( )국10313.fm

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1 Carbn Letters Vl. 10, N. 3 September 2009 pp Nuclear Graphites (I) : Oxidatin Behavirs Wng-Ki Chi 1, Byung-J Kim 2, Se-Hwan Chi 3 and S-Jin Park 1, 1 Dept. f Chemistry, Inha Univ., 253, Nam-gu, Inchen , Krea 2 Jenju Institute f Mechinery and Carbn Cmpsites Palbkdng-2ga, 817, Jenju, Jellabukd , Krea 3 Dept. f Nuclear Hydrgen Prject, KAERI, Daejen , Krea sjpark@inha.ac.kr (Received August 3, 2009; Accepted September 11, 2009) 1. lp s p ~v s p p qm p p. a, b p, c p van der Waals p p p sp. lp rp n kr l, r rq,, q, q l n pp, q n lp q l p l p p q ~ vv~l n p [1-4]. np 4 m d (very high temperature reactr, VHTR) p 900 C p l nrp qp lž}, p lr, p t q vp p lp e sq, q, ql pn p. lp t ql p pl t ql e p lv Ž} eq [5]. q l lp p q l p np l p p p p rl pp Ž}l p p p rl np kk q nml rp. lp p t q s l p l Ž}p er v l p nm p q p [6]. q l n lp t ql p ˆ v sv l sq l rp pp l p eˆ. q l n lp p r v npp m p l CO 2 pp p [2,7]. lp rp tl 450 C l pl. q 800 C p p ml l l v l l ~ ~p k p d n p, v nm t l p pp dl l p p p m r l pl p p pl p n tn. q q l p r p 40%l tp n ƒ q l n q lp n p n p p. l n,, lp p nˆ p IG-110p t n p. IG-110p n p 20 ppm p p p 1.77 g/cm 3 l l t,, l q lp n lv p. q lp t ql p l l pp l p rp l v k p. q lp l p q p kr ~ re tn pq q lp l q kr l n tn q q l l p l m t qp lt v q q r, t q q v kkk k,, l l v v k p v plk. q n v, l, t, p p. lp q n q p n lp q p p sn tn pqp [8,9]. v p q p p p l rp l p q l p q r l pv k. l m n l n l l v, n [10]. lp l p p 2,000 C r v q m v p pv, l p p l l tp l n nl t p n. p rp l q n t r p pp l n q q q q p el t q p p t p, l pp v ep tl lv q p. t q lv,

2 240 Wng-Ki Chi et al. / Carbn Letters Vl. 10, N. 3 (2009) Table 1. IG (Ty Tans)m NBG (SGL) lp Fig. 1. m d n l. IG-110 IG-430 NBG-18 NBG-25 Density (g/cm 3 ) Prsity (ttal) Prsity (pen) CTE Grain size (µm) Thermal Cnductivity (W/mK) Cke petrleum pitch pitch petrleum Resistivity (µω) Weidmann-Franz Rati (R WF ) Frming methd is-static is-static vibratin vibratin q p pn p rp r e l p t n l. ml p nr p q ql lq, l l l ˆ ˆ v p k 1mmp l pq, ql p n pp s q l rn l p q n s l p r p n sqp p re n erp. Fig. 1 Fig. 2 m d l rn l q p te lt p [13]. p Fig. 2. m d p te. r qp q l nl t,, v p p. p q ep n l n nl p ql n vl ˆ l p tn, el lv l t q p ql p l p p l m tn [11,12] m d (High Temperature Gas cled Reactr, HTGR) l d r q l qp m k 1000 C mp, lp m d l pn el r p r p, l pp p p q p. s q kr edšp eˆ p k k l v pn p qrp v p. p qr l m d p l mp p p n 1960 JAERI (Japan atmic energy research institute) p t l l p p lr m. l 2020 p r e p m l q lp p n. p p p n lp lp p p p lp p l l p dv k, lp l p p np p. v, lp p r p n lr ˆ p. lp s p p ˆ q lrs e k l rq p v l l p p. macr lp, micr p p p. Table 1p q l (IG-110, IG-430, NBG-18, NBG-25)p p rp p ˆ p Fig. 3p p lp rs lp rs p ˆ p [14] q lp q lp p (density), X r (XRD) 15, l (TGA), FT-IRp r m. q lp p Table 2l m p e l n 3 vp l p l p llp, IG-110p (apparent density) 3p 1.76 g/cm

3 Nuclear Graphites (I) : Oxidatin Behavirs 241 Table 3. q l (IG-11, IG-110, IG-430)p d (002) L c r Grade d (002) +Ë, L c +Ë, IG IG IG Fig. 3. p lp rs lp rs. Table 2. q lp Grade IG-110 IG-11 IG-430 Bulk Density (g/cm 3 ) Flexural Strength (MPa) Cmpressive Strength (MPa) C.T.E (350~450 C) Electrical Resistivity (µ Ωcm) Fig. 4. IG-110p XRD r [16]. r l. p e p rp 1.77 ± 0.02 l v k ltlp, p lp IG-110 p rs p vp cld is-stactic pressing (CIP) p r p IG-110 lp p p v p IG-110p v p n pp pl. Fig. 4 IG-110p l p Žk d (002) L c p Fig. 5. IG-110p FT-IR r [16]. l r XRD p. d (002) L c p k p Braggp e Sherrerp ep m. nλ =2d sinθ (1) L Kλ = βcsθ λp X p Žqp K pq 0.9 v 1.84p p β e (prfile)l spqp rp r p p. Ll p p lp n c p p ~ L c. p p Lrenz fittingp ee m p k m p ep p p fitting l p. y=y0+(2 A/PI) (w/(4 (x xc) 2 +w 2 )) (1) pl p XRD q l p IG-110p 2θ p 26.5 pp k plp r p p 0.362pp k p. p p p el p l d (002) L c p p Table 3l ˆ l. Table 3l p p p d (002) p Ëpp k plp L c p Ëp k pl. p rp ll p p ˆ l p l kr spp p pl. q l (IG-110)p s, v p p, q ˆ p r FT-IRp Fig. 5l ˆ l. p rp C=C pt p p pp p pp l pp l. q l (IG-110)p lkr p Ž p TGA r Fig. 6l ˆ l. q l n (2)

4 242 Wng-Ki Chi et al. / Carbn Letters Vl. 10, N. 3 (2009) Fig. 6. IG-110 q lp TGA r ; (a) N 2 atmsphere, (b) air atmsphere[16]. lp k q l p l } k q pp lr kr rp q p m m p 900 C p 1100 Cl r l 770 C q p 99.6% ltl p q p p p q p tl Ž l v k q p m r q 100% l t p Ž l v. p IG-110p p p r p lt p. tp 1100 C TGA e qpp 62.1% r l. l 70 C p 700Ë l qpp eq p 900 C qpp 91.2% Žk l. p rp n lp l p 900 C q p 10% p rp, 900 Cl p k 1% p ep IG-110 lp q ne kr l e rp p [16] q lp m d p e q n lp He q p p p l p e p pp p. q l p lp tn p p pp [17]. C(sild)+O 2 (gas)co 2 (1) C(sild)+H 2 O(gas)2CO (2) C(sild)+CO 2 (gas)2co (3) C(sild)+2H 2 (gas)ch 4 (4) m l lp 3 v [18]. m p nl ppˆ p ~ lp pp n }} pl. ~ l p p Œ lp v p pl. p mlp p (chemical regime) v ml p, ml pp n pl l ~ lp l p pp p l, lp p p p l p pl v k. p mlp v pml (mass transfer cntrlled regime)p. ml (In-pre diffusin cntrlled regime)l p v pp el pl, lp l p mlp pl v rp. p pml p m mlp p rp 600 C p l p ml, 600 Cl 900 C pl m l, 900 C p l v pmlp pp, p m p e p,, lp s l p k r p. ml l pp Fig. 7l ˆ l [19]. Fig. 8 9 q l (IG-11, IG-110, IG-430)p ml 1200 C v t ˆ l. m v l l p pl p. IG-11[20]p n e 500 C eq l IG-110 IG-430l r p m l eq l. IG-110 Fig. 7. m mll pp [19].

5 Nuclear Graphites (I) : Oxidatin Behavirs 원자로급 흑연 (IG-11, IG-110, IG-430)의 온도에 따른 무게감소 변화[19]. Fig. 10. Fig. 8. 원자로급 흑연 (IG-11, IG-110, IG-430)의 온도에 따른 산화량의 변화[19]. Fig. 9. IG-430의 경우 산화에 의한 무게감소 경향이 비슷하게 나타나 나 IG-430의 산화가 더디게 나타났다. 그리고 산화속도의 경 우 IG-11의 산화속도가 확연하게 빨랐고 IG-110과 IG-430의 산화속도는 상대적으로 느리게 나타났다. 그리고 3개 시험편 모두에서 500~600 C 부근에서는 산화가 느리게 진행되다가 700~900 C 부근에서 산화속도가 급격히 증가하고 1000 C 이 상에서는 일정한 산화속도를 나타내고 있다[19,20]. 이는 E. Lren Fuller, Lu Xiawei등 이 언급한 500~600 C 부근, 700~ 900 C 부근, 1000 C 이상의 3개 산화영역으로 각각 화학반응, 확산반응, 표면반응에 해당 한 것이다[2]. Fig. 10은 산화를 통해 0%, 6.15%, 10.50% 감량된 원자로 급 흑연 (IG-11)의 사진으로 육안으로 확인 하기에도 표면형 상의 차이가 있으며 산화가 진행되어 짐에 따라 흑연표면에 기공이 많이 관찰 되었으며, 6.15% 산화된 시편의 경우에는 국부적으로 커다란 기공들이 형성된 것이 관찰되었다. 이는 243 0%, 6.15%, 10.50%의 산화 된 흑연 (IG-11)[22]. 0%, 6.15%, 10.50%의 산화된 흑연의 SEM측정 결과 (IG-11)[22]. Fig. 11. SEM분석을 통해서도 확인할 수 있었다. SEM 분석 결과 산화 가 진행됨에 따라 흑연 표면에 기공이 발달이 관찰되었다. 관 찰배율을 200배로 관찰한 SEM 사진 (Fig. 11)을 보면 기공 주 위의 표면 산화 반응을 좀 더 용이하게 확인할 수 있다. 산화 전 표면 (0%)은 산화 후 (6.15% 및 10.50%)의 표면에 비하여 매끄러운 상태를 유지하고 있음을 확인할 수 있으며, 산화반 응이 진행되어짐에 따라 기공 주위의 평평한 표면의 요철이 증가함을 관찰할 수 있다. 이는 기공뿐 아니라 흑연을 구성하 는 조직 중 흑연화도가 높은 입자 (ckes)의 주위를 구성할 것 으로 예측되는 흑연화도가 낮은 영역 (disrdered binder)의 산 화가 빠르게 진행된다는 것을 의미한다. 따라서 관찰이 용이 한 커다랗게 발달된 기공 뿐 아니라 관찰되지 않은 매우 미세 한 기공이 잘 발달되었음을 추측할 수 있었다[22]. Table 4는 Archimedian methd (AM)로 측정한 기공율과 밀도 를 나타낸 결과이고, Fig. 12에서는 기공율과 밀도의 변화 관계를

6 244 Wng-Ki Chi et al. / Carbn Letters Vl. 10, N. 3 (2009) Table 4. Archimedian methdp p r wt. Lss s t p (%) (g) (g) (g) (%) (g/cm 3 ) (Emissivity)p r eˆ p. r p n q p l p l, ~p lr ˆ p l t pn [24]. Emissivity ppm p ~ l m pm p ~ l p p p rp. q v k v emissivity r p r, r l r p 3 v pp, r (radimetric emissivity methd)p e q~ l p m p ~ m r p [25,26] r (reflectivity measurement methd)p p p l e l p e e l p p, e p p emssivity p. l r (calrjmetric methd) e p e t e l p d Ž- v (Stefan-Bltzmann) p pn l r pp p. Emissivity ppp m l m, p m p ~ l mp p. m Tp ~ m l p l ~l p. m Tp ~ (black bdy) (emissin pwer) d Ž- v l p l p p tlv. E b =σt 4 (w/m 2 ) (1) Fig. 12. p p [21]. e m. v k q l (IG-11, 0% )p g/cm r l p l ˆ r l. p p rm pv, e v rpv p rp n p Ž l v. pp v 3l g/cm 1.67 g/cm mp, pp 10.56%l 19.90% v m [21] q lp Emissivity l lrp l vp pq p ll v rql v r l rp. l rqžp psp r vp l p rž, v qn l, p [23]. l r r ( ) r l σp d Ž- v (σ= ), T p tlv ~p r m (K) E b ~p p. p rp ~ ~ p e(1)l p. r m Tp ~ E p. E=εE b = εσt 4 (2) l ε emissivity 0 1 pp p v er ppp ~p emissivity 1 q. Table 5 m l emissivityp ˆ p m v emissivity v p ˆ lp 5%m 10%e p emissivityp p v k k. m l emissivityp p Fig. 13l ˆ l p, m l emissivityp v p q ll p m. rm 500 Cl 0%l 10% v l emissivityp v pp IG-430 (23.6%), IG-110 (21.0%), PCEA (16.8%), NBG-18 (13.7%), IG-11 (12.2%) p ˆ p, p p p r p v p r p l emissivity v p Ž. 10% NBG-18p emissivity rm 100 Cl 0.89 p f re t q p p llrp, 0% NBG- 18p rm 400 Cl f q p p ˆ l. 10% IG-430p emissivity rm 100~500 Cp r

7 Nuclear Graphites (I) : Oxidatin Behavirs 245 Table 5. q lp p, rm l emissivity wt. lss Temperature (%) ( C) 0% 5% 10% Emissivity IG-11 IG-110 PECA IG-430 NBG Fig. 13. m l emissivityp ; (a) IG-11, (b) IG- 110, (c) PCEA, (d) IG-430, (e) NBG-18[27]. l ~ 0.8 p p p emissivity ˆ l [27]. Fig. 14. IG-110 lp 1150~1250 Cl s np q l er rn q l Fig. 14 m d l n q l (IG-11)p 1150~1250 Cl t q s np p er p. s l p p t q s p v l ƒv. p l v AGm WGp pp v kp, p s m l r k 850 C }l n qp s m [28]. lž} s p v l s p l kt s v. p p s m l s m p lž} p ˆ s p p p nl p ˆ. 20 C l s m vp lž} s l p Fig. 15l ˆ l [29]. lr pp m ps p s l p Fig. 16l ˆ l. (a) s r, (b) s p. q lp lr t p l p v p p r l p l r l ps. r p s p v m v, lr pp s p l s p v p v k. p p p p l vp k p. s m l v ˆ l r. p ˆ m s p v m p m yp n p ˆ. q lp ˆ p n l p rl qp v v s l p v. v pp s p l, s p v m q. s l v pp s m p [30]. n tp l d l m lp p v s creepl p p p m.

8 246 Wng-Ki Chi et al. / Carbn Letters Vl. 10, N. 3 (2009) Fig. 15. IG-110 lp 1150~1280 Cl s np lž }. Fig. 17. q lp s creep. p p m p r ˆ s creep v. Fig. 17p s q lp s creep p e p s m l p ˆ. q l p p p l CO 2 l v m r p ˆp r 4 q p m d (VHTR) ~ p. lp tn s n m d (VHTR)l lp lr, r, r p ( m t q s (neutrn irradiatin))l p l p q p lp l p lr, r, r Žk p q, nr kr p ~ pp [31,32]. l lp lr, r, r r p (He q, l) e t pl l r l n p r VHTRp e skr m l n t n r p v. kr p q m d p p r kl q p r n p l p q l e l rrp l p p. p rl m d p krp lp r l n tn. lp r e skr p p tn npp qn l lq p l lr, r, r, l q p r, r n l rr kr l n tn n Fig. 16. IG-110 lp s l p lr p ; (a) s r, (b) s np r v p l l kr

9 Nuclear Graphites (I) : Oxidatin Behavirs 247 r, p prp p m d p VHTRp qrp p, n s q ll q e p p [28]. q GIF VHTR ECp HTR-M, M1 l l l ~ r, l l s l l tl p. GENÏl m nr tp kr r l reactr vessl ll emissivity l q t n p r pp metal p reactr vessell emissivity l p. Oak Ridge l l reactr pressure vessell emissivity l pp, VHTRl rn q p vl l Winscnsin-Madisnl eq p. q n lp m crack kr l m Bath p McEnaney l p. pl v k n crack pl lr p p 3 v mlp. (1) an initial rise attributed t develpment f bridging in the crack wake zne. (2) a plateau regin where the prcess zne ahead f the crack bridging zne reach steady states, (3) a falling R curve r a rising and KR decrease prgressively and the plateau becme shrter. : ( ~11%) l R KRp p rvrp, pl plateaux w kr. 11%l l prcess zne sizep rvr v l plateaux v p p. ˆ EC, d, p p l l p n k p. -EC: r, kr, l p, qpn l l eq edš ( HTR) p 5 EURATOM Framewrk prgramme (HTR-M, HTR-M1)l EC5 l, m, s e l ( l l kr ) rp l 5 q lq l m, s e t (HFR-Petten,, s s : 25 dpa, 900 C p, m :1,800 ). - d : rp 2010 v Direct Cycle Mdular type m (HTR) l t rp l pp p 1,000 C p p GCR ( d )m r p kr p GCR s p GCRp, q rp r lpnp el Actinide t q Spectrump GCR p rp pl n lq p tl p. HTR kr m, pl p l rm pl lkr r q s (prsity, impurity, density) s (m, d flw rate) tr tl p. - p :p p 1960 TOYO TANSO C. q l (IG-110)p q l n k e l p l m. ˆp Oarail m d (HTGR) n l t q qrp m HTGR m p ql t e l m l ( e ) tp m, s l p l m (Mdeling)l n q l 2004 JMTRp pn, m, s e mr (950 C p, He, s : ncm 2, 10 dpa)p l m ls e q rq mp, GIF VHTR EC p HTR-M M1 l l r rp l l ~r, l l q tl p. - :r 4 q (Gen-IV)p n q p 2017 p v pp, 2010 v n q m. pl n lq q UCARl H-451grade (GIF t l grade) r, q ORNLp tep 900 C p ms Fig. 18. q lp XPS r ; (a) NBG-17, (B) NBG-25.

10 248 Wng-Ki Chi et al. / Carbn Letters Vl. 10, N. 3 (2009) Fig. 19. r q lp high reslutin O1S spectra; (a) NBG-17, (B) NBG-25. e p tl p (s : ncm 2, E>50 KeV) p l 4 q p n m d p p q lp r p p l p,. q l l k q lp q l rp l p, pms lp, r s p, r t m lp p. v l q lp s p m l lp p p f, t lp r vr m p l tl p. Fig. 18p q lp r p XPS r l l lp l v ev Fig. 20. q lp high reslutin O1S spectra; (a) NBG-17, (B) NBG-25. l C 1Sm O 1Sp plp, q lp n O 1S rp O 1S l v p p pl. Fig p r p q lp high reslutin O 1S spectra rl C=O grup (Ketne, Lactne, and Carbnyl) OH grup (B.E ev) ˆ v l O-C-O peak (B. E ev) v p p pl [33-35].p Ž q lp l l p Ž l v. 4. qp t 1 l vp t vll q l p krrp p l n p kr

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