• 한국세라믹학회지
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• 제52권2호
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• pp.92-102
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• 2015

Current plans for legacy nuclear wastes stored in underground tanks at the U.S. Department of Energy's Hanford Site in Washington are that they will be separated into high-level waste and low-activity waste fractions that will be vitrified separately. Formulating optimized glass compositions that maximize the waste loading in glass is critical for successful and economical treatment and immobilization of these nuclear wastes. Glass property-composition models have been developed and applied to formulate glass compositions for various objectives for the past several decades. Property models with associated uncertainties combined with composition and property constraints have been used to develop preliminary glass formulation algorithms designed for vitrification process control and waste-form qualification at the planned waste vitrification plant. This paper provides an overview of the current status of glass property-composition models, constraints applicable to Hanford waste vitrification, and glass formulation approaches that have been developed for vitrification of hazardous and highly radioactive wastes stored at the Hanford Site.

• Nuclear Engineering and Technology
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• 제48권2호
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• pp.360-367
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• 2016

A windowless spallation target can provide a neutron source and maintain neutron chain reaction for a subcritical reactor, and is a key component of China's nuclear waste transmutation of coupling accelerator and subcritical reactor. The main issue of the windowless target design is to form a stable and controllable free surface that can ensure that energy spectrum distribution is acquired for the neutron physical design when the high energy proton beam beats the lead-bismuth eutectic in the spallation target area. In this study, morphology and flow characteristics of the free surface of the windowless target were analyzed through the volume of fluid model using computational fluid dynamics simulation, and the results show that the outlet cross section size of the target is the key to form a stable and controllable free surface, as well as the outlet with an arc transition. The optimization parameter of the target design, in which the radius of outlet cross section is $60{\pm}1mm$, is verified to form a stable and controllable free surface and to reduce the formation of air bubbles. This work can function as a reference for carrying out engineering design of windowless target and for verification experiments.

• 공업화학
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• 제31권4호
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• pp.438-442
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• 2020

Calcium silicate, larnite, merwinite, akermanite 로 구성된 무해화된 폐석면으로부터 화학적 처리를 통한 유가금속 회수를 위한 성분별 회수 조건, 유가금속 회수 공정 최적화 등에 대한 연구를 수행하였다. DACW (detoxified asbestos-containing waste)의 주성분인 Si, Ca, Mg을 SiO₂, CaSO₄, Mg(OH)₂ 화합물 형태로 분리, 회수하였다. 분리된 각 성분은 XRD 및 ICP 분석을 통하여 확인하였다. 성분별 회수 조건은 산을 처리하여 SiO₂를 우선 분리하고 연속해서 H₂SO₄ 처리하여 Ca는 황산염인 CaSO₄ 형태로 회수하였다. 남은 Mg는 강염기 조건에서 Mg(OH)₂로 침전시켜 회수하였다. 본 연구는 지정 폐기물인 폐석면을 무해화하여 구성 성분을 회수 하여 매립에 의한 석면 폐기물의 기존 처리 과정을 자원 순환형 녹색 기술로의 전환이 가능함을 제시하였다.

• 방사성폐기물학회지
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• 제18권4호
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• pp.509-516
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• 2020

An important property of glass and ceramic solid waste forms is processability. Tellurite materials with low melting temperatures and high halite solubilities have potential as solid waste forms. Crystalline TiTe3O8 was synthesized through a solid-state reaction between stoichiometric amounts of TiO2 and TeO2 powder. The resultant TiTe3O8 crystal had a three-dimensional (3D) structure consisting of TiO6 octahedra and asymmetric TeO4 seesaw moiety groups. The melting temperature of the TiTe3O8 powder was 820℃, and the constituent TeO2 began to evaporate selectively from TiTe3O8 above around 840℃. The leaching rate, as determined using the modified American Society of Testing and Materials static leach test method, of Ti in the TiTe3O8 crystal was less than the order of 10-4 g·m-2·d-1 at 90℃ for durations of 14 d over a pH range of 2-12. The chemical durability of the TiTe3O8 crystal, even under highly acidic and alkaline conditions, was comparable to that of other well-known Ti-based solid waste forms.

• Advances in environmental research
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• 제5권4호
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• pp.237-249
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• 2016

The management of municipal solid waste (MSW) is essential for every community; and, it is currently a major challenge in Nigeria. This paper provides an overview of the current MSW management trends in Nigeria and proposes new sustainable MSW management systems. Across Nigerian cities, MSW management is characterized by inefficient collection and transportation to disposal sites. Collection services do not reach some unplanned areas and slums due to poor street network. Even some planned areas are not reached by collection services. The informal sector contributes to waste collection, resource recovery and recycling; however, their activities are not recognized by the governments. Markets exist for recovered materials but more efforts need to be geared towards intensive recovery of materials and expansion of these markets. Despite the high proportion of putrescible matter in MSW, the only form of treatment commonly used currently is open burning for volume reduction. The high organic fraction presents a great opportunity for composting and anaerobic digestion. Ultimate disposal is currently done in open dumpsites. This needs to be upgraded to engineered landfills that are properly sited and adequately operated by well trained personnel. There is an emerging waste stream of concern, electronic-waste (e-waste), that requires urgent sustainable management as e-waste are currently co-disposed with other waste streams or burnt in the open posing detrimental health impacts.

• 한국방사성폐기물학회:학술대회논문집
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• 한국방사성폐기물학회 2005년도 춘계 학술대회
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• pp.278-283
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• 2005

원자력 발전소에서 발생한 시멘트 또는 파라핀 고화체 중의 핵종분석을 하기 위해서는 시료의 용액화가 필요하다. 이를 위하여 산 침출법과 극초단파 산분해법을 이용하여 SRM(standard reference material)을 용액화한 다음 AAS와 ICP-AES를 사용하여 용액 속의 원소들을 분석 비교하였다. 완전 용액화가 가능한 극초단파 산분해법으로 처리한 결과와 일치하는 산 침출조건을 제안하여 많은 양의 시료를 한 번에 처리할 수 있는 산 침출법으로 방사성 고화체 시료 중의 비휘발성핵종분석을 위한 고화체 용액화 방법을 확립하였다. 방사성 고화체의 산 침출시마다 Re을 첨가하여 시료 전처리 단계에서의 회수율은 $80\%$ 이상으로 나타났다.

• 한국방사성폐기물학회:학술대회논문집
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• 한국방사성폐기물학회 2003년도 가을 학술논문집
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• pp.215-219
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• 2003

현재 국내에서 개발 중인 사용후 핵연료의 금속전환공정에서 발생이 예상되는 LiCl 염폐기물을 제올라이트로 고정화한 후 최종 고화체를 만드는 기술을 개발 중에 있다. 여러 혼합조건에 대해 고정화 생성물의 결정을 분석한 결과 모든 혼합조건에서 제올라이트 A형이 제올라이트 Li-A으로 전이되었으며, 일부 혼합조건에서는 Minor phase로 소달라이트 형도 발견되었다. 자유염 발생이 최소가 되는 혼합조건은 Cs, Sr 핵종이 포함된 LiCl 제올라이트 비가 1.0인 조건이었다.

• 방사성폐기물학회지
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• 제21권4호
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• pp.465-479
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• 2023

To ensure the safety of disposal facilities for radioactive waste, it is essential to quantitatively evaluate the performance of the waste disposal facilities by using safety assessment models. This paper addresses the development of the safety assessment model for the underground silo of Wolseong Low-and Immediate-Level Waste (LILW) disposal facility in Korea. As the simulated result, the nuclides diffused from the waste were kept inside the silo without the leakage of those while the integrity of the concrete is maintained. After the degradation of concrete, radionuclides migrate in the same direction as the groundwater flow by mainly advection mechanism. The release of radionuclides has a positive linear relationship with a half-life in the range of medium half-life. Additionally, the solidified waste form delays and reduces the migration of radionuclides through the interaction between the nuclides and the solidified medium. Herein, the phenomenon of this delay was implemented with the mass transfer coefficient of the flux node at numerical modeling. The solidification effects, which are delaying and reducing the leakage of nuclides, were maintained the integrity of the nuclides. This effect was decreased by increasing the half-life and the mass transfer coefficient of radionuclides.

• 한국방사성폐기물학회:학술대회논문집
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• 한국방사성폐기물학회 2005년도 춘계 학술대회
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• pp.284-289
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• 2005

중저준위 방사성폐기물의 핵종 관리를 포함한 안전 규제 정책에 따라 핵종 유출을 방지하고 제조된 고화체로부터 C-14의 회수율을 알고자 국내 원자력 발전소에서 발생되는 중 저준위 방사성 폐기물 중 농축폐액을 시멘트로 일정시간 고화시켜 시료를 준비하였다. 이들 시멘트 고화체는 화학적 산화법을 적용하여 C-14를 분리하였으며, 화학적 분리된 C-14는 액체섬광계수기를 이용하여 방출되는 베타선을 계측하였고, 소광보정 곡선을 이용하여 방사능을 측정하였다. 또한 원전에서 제조된 시멘트 고화체를 동일한 방법으로 C-14를 정량하였으며, 그 방사능 결과는 $2.7E+00\;{\sim}\;3.1E+02$ Bq/g의 범위로 분리 검출되었다.

• 한국환경과학회지
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• 제8권2호
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• pp.227-231
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• 1999

This study was conducted to investigate the removal characteristics of $PO_4^{3-}-P$ contained in livestock wastewater using waste concrete. With small particle size, increased dosage and temperature of water, $PO_4^{3-}-P$ was well removed by waste concrete.$PO_4^{3-}-P$ was removed by adsorption reaction in low pH of the primary phase, but the crystallization reaction predominated for increasing pH with passed time. As a result of adapting the adsorption isotherm equation, $PO_4^{3-}-P$ removal was more affected by the crystallization reaction than the adsorption reaction. In the SEM micrograph, there was no evident change on the waste concreter surface. Particle size was plate-phase before reaction but appeared a dense form to progress in the crystallization reaction.