AP1000　nuclear　power　plant　adopts　several　severe　accident　management　strategies　aiming　at　terminating　the　core　melting　process　and　maintaining　the　containment　integrity,　thus　limiting　the　risk　of　significant　radioactive　releases　to　the　environment.　Analyses　are　carried　out　to　evaluate　the　effectiveness　of　these　management　strategies　using　integral　severe　accident　computer　code　MIDAC.　Simulations　and　analyses　of　severe　accidents　initiated　by　1-in,　2-in　and　5-in　LOCAs　are　performed　first,　then　1-in　LOCA　is　selected　to　assess　the　severe　accident　management　strategies.　Different　assumptions　are　defined　in　different　cases　for　a　specific　management　strategy.　Results　show　that　ADS　can　significantly　reduce　the　primary　system　pressure,　thus　resulting　in　the　injection　of　cold　water　from　CMTs　and　ACCs　into　the　core　rapidly.　In　addition,　high-pressure　melt　ejection　is　prevented　due　to　low　in-vessel　pressure　and　the　hydrogen　generation　in-vessel　is　significantly　decreased.　After　cavity　injection　system　operates　at　core　exit　temperature　1367　K,　water　from　IRWST　will　flood　the　cavity　up　to　the　hot　legs　level.　Consequently,　heat　in-vessel　is　removed　by　external　reactor　vessel　cooling　(ERVC)　and　the　goal　of　in-vessel　melt　retention　is　achieved.　As　the　final　heat　sink,　PCCS　can　significantly　decrease　the　containment　pressure　and　gas　temperature　to　ensure　the　containment　integrity.　Igniters　arranged　at　different　locations　of　the　containment　will　lead　to　local　hydrogen　combustion,　therefore,　the　fraction　of　hydrogen　in　each　compartment　is　maintained　less　than　6%　and　hydrogen　deflagration　or　hydrogen　detonation　is　consequently　avoided.　Copyright　©　2015　by　JSME.