Wooyong Um

This paper evaluates the efficacy of magnesium potassium phosphate cements (MKPCs) as waste formsfor the solidification of radioactive concrete powder wastes produced by the decommissioning of nuclearpower plants. MKPC specimens that contained up to 50 wt% of simulated concrete powder wastes(SCPWs) were evaluated. We measured the porosity and compressive strength of the MKPC specimens,observing them using scanning electron microscopy and X-ray diffraction. The addition of SCPWsreduced the porosi

This study presents a method to solidify spent ion-exchange resin (IER) in a metakaolin-based geopolymer and shows results of mechanical strength, immersion, leaching, irradiation, and thermal cycling tests for waste acceptance criteria (WAC) to repository. The geopolymer waste form with 20 wt% of simulated spent IER met the WAC in South Korea (ROK), and the leaching tests of various sized-waste forms up to 15.0 30.0 cm and waste loadings up to 20 wt% for 1e5 d and 1e90 d achieved a leachabilit

원자력 발전소 중대사고에 의해 방사성 세슘(137Cs)이 지하수계로 유출될 경우를 가정하여, 연구지역의 깊이에 따른 암석매질의 특성을 규명하고 세슘의 흡착계수를 정량적으로 평가하였다. 대상지역인 신고리 원전 3, 4호기의 지하 암석매질은 주로 석영 및 장석류로 이루어진 화강암 계열이며, 운모류를 10∼20% 함유하고 있다. 비교적 얕은 심도(6.3∼7.4 m)의 파쇄대에서 2차 광물인 녹니석이 일부 포함되어 있었지만, 기반암에서는 거의 발견되지 않았다. 137Cs의 흡착분배계수(Kd)는 파쇄대 지역에서 약 880∼960 mL/g로 기반암 지역에서의 820∼840 mL/g보다 비교적 높게 나타났으며, 이는 파쇄대에 포함되어 있는 풍화생성물인 2차 광물들에 의한 영향으로 판단된다. 따라서 137Cs이 지하 매질로 유출될 경우 대부분은 천부 지역에 흡착되어 세슘에 의한 오염 확산 속도가 지연될 것이라고 예상되며, 이러한 결과는 원자력 발전소 안정성 평가인자 자료로 활용될 것으로 기대된다.

Decontamination techniques proposed and used to remove Chalk River unidentified deposit (CRUD) inradioactive waste management. In cases of huge volumes of metal or radionuclides contaminated byCRUD, removal of CRUD by mechanical or chemical decontamination is difficult. An advancedelectrokinetic process combined with chemical decontamination was applied to remove CRUD andexperimentally evaluated. Oxalic acid was used for CRUD removal, and cobalt (Co) released from theCRUD was transferred to the

Oxyapatite[Ca2Nd8(SiO4)6O2] glass-ceramics have been suggested as wasteforms for the immobilisationof rare-earth radioactive nuclides because of their high waste-loading capability and good chemicaldurability. In particular, a partitioning effect is predicted to contribute to an enhancement of corrosionresistance in glass-ceramics compared with that of conjugate glasses of the same composition. Becauserare-earths are inherently insoluble nuclides, detection of changes in corrosion behavior betwe

A robust approach was conducted to determining the absolute oral bioavailable (fab) fractions of 238U and 232Th in rats exposed to contaminated soil along with their hematotoxicity and nephrotoxicity. The soil sample is the International Atomic Energy Agency-312 (IAEA-312) certified reference material, whereas blood, bones, and kidneys of in vivo female Sprague-Dawley (SD) rats estimate 238U- and 232Th-fab fractions post-exposure. We predict the bioavailable concentration (Cab) and fab values of

본 연구에서는 원자력 시설물에 존재하는 핵종의 의도치 않은 유출사고를 대비하기 위해서 세 가지 대표 핵종(60Co, 137Cs, 125Sb)을 원자력 시설물 지역에서 채취한 시료와 반응하여 핵종들의 흡착 및 거동 특성을 조사하였다. 가장 높은 흡착계수 값들은 (60Co=947 mL/g, 137Cs=2105 mL/g, 125Sb=81.3 mL/g) 지하수 환경일 때 상부토층 시료에서 나타났으며, 파쇄대 > 기반암 시료의 순으로 Kd 값이 감소하였다. 상부토층과 파쇄대에서 60Co의 높은 흡착계수는 상부토층 및 파쇄대에 존재하는 점토광물에 의한 것으로 사료되며, 해수 조건에서는 높은 이온강도로 인해서 Kd 값은 약 58 – 69% 감소하였다. 137Cs의 흡착은 주로 백운모의 Flayed edge site (FES)에서 K+과의 이온교환 반응에 의한 것으로 사료된다. 137Cs의 흡착이 해수 조건에서 가장 크게 영향을 받으며 (89 – 97 % 감소), 125Sb은 대표핵종 중 해수에

A novel integrated modified sulfur cycle and ammonia production process was suggested for the co-generation of sulfuric acid. Exergy analysis, heat integration, and safety assessment were conducted to investigate the feasibility and analyze the process. The exergy analysis showed that the highest exergy destruction occurred in the section with the most considerable temperature difference involved with a large flow rate. The heat integration - an economic assessment, confirmed that the total cost

The thermal stability and crystallization behaviors of La2O3 containing B2O3-CaOeAl2O3 glass wasteforms were investigated to evaluate the stability of waste form during emergencies in deep geologicaldisposal. For glasses containing 15% La2O3, LaBO3 phases were observed as major crystals from 780 Cand exhibited needlelike structures. Al, Ca, and O were homogeneously distributed throughout the entirespecimen, while some portions of B and La were concentrated in some parts. By differential thermala

Uranium (U), an essential source for nuclear energy production, poses serious environmental and radiological threat due to its high mobility and long half-life. Uranophane [Ca(UO2 )2 SiO3 (OH)2 ·5H2 O], a secondary U silicate mineral, is known as a solubility-limiting phase in U mining deposits and nuclear waste repositories (controlling U immobilization). However, research on uranophane dissolution, particularly under the influence of organic and inorganic ligands, remains lacking. This study i

The exposure of long-lived radionuclides is extremely hazardous to the living organism and environments. Radionuclides can be broadly divided into α, β, and/or γ emitter, all of which exhibit diverse chemistry/chemical properties, and therefore, require diff erent analytical tools/techniques for their measurements in the defi ned samples. In this review, we discuss the major progress in chemistry and analysis of α, β, and γ emitting radionuclides. More specifi cally, we focus on uranium-238 ( 23

Two waste forms, namely cement and geopolymer, were investigated and tested in this study to solidify the corrosive sludge generated from the surface and precipitates of the tubes of steam generators in nuclear power plants. The compressive strength of the cement waste form cured for 28 days was inversely proportional to waste loading (24.4 MPa for 0wt% to 2.7 MPa for 60wt%). The corrosive sludge absorbed the free water in the hydration reaction to decrease the cementation reaction. When the cor

Radioactive iodine isotopes (129I and 131I) from spent nuclear fuel pose significant environmental risks due to high radioactivity and mobility in aqueous systems. This study embedded NiAl Layered Double Hydroxide (LDH) within sodium alginate and poly vinyl alcohol matrices by crosslinking with CaCl2 to fabricate bead-type sorbents for I– removal. XRD and FT-IR analyses confirmed that the crystallinity of NiAl LDH was retained within the beads, indicating structural stability. However, the sorpt

The decommissioning of a nuclear power plant generates large amounts of radioactive waste, which is of several types. Radioactive concrete powder is classified as low-level waste, which can be disposed of in a landfill. However, its safe disposal in a landfill requires that it be immobilized by solidification using cement. Herein, a safety assessment on the disposal of solidified radioactive concrete powder waste in a conceptual landfill site is performed using RESRAD. Furthermore, sensitivity a