네오듐 고용 이산화우라늄의 고온 산화거동

이재원; 강상준; 김영환; 조광훈; 박근일; 이정원; Jae-Won Lee; Sang-Jun Kang; Young-Hwan Kim; Kwang-Hun Cho; Guen-IL Park; Jung-Won Lee

Applied Chemistry for Engineering, Vol.24, No.3, 227-230, June, 2013

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네오듐 고용 이산화우라늄의 고온 산화거동

High Temperature Oxidation Behavior of Nd-doped UO2

이재원^†, 강상준, 김영환, 조광훈, 박근일, 이정원

한국원자력연구원

Jae-Won Lee^†, Sang-Jun Kang, Young-Hwan Kim, Kwang-Hun Cho, Guen-IL Park, and Jung-Won Lee

Korea Atomic Energy Research Institute, Daejeon 305-353, Korea

E-mail:

초록

(U1-xNdx)O2 소결체를 500 ℃에서 산화하여 얻은 (U1-xNdx)3O8 분말의 상변화를 900∼1500 ℃의 공기 중에서 고온 산화 열처리를 하여 조사하였다. 1100 ℃ 이상의 온도로 산화 열처리할 경우에 Nd 농도가 높은 (U1-yNdy)O2+z 상과 U3O8 상이 생성됨을 확인하였으며, 산화 열처리 온도가 높아질수록 (U1-yNdy)O2+z 상에서의 Nd 농도는 감소하였다. 산화 열처리 온도의 증가에 따라서 U3O8-w 입자로부터 (U1-yNdy)O2+x 입자로의 U 양이온 및 Nd 양이온이 두 입자의 계면을 통해 농도 구배에 따른 확산에 의해서 (U1-yNdy)O2+x 상 내에 U의 농도는 증가하고 Nd의 농도는 감소하게 된다. 이러한 현상은 산화 열처리 온도증가에 따라서 U3O8 상에 대한 (U1-yNdy)O2+z 상의 X-선 회절피크의 적분강도비 증가와 (U1-yNdy)O2+z 상의 입자가 커지는 것과 연관하여 해석할 수 있었다.

The phase change of (U1-xNdx)3O8 powder produced by oxidation of Nd-doped UO2 pellet at 500 ℃ was investigated by high temperature oxidation heat treatment at 900∼1500 ℃ under an air atmosphere. The XRD analysis results showed that the formation of (U1-yNdy)O2+z phase and U3O8 phase from metastable (U,Nd)3O8 phase initiated at a temperature of 1000 ℃. The relative integrated intensity of (U1-yNdy)O2+z phase to U3O8 phase increased with increasing of the oxidation temperature from 1100 to 1500 ℃. And also, it was found from the SEM observation that the particle size of (U1-yNdy)O2+z phase increased with increasing of the oxidation temperature. However, electrone probe X-ray microanalyzer (EPMA) analysis results showed that Nd contents in (U1-yNdy)O2+z phase decreased with increasing of the oxidation temperature. This behavior on the ground of XRD, SEM, and EPMA analysis data could be interpreted in terms of the transportation of U ions from U3O8 phase into (U1-yNdy)O2+z phase through the interface of two phases during high temperature oxidation.

Keywords:thermal oxidation;phase separation;neutron absorber;neodymium;uranium oxides

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[2] McEachern RJ, Taylor P, J. Nucl. Mater., 254, 87 (1998)

[3] Labroche D, Dugne O, Chatillon C, J. Nucl. Mater., 312, 21 (2003)

[4] Labroche D, Dugne O, Chatillon C, J. Nucl. Mater., 312, 50 (2003)

[5] Taylor P, McEachern RJ, WO 96/36971 (1996)

[6] Yang JH, Kang KW, Kim KS, Song KW, Kim JH, J. Korean Nucl. Soc., 33, 307 (2001)

[7] Keller C, Engerer H, Leitner L, Sriyotha U, J. Inorg. Nucl.Chem., 31, 965 (1969)

[8] Keller C, Boroujerdi A, J. Inorg. Nucl. Chem., 34, 1187 (1972)

[9] Berndt U, Tanamas R, Keller C, J. Solid State Chem., 17, 113 (1976)

[10] De Alleluia IB, Hoshi M, Jocher WG, Keller C, J. Inorg.Nucl. Chem., 43, 1831 (1981)

[11] Ackermann RJ, Chang AT, J. Chem. Thermodyn., 5, 873 (1973)

[12] Lynch ED, Handwerk JH, Hoenig CL, J. Amer. Ceram.Soc., 43, 520 (1960)

[13] Anthony AM, Kiyoura R, Sata T, J. Nucl. Mater., 10, 8 (1963)