The　development　and　verification　of　a　coupling　code　system　named　NECP-X/SUBSC　which　integrates　a　high-fidelity　neutronics　code　NECP-X　and　a　thermal-hydraulics　(T/H)　subchannel　code　SUBSC　are　presented.　The　VERA　core　physics　benchmark　progression　problems　3　is　utilized　to　verify　NECP-X　and　the　high-quality　experimental　data　provided　by　the　OECD/NRC　PWR　Subchannel　and　Bundle　Tests　(PSBT)　benchmark　is　used　to　validate　SUBSC.　After　assessing　the　two　codes,　an　internal　coupling　method　is　used　to　integrate　SUSBC　with　NECP-X.　Finally,　the　coupling　code　system　NECP-X/SUBSC　is　applied　to　the　VERA　core　physics　benchmark　problem　#6,　3D　Hot　Full　Power　(HFP).　The　calculated　eigenvalue,　normalized　radial　power　distribution　and　subchannel　exit　coolant　temperature　are　compared　to　results　from　published　literatures.　©　2016　Association　for　Computing　Machinery　Inc.　All　Rights　Reserved.