• Journal of the Korean Society of Systems Engineering
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• v.17 no.1
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• pp.76-84
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• 2021

Radioactive waste generated from nuclear power plant decommissioning shall be strictly managed so that radioactive materials above the allowable limit are not leaked into the environment. Radioactive wastes shall be classified and treated for management based on characteristics such as the type of waste, physicochemical properties, nuclide concentration and radioactivity. Waste characterization report shall be prepared and submitted to the disposal facility operator to ensure that the treated waste is suitable for disposal. The disposal facility operator shall review the waste Characterization report and visit the nuclear power plant decommissioning site to ensure that the wastes are processed step by step according to the plan. The waste Characterization report may be used as input data to evaluate disposal facility safety. Domestic and foreign data are collected and reviewed to confirm the entire processes from waste generation to delivery. This paper proposes the method to prepare the waste Characterization report which contains data and information on waste characteristics, treatment facilities & method and packaging method & container.

• Nuclear Engineering and Technology
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• v.54 no.4
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• pp.1355-1362
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• 2022

Nuclear fuel, including its fresh state, must be handled safely due to its critical and hazardous nature. Under normal transport conditions, several interactions take place among different components, such as transport cask used for loading the nuclear fuel and tie-down structure to attach with the vehicle. To ensure structural integrity of the nuclear fuel, vibrations and impacts transmitted from the vehicle must be sufficiently reduced. Therefore, in this study, we conducted two transportation tests from Daejeon to Kijang in Korea to verify the vehicle-induced vibrational characteristics of the KJRR-F fresh nuclear fuel when transported under normal transport conditions. The speed and location of the vehicle were obtained via GPS, and the accelerations between the vehicle and the KJRR-F fresh nuclear fuel were measured. Additionally, using the acceleration results, a structural analysis was conducted to confirm the structural integrity of the nuclear fuel under the most severe conditions during normal transport.

• Journal of the Korean Society of Systems Engineering
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• v.17 no.1
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• pp.65-75
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• 2021

When the decommissioning of South Korea nuclear power plants is promoted in earnest with the permanent shutdown of Kori Unit 1 in 2017, a large amount of various types of radioactive waste will be generated. For minimal generation and safe management of decommissioning waste, the waste should be made by appropriate classification of the dismantling waste characteristics in accordance with physical, chemical and radiological characteristics to meet the acceptance criteria of disposal facilities. Replacing the preliminary inspection at the site for the compliance of the waste acceptance criteria (WAC) of medium and low-level radioactive waste with the generator's own radioactive waste certification program (WCP), from the perspective of disposal, the optimization of waste management at the national level contributes to the efficient availability of disposal, such as the processing of non-conforming radioactive wastes at the site. To this end, it is important to evaluate radioactivity in each system and area such as nuclear reactors before decommissioning is carried out in earnest, and the prior removal of harmful wastes is important. From waste collection to waste disposal, decommissioning waste should be managed at each stage in consideration of the acceptance criteria of disposal facilities to minimize the generation of non-conforming waste.

• Journal of the Korean Society of Systems Engineering
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• v.17 no.1
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• pp.85-96
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• 2021

Radioactive mixed waste (RMW) means waste mixed with radioactive substances and hazardous substances. In Korea, there are definitions and disposal restrictions on RMW in the Nuclear Safety Management Act, but it is difficult to apply because the contents are insufficient, so this paper proposed applicable management standards. The main RMW generated from nuclear power plants is waste oil, waste asbestos, PCB, and waste fluorescent liquid, and their radiation characteristics are mostly at very low levels and some are estimated at low levels. In addition to nuclear power plants, RMW also occurs in research institutes, industries, and hospitals. The acceptance criteria of all disposal facilities in the world basically prohibit disposal of RMW unless the hazardous substances of RMW are removed or mitigated below the standard value. Cases in Korea, the United States, Japan and Europe were reviewed to propose the RMW management standards in Korea. With reference to the results of the above review, this paper clearly defined RMW and proposed detailed management standards for the separation, storage, treatment and disposal of hazardous substances by applying the Waste Control Act. It also mentioned legislation of management standards, regulatory methods, and acceptance criteria of disposal facility operator.

• Proceedings of the Korean Nuclear Society Conference
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• 1995.05a
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• pp.879-884
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• 1995

The results of performance assessment analyses have shown that the long-lived radionuclides such as I-129 control the potential individual dose impact to the public. I-129 is difficult-to-measure(DTM) in low-level waste because it is non-gamma emitting radionuclides and exists at extremely low concentrations in radioactive waste generated by nuclear reactors. In this study, computer modeling technique to predict release rate of I-129 is developed to provide another tools far performance assessment of land disposal facilities and characteristics of radwaste. Model suggested in this study will give conservative values of I-129 release rate far determination of radwaste characteristics. More detailed approach is implemented to account for release conditions of fuel source-nuclides. 1-131 concentration measured from reactor coolant and released fraction from tramp fuel have dominant roles in calculating release rate of I-129 with fuel defect conditions.

• Nuclear Engineering and Technology
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• v.56 no.2
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• pp.375-388
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• 2024

In this study, to evaluate the shock and vibration load characteristics of used fuel, a sea transportation test was conducted using simulated fuel assemblies under normal transport conditions. An overall test data analysis was performed based on the measured strain and acceleration data obtained from cruise, rotation, acceleration, braking, depth of water, and rolling tests. In addition, shock response spectrum and power spectral densities were obtained for each test case. Amplification and attenuation characteristics were investigated based on the load path. The load was amplified as it passed from the overpack to the simulated used fuel-assembly. As a result of the RMS trend analysis, the fuel-loading position of the transportation package affected the measured strain in the fuel rod, and the maximum strains were obtained at the spans with large spacing. However, even these maximum strains were very small compared to the fatigue strength and the cladding yield strength. Moreover, the fuel rods located on the side exhibited a larger strain value than those at the center.

• Analytical Science and Technology
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• v.9 no.1
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• pp.20-25
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• 1996

Trace levels of uranium and thorium in geologic samples are determined rapidly by a direct wavelength-dispersive X-ray fluorescence method. Relative intensity of scattered tube radiation was used as an internal standard to compensate for variations in instrumental operating characteristics. U and Th can be determined within a precision of ${\pm}10%$ and accuracy of ${\pm}15%$ or less with measuring times of 50 seconds for Th and 400 seconds for U, respectively. The results of XRF analysis were in good agreement with those of other methods such as nutron activation analysis and inductively coupled plasma atomic emission spectrometry.

• Journal of Radiation Protection and Research
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• v.10 no.2
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• pp.113-121
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• 1985

For the safety assessment of radwaste treatment and disposal, the leaching characteristics of $Cs^+\;and\;Sr^{++}$ from the cement-solidified radwastes was investigated by means of the survey and analysis of the activity leach rate and cumulative leach fraction of $^{137}Cs\;and\;^{90}Sr$ leaching from solidified radwastes. The cylindrical cement-solidified samples were made by the sodium silicate method and neutralization method changing the mole density of simulated liquid radwaste, type of cement, adding material and concentration of boric acid. The leaching study was carried out by the method using simulated PWR concentrated liquid radwaste solidified in cement that had been processed following the recommendations of IAEA. All the experimental results are in well accordance with the research data reported previously, but the watertight cement-solidified radwastes show rather high leach rate of radioactivity. It is learned, therefore, that the watertight cement is not adequate as the material for the solidified radwastes.

• Nuclear Engineering and Technology
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• v.54 no.11
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• pp.4030-4048
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• 2022

In this study, road transportation tests were conducted with surrogate fuel assemblies under normal conditions of transport to evaluate the vibration and shock load characteristics of spent nuclear fuel (SNF). The overall test data analysis was conducted based on the measured acceleration and strain data obtained from the speed bump, lane-change, deceleration, obstacle avoidance, and circular tests. Furthermore, representative shock response spectrums and power spectral densities of each test mode were acquired. Amplification or attenuation characteristics were investigated according to the load transfer path. The load attenuated significantly as it transferred from the trailer to the cask. By contrast, the load amplified as it transferred from the cask to the surrogate SNF assembly. The fuel loading location on the cask disk assembly did not exhibit a significant influence on the strain measured from the fuel rods. The principal strain was in the vertical direction, and relatively large strain values were obtained in spans with large spacing between spacer grids. The influence of the lateral location of fuel rods was also investigated. The fuel rods located at the side exhibited relatively large strain values than those located at the center. Based on the strain data obtained from the test results, a hypothetical road transportation scenario was established. A fatigue evaluation of the SNF rod was performed based on this scenario. The evaluation results indicate that no fatigue damage occurred on the fuel rods.

• Nuclear Engineering and Technology
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• v.21 no.4
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• pp.321-331
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• 1989

A bench scale incineration process for the burnable radwaste has been constructed and operated at KAERI as a self-surpported development of incineration technology. The purposes of operating the process are to get experience in incineration, to analyze the characteristics of combustion and to test the performance of off-gas treatment units. Simulated paper and polyethylene wastes were incinerated. Volume reduction ratio and decontamination factor of the process have been determined to observe the economical efficiency and operational capability of the process. A methodology to estimate the acceptance limit of specific activity to an incineration facility by using a decontamination factor and to calculate the volume reduction ratio of the facility is introduced. The acceptance criteria for different radionuclides in the combustible waste at the bench scale incineration process are suggested using this methodology.