As the management procedure for self-disposal wastes stored in the radiation controlled area within the Korea Atomic Energy Research Institute (KAERI) have been established, and the types and quantities of wastes are increasing. In order to carry out the disposal of wastes with various generation histories, we expanded the processing range from surface contaminated waste, which was already in progress, to volumetric contaminated waste. In this paper, a case study of self-disposal of volumetric contaminated radioactive waste for which final disposal has been completed is described. In order to carry out of self-disposal of volumetric contaminated waste, it is important to collect representative samples and prove their representativenss. Based on this, a treatment plan was established after reviewing the history of the waste to be disposed of, and the treatment work was carried out as follows; waste collection, classification by size and shape, radiation (activity) measurement, sampling of representative samples, radioactivity concentration analysis, notification to regulatory bodies and question-and-answer, final disposal. The waste is judged have no potential for contamination because the polywood used to set the flat floor between the steel frame and floorboards in the experimental greenhouse didn’t come into contact with radioactive material. However, due to the conservative approach to the presence or absence of contamination, the treatment plan was established assuming volumetric contaminated waste. The type of waste is single wood, and the major contaminating radionuclides are Sr-85 and Cs-137. After the waste was collected and sorted by size and shape, it was weighed and a representative sampling amount and sampling method were set up. A direct method of surface contamination was performed on the entire area, and the representative sample was divided into three groups of homogenized population samples using the trisection method, with three points (upper/middle/below) were sampled at a 200:1 ratio, and radioactivity concentration analysis was conducted. After confirming that the concentration was below the allowable concentration for selfdisposal, the final disposal was completed after receiving approval after reporting to the regulatory body. As a result of radioactivity concentration analysis of representative samples, the maximum radioactivity concentration for each nuclide was Sr-85: < MDC (0.00178), Cs-137 : 0.00183 Bq/g (Sr-85 : 1 Bq/g, Cs-137 : 0.1 Bq/g), which meets the nuclide allowable concentration standard. It was confirmed that the total maximum fraction of 0.02 Bq/g satisfies the criteria (In the case of mixed nuclides, the sum of the fraction is less than 1). This paper introduces the establishment and implementation of self-disposal procedures based on the experience of self-disposal of radioactive waste with volumetric contaminants, and is going to utilize it as a basic material for self-disposal of radioactive waste with volumetric contaminants that will continue in the future and contribute to the reduction of radioactive wastes.

Preparation of activated carbons from wood waste including northern hardwood pins-fines and wood dust was conducted and then compared through the following methods: physical pyrolysis and CO2 activation, vacuum pyrolysis and CO2 activation, CO2 gasification, and vacuum CO2 gasification processes. Experimental results show that chars and activated carbons with high surface area and pore volume are produced from wood waste through a vacuum CO2 pyrolysis/gasification process. The effects of operation variables of vacuum pyrolysis/gasification on the properties of chars and activated carbons were investigated to identify and optimize the temperature, heating time, and heating rate. The optimized vacuum CO2 gasification conditions were found to be a temperature of 800 °C, a heating rate of 20 °C/min, and a holding time of 2 h respectively. The prepared wood-chars and activated carbons were characterized by nitrogen physisorption, scanning electron microscopy (SEM). Fourier transform infrared (FTIR) spectra determined any changes in the surface functional groups produced during different preparation stages.

The IPCC methodology for estimating methane emissions from a solid waste landfill is based on the first order decay (FOD) method. One emission factor in the model is the methane generation potential (L0) that is estimated from the amount of decomposable degradable organic carbon (DOC) in a solid waste landfill. L0 is estimated based on the fraction of DOC in the waste, the fraction of the degradable organic carbon that decomposes under anaerobic conditions (DOCf), methane correction factor (MCF), and the fraction of methane in generated landfill gas (F). The other emission factor is the methane generation rate constant (k). The IPCC recommended that every country needs to develop country-specific key parameters (DOC, DOCf, k) more appropriate for its circumstances and characteristics. The objective of this research was to investigate the greenhouse gas emission factor (k) and parameters (DOC, DOCf) for wood wastes in a solid waste landfill. To investigate DOC, DOCf, and k for wood wastes, the biodegradable rate of wood wastes was determined by comparing the composition of excavated samples (L-1, L-2) with their fresh ones (F-1, F-2). The DOC values were found to be 48.36% and 45.27% for F-1 and F-2, respectively. It showed that the IPCC default value of DOC for wood wastes is appropriate for estimating methane emission. The maximum DOCf (0.17 and 0.18) or each wood waste excavated from G landfill was found to be lower compared with those for IPCC. The IPCC provided that default values of DOCf 0.5. The k values were found to be 0.0055 and 0.0058 year−1 for F-1 and F-2, respectively. The result confirmed that the biodegradation rate of wood wastes was very slow due to its lignin.