• The Korean Journal of Nuclear Medicine Technology
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• v.17 no.1
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• pp.3-6
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• 2013

Purpose: The treatment of thyroid cancer patients was continuously increased. According to the increment of thyroid cancer patients, the establishment of iodine therapy site was also increased in each hospital. This treatment involves the administration of radioactive iodine, which will be given in the form of a capsule. Therefore, protections and managements for radioactive source pollution and radiation exposure should be necessary for radiation safety. Among the many problems, the problem of disposing the radioactive wastes was occurred. In this study, The date for self-disposal for radioactive wastes, which were contaminated in clothes, bedclothes and trash, were calculated. Materials and Methods: The number of iodine therapy ward was 15 in Korea Institute of Radiological Medical and Sciences. Recently, 8 therapy wards were operated for iodine therapy patients and others were on standby for emergency treatment ward of any radiation accidents. Radioactive wastes, which were occurred in therapy ward, were clothes, bedclothes, bath cover for patients washing water and food and drink which was leftover by patients. Each sample was hold into the marinelli beaker (clothes, bedclothes, bath covers) and 90 ml beaker (food, drink, and washing water). The activities of collected samples were measured by HpGe MCA device (Multi Channel Analysis, CANBERRA, USA) Results: The storage period for the each kind of radioactive wastes was calculated by equation of storage periods based on the measurement outcomes. The average storage period was 60 days for the case of clothes, and the maximum storage period was 93 days for patient bottoms. The average storage period and the maximum storage period for the trash were 69 days and 97 days, respectively. The leftover foods and drinks had short storage period (the average storage period was 25 days and maximum storage period was 39 days), compared with other wastes. Conclusion: The proper storage period for disposing the radioactive waste (clothes, bedclothes and bath cover) was 100 days by the regulation on self-disposal of radioactive waste. In addition, the storage period for disposing the liquid radioactive waste was 120 days. The current regulation for radioactive waste self-disposing was not suitable for the circumstances of each radioactive therapy facility. Therefore, it was necessary to reduce the leftover food and drinks by adequate table setting for patients, and improve the process and regulation for disposing the short-half life radioactive wastes.

• The Journal of the Korea Contents Association
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• v.19 no.12
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• pp.68-83
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• 2019

The characteristics of intermediate-level waste treatment services are likely to have a negative effect because they act as a factor in promoting incentives of earnings management in the relationship between financial characteristics and earnings management in companies which are possible for earnings management. The researchers conducting this study attempted to empirically verify relationships between financial characteristics and earnings management against domestic construction waste disposal companies in consideration of the characteristics of intermediate-level waste disposal businesses, and the results are as follows. As construction waste disposal businesses grew larger, and the trade receivables collection period lengthened, the intention to increase profits via real activities strengthened. As the ability to generate cash via sales activities weakened, and the difference between the EBITDA margin and the operating margin was lower than the difference in industrial average ratio, discretionary accruals and earnings management via real activities were greater. In particular, there were differences in the variables of intermediate treatment business characteristics which reveal moderating effects by financial characteristics. This study is meaningful in that the scope of relationships between financial characteristics and earnings management in accounting is expanded to cover the construction waste disposal industry.

• Geomechanics and Engineering
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• v.34 no.4
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• pp.449-459
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• 2023

The design and development of underground nuclear waste repositories should cover the performance evaluation of the different components such as the construction materials because the long term stability will depend on their response to the surrounding conditions. In South Korea, Gyeonju bentonite has been proposed as a candidate to be used as buffer and backfilling material, especially in the form of blocks to speed up the construction process. In this study, various cylindrical samples were prepared with different dry density and water content, and their physical and mechanical properties were analyzed and correlated with X-ray CT observations. The main objective was to characterize the samples and establish correlations for non-destructive estimation of physical and mechanical properties through the utilization of X-ray CT images. The results showed that the Uniaxial Compression Strength and the P-wave velocity have an increasing relationship with the dry density. Also, a higher water content increased the values of the measure parameters, especially for the P-wave velocity. The X-ray CT analysis indicated a clear relation between the mean CT value and the dry density, Uniaxial Compression Strength, and P-wave velocity. The effect of the higher water content was also captured by the mean CT value. Also, the relationship between the mean CT value and the dry density was used to plot CT dry densities using CT images only. Moreover, the histograms also provided information about the samples heterogeneity through the histograms' full width at half maximum values. Finally, the particle size and heterogeneity were also analyzed using the Madogram function. This function identified small particles in uniform samples and large particles in some samples as a result of poor mixing during preparation. Also, the μ_max value correlated with the heterogeneity, and higher values represented samples with larger ranges of CT values or particle densities. These image-based tools have been shown to be useful on the non-destructive characterization of bentonite samples, and the establishment of correlations to obtain physical and mechanical parameters solely from CT images.

• Journal of the Korean Society of Safety
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• v.14 no.4
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• pp.135-141
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• 1999

This study is an experimental study to investigate the possibility of the utilization of paper ash as the cover, liner in waste disposal landfill and other construction materials. The sample used in these tests was obtained from Daehan paper mill. A series of tests were peformed to evaluate basic properties, compaction, permeability, compressive strength, consolidation, leaching, and CBR of paper ash. In order to investigate the soil engineering properties of paper ash, the test results were compared with those obtained of fly ash. The results of unconfined compression tests show that paper ash had a larger strength than the fly ash. Also, the maximum dry unit weight of paper ash was approximately 59～76.9% less than that of the fly ash. It was found from the results of leaching test that paper ash is classified as non-detrimental general wastes according to the waste management law.

• Journal of the Korean Geotechnical Society
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• v.15 no.2
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• pp.43-71
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• 1999

This research is an experimental work of developing a construction material using municipal wastewater sludge as liner and cover materials for waste disposal landfill. Weathered granite soil and flyash, produced as a by-product in the power plant, were used as the primary additives to improve geotechnical engineering properties of sludge. For secondary additives, bentonite and cement were mixed with sludge to decrease the permeability and to increase the shear strength, respectively. Various laboratory test required to evaluate the design criteria for liner and cover materials, were carried out by changing the mixing ratio of sludge with the additives. Basic soil properties such as specific gravity, grain size distribution, liquid and plastic limits were measured to analyze their effects on permeability, compaction, compressibility and shear strength properties of mixtures. Laboratory compaction tests were conducted to find the maximum dry densities and the optimum moisture contents of mixtures, and their effectiveness of compaction in field was consequently evaluated. Permeability tests of variable heads with compacted samples, and the stress-controlled consolidation tests with measuring permeabilities of samples during consolidation process were performed to obtain permeability, and to find the compressibility as well as consolidational coefficients of mixtures, respectively. To evaluate the long term stability of sludges, creep tests were also conducted in parallel with permeability tests of variable heads. On the other hand, for the compacted sludge decomposed for a month, permeability tests were carried out to investigate the effect of decomposition of organic matters in sludges on its permeability. Direct shear tests were performed to evaluate the shear strength parameters of mixed sludge with weathered granite, flyash and bentonite. For the mixture of sludge with cement, unconfined compression tests were carried out to find their strength with varying mixing ratio and curing time. On the other hand, CBR tests for compacted specimen were also conducted to evaluate the trafficability of mixtures. Various test results with mixtures were assessed to evaluate whether their properties meet the requirements as liner and cover materials in waste disposal landfill.

• Journal of the Korean Geosynthetics Society
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• v.7 no.2
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• pp.49-52
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• 2008

Most of waste sludge has generally been disposed in landfill site or dumped in the ocean, which will be banned by the content of its heavy metals according to London Dumping Convention in Korea. Therefore, environmentally friend methods are urgently required for the treatment and disposal of the sewage sludge. Thermal hydrolysis is one of the good treatment methods to solve the sludge problems. In this study, the physical and environmental testing was conducted to evaluate the feasibility of by-product cake from the thermal hydrolysis as liner or cover materials in landfill.

• Journal of the Korean GEO-environmental Society
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• v.4 no.4
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• pp.25-34
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• 2003

This paper is focused on an experimental study in order to investigate the utilization of sewage sludge ash as the cover and liner materials for the waste disposal landfill or as construction materials. A series of tests were performed to evaluate the basic properties, compaction, compressive strength, consolidation, permeability, and CBR of sewage ash. Specially, clay bricks were made as increasing replacement ratio of sewage ash (such as 5, 10, 15, 20, 25, 30%). And tests were fulfilled for its quality. Bentonite and lime were used as the additives to improve permeability properties of sewage sludge ash. As a result of tests, it was shown that the permeability coefficient decreases as increasing bentonite content and the percentage of bentonite was roughly needed 20% to keep the permeability coefficient below $1{\times}10^{-7}cm/sec$. The results of unconfined compression tests show that sewage ash meets the criteria of the unconfined compression strength for cover material. It was shown that the compressive strength decreases as increasing the replacement ratio of sewage sludge ash and the maximum replacement ratio of sewage sludge ash to satisfy the quality standards of the third degree bricks was about 15%.

• The Journal of Engineering Geology
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• v.26 no.1
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• pp.79-85
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• 2016

A concrete silo plays an important role in subsurface low- and intermediate-level waste facilities (LILW) by limiting the release of radionuclides from the silo geosphere. However, due to several physical and chemical processes the performance of the concrete structure decreases over time and consequently the concrete loses its effectiveness as a barrier against groundwater inflow and the release of radionuclides. Although a number of processes are responsible for degradation of the silo concrete, it is determined that the main cause is corrosion of the reinforcing steel. Therefore, the time it takes for the silo concrete to fail is calculated based on two factors: the initiation time of corrosion, defined as the time it takes for chloride ions to penetrate through the concrete cover, and the propagation time of corrosion. This paper aims to estimate the time taken for concrete to fail in a LILW disposal facility. Based on the United States Department of Energy (DOE) approach, which indicates that concrete fails completely once 50% of the volume of the reinforcing steel corrodes, the corrosion propagation time is calculated to be 640 years, which is the time it takes for corrosion to penetrate 0.640 cm into the reinforcing steel. In addition to the corrosion propagation time, a diffusion equation is used to calculate the initiation time of corrosion, yielding a time of 1284 years, which post-dates the closure time of the LILW disposal facility if we also consider the 640 years of corrosion propagation. The electrochemical conditions of the passive rebar surface were modified using an acceleration method. This is a useful approach because it can reduce the test time significantly by accelerating the transport of chlorides. Using instrumental analysis, the physicochemical properties of corrosion products were determined, thereby confirming that corrosion occurred, although we did not observe significant cracks in, or expansion of, the concrete. These results are consistent with those of Smartet al., 2006 who reported that corrosion products are easily compressed, meaning that cracks cannot be discerned by eye. Therefore, it is worth noting that rebar corrosion does not strongly influence the hydraulic conductivity of the concrete.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.4 no.1
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• pp.87-93
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• 2006

Inventories, and characteristics such as dimension, fuel rod array, weight, $^{235}U$ enrichment, and discharge burnup of spent nuclear fuel (SNF) generated from existing and planed nuclear power plants based on National 2nd Basic Plan for Electric Power Demand and Supply were investigated and projected to support geological disposal system design. The historical and projected inventory by the end 2057 is expected to be 20,500 and 14,800MTU for PWR and CANDU spent nuclear fuel, respectively. The quantity of SNF with initial $^{235}U$ enrichment of 4.5 wt.% and below was shown to be 96.5% in total. Average burnup of SNF revealed $\sim36$ GWD/MTU and $\sim40$ GWD/MTU for the period of 1994-1999 and 2000-2003, respectively. It is expected that the average burnup of SNF will be $\sim45$ GWD/MTU at the end of 2000's. From the comprehensive study, it was concluded that the imaginary SNF with $16\times16$ Korean Standard Fuel Assembly, cross section of $21.4cm\times21.4cm$, length of 453cm, mass of 672 kg, initial $^{235}U$ enrichment of 4.5 wt.%, discharge burnup of 55 GWD/MTU could cover almost all SNFs to be produced by 2057.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.46 no.4
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• pp.85-92
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• 2014

The disposal of the paper mill sludge and the paper mill sludge ash become more important issue, because the environment regulation becomes more strict. In this study, the new mulching system was developed by using the paper sludge ash. The soil surface hardening mechanism for mulching with paper sludge ash, red clay and coal ash was evaluated. Since the CaO in the paper sludge ash provided the harden structure with water, the surface hardening mulching structure could cover the field surface and prevent the germination of weeds. More than 50 w.t.% of red clay and 10 w.t.% of paper sludge ash were required to create the solid soil surface structure for mulching. The field test with the new soil surface hardening mulching system for three months showed the generation of weeds could successfully be inhibited by the system.