• Nuclear Engineering and Technology
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• v.51 no.4
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• pp.1176-1179
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• 2019

Measurements of activity concentrations of radionuclides in atmospheric releases were performed in 2017-2018 at vent stacks of seven Russian nuclear power plants. The selected instruments and research methods, with detection limits significantly lower than the existing detection limit of Russian NPPs routine control, allowed to reliably determine up to 26 radionuclides. Analysis of experimental data allows to determine the list of radionuclides for calculation the effective dose rates to public and the permissible annual discharge levels for each Russian NPP. Radiocarbon is determined as major contributor for the dose from the atmospheric releases of LWGR reactors - up to 98% for EGP-6 and RBMK-1000 (Smolensk NPP) reactors. For PWR reactors (VVER) radionuclides contribution to the annual dose from atmospheric releases is more complicated, but, in general, dose is formed by tritium, $^{14}C$ and noble gases. The special monitoring results with ranking of measured radionuclides according to their contribution to the effective dose makes it possible to optimize the list of controlled radionuclides in airborne releases of Russian NPPs from 94 to 8-16 for different NPPs.

• Journal of Radiation Protection and Research
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• v.25 no.2
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• pp.81-87
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• 2000

XOQ_DW code is currently used to assess the atmospheric dispersion fur the routine releases of radioactive gaseous effluents at Yonggwang nuclear power plants. This code was developed based on XOQDOQ code and an additional code is required to assess the atmospheric dispersion for potential accidental releases. In order to assess the atmospheric dispersion fer the accidental releases, XOQAR code has been developed by using PAVAN code that is based on Reg. Guide 1.145. The terrain data of XOQ_DW code inputs and the relative concentrations (X/Q) of XOQ_DW code outputs are used as the inputs of the XOQAR code through the interface with XOQ_DW code. By using this code, the maximum values of X/Q at exclusion area and low population zone boundaries except for sea areas were assessed as $1.33{\times}10^{-4}$ and $7.66{\times}10^{-6}$ sec/$m^3$, respectively. Through the development of this code, a rode system is prepared for assessing the atmospheric dispersion for the accidental releases as well as the routine releases. This developed code ran be used for other domestic nuclear power plants by modifying the terrain input data.

• Nuclear Engineering and Technology
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• v.11 no.2
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• pp.127-132
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• 1979

A model is considered in order to evaluate the potential risk from a nuclear facility directly combining the on-site meteorological data. The model is utilized to evaluate the environmental consequences from the routine releases during normal plant operation as well as following postulated accidental releases. The doses to individual and risks to the population-at-large are also analyzed in conjunction with design of rad-waste management and safety systems. It is observed that the conventional analysis, which is done in two separate unaffiliated phases of releases and atmospheric dispersion tends to result in unnecessary over-design of the systems because of high resultant doses calculated by multiplication of two extreme values.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.19 no.2
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• pp.177-186
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• 2021

Radioactive materials from nuclear power facilities can be released into the atmosphere through various channels. Recently, the dispersion of radioactive materials has become critical issue in Korea after Kori Unit 1 and Wolsong Unit 1 were permanently shut down. In this study, annual atmospheric dispersion factors were compared based on the continuous release and purge release using the XOQDOQ computer program, a method for calculating atmospheric dispersion factors at commercial nuclear power stations. The meteorological data analyzed in this study was based on the Shin Kori nuclear power meteorological tower which has the largest operating nuclear power plants in Korea, for three years (from 2008 to 2010). The analysis results of the dispersion factor of the radioactive material release obtained using the XOQDOQ program showed that the difference between the continuous release and purge release was within two times. This study will be valuable helpful for revealing the uncertainty of the predictive atmospheric dispersion factor to achieve regulation.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2008.10a
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• pp.406-407
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• 2008

• Journal of Korean Society for Atmospheric Environment
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• v.24 no.1
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• pp.1-15
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• 2008

Chemical Accident Response Information System (CARIS) which has been designed for the efficient emergency response of chemical accidents produces the real-time atmospheric fields through the Regional Atmospheric Modeling System, RAMS. The previous studies were emphasized that improving an initial input data had more effective results in developing prediction ability of atmospheric model. In a continuous effort to improve an initial input data, we replaced the land-use dataset using in the RAMS, which is a high resolution USGS digital data constructed in April, 1993, with the latest land-use data of the Korea Ministry of Environment over the South Korea and simulated atmospheric fields for developing a real-time prediction in dispersion of chemicals. The results showed that the new land-use data was written in a standard RAMS format and shown the modified surface characteristics and the landscape heterogeneity resulting from land-use change. In the results of sensitivity experiment we got the improved atmospheric fields and assured that it will give more reliable real-time atmospheric fields to all users of CARIS for the dispersion forecast in associated with hazardous chemical releases as well as general air pollutants.

• Journal of Radiation Protection and Research
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• v.23 no.2
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• pp.103-107
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• 1998

The influence of calm conditions on the atmospheric dispersion analyses at KAERI site, which is located at a complex inland basin, was investigated. The U. S. NRC's computer programs XOQDOQ and PAVAN were used to estimate dispersion factors for routine and postulated accidental releases from nuclear facilities, respectively. The joint frequency distribution was obtained from the annual meteorological data measured in 1997 and used as input data of the computer programs. When the definition of calm is changed from 0.5 m $sec^{-1}$ to 0.21 m $sec^{-1}$, the maximum sector dispersion factor becomes 1.62 and 2.16 times higher for routine and postulated accidental releases, respectively.

• Journal of the Korean Institute of Gas
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• v.1 no.1
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• pp.73-80
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• 1997

This study was performed to develop the dispersion modeling methodology for quantitative prediction of the hazard distance or toxic buffer distance by comparing 10-min average, 30-min average, and 1-hr average maximum ground-level concentration with $Cl_2$ regultaion concentration, IDLH and ERPG-3 concentration for hazardous toxic gas, $Cl_2$ releases from the storage tank of the chemical plant facilities. For this dispersion modeling, the source term model, dispersion model, meteorological and topographical data are incorporated into the SuperChems model, and then the effects of the atmospheric stability, wind speed, and surface roughness length changes on the maxum ground-level concentration were estimated.

• Journal of Environmental Science International
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• v.26 no.1
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• pp.37-46
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• 2017

As a result of broadcasters' websites, there were more reports during the typhoon Bolaven/Tembin in 2012 than in 2002 and 2003. Checking related press releases of each broadcaster on NAVER, YTN reports are 3 times more than KBS. Considering great technology progress in the Internet and smart phone user environment compared to the past, it is thought to be rather regretful in that KBS has been the supervising broadcaster over Korean disaster. As a result of daily reports, the year 2002 typhoon Rusa was reported from the date of its arrival on Korean Peninsular to 3 days, but the information required to be provided for disaster prevention before its arrival was too scarce. 2003 typhoon Maemi was reported as many times as the 2002 typhoon, but its information was provided before its arrival. This is meaningful because the information provision was intended for disaster prevention unlike the past. In 2012, the number of weather forecast broadcast on the typhoon Bolaven/Tembin increased greatly compared to 2002 and 2003. This was also determined to be due to abundant information provided by broadcasters and the Internet portal sites as a result of great progress in Korea internet industry.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.14 no.4
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• pp.423-434
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• 2016

The importance of severe nuclear accidents and probabilistic safety assessment (PSA) were brought to international attention with the occurrence of severe nuclear accidents caused by the extreme natural disaster at Fukushima Daiichi nuclear power plant in Japan. In Korea, studies on level 3 PSA had made little progress until recently. The code systems of level 3 PSA, MACCS2 (MELCORE Accident Consequence Code System 2, US), COSYMA (COde SYstem from MAria, EU) and OSCAAR (Off-Site Consequence Analysis code for Atmospheric Releases in reactor accidents, JAPAN), were reviewed in this study, and the disadvantages and limitations of MACCS2 were also analyzed. Experts from Korea and abroad pointed out that the limitations of MACCS2 include the following: MACCS2 cannot simulate multi-unit accidents/release from spent fuel pools, and its atmospheric dispersion is based on a simple Gaussian plume model. Some of these limitations have been improved in the updated versions of MACCS2. The absence of a marine and aquatic dispersion model and the limited simulating range of food-chain and economic models are also important aspects that need to be improved. This paper is expected to be utilized as basic research material for developing a Korean code system for assessing off-site consequences of severe nuclear accidents.