EffectoftheyawinjectionangleontheECCbypassincomparisonwiththehorizontalDVIOriginalResearchArticle

Thecomparisontestsforthedirectemergencycorecooling(ECC)bypassfractionwereexperimentallyperformedwithatypicaldirectvesselinjection(DVI)nozzleandanECCcolumnnozzlehavingayawinjectionangletothegravityaxis.TheECCyawinjectionnozzleisnewlyintroducedtomakeanECCwatercolumninthedowncomerregion.TheyawinjectionangleoftheECCwaterrelativetothegravityaxisisvariedfrom0to(±)90°steppedby45°.Thetestsareperformedintheair–waterseparateeffecttestfacility(directinjectionvisualizationandanalysis(DIVA)),whichisa1/7.07linearlyscaled-downmodeloftheAPR1400nuclearreactor.Thetestresultsshowthat(1)iftheECCwatercolumnisinjectedintothewakeregionwhichisinducedbythehotlegbluntbodyinthedowncomerannulus,theECCbypassfractionisgreatlyreducedcomparedwiththetypicalhorizontalECCinjectionwhichmakesECCfilmonthedowncomerwall.Atthesametime,theECCpenetrationtowardthelowerdowncomerregionbecomeslargerthanthoseofatypicalhorizontaltypeofdirectvesselinjectiononthedowncomerwallvertically.(2)IftheECCwatercolumnisinjectednearthebrokencoldleg,theECCwaterisdirectlybypassed.Thus,theECCpenetrationfractionisgreatlyreducedcomparedwithatypicalfilmtypeofthehorizontalECCinjection.(3)InordertominimizetheECCbypassfraction,theECCwatershouldbeinjectedtowardthewakeregionofthehotlegbluntbodies.