• Journal of Radiation Protection and Research
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• v.41 no.4
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• pp.354-358
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• 2016

Background: To find out the leak characteristic of research reactor 'HANARO' building in a typhoon condition Materials and Methods: MELCOR code which normally is used to simulate severe accident behavior in a nuclear power plant was used to simulate the leak rate of air and fission products from reactor hall after the shutdown of the ventilation system of HANARO reactor building. For the simulation, HANARO building was designed by MELCOR code and typhoon condition passed through Daejeon in 2012 was applied. Results and Discussion: It was found that the leak rate is $0.1%{\cdot}day^{-1}$ of air, $0.004%{\cdot}day^{-1}$ of noble gas and $3.7{\times}10^{-5}%{\cdot}day^{-1}$ of aerosol during typhoon passing. The air leak rate of $0.1%{\cdot}day^{-1}$ can be converted into $1.36m^3{\cdot}hr^{-1}$, but the design leak rate in HANARO safety analysis report was considered as $600m^3{\cdot}hr^{-1}$ under the condition of $20m{\cdot}sec^{-1}$ wind speed outside of the building by typhoon. Conclusion: Most of fission products during the maximum hypothesis accident at HANARO reactor will be contained in the reactor hall, so the direct radiation by remained fission products in the reactor hall will be the most important factor in designing emergency preparedness for HANARO reactor.

• Journal of Radiation Protection and Research
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• v.8 no.2
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• pp.15-35
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• 1983

High voltage paper-electrophoresis of fission products from 24 hour neutron-irradiated and 150 days-decayed 90% highly enriched uranyl nitrate solution has been carried out by using the specially designed migration apparatus. The separation of Zr-95 and Nb-95 from the other fission products is possible under the migration condition of 0.1 $M-HClO_4$ (pH=0.85), 0.05 M-HCl+0.09M-KCl (pH=0.9), 0.1M-HCl (pH=1.1) and 0.01 M-HCl (pH=2.0). Zr-95 and Nb-95 are separated out at+1cm from the fiducial point. The separation of Zr-95 and Nb-95 from each other is possible under the migration condition of 0.1 $M-HClO_4$, 0.05 M-HCl+0.09 M-KCl, 0.1 M-HCl and 0.1 M-HAc+0.1 M-NaAc (pH=4.68) together with 2% ammonium oxalate. Nb-95 is separated out at $-6{\sim}-7cm$ from the fiducial point and Zr-95 at $+1{\sim}-lcm$. The separation of Ru-103 from the other fission products is possible under the migration condition of 0.025 $M-Na_2CO_3+0.025\;M-NaHCO_3$ (pH=10.0), 0.01M-$Na_3PO_4$ (pH=11.7) and 0.1 M-NaOH (pH=13.2). Ru-103 migrates towards the anode -6cm, -4cm and -3cm, respectively.

• Nuclear Engineering and Technology
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• v.47 no.1
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• pp.1-10
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• 2015

After the Fukushima Daiichi nuclear power plant (NPP) accident, new regulatory requirements were enforced in July 2013 and a backfit was required for all existing nuclear power plants. It is required to take measures to prevent severe accidents and mitigate their radiological consequences. The Regulatory Standard and Research Department, Secretariat of Nuclear Regulation Authority (S/NRA/R) has been conducting numerical studies and experimental studies on relevant severe accident phenomena and countermeasures. This article highlights fission product (FP) release and hydrogen risk as two major areas. Relevant activities in the S/NRA/R are briefly introduced, as follows: 1. For FP release: Identifying the source terms and leak mechanisms is a key issue from the viewpoint of understanding the progression of accident phenomena and planning effective countermeasures that take into account vulnerabilities of containment under severe accident conditions. To resolve these issues, the activities focus on wet well venting, pool scrubbing, iodine chemistry (in-vessel and ex-vessel), containment failure mode, and treatment of radioactive liquid effluent. 2. For hydrogen risk: because of three incidents of hydrogen explosion in reactor buildings, a comprehensive reinforcement of the hydrogen risk management has been a high priority topic. Therefore, the activities in evaluation methods focus on hydrogen generation, hydrogen distribution, and hydrogen combustion.

• Proceedings of the Korean Nuclear Society Conference
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• 2003.10a
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• pp.342.2-342.2
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• 2003

• Proceedings of the Korean Nuclear Society Conference
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• 2005.10a
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• pp.280-281
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• 2005

• Proceedings of the Korean Nuclear Society Conference
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• 2005.10a
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• pp.173-174
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• 2005

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2017.05a
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• pp.287-288
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• 2017

• The Korean Journal of Zoology
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• v.11 no.3
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• pp.85-91
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• 1968

Artificial and natural radioactivity in airborne, rain-out and fallout dusts in Seoul district in the period of 1963-1967 were studied by measuring gross-activity and by analyzing nuclides by means of $\\gamma$-spectrometry. Short-lived radium and thorium decay products give rise to most of the airborne activity unless the fission product concentration is extremely high and it is likely to be said activity remaining after a few days is attributable to fission products. Of seven Chinese nuclear explosions performed at Lop Nor, Sinkiang Province, two exhibited the activity of extremely high concentration of fission product and reached Seoul district around 30 hours after the explosion. The activity was followed by a sudden decrease in less than a week, in contrast to the long-lasted activity of low concentration originating from the huge tests performed by the United States and the USSR in 1956-1962. The radioactive environmental contamination in Seoul district, due to the Chiness nuclear test explosions, largely depends on the height above the earth at which the nuclear explosion is performed and the type of nuclear device as well as the weather system at the time and immediately after the explosion, especially the jet stream in middle latitude in the upper troposphere.

• Journal of Radiation Protection and Research
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• v.14 no.2
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• pp.30-36
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• 1989

A FISSLIB, 51 group nuclear data set for 22 product nuclides, which are present in spent fuel and significantly affect the criticality of spent fuel, was generated from ENDF/B-IV using XLACS-II. The FISSLIB is ready to be used together with a data set generated from DLC-43/CSRL using AMPX system. The reliability of FISSLIB was verified by comparison with the data reported in BNL-325. Using FISSLIB, the criticality of KORI-1 spent fuel rod arranged infinitely was analyzed, and it was found that $K_{eff}$ of the spent fuel including fission products was lower by 9-14% than that calculated without fission products.

• Nuclear Engineering and Technology
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• v.50 no.6
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• pp.820-828
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• 2018

The growing nuclear threat has amplified the need for developing diverse and accurate nuclear forensics analysis techniques to strengthen nuclear security measures. The work presented here is part of a research effort focused on developing a methodology for reactor-type discrimination of weapons-grade plutonium. To verify the developed methodology, natural $UO_2$ fuel samples were irradiated in a thermal neutron spectrum at the University of Missouri Research Reactor (MURR) and produced approximately $20{\mu}g$ of weapons-grade plutonium test material. Radiation transport simulations of common thermal reactor types that can produce weapons-grade plutonium were performed, and the results are presented here. These simulations were needed to verify whether the plutonium produced in the natural $UO_2$ fuel samples during the experimental irradiation at MURR was a suitable representative to plutonium produced in common thermal reactor types. Also presented are comparisons of fission product and plutonium concentrations obtained from computational simulations of the experimental irradiation at MURR to the nondestructive and destructive measurements of the irradiated natural $UO_2$ fuel samples. Gamma spectroscopy measurements of radioactive fission products were mostly within 10%, mass spectroscopy measurements of the total plutonium mass were within 4%, and mass spectroscopy measurements of stable fission products were mostly within 5%.