Thermal fatigue estimation due to thermal stratification in the RCS branch line using one-way FSI scheme

Transcription

1 Journal of Mechancal Scence and Technology 22 (2008) 2218~2227 Journal of Mechancal Scence and Technology DOI /s Thermal fague esmaon due o hermal srafcaon n he RCS branch lne usng one-way FSI scheme Kwang-Chu Km 1, Jong-Han Lm 2 and Jun-Kyu Yoon 2,* 1 Korea Power Engneerng Company, Inc., Yongn, Gyeongg, Republc of Korea 2 Deparmen of Mechancal & Auomovve Engneerng, Kyungwon Unversy,Seongnam, Gyeongg, Republc of Korea (Manuscrp Receved June 26, 2007; Revsed Aprl 15, 2008; Acceped Sepember 12, 2008) Absrac The scheme and procedure for hermal fague esmaon of a hermally srafed branch lne were developed. Oneway FSI (flud and srucure neracon) scheme was appled o evaluae he hermal srafcaon ppng. Thermal flow analyss, sress analyss and fague esmaon were performed n seral order. Fnally, dealed monorng locaons and mgaon scheme for he negry manenance of ppng were recommended. All wall mesh and ransen emperaure dsrbuon daa obaned from he CFD (compuaonal flud dynamcs) analyss were drecly mpored no he npu daa of sress analyss model whou any calculaon for hea ransfer coeffcens. Cumulaed usage facors for fague effec revew wh nodes were calculaed. A modfed mehod ha combnes ASME Secon III, NB-3600 wh NB-3200 was used because he prevous mehod canno consder he hermal srafcaon sress nensy. As he resuls of evaluaon, he SCS (shudown coolng sysem) lne, branch ppng of he RCS (reacor coolan sysem) lne, shows ha he CUF (cumulave usage facor) value exceeds 1.0, ASME Code lm, n case hermal srafcaon load s ncluded. The HPSI (hgh pressure safey njecon) lne, re-branch ppng, shows ha emperaure dfference beween op and boom of ppng exceeds he creron emperaure, 28, and ha he CUF value exceeds 1.0. Therefore, hese branch ppngs requre a dealed revew, monorng or analyss. In parcular, s recommended ha he HPSI ppng should be shfed backward o decrease he nfluence of urbulen peneraon nensy from he RCS ppng. Keywords: Thermal srafcaon; Thermal fague esmaon; RCS branch lne; FSI scheme Inroducon As more experence s accumulaed n he operaon of exsng power plans, he long-erm effecs of hermal hydraulc phenomena, unaccouned for n he orgnal desgns, are beng observed. [1-5] One of hese effecs s he hermal srafcaon phenomenon. Thermal srafcaon s flow ha s sablzed wh emperaure layers due o he densy dfference beween ho and cold waer. [6, 7] Ths hermal srafcaon n ppng s capable of causng bendng sress, a Ths paper was recommended for publcaon n revsed form by Assocae Edor Jae Young Lee * Correspondng auhor. Tel.: , Fax.: E-mal address: jkyoon@kyungwon.ac.kr KSME & Sprnger 2008 serous deformaon n ppng, and suppor damage. Especally, perodc hermal srafcaon s capable of causng he hermal fague crackng of ppng. [8-11] In 1987 and 1988, hermal fague crackng and leakage n several PWR (pressurzed waer reacor) plans resuled n he ssuance of NRC Bullen [10] In 1995, leakage from a dran lne n he TMI-1 plan was arbued o he effecs of urbulence peneraon no he nomnally sagnan unnsulaed lne. Smlar hermal cyclng ncdens have connued o occur n oher plans, ncludng Thange-1 and Damperre-1, among ohers. [12, 13] In 1997, leakage from an HPI (hgh pressure njecon)/makeup lne a Oconee ncreased he awareness of he NRC (Nuclear Regulaory Commsson) ha here were connued occurrences of hermal fague n small-dameer RCS

2 K.-C. Km e al. / Journal of Mechancal Scence and Technology 22 (2008) 2218~ (reacor coolan sysem)-aached ppng. In early 1998, here were dscussons beween he nuclear ndusry and he NRC regardng he need for addonal volumerc examnaon of Class 1 hghpressure safey njecon ppng. Several nvesgaons have aemped o denfy hermal fague mechansms and o develop ools o assess ppng suscepbly o hermal fague effecs. The hermal srafcaon, cyclng, and srppng (TASCS) program denfed several crcal parameers and offered predcve ools o asss n assessng fague loadngs for hermal-srucural analyss. [6] Oher sudes pursued expermenal nvesgaon no he hermal cyclng phenomena based on scaled expermens [14-18] or full-scale plan operaon. [19] Mos noably, has been shown ha a swrlng, vorcal flow srucure, as opposed o urbulence peneraon, can be esablshed n a dead-ended branch lne due o he flow n he RCS lne. [14, 17] In hs sudy, hermal fague esmaon due o hermal srafcaon n he RCS branch lne of KSNPP (Korea Sandard Nuclear Power Plan) s performed usng one-way FSI (flud and srucure neracon) scheme. Dealed hermal loadng due o hermal srafcaon and cyclng s evaluaed based on emperaure dsrbuons wh me, whch s calculaed by he CFD analyss. Fague effecs are conservavely esmaed by a modfed mehod ha combnes ASME NB-3600 wh NB Fnally, dealed nspecon locaons and mgaon schemes for he negry manenance of ppng are recommended. 2. Esmaon schemes 2.1 Esmaon model descrpon Schemac dagram for he SCS (shudown coolng sysem) ppng branched o RCS ppng s shown n Fg. 1. The SCS of a nuclear power plan akes charge of connually removng hea when he reacor shudown occurs. All valves n he SCS ppng are solaed durng normal or sarup operang condon. Also, urbulen peneraon n ha he hgher emperaure coolan ou of he RCS ppng peneraes no he SCS ppng ha s sagnan occurs. In Fg. 1, he RCS ho-leg ha he hgher emperaure coolan passes s ppng wh nner dameer of 1.07 m. The SCS ppng concerned n hs sudy s ppng ha he nomnal dameer s m and he schedule s 160. Also, he SCS Fg. 1. Schemac dagram of he branch lnes conneced o he RCS ppng. ppng has ho-leg HPSI (hgh pressure safey njecon) ppng and he RDT (reacor dran ank) ppng. Nomnal dameer of he HPSI ppng s m and nomnal dameer of he RDT ppng s m. 2.2 Esmaon procedure In hs sudy, a one-way FSI scheme s appled o evaluae he hermal srafcaon ppng. Fg. 2 shows hs esmaon procedure performed by usng he one-way FSI scheme. Frs, geomery and mesh for numercal analyss s generaed. Nex, hermal flow analyss on hermal srafcaon ppng s performed by he CFD code. Temperaure dfference beween op and boom of ppng s compared wh he creron emperaure, 28 (50 ) saed n reference. [6, 10, 11] The only sold regon excep he flud regon ou of he CFD resuls s ransferred no he sress analyss. A hs me, geomery, mesh and emperaure dsrbuon daa of sold regon are convered no npu daa forma for sress analyss by some user s operaon for MpCCI (mesh-based parallel code couplng nerface) beween CFD code and CSD (compuaonal srucure dynamcs) code. A specal MpCCI code was no used. Therefore, all wall mesh and emperaure dsrbuon daa wh me were drecly mpored no he npu daa of sress analyss model whou any calculaon for hea ransfer coeffcens. Ths scheme s dfferen from prevous sudes whch use he average hea ransfer coeffcens of wall surface n sress analyss and s more realsc. Fague effecs are esmaed by a modfed mehod ha combnes ASME NB-3600 wh NB Ths s o reflec he hermal srafcaon load o he exsng desgn sress. Fnally, dealed monorng locaons and mgaon schemes for he negry manenance of ppng are recommended.

3 2220 K.-C. Km e al. / Journal of Mechancal Scence and Technology 22 (2008) 2218~2227 µ ε ( ρu jε ) = µ + x j xj σ ε xj ε + C1( Pk + Gb) C2ρε k Sress equlbrum equaon σ j + bj = 0 x (4) (5) where, b j s exernal force. Fg. 2. Esmaon procedure usng one-way FSI scheme. Energy equaon µ k f T ( ρut j ) = + x j x j σ C p xj (6) 3. Numercal analyss 3.1 Governng equaons For he FSI evaluaon, governng equaons for hermal flow and srucure are needed. In hs sudy, unseady, ncompressble and hree-dmensonal conservaon equaons are used as governng equaons for he hermal flow analyss. Sress equlbrum equaon s used for he sress analyss. Sandard k-ε model s used for urbulen model and Boussnesq s approxmaon s used for he buoyancy effecs. Assumng ha all properes are consan under gven emperaure and pressure, he governng equaons used are as follows: Connuy equaon x ρu ( ) = 0 Momenum Equaon p ( ρuu j ) = + ρgβ( T Tcold) xj x u u j 2 + ( µ + µ ) + kδ xj xj x 3 j Turbulen equaon (sandard k-ε) µ k ( ρ uk j ) = µ + x j xj σ k xj + P + G ρε k b (1) (2) (3) where, he coeffcen, source erm, and urbulen consans are as follows: µ = ρck 2 µ / ε u u j u µ x j x xj Pk = + µ T Gb = gβ σ x σ = 0.85, σk = 1.0, σ ε = 1.3, C µ = 0.09, C = 1.44, C = Numercal schemes The FLUENT code [20] based on fne volume mehod s used for he CFD analyss. The ABAQUS code [21] based on he fne elemen mehod s used for sress analyss. Fnally, fague esmaon s performed by he PIPSIS program. [22] The grd sysem for CFD analyss s shown n Fg. 3. The number of cells s 87,776. The lengh from he connecon pon of he RCS ppng wh he SCS ppng o he oule of he RCS ho-leg s assumed o be more han 20 mes he SCS ppng dameer o reflec on flow change n he connecon par and o mprove convergence. The range of analyss for he SCS ppng, for he HPSI ppng, and for he RDT ppng s se o he exen of suable lengh passng he 1 s valve n consderaon of hermal srafcaon effec and suppor poson. The SIMPLE (sem-mplc mehod for pressure lnked equaons) algorhm s used o calculae he pressure feld a each cell. [23] Upwnd scheme s

4 K.-C. Km e al. / Journal of Mechancal Scence and Technology 22 (2008) 2218~ Fg. 3. Grd sysems for he numercal analyss. used o deermne he convecon erm. The convergence creron s ha he resdual s less han a he each me sep. To sasfy hs convergence creron, eraons of less han 50 mes per me sep of 1 second are needed. Unseady CFD calculaon s performed unl 3000 second. To mprove he convergence, under-relaxaon facors are appled. Compuer me for only CFD calculaon ook abou 16 days usng he Penum 2.0 GHz. In hs sudy, hermal srppng of he emperaure layer n he flud regon and wo-way FSI scheme are gnored. To smulae he srppng, a hgh urbulen model lke LES model s needed. However, hs hgh urbulen model and wo-way FSI mehod demand oo much more me and he problem s dffcul o solve acually. 3.3 Boundary condons Temperaure and flow rae of coolan n nle of he RCS ho-leg are 327 and 7718 kg/s, respecvely. Inle urbulen nensy s assumed o be 10 percen for hydraulc dameer. Oule boundary condon s he consan pressure condon. All ouer surfaces of ppng ncludng he RCS ppng are assumed o be adabac wall. All valves n he SCS ppng, he HPSI ppng and he RDT ppng are assumed o be solaed. There s no leakage hroughou valve dsks. The dsk hckness n valves s assumed o be as wo mes as ppng hckness. Each end surface of branch ppng n he range of analyss s assumed o be solaed and o be a low emperaure wall of 49. In he process of numercal calculaon, he nal emperaure condon s se o be 49. The values for condon of average emperaure n Fg. 4. Expermen schemac for verfcaon of numercal schemes. Fg. 5. The comparson of CFD resuls wh expermenal resuls MPa are used for he properes of flud. The maeral of sold s assumed o be SUS Expermenal verfcaon To verfy he numercal schemes used n hs analyss, a smplfed expermen wh one branch lne as shown n Fg. 4 was performed a small scale. [18] Ho waer emperaure and flow rae of he man ppng were 80 and 4.65 kg/s and cold waer emperaure was 20. CFD calculaon for comparson wh expermenal resuls was performed wh he same schemes (he number of meshes, urbulen model, algorhm and so on) menoned n sesson 3.2. Fg. 5 shows a comparson of he CFD resul

5 2222 K.-C. Km e al. / Journal of Mechancal Scence and Technology 22 (2008) 2218~2227 wh he expermenal resul. There s some dfference n accuracy bu he rend s smlar. Therefore, numercal schemes adoped n hs sudy are consdered o be suable because he purpose of hs esmaon s o look for he dealed monorng locaon and mgaon scheme for he negry manenance of ppng, and because much mesh and hgh urbulen model demand oo much me and are capable of generang unsable convergence. 4. Resuls and dscussons 4.1 Thermal flow analyss To evaluae he emperaure dsrbuons for he SCS, HPSI and RDT lnes due o he urbulen peneraon, a ransen 3-dmensonal numercal hermal hydraulc analyss was performed by he CFD code, FLUENT. Fg. 6 o Fg. 7 shows he emperaure dsrbuons wh me n he SCS ppng ncludng he HPSI ppng and he RDT ppng. Turbulence occurs when he man flow n he RCS lne creaes a secondary flow n a branch lne. Lengh of urbulen peneraon n branch lne depends on he velocy and emperaure of he RCS flow. Ths urbulen peneraon manly occurs durng plan hea-up and cooldown operaons and becomes he source of hermal srafcaon. [6, 19, 24, 25] Fg. 6 shows he emperaure dsrbuon a 100 sec. Turbulence peneraes rapdly no he SCS ppng from he RCS ppng; herefore, a hermal srafcaon effec n he horzonal ppng of he HPSI lne appears due o he urbulen peneraon from he SCS ppng. A he begnnng of peneraon, he fas nflow from he RCS ppng generaes a hgher emperaure for he nner wall han he ouer wall n he SCS ppng. Fg. 7 shows he emperaure dsrbuon a 500 sec. Thermal srafcaon phenomenon s shown n he horzonal par of he SCS ppng. However, hs effec n he HPSI ppng was largely decreased despe connuous peneraon. Ths s judged o resul from a srong hermal mxng effec as he ppng dameer s (a) Inner wall (b) Ouer wall (a) Inner wall (b) Ouer wall (c) Deal conour n cross seconal area Fg. 6. Temperaure dsrbuons wh me n branch lnes (=100 sec). (c) Deal conour n cross seconal area Fg. 7. Temperaure dsrbuons wh me n branch lnes (=500 sec).

6 K.-C. Km e al. / Journal of Mechancal Scence and Technology 22 (2008) 2218~ small. Fg. 8 shows measuremen posons for emperaure dfference revew. Nne posons were oally nvesgaed. Fg. 9 represens he emperaure changes wh me a pon 1 n he vercal ppng of he SCS ppng ha s near he RCS ppng. Four pons ha were locaed a nervals of 90 n he cross-seconal area were examned. A he begnnng of urbulen peneraon from he RCS ppng, each pon has a dfferen emperaure due o he flow drecon and he dfference of peneraon nensy. However, he emperaure dfference s rapdly decreased as me passes, and he emperaure values a all pons begn o be smlar afer 400 sec. Fg. 10 shows he emperaure dfference changes beween op and boom nner wall a pon 3 wh me. Pon 3 s locaed a he sarng pon of he horzonal ppng passng he 1 s elbow of he SCS ppng. The maxmum emperaure dfference of 19.4 s observed a 500 sec and he emperaure dfference s decreased afer 500 sec. Fg. 11 represens he emperaure dfference changes beween op and boom nner wall a he pons 5, 6 and 7 wh me. The pons 5 o 7 are locaed n he horzonal par of he HPSI ppng conneced wh he SCS ppng. As all pons are drecly affeced by urbulen peneraon from he SCS ppng, a severe emperaure dfference s shown ha exceeds he creron emperaure, 28. Fg. 12 represens he emperaure dfference changes beween op and boom nner wall a pon 8 wh me. Ths pon s locaed n he horzonal ppng of he RDT ppng conneced wh he SCS ppng. A emperaure dfference appears bu s ny. I s judged ha hs resul s because he dran ppng s locaed backward compared wh he HPSI ppng and he magnude of urbulen peneraon from he SCS ppng s only slgh. 40 Shudown Coolng Lne 30 T [ o C ] O C pon Tme [sec] Fg. 8. Schemac dagram of he posons for emperaure measuremen. Fg. 10. Temperaure changes wh me a pon Ho Leg Injecon Lne Temperaure [ o C ] Shudown Coolng Lne pon 1(I) pon 1(II) pon 1(III) pon 1(IV) Tme [sec] T [ o C ] O C Tme [sec] pon 5 pon 6 pon 7 Fg. 9. Temperaure changes wh me a pon 1. Fg. 11. Temperaure changes wh me a pons 5, 6 and 7.

7 2224 K.-C. Km e al. / Journal of Mechancal Scence and Technology 22 (2008) 2218~2227 T [ o C ] 10 Reacor Dran Tank Lne 8 pon Tme [sec] Fg. 12. Temperaure changes wh me a pon 8. Table 1. Thermal srafcaon sress nenses. Lne Shudown Coolng Ho Leg Safey Injecon No. of Node Locaon S T/S (MPa) 5 Weldmen of Nozzle Elbow Tee Juncon Tee Juncon Weldmen of Valve Elbow Suppor Elbow Weldmen of Valve Sress/fague analyss All wall emperaure dsrbuon and mesh daa wh me were drecly mpored no he npu daa of sress analyss model whou any calculaon for hea ransfer coeffcens. Thermal sress loads due o he urbulen peneraon were analyzed by he FEM code, ABAQUS. For each node locaon as shown n Fg. 1, hermal srafcaon sress nensy, S T/S, s ndcaed n Table 1. As only hermal load was consdered, herefore, pressure and momen loads should be ncluded n he peak sress o evaluae he fague effecs of each lne. To nclude hermal srafcaon sress nensy, a modfed peak sress nensy range, S p *, was calculaed as follows: S p * = S p + S T/S (7) where, S p s a desgn peak sress nensy ha s calculaed by Eq. 11 of ASME Secon III, NB , and S T/S s a hermal srafcaon sress nensy ha s calculaed by NB Usng he PIPSYS program, whch s he ppng desgn program of KSNPP, alernang sress nensy, S al, was calculaed by NB or NB and he cumulave usage facors (CUF) were evaluaed by NB and NB For each node locaon as shown n Fg. 1, desgn CUF and revsed CUF are summarzed n Table 2. The CUF of node 40, where a ee juncon s conneced beween he SCS ppng and HPSI ppng, was ncreased suddenly because of hermal srafcaon n he HPSI ppng due o he secondary urbulen peneraon. Also, he CUF of node 60, where a ee juncon s conneced beween he SCS ppng and RDT ppng, was ncreased. The ncrease of he CUF Table 2. Cumulaed usage facors (CUF). Lne Shudown Coolng Ho Leg Safey Injecon No. of Node a oher locaons was nsgnfcan o manan he fague negry. 4.3 Recommendaons Desgn CUF S * P (MPa) Revsed CUF < <0.001 In branch layou lnes ha he CUF s shown hghly n hs sudy, s recommended ha for hese pars for a fully dealed sress analyss should be performed or should be managed n he mnmum usng enhanced nspecon or monorng for possble fague falure or leakage. In parcular, a scheme o mgae he hermal srafcaon effec n he HPSI ppng should be consdered. Fg. 13 s a schemac dagram suggesed o mgae he hermal srafcaon effec n he HPSI ppng. To mnmze he calculaon me, he layou of he SCS and he HPSI lnes was smplfed and he RDT lne was excluded. Fg. 14 shows emperaure dfference n he HPSI ppng compared o he case conneced o vercal ppng of he SCS lne wh he case conneced o horzonal ppng of he SCS lne. Temperaure dfference of he case conneced

8 K.-C. Km e al. / Journal of Mechancal Scence and Technology 22 (2008) 2218~ Conclusons (a) Case conneced o he vercal ppng (b) Case conneced o he horzonal ppng Fg. 13. Schemac dagram suggesed o mgae he hermal srafcaon effec of HPSI lne. T [K] Tme [sec] md-vercal md-horzonal Fg. 14. Temperaure dfference change n he HPSI ppng compared he case conneced o vercal ppng of SCS lne wh he case conneced o horzonal ppng of SCS lne. o horzonal ppng s lower han ha of he case conneced o vercal ppng. Thus, s recommended ha HPSI ppng should be shfed backward o decrease he nfluence of urbulen peneraon nensy from he RCS ppng. A hermal fague esmaon scheme for a hermally srafed branch lne ha has re-branch lne was developed. Generally, he hermal srafcaon effec of re-branched lnes has no been consdered n he fague evaluaon for plan desgn. In hs sudy, a one-way FSI scheme s used o evaluae he hermal srafcaon ppng. Thermal flow analyss, sress analyss and fague esmaon were performed n seral order. Fnally, dealed monorng locaons and mgaon scheme for he negry manenance of ppng were recommended. All wall mesh and ransen emperaure dsrbuon daa obaned n he CFD analyss were drecly mpored no he npu daa of sress analyss model whou any calculaon for hea ransfer coeffcens. Ths scheme s dfferen from he prevous sudes whch have used he average hea ransfer coeffcens of wall surface n sress analyss and s more realsc. The CUF, cumulaed usage facors, for fague effec revew wh node were calculaed. A modfed mehod ha combnes ASME NB-3600 wh NB was used. Ths s because he prevous esmaon mehod uses jus he ASME Secon III, NB-3600 ha canno consder he hermal srafcaon sress nensy. Thermal srafcaon sress nensy s obaned from ASME Secon III, NB Modfed peak sress ncludes hermal srafcaon sress nensy o desgn peak sress nensy obaned from ASME Secon III, NB In hs sudy, he SCS lne, branch ppng of he RCS lne, shows ha he CUF value exceeds 1.0, ASME Code lm, n case hermal srafcaon load s ncluded. The HPSI lne, re-branch ppng, shows ha he emperaure dfference beween op and boom of ppng exceeds he creron emperaure, 28 and ha he CUF value exceeds 1.0. Therefore, on hese branch lnes, a dealed revew, monorng or analyss s requred. In parcular, s recommended ha he HPSI ppng should be shfed backward o decrease he nfluence of urbulen peneraon nensy from he RCS ppng. Thermal srppng and wo-way FSI mehod were gnored n hs sudy, bu hese can be possble f an economcal hgh urbulence model and rapd compuer s developed. Therefore, furher sudy on hese s requred.

9 2226 K.-C. Km e al. / Journal of Mechancal Scence and Technology 22 (2008) 2218~2227 References [1] Boulder, Co., Nuclear Power Experence (NPE), Publshed by RCG/Hagler, Bally, Inc., (1993). [2] Framaome, RHRS Elbow Crackng a Cvaux 1, Sgnfcan Even Repor No. 14, (1988). [3] Hagk Youm, e al., Numercal Analyss for Unseady Thermal Srafed Turbulen Flow n a Horzonal Crcular Cylnder, ICONE-4 Conference, (1996). [4] Hagk Youm, e al., Developmen of Numercal Analyss Model for Thermal Mxng n he Reacor Pressure Vessel, ASME, PVP-2000 Conference, (2000). [5] KEPRI & KOPEC, Pressurzed Thermal Shock Evaluaon for Reacor Pressure Vessel of Kor Un 1, Techncal Repor-TR.96BJ12.J , (1999). [6] EPRI, Thermal Srafcaon, Cyclng and Srpng (TASCS), TR , (1994). [7] D. H. Roary, P. L. Srauch and J. H. Km, Thermal Srafcaon, Cyclng and Srpng Evaluaon Mehodology, Changng Prores of Codes and Sandards: Falure, Fague, and Creep, ed. K. R. Rao and J. A. Todd, J. of ASME PVP,. 286, (1994) [8] EPRI, Operang Experence Regardng Thermal Fague of Unsolable Ppng Conneced o PWR Reacor Coolan Sysems (MPR-25), TR , (2000). [9] NRC, Crackng n Feedwaer Sysem Ppng, Bullen No , (1979). [10] NRC, Thermal Sresses n Ppng Conneced o Reacor Coolan Sysems, Bullen 88-08, (1988). [11] NRC, Pressurzer Surge Lne Thermal Srafcaon, Bullen No , (1988). [12] OECD NEA, Thermal Cyclng n LWR componens n OECD-NEA member counres, (2005). [13] R. Magee, e al., J. M. Farley Un 2 Engneerng Evaluaon of he Weld Jon Crack n he 6" SI/RHR ppng, WCAP-11789, (1988). [14] M. Rober, Corkscrew Flow Paern n Ppng Sysem Dead Legs, NURETH-5 Conferenc, (1992). [15] N. Nakamor, K. Hanzawa, T. Ueno, J. Kasahara, and S. Shrahama, Research on Thermal Srafcaon n Un-solable Ppng of Reacor Coolan Pressure Boundary, Experence wh Thermal Fague n LWR Ppng Caused by Mxng and Srafcaon, Specals Meeng Proceedngs, (1998). [16] R. M. Rod and J. H. Km, Analycal and Expermenal Sudes of a Srafed Flow n a Ppe, NURETH-6 Conference, France, Ocober 5-8, I, (1993) [17] J. H. Km, R. M. Rod and A. F. Deardorff, Thermal Srafcaon and Reacor Ppng Inegry, Nuclear Engneerng and Desgn, 139, No. 1, (1993) [18] S. N. Km, S. H. Hwang and K. H. Yoon, Journal of Mechancal Scence and Technology, 9, No. 5, (2005) [19] EPRI, EDF Thermal Fague Monorng Experence on Reacor Coolan Sysem Auxlary Ppng (MRP-69), TR , (2001). [20] FLUENT User s Gude, Fluen Inc., (1998). [21] ABAQUS Sandard User s Manual, Hbb, Karlsson & Sorensen, Inc.: Pawucke, (1998). [22] S&L, Inegraed Ppng Analyss Sysem, S&L Program No , (1995). [23] S. V. Parankar, Numercal Hea Transfer and Flud Flow, McGraw-Hll Book Company, (1980). [24] M. H. Park and K. C. Km, Thermal srafcaon phenomenon and evaluaon n ppng, Ppng Journal, 18, No. 6, (2004) [25] M. H. Park and K. C. Km, Thermal srafcaon phenomenon and evaluaon n ppng, Ppng Journal, 18, No. 7, (2004) Kwang-Chu Km receved hs B.S., M.S. and Ph.D degrees from deparmen of mechancal engneerng, Kyunghee Unversy n 1993, 1995 and 2000, respecvely. He has worked for Korea Power Engneerng Company snce 1995 and he s now a senor researcher. Dr. Km s research area ncludes CFD analyss, flow conrol, plan desgn and smulaor. Jong-Han Lm receved hs B.S. degree from deparmen of mechancal engneerng, Chosun Unversy n 1981, M.S. and Ph.D degrees from deparmen of mechancal engneerng, Kyunghee Unversy n 1986 and 1992, respecvely. He worked for Hyunda Moors Company durng 1986-

10 K.-C. Km e al. / Journal of Mechancal Scence and Technology 22 (2008) 2218~ He s now a professor n deparmen of mechancal & auomove engneerng, Kyungwon Unversy. Dr. Lm s research neress are n he area of hermal flow, nernal combuson and lqud aomzaon. Jun-Kyu Yoon receved hs B.S. degree from deparmen of mechancal engneerng, Chosun Unversy n 1981, M.S. degree from deparmen of mechancal engneerng, Kyunghee Unversy n 1987 and Ph.D degree from deparmen of mechancal engneerng, Myongj Unversy n He worked for Hyunda Moors Company and Asa Moors Company durng He s now a professor n deparmen of mechancal & auomove engneerng, Kyungwon Unversy. Dr. Yoon s research neress are n he area of flow conrol, hea ransfer, lqud aomzaon, spray and combuson.