ComputationandmeasurementofcalandriatubesaginpressurizedheavywaterreactorOriginalResearchArticle

Calandriatubesandliquidinjectionshutdownsystemnozzlesinapressurizedheavywaterreactoraretosagduetoirradiationcreepandgrowthduringplantoperation.Whenthesagofcalandriatubebecomesbigger,thecalandriatubepossiblycomesincontactwithliquidinjectionshutdownsystemtubecrossingbeneaththecalandriatube.Thecontactsubsequentlymaycausethedamageonthecalandriatuberesultinginunpredictedoutageoftheplant.Itisthereforenecessarytocheckthegapbetweenthetwotubesinordertoperiodicallyconfirmnocontactbyusingapropermeasureduringtheplantlife.AnultrasonicgapmeasurementprobeassemblywhichcanbeinsertedintotwoviewingportsofthecalandriawasdevelopedinKoreaandutilizedtomeasurethesagbetweenbothtubesinthereactor.Itwasfoundthatthecenterlinesofcalandriatubesandliquidinjectionshutdownsystemtubescanbepreciselydetectedbyultrasonicwave.Thegapsbetweentwotubeswereeasilyobtainedfromtherelativedistanceofthemeasuredcenterlineelevationsofthetubes.Basedontheirradiationcreepequationandthemeasurementdata,acomputerprogramtocalculatethesagswasalsodeveloped.Withthecomputerprogram,thesagattheendofplantlifewaspredicted.