• Nuclear Engineering and Technology
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• 제51권3호
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• pp.755-760
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• 2019

Compound samples based on the mineral-like magnesium potassium phosphate matrix $MgKPO_4{\times}6H_2O$ were synthesized by solidification of high level waste surrogate. Phase composition and structure of synthesized samples were studied by XRD and SEM methods. Compressive strength of the compounds is $12{\pm}3MPa$. Coefficient of thermal expansion of the samples in the range $250-550^{\circ}C$ is $(11.6{\pm}0.3){\times}10^{-6}1/^{\circ}C$, and coefficient of thermal conductivity in the range $20-500^{\circ}C$ is $0.5W/(m{\times}K)$. Differential leaching rate of elements from the compound, $g/(cm^2{\times}day)$: $Mg-6.7{\times}10^{-6}$, $K-3.0{\times}10^{-4}$, $P-1.2{\times}10^{-4}$, $^{137}Cs-4.6{\times}10^{-7}$; $^{90}Sr-9.6{\times}10^{-7}$; $^{239}Pu-3.7{\times}10^{-9}$, $^{241}Am-9.6{\times}10^{-10}$. Leaching mechanism of radionuclides from the samples at the first 1-2 weeks of the leaching test is determined by dissolution ($^{137}Cs$), wash off ($^{90}Sr$) or diffusion ($^{239}Pu$ and $^{241}Am$) from the compound surface, and when the tests continue to 90-91 days - by surface layer depletion of compound. Since the composition and physico-chemical properties of the compound after irradiation with an electron beam (absorbed dose of 1 MGy) are constant the radiation resistance of compound was established.

• Nuclear Engineering and Technology
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• 제7권3호
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• pp.213-222
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• 1975

알카리로 처리한 국산 blown asphalt를 사용해서 방사성 폐액을 180-20$0^{\circ}C$ 범위 내에서 고화처리한 것이 산처리 한것보다 좋은 결과를 얻었으며, 방사선 조사선량이 4.0$\times$$10^{7}$ rad까지도 안정된 고화체로 존재하고 있다. 한편 40wt%의 고형분이 함유되어 있는 $^{137}$Cs-asphalt 고화체의 증류수에 의한 $^{137}$Cs의 용출율이 8.27$\times$$10^{-4}$ g/$\textrm{cm}^2$-day 인데 반하여 $^{90}$ Sr은 낮았으며, 일반적으로 증류수보다 해수때가 또한 pH가 증가함에 따라 용출율은 낮아진다.

• 한국초지조사료학회지
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• 제26권4호
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• pp.177-186
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• 2006

본 연구는 가축분뇨의 종류와 시용수준에 따른 사일리지용 옥수수의 생산성과 N과 P의 용탈량을 조사하여 친환경 조사료 생산을 위한 기초자료를 제공하기 위해 수행되었다. 본 시험은 건국대학교 초지 시험포장 내의 사양토로 충전된 Lysimeter(직경 30cm, 깊이 1m)를 이용하여 화학비료, 우분액비 및 톱밥발효돈분에 대하여, N 시용수준을 100kg/ha, 200kg/ha, 400kg/ha씩으로 시험구를 배치 수행하였다. 옥수수 건물 및 질소 생산성은 화학비료>우분액비>톱밥발효돈분 순이었고(p<0.05), 시용수준이 증가함에 따라 그 생산성도 증가하는 경향을 나타냈다(p<0.05). 옥수수의 조단백질 함량은 화학비료>톱밥발효돈분>우분액비 순이었으나 시용수준이 증가함에 따라 조단백질 함량은 증가하는 경향으로 나타났다. 분뇨시용 형태별 용탈수 중의 $NO_{3^-}N$ 함량은 톱밥발효돈분>화학비료>우분액비 순이었으며(p<0.05), $NH_{4^-}N$ 함량은 큰 차이를 보이지 않았고, 질소시용수준이 증가함에 따라 비례하여 증가하는 경향을 나타냈다. 그러나 결코 1 mg/L을 상회하지는 않았다. 가축분뇨의 시용형태별 평균 $PO_{4^-}P$ 농도는 톱밥발효돈분>화학비료>우분액비 순이었고 시용수준이 증가함에 따라 유의적으로 증가하였지만(p<0.05), 용탈량은 매우 적었다.

• 한국방사성폐기물학회:학술대회논문집
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• 한국방사성폐기물학회 2008년도 학술논문요약집
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• pp.51-52
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• 2008

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 2005년도 춘계학술발표회
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• pp.229-230
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• 2005

• 한국방사성폐기물학회:학술대회논문집
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• 한국방사성폐기물학회 2004년도 Proceedings of the 4th Korea-China Joint Workshop on Nuclear Waste Management
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• pp.83-95
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• 2004

The removal efficiency of several washing agents on the $Cs^+$ ion was investigated. Leaching of $Cs^+$ ion from the soil surface by washing agents is affected by the exchange capability of the washing solution. Reuse tests of the effective soil washing agents such as $BaCl_2$, NaOH, citric acid＋ $HNO_3$ and oxalic acid were performed. NaOH, citric acid ＋ $HNO_3$ and oxalic acid solutions can be reused after passing through the ion exchange column. Among the tested solutions, both of citric acid＋ $HNO_3$ and oxalic acid were effective for the decontamination of TRIGA research reactor soil. The radioactivity of soils can be reduced to a release level by the successive application.

• Nuclear Engineering and Technology
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• 제53권12호
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• pp.3952-3965
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• 2021

In this study, volcanic ash was used as raw material to prepare waste forms with different silicon/aluminum (Si/Al) molar ratios to immobilize sodium-salt waste (SSW) containing simulated ¹³⁷Cs. Effects of Si/Al molar ratios (3:1 and 2:1) and sodium salts on sintering behavior of waste forms and immobilization mechanism of Cs⁺ were investigated. Results indicated that the main mineral phase of sintered waste-form matrixes was albite, and the formation of major phases was found to depend on Si/Al molar ratios. Si/Al molar ratio of 2 was favorable for the formation of pollucite, and the formation and crystallization of mineral phases were also decided based on physicochemical characteristics of sodium salts. Furthermore, product consistency test results indicated that the immobilization of Cs⁺ was related to Si/Al molar ratio, types of sodium salts, and glassy phase. Waste forms with Si/Al molar ratio of 2 exhibited better ability to immobilize Cs⁺, whereas the influence of sodium salts and glassy phases on the immobilization of SSW showed more complicated relationship. In waste forms with Si/Al molar ratio of 2, Cs⁺ leaching concentrations of samples containing Na₂B₄O₇·10H₂O and NaOH were low. Na₂B₄O₇·10H₂O easily transformed into liquid phase during sintering to consequently achieve low temperature liquid-phase sintering, which is beneficial to avoid the volatilization of Cs⁺ at high temperature. Results clearly reveal that waste forms with Si/Al molar ratio of 2 and containing Na₂B₄O₇·10H₂O show excellent immobilization of Cs⁺.

• 한국초지조사료학회지
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• 제22권2호
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• pp.85-92
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• 2002

본 연구는 lysimeter에서 돈분액비, 톱밥발효 돈분 및 화학비료를 각각 100, 200, 400kg/ha 수준으로 시용하였을 때 옥수수의 생산성, 질소의 이용효율 및 N $O_3^{-}$와 P 용탈에 의한 환경 오염에 미치는 영향을 정확히 규명, 가축분뇨의 자원화는 물론 가축분뇨에 의한 환경오염 방지대책 수립을 위한 기초자료를 제공하고자 수행되었으며 그 연구결과는 다음과 같다. 1. 옥수수의 건물수량은 돈분액비, 톱밥발효 돈분 및 화학비료 모두 시용수준과 비례하여 증가하는 경향을 보였으며, 화학비료> 돈분액비 > 톱밥발쵸돈분의 순으로 높은 경향을 나타내었다. 2. 돈분액비, 톱밥발효돈분 및 화학비료 시용구간 silage용 옥수수의 질소 함량은 화학비료 > 돈분액비 > 톱밥발효돈분 순으로 높았고, 시용수준과 비례하여 증가되는 경향을 보였다. 3. $NO_3^{-}$와 P의 용탈량은 돈분액비, 톱밥발효 돈분 및 화학비료 모두 시용수준과 비례하여 증가하였으며 계절적으로는 $NO_3^{-}$는 단지 시험초기 집중호우기에 높은 용탈량을 나타낸 반면 P는 강우시마다 지속적으로 높은 경향을 보여주었고, $NO_3^{-}$와 P의 최고 용탈량은 각각 14.8ppm과 0.26ppm이었다.

• Nuclear Engineering and Technology
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• 제55권4호
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• pp.1300-1309
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• 2023

Simulated debris was synthesized using UO₂, Zr, and stainless steel and a heat treatment method under inert or oxidizing conditions. The primary U solid phase of the debris synthesized at 1473 K under inert conditions was UO₂, whereas a (U, Zr)O₂ solid solution formed at 1873 K. Under oxidizing conditions, a mixture of U₃O₈ and (Fe, Cr)UO₄ phases formed at 1473 K, whereas a (U, Zr)O_2+x solid solution formed at 1873 K. The leaching behavior of the fission products from the simulated debris was evaluated using two methods: the irradiation method, for which fission products were produced via neutron irradiation, and the doping method, for which trace amounts of non-radioactive elements were doped into the debris. The dissolution behavior of U depended on the properties of the debris and aqueous solution for immersion. Cs, Sr, and Ba leached out regardless of the primary solid phases. The leaching of high-valence Eu and Ru ions was suppressed, possibly owing to their solid-solution reaction with or incorporation into the uranium compounds of the simulated debris.

• Nuclear Engineering and Technology
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• 제54권9호
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• pp.3250-3259
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• 2022

A new approach to the use of rice straw as a difficult-to-recycle agricultural waste was proposed. Potassium aluminosilicate was obtained by spark plasma sintering as an effective material for subsequent immobilization of ¹³⁷Cs into a solid-state matrix. The sorption properties of potassium aluminosilicate to ¹³⁷Cs from aqueous solutions were studied. The effect of the synthesis temperature on the phase composition, microstructure, and rate of cesium leaching from samples obtained at 800-1000 ℃ and a pressure of 25 MPa was investigated. It was shown that the positive dynamics of compaction was characteristic of glass ceramics throughout the sintering. Glass ceramics RS-(K,Cs)AlSi₃O₈ obtained by the SPS method at 1000 ℃ for 5 min was characterized by a high density of ~2.62 g/cm³, Vickers hardness ~ 2.1 GPa, compressive strength ~231.3 MPa and the rate of cesium ions leaching of ~1.37 × 10^-7 g cm^-2·day^-1. The proposed approach makes it possible to safe dispose of rice straw and reduce emissions into the atmosphere of microdisperse amorphous silica, which is formed during its combustion and causes respiratory diseases, including cancer. In addition, the obtained is perspective to solve the problem of recycling long-lived ¹³⁷Cs radionuclides formed during the operation of nuclear power plants into solid-state matrices.