• Nuclear Engineering and Technology
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• v.54 no.10
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• pp.3957-3961
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• 2022

Deposition behaviors of Sr and Cs in various liquid cathodes, such as Zn, Bi, Cd, and Pb, were examined to evaluate their recovery from LiCl-KCl eutectic salt. Cations in the salt were deposited on the liquid cathode, exhibiting potential of -1.8 to -2.1 V (vs. Ag/AgCl). Zn cathode had successful deposition of Sr and exhibited the highest recovery efficiency, up to 55%. Meanwhile, the other liquid cathodes showed low current efficiencies, below 18%, indicating LiCl-KCl salt decomposition. Sr was recovered from the Zn cathode as irregular rectangular SrZn₁₃ particles. A negligible amount of Cs was deposited on the entire liquid cathode, indicating that Cs was hardly deposited on liquid cathodes. Based on these results, we propose that liquid Zn cathode can be used for cleaning Sr in LiCl-KCl salt.

• Nuclear Engineering and Technology
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• v.52 no.1
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• pp.115-122
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• 2020

A promising method for removal of Cs ions from water and their incorporation into stable crystal structure ready for safe and permanent disposal was described. Cs-exchanged X zeolite was hot-pressed at temperature ranging from 800 to 950 ℃ to fabricate dense pollucite ceramics. It was found that the application of external pressure reduced the pollucite formation temperature. The effect of sintering temperature on density, phase composition and mechanical properties was investigated. The highest density of 92.5 %TD and the highest compressive strength of 79 MPa were measured in pollucite hot-pressed at 950 ℃ for 3 h. Heterogeneity of samples obtained at 950 ℃ was determined using scanning electron microscopy. The pollucite hot-pressed at 950 ℃ had low linear thermal expansion coefficient of ~4.67 × 10^-6 K^-1 in the temperature range from 100 to 1000 ℃.

• Journal of the Korea Institute of Military Science and Technology
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• v.13 no.6
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• pp.1147-1152
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• 2010

This paper reports a safe and environmentally-benign demilitarization method for the K305 35mm CS gas grenades launcher set(also known as E-8 launcher). The launcher system was disposed by a two-step process; complete recovery of the explosive cords and the gas grenades from the launcher followed by incineration of the recovered items in the APE-1236 Flashing Furnace. All of the 64 grenades within the 16 tubes of the E-8 launcher were safely recovered and incinerated. In this study, 32 sets of the launcher were used to make a standard operating procedure for the safe demilitarization of the launcher system and the 35mm CS cartridges were all safely destroyed in the experimental burning tests meeting the related environmental regulations.

• Nuclear Engineering and Technology
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• v.33 no.2
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• pp.231-240
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• 2001

When it is assumed that PWR, CANDU and DUPIC spent fuels are disposed of in deep geological repository, consequent annual individual doses are calculated, and it is shown that doses meet the regulatory limit. From these results, the hazardous radionuclides applicable to partitioning and transmutation are selected. These selected radionuclides such as Tc-99, Ⅰ-129, Cs-135 and Np-237 are then reviewed in terms of partitioning and transmutation. Separation of I-129, Np-237 and Tc-99 from spent fuels is considered desirable, and transmutation of these radionuclides results in remarkable hazard reduction. However, it is concluded that separation and transmutation of Cs-135 may be ineffective although it is classified into a hazardous radionuclide.

• Nuclear Engineering and Technology
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• v.27 no.1
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• pp.25-32
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• 1995

Batch sorption experiments were conducted to investigate the sorption characteristics of $^{137}$ Cs, known for the primary target of safety assessment in low-level radwaste disposal, onto domestic rocks such as Granite and Tuff. A response surface analysis method was applied to quantify the effect of 3 independent variables (［Cs］, ［Vol/Wt］, ［pH］) on the sorption. Ac a result, initial Cs concentration appeared to be the most important variable within the range of the study. A significant effect of ［Vol/Wt］ on Kd was observed. The sorption of Cs was pH-insignificant. The sorption extent of nuclides onto tuff was more significant than that onto granite. The pH-insignificant sorption behavior of Cs was discussed in terms of the surface electrical properties and the solution chemistry. The sorption tendency of nuclides onto geomedia studied was interpreted by adopting the water structure modification theory.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2017.10a
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• pp.153-154
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• 2017

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2017.10a
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• pp.157-158
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• 2017

• Nuclear Engineering and Technology
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• v.10 no.3
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• pp.153-163
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• 1978

The problems of solid waste disposal into the ground in connection with environmental aspects in the vicinity of a site would be very significant, though ground disposal for solid waste is safe and economical method. Studies of the waste-movement and migration of radionuclides (Sr-90 and Cs-137) for the disposal into the ground were performed under laboratory and field conditions. Affinity of the soils for radionuclide solution was higher than that in the acid solution. The sorption of radionuclides by the soils showed a time-dependent reation. The migration rates of radiostrontium and radiocesium were a range of 3.73$\times$10$^{-3}$ to 10.9$\times$10$^{-3}$ cm/day. The nuclides in the soil migrate much more slowly than the water, probably due to its high exchange capacity. The observed distribution of tritium was compared with that calculated by a mathematical model based on diffusivity. This study suggests that the tritiated water can be used to trace the movement of ground water.

• Nuclear Engineering and Technology
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• v.35 no.5
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• pp.387-398
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• 2003

For reference human intrusion scenarios constructed in previous study, a probabilistic safety assessment to derive the radionuclide concentration limits for the low- and intermediate- level radioactive waste disposal facility is conducted. Statistical approach by the Latin Hypercube Sampling method is introduced and new assumptions about the disposal facility system are examined and discussed. In our previous study of deterministic approach, the post construction scenarios appeared as most limiting scenario to derive the radionuclide concentration limits. Whereas, in this statistical approach, the post drilling and the post construction scenarios are mutually competing for the scenario selection according to which radionuclides are more important in safety assessment context. Introduction of new assumption shows that the post drilling scenario can play an important role as the limiting scenario instead of the post-construction scenario. When we compare the concentration limits between the previous and this study, concentrations of radionuclides such as Nb-94, Cs-137 and alpha-emitting radionuclides show elevated values than the case of the previous study. Remaining radionuclides such as Sr-90, Tc-99 I-129, Ni-59 and Ni-63 show lower values than the case of the previous study.

• Journal of Soil and Groundwater Environment
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• v.26 no.5
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• pp.29-38
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• 2021

This study investigated the mineralogical properties of bentonite and illite and evaluated the Cs sorption at various concentrations (C_w≈1-10⁵ ㎍/L). Bentonite samples, collected from South Korea and USA, majorly consisted of Ca- and Na-montmorillonite, showed large cation exchange capacity (CEC, 91.4 and 47.3 meq/100 g) and specific surface area (SSA, 46.1 and 39.7 m²/g). In contrast, illite sample (USA) had relatively low values for 14.4 meq/100g of CEC and 29.3 m²/g of SSA, respectively. Bentonite and illite had different non-linear sorption for Cs along with C_w. At low C_w<10 ㎍/L, illite showed higher sorption capacity than bentonite despite low CEC because of the existence of specific sorption sites at the weathered mineral edge. However, as C_w increased, bentonite represented high sorption capacity because the cation exchange between Cs and interlayer cations was effective at high C_w conditions. These results implicated that the Cs concentration is important to evaluate the sorption performance of bentonite and illite. Finally, the Cuadros' kinetic model for illitization using various K concentrations (2×10^-5 and 1.7×10^-3 mol/L) and temperature (100-200℃) showed that up to 50% of the montmorillonite in bentonite could be converted to illite, suggesting that the illitization should be considered to evaluate the sorption performance of the bentonite in deep geological disposal repository.