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1 Jurnal f the Krean Ceramic Sciety Vl. 44, N. 3, pp. 169~174, A Study n the CVD Depsitin fr SiC-TRISO Cated Fuel Material Fabricatin Jun Gyu Kim, E-Sul Kum, D Jin Chi, Sung Sn Kim, Hng Lim Lee, Yung W Lee,* and Ji Yen Park* Department f Ceramic Engineering, Ynsei University, Seul , Krea *Functinal Materials, Krea Atmic Energy Research Institute, Daejen , Krea (Received January 8, 2007; Accepted March 13, 2007) yw w gq w w ½ ³Á Á Á½ Á y Á *Á * w œw *w q ( ; ) ABSTRACT TRISO cated fuel particle is ne f the mst imprtant materials fr hydrgen prductin using HTGR (high temperature gas cled reactrs). It is cmpsed f three istrpic layers: inner pyrlytic carbn (IPyC), silicn carbide (SiC), uter pyrlytic carbn (OPyC) layers. In this study, TRISO cated fuel particle layers were depsited thrugh CVD prcess in a hrizntal ht wall depsitin system. Als the cmputatinal simulatins f input gas velcity, temperature prfile and pressure in the reactin chamber were cnducted with varying prcess variable (i.e temperature and input gas ratis). As depsitin temperature increased, micrstructure, chemical cmpsitin and grwth behavir changed and depsitin rate increased. The simulatin shwed that the change f reactant states affected grwth rate at each psitin f the susceptr. The experimental results shwed a clse crrelatin with the simulatin results. Key wrds : TRISO, IPyC, SiC, OPyC, CVD 1. gq w w w v w» w w k (Buffer C), ü š wk (IPyC), ky³ (SiC) š š w k (OPyC)d. ƒ d w w k d w qr l ƒ PyCd š w» ƒ w yw. ü, š w k d w ƒ y w w SiCd g š», yw l SiCd y w w w. ky³ d ky³ û, w š w, ù ƒ š š š 1900 C¾ j w Crrespnding authr : D Jin Chi [email protected] Tel : Fax : » š w y w» v w g q w ƒ w d. 1-5) gq w w» w» ƒ k l v š d, x,, w w yw w gq w ƒ d w. gq w» w d w yw (FB-CVD) w 500 µm w š w k d, ky ³ d w v d. 6,7) ƒ w. w x w» w yw œ» ky³ w œ,, ƒ w. w œ y w w» w x SOLGAS- MIX PV v w w sx k w š y w œ w w m x w» gq w 169

2 170 ½ ³Á Á Á½ Á y Á Á r w. w ƒ w d ky³ d» w t x y r. 2. x w p,,» y w sx k w k (Buffer C), ü š wk (IPyC), ky³ (SiC)» sx w» w SOLGAS-MIX PV ful v w. š FB-CVDœ x š w ü y w œ Fluent 6.0 ful v w w. 8) x w Fig. 1 yw» ht-wallx s w.» œ ü w» w» (carrier gas) š» yw g» (dilute gas). w k d p (Acetylene, Fig. 1. Schematic diagram f super kanthal furnace CVD system. C 2 H 2 ),» (diluent gas) Ar w. š w k d v v (Prpylene, C 3 H 8 )» wš, Ar» w w. TRISO v w ƒ w w w ky³ d Si C w ƒ yw» š, w w w œ MTS(methyltrichlrsilane; CH 3 SiCl 3, Acrs Organics C., U.S.A) w. yw 9,10) Fig. 2. Thermdynamic yield f buffer C and PyC layers as a functin f depsitin parameter. w wz

3 »q(substrate) ky³ q ƒ w š (Tkai Carbn C., G347, Japan) w. š z y w 10 tilt susceptr w. ky³ d X z w w t w XPS(X-ray phtelectrn spectrscpy) w w. SEM mw,» t y w p gq w w. w EDS mw gq w w. 3. š gq w ƒd sx MTS(CH 3 SiCl 3 ) w kz³ d p (Acetylene, C 2 H 2 ), v v (Prpylene, C 3 H 8 ) ƒ w w k, š w k d e ù w,,» (MTS/H 2, ky /Ar) y SOLGAS-MIX PV yw w gq w w 171 ful v w w sx k Buffer C, PyC, SiC» sx w ùkü. ky³ d 0.9 atm» y SiC C sx» ƒ 30, 1300~1550 C 90% SiC w. Fig. 2(a), (b) w k d» w» C 2 H 2 š w k d» C 3 H 8 ƒ š w d w, š w k d TRISO w d x w» Ar w ƒ w» 1 w w. w k d 0.9 atm 1100~1300 C š š w k d k d w 0.9 atm z 1300~1450 C. k d ƒ w k d w e mrphlgy v w. Fig. 3 FBCVD(Fludized Bed CVD)œ x š w ü y Fig. 3. (a) Cmputer simulatins temperature distributin in hrizntal reactr and¾(b) variatins f temperature & velcity at depsitin in susceptr (clsed symbl : temperature, pen symbl : velcity). 44«3y(2007)

4 172 ½ ³Á Á Á½ Á y Á Á w œ Fluent 6.0 ful v w w 1500 C,» 50, 0.9 atm susceptr ƒ e w ƒ inlet utlet ƒ š. w input gas w ht zne inlet utlet. w x š z y w» 8) w 10 tilt susceptr w utlet œ x w 11,12) CVD œ funnel zne p, w. w input gas w š» s š m w y. gq w ƒ w ky ³ d w r C ky³ d (111) w š w ùkûš, ƒ ƒ w (220) (311). Fig. 4 XPS w d t w C,» 50, 0.9 atm w ky³ d r w. x š ky ³ w C1s peak e ev š ky ³ w Si2p peak e ev. Peak 13,14) Gaussian- Lrentzian xk š ƒ w w C1s peak w ƒ f C-Si, C-C w wš Fig. 4(a) y w. w j» C-Si ev, C-C ev. Fig. 4(b) Si2p peak w (decnvlutin) Si-C w ev. w t mw β-sicƒ y š, Si/C 1.19ƒ ù. ƒ 1450, 1500 C w d w ƒ ƒ x ùkû ƒ ƒ excess carbn w» k w yw ƒ w ƒ leaf-like ƒ x ƒ w y. 15) Fig. 5 w k d ky ³ d w z t x w. š, š graphite w ky ³ d faceted š ƒ ƒ w grain j»ƒ f e x. w k d wš ky³ d w t facet granular yw š grain j».» d t ƒ z d w y š,» d z w d š w. gq w» w d w w Table 1 ùkü. Fig. 4. XPS analysis f SiC cating layer (Depsitin at 1400 C, α : 50, 0.9 atm). Fig. 5. SiC layer depsited after PyC layer depsitin (1500 C, α = 50, 0.9 atm). w wz

5 화학증착법을 이용한 삼중 코팅 핵연료 제조에 관한 연구 Depsitin Cnditin fr SiC-TRISO Cating Layer Input gas rati Depsitin temperature (C) Buffer C layer 1250 Ar/C2H2 24 IPyC & OPyC layers 1300 Ar/C3H SiC layer H2/MTS Table 1. Fig (a~c) SEM images f fractured crss sectin n TRISO layers f which SiC layers depsited at varius temperatures (α = 30, 0.9 atm) f (a) 1400C, (b) 1450C, and (c) 1500C, respectively. Fig. 6은 입력 기체비 30, 0.9 atm에서 1400 C에서 1500 C 까지 온도 변수를 달리하면서 증착된 탄화규소층을 가지 는 삼중 코팅된 핵연료의 SEM image이다. 온도를 달리 하였지만 모두 삼중층이 성공적으로 증착 되었고 이렇게 증착된 각층의 스팟에서의 EDS 분석(Fig. 7)을 통하여 각 Fig. 7. Depsitin time (min) Depsitin pressure (atm) 층들이 또렷하고 균일하게 증착 되었음을 확인 하였으며 각 층의 경계 구분은 온도가 낮을수록 또렷하였다. 온도 에 따른 각 층의 두께는 Table 2에 나타내었다. 온도 변 수 별로 비교 할 때 저밀도 열분열 탄소층은 거의 비슷 한 두께로 증착되었으며 탄화 규소층의 경우는 온도가 증 EDS results fr elemental weight percents f each layer (α = 30, 0.9 atm). Thickness f Each Layer n TRISO Layers as a Functin f Depsitin Temperature (α = 30, 0.9 atm) (Unit : µm) Buffer C IPyC SiC OpyC 1400 C C C Table 2. Fig. 8. SEM images f fractured crss sectin n TRISO layers f which SiC layers depsited at varius input gas ratis (1450C, 0.9 atm) f (a) α = 70, (b) α = 50, (c) α = 30, and (d) α = 10. 제 44 권 제 3호(2007)

6 174 ½ ³Á Á Á½ Á y Á Á ƒ w ̃ ƒw. š Á š w k d š w k d wš 1450, 1500 C ƒ ƒw ̃ É. ky³ d w ¾ w ez ƒ w ƒ ƒw w w š. Fig C, 0.9 atm w» ky³ d ƒ gq w» ƒ ƒd wš ³ w.» ƒ w ù» ky³ d ̃ ƒw w ùkü š ƒ. 4. p,,» y w s x k w k (Buffer C), ü š wk (IPyC), ky³ (SiC)» sx 0.9 atm, 1100~ 1300 C w k d 0.9 atm, 1300~1450 C š w k d w, œ s š sƒ y y w. ƒ ƒw ky³ d (111) w (220) w ë (311) ùkù. ky³ Si/C 1400 C 1.19 ƒ ƒ k w. w š š faceted structure ƒ ky³ d sub-depsited d w š w k d x grain j». gq w ƒ d ƒ û ùkù ky³ d ƒ ̃ ƒw» ƒ w ù» ky³ d ̃ ƒ w w ùkü m k y³ gq w yw» ƒ š w 1400 C» ƒ 30 gq w. Acknwledgment w. REFERENCES 1. H. Nickel, H. Nabielek, G. Ptt, and A. W. Mehner, Lng Time Experience with the Develpment f HTR Fuel Elements in Germany, Nucl. Eng. Des., (2002). 2. K. Minat and K. Fukuda, CHemical Vapr Depsitin f Silicn Carbide fr Cated Fuel Particles, J. Nucl. Mater., (1987). 3. S. J. Xu, J. G. Zhu, and B. Z. Zhang, Effect f Depsitin Temperature n the Prperties f Pyrlytic SiC, J. Nucl. Mater., (1995). 4. B. G. Kim, Y. Chi, J. W. Lee, Y. W. Lee, D. S. Shn, and G. M. Kim, Multi-Layer Cating f Silicn Carbide and Pyrlytic Carbn n UO 2 Pellets by a Cmbustin Reactin, J. Nucl. Mater., (2000). 5. G. K. Miller, D. A. Petti, D. J. Varacalle Jr., and J. T. Maki, Statistical Apprach and Benchmarking fr Mdeling f Multi-Dimensinal Behavir in TRISO-Cated Fuel Particles, J. Nucl. Mater., (2003). 6. R. Mene, L. F. Kramer, J. Schnman, M. Makkee, and J. A. Mulijn, Synthesis f High Surface Area Silicn Carbide Byfluidized Bed Chemical Vapur Depsitin, Appl. Catalysis A: General, (1997). 7. S. Kuadri-Mstefa, P. Serp, M. Hemati, and B. Caussat, Silicn Chemical Vapr Depsitin (CVD) n Micrprus Pwders in a Fluidized Bed, Pwder Technlgy, (2001). 8. Y. J. Lee and D. J. Chi, Cmparisn f Diluent Gas Effect n the Grwth Behavir f Hrizntal CVD SiC with Analytical and Experimental Data, Surface & Cating Tech., (2004). 9. D. J. Kim and D. J. Chi, High-Temperature Crrsin Resistance f Chmically Vapr Depsited Silicn Carbide Against Hydrgen Chlride and Hydrgen Gaseus Envirnments, J. Am. Ceram. Sc., 79 [2] (1996). 10. D. J. Chi, J. G. Lee, J. S. S, Y. W. Kim, and D. J. Kim, Lw Pressure Chmical Vapr Depsitin f Silicn Carbide(in Krean), J. Kr. Ceram. Sc., 31 [3] (1994). 11. Y. J. Lee, D. J. Chi, J. Y. Park, and G. W. Hng, The Effect f Diluent Gases n the Grwth Behavir f CVD SiC Films with Temperature, J. Mater. Sci., (2000). 12. J. H. Oh, B. J. Oh, and D. J. Chi, The Effect f Input Gas Rati n the Grwth Behavir f Chemical Vapr Depsited SiC Films, J. Mater. Sci., (2001). 13. P. A. Taylr, M. Bzack, W. J. Chyke, and J. T. Yates, X- Ray Phtelectrn Spectrscpy Study f Si-C Film Grwth by Chemical Vapr Depsitin f Ethylene n Si(100), J. Appl. Phys., 65 [3] (1989). 14. D. Briggs and M. P. Seah, Practical Surface Analysis, vl. 1, Jhn Wiley & Sns Ltd., D. Lespiaux, F. Langlais, and R. Naslain, Chemisrptin n β-sic and Amrphus SiO 2 during CVD f Silicn Carbide frm the Si-C-H-Cl System Crrelatins with the Nucleatin Prcess, J. Mater. Sci., (1995). w wz