• Proceedings of the Korean Nuclear Society Conference
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• 2001.10a
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• pp.149-149
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• 2001

• Proceedings of the Korean Nuclear Society Conference
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• 1998.10a
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• pp.180-180
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• 1998

• Proceedings of the Korean Nuclear Society Conference
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• 2001.10a
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• pp.150-150
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• 2001

• Nuclear Engineering and Technology
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• v.34 no.4
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• pp.344-357
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• 2002

The present paper reports spontaneous steam explosions observed in fuel coolant interaction experiments using prototypic reactor materials. Pure ZrO$_2$ and a mixture of UO$_2$ and ZrO$_2$ are used. A high temperature molten material in the form of a jet is poured into a subcooled water pool located in a pressure vessel. An induction skull melting technique is used for the melting of the reactor material. In both tests using pure ZrO$_2$ and a mixture of UO$_2$ and ZrO$_2$, either a quenching or a spontaneous steam explosion was observed. The morphology of debris and pressure profile clearly indicate the differences between the qunching cases and explosion cases. The dynamic pressure. dynamic impulse, water temperature, melt temperature, and static pressure Inside the containment chamber were measured . As the spontaneous steam explosion for the reactor material is firstly observed in the present experiments, the results of present experiments could be a siginificant step forward the understanding the explosion of the reactor material.

• Journal of the Korean Chemical Society
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• v.54 no.4
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• pp.395-401
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• 2010

A series of macrocyclic complexes of the type [M(L/L')$(NO_3)_n$].$mH_2O$ and [VO(L/L')($SO_4$)].$2H_2O$, where L/L' is a Schiff base "3,4,10,11-tetraphenyl/tetramethyl-1,2,5,6,8,9,12,13-octaaza cyclotetradeca-2,4,9,11-tetraene-7,14-dithione" derived from thiocarbohydrazide (TCH), benzilmonohydrazone (BMH)/diacetylmonohydrazone (DMH) and carbon disulphide, M = $UO_2$ (VI), Th(IV) and ZrO(IV), n = 2, 4, m = 2, 3, have been synthesized via metal ion template methods. The complexes are characterized on the basis of elemental analysis, thermal analysis, molar conductivity, magnetic moment, electronic, infrared and $^1H$-NMR spectral studies. The ESR and cyclic voltammetry studies of the vanadyl complexes have been carried out. The results indicate that the VO(IV) ion is penta-coordinated yielding paramagnetic complexes; $UO_2$(VI) and ZrO(IV) ions are hexacoordinated where as Th(IV) ion is octa-coordinated yielding diamagnetic complexes of above composition.

• Journal of the Korean Chemical Society
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• v.55 no.2
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• pp.317-322
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• 2011

• Journal of the Mineralogical Society of Korea
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• v.15 no.1
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• pp.78-84
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• 2002

New pyrochlore-type phases($A_2$$B_2$$O_{7}$) were synthesized in the systems: CaO-C$eO_2$-T$iO_2$, CaO-$UO_2$(T$hO_2$)-Z$rO_2$, CaO-$UO_2$(T$hO_2$)-$Gd_2$$O_3$-T$iO_2$-Z$rO_2$, 및 CaO-T$hO_2$-S$nO_2$. The starting materials were pressed with the pressure of 200~400 MPa and sintered at 1500~ 155$0^{\circ}C$ for 4~8 hours in air and at 1300~ 135$0^{\circ}C$ for 5 ~50 hours under oxygen atmosphere. The products were characterized using XRD, SEM/EDS and TEM. In the bulk compositions of CaCe$Ti_2$$O_{7}$, CaTh$Zr_2$$O_{7}$,($Ca_{0.5}$ Gd$Th_{0.5}$)(ZrTi)$O_{7}$) ($Ca_{0.5}$Gd$Th_{0.5}$)(ZrTi)$O_{7}$, ($Ca_{0.5}$G$dU_{0.5}$)(ZrTi)$O_{7}$ and CaTh$Sn_2$$O_{7}$ , pyrochlore was the major phase, together with other oxide phase $of_2$$O_{7}$ fluorite structure. In the samples with target compositions CaU$Zr_2$$O_2$및 $Ca_{0.5}$ G$dU_{0.5}$)$Zr_2$T$iO_{7}$ pyrochlore was not identified, but a fluorite-structured phase was detected. The formation factor as the stable phase depended on crystal chemical characteristics of the actinide and lanthanide elements of the system concerned.

• Journal of the Korean Chemical Society
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• v.52 no.5
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• pp.468-475
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• 2008

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.11a
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• pp.119-119
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• 2003

탄화규소나 열분해 탄소는 고온 특성 및 화학적인 안정성 이 우수하여 단미 혹은 코팅재로로 소재의 성능을 향상시키기 위하여 에너지 관련 분야, 반도체 치구 분야, 방위산업 및 항공우주 분야와 원자력 분야에서 다양하게 사용된다. 특히 원자력 분야에서는 고온형 원자로의 노심 요소 부품으로 적용 및 개발을 고려하고 있으며, 대표적인 예로 수소생산용 초고온 가스냉각로의 코팅 핵연료 입자를 들 수 있다. 일반적으로 TRISO라 불리는 가스냉각로 핵연료는 구형 $UO_2$ kemel의 주변을 PyC-SiC -PyC의 삼중 코팅층으로 둘러싸는 구조를 하고 있으며, 이 코팅층들은 kernel물질이 분열하는 동안 발생되는 내부 기체 압력을 견디는 압력용기 역할과 기체나 금속 핵분열 생성물들을 가두는 확산 장벽 역할을 하게 된다. 본 연구에서는 구형의 $UO_2$대신 선행연구를 위하여 구형 ZrO$_2$를 이용하여 증착온도나 시간 및 입력기체비 등의 화학증착 변수로 조절하여 SiC 및 PyC을 코팅하고, 각 변수들에 의한 증착층의 거동을 고찰하고자 하였다.

• Nuclear Engineering and Technology
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• v.55 no.4
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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.