The　best　estimate　plus　uncertainty　(BEPU)　methodology　is　developed　to　carry　out　realistic　safety　analysis　of　the　nuclear　power　plant.　However,　the　sensitivity　analysis　in　the　conventional　methodologies　often　leads　to　inaccurate　results　when　lacking　of　the　phenomenon　identification　and　ranking　table　(PIRT)　or　adopting　the　local　sensitivity　analysis　methods.　As　the　initial　inputs　determined　in　short　of　the　PIRT　may　neglect　some　important　parameters　or　identify　some　unimportant　parameters,　and　the　local　methods　are　not　appropriate　for　complex　and　non-linear　systems.　In　this　study,　an　optimized　moment-independent　global　sensitivity　analysis　method　with　very　low　computational　cost　was　utilized　to　improve　the　sensitivity　analysis　framework　of　the　BEPU　methodology.　The　reliability　as　well　as　the　applicability　of　the　method　were　assessed　through　some　tests　and　a　large　break　loss　of　coolant　accident　(LBLOCA)　of　the　LOFT　facility.　The　improved　sensitivity　analysis　framework　was　then　applied　to　the　BEPU　analysis　of　a　typical　three-loop　pressurized　water　reactor　CPR1000,　and　the　reliability　of　the　optimized　moment-independent　method　was　further　confirmed　by　comparing　the　sensitivity　analysis　result　of　the　method　to　the　results　of　the　BEMUSE　project　and　the　Spearman　method.　Besides,　two　new　parameters　were　identified　to　have　great　influence　on　the　PCT,　and　the　two　parameters　should　be　taken　into　consideration　in　the　uncertainty　analysis　of　the　BEPU　methodology.　©　2020　Elsevier　Ltd