ACFDapproachtotheatmosphericdispersionofradionuclidesinthevicinityofNPPsOriginalResearchArticle

MoststudiesofatmosphericdispersionofradionuclidesreleasedfromNuclearPowerPlants(NPPs)arebasedonGaussianplumemodelsorontheuseofaconvection–diffusionequation.Suchmethods,whichdonotinvolvesolvingtheflowproblem,areusefulintheatmosphericmesoscale,oftheorderof2–2000kmfromtheNPP.However,theydonotaccountfortheturbulencegeneratedbytheinteractionofthewindwithobstaclesandwiththereleasedmaterialstream,whicharethedominantfactorsinthelocalscale,oftheorderof0–2kmfromthesourceofemission.Here,theauthorsadvocatetheuseofcomputationalfluiddynamics(CFD)tostudythedispersionproblem.ThephysicalmodelcomprisestheNavier–Stokesequations,aconvection–diffusionenergyequation,andtransportequationsfortheradionuclides.Thepaperdetailsthestabilizedfiniteelementformulationused,stressingitsconnectionwiththevariationalmultiscale/largeeddysimulationapproach.Adaptivetechniquescombiningerrorestimationandremeshingarealsoemployed.ThemethodisimplementedonaBeowulfparallelcomputingsystemusingdomaindecompositionandthemessagepassinginterface(MPI).Controlledemissionsfromachimneyandreleasefromsevereaccidentshavebeensimulated,showingtheimportanceofthelocalphenomenaonthedispersionproblem.