well with model predictions.

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Analysis of Metabolism and Effective Half-life for Tritium Intake of Radiation Workers at Pressurized Heavy Water Reactor (중수로원전 종사자의 삼중수소 체내섭취에 따른 인체대사모델과 유효반감기 분석)

  • Kim, Hee-Geun;Kong, Tae-Young
    • Journal of Radiation Protection and Research
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    • v.34 no.2
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    • pp.87-94
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    • 2009
  • Tritium is the one of the dominant contributors to the internal radiation exposure of workers at pressurized heavy water reactors (PHWRs). This nuclide is likely to release to work places as tritiated water vapor (HTO) from a nuclear reactor and gets relatively easily into the body of workers by inhalation. Inhaled tritium usually reaches the equilibrium of concentration after approximately 2 hours inside the body and then is excreted from the body with a half-life of 10 days. Because tritium inside the body transports with body fluids, a whole body receives radiation exposure. Internal radiation exposure at PHWRs accounts for approximately 20-40% of total radiation exposure; most internal radiation exposure is attributed to tritium. Thus, tritium is an important nuclide to be necessarily monitored for the radiation management safety. In this paper, metabolism for tritium is established using its excretion rate results in urine samples of workers at PHWRs and an effective half-life, a key parameter to estimate the radiation exposure, was derived from these results. As a result, it was found that the effective half-life for workers at Korean nuclear power plants is shorter than that of International Commission on Radiological Protection guides, a half-life of 10 days.