An investigation on environmental contamination by radioactive elements from advanced boiling water reactor (ABWR) was conducted. In this work, the assumption made was that a 0.3g acceleration caused by an earthquake which exceeds the plant design led to a crack in the containment of 2000 cm 2 , a steam line break of 800 cm 2 inside the dry well followed by a total station blackout after 30 seconds. PCTRAN - HTR functional simulator was used for investigation. Results showed that a steam line break resulted into a rapid drop of total steam flow and triggered a SCRAM within 15.5 seconds. The peak fuel and cladding temperatures were 1262.707 °C and 539.392 °C respectively. The safety systems maintained the reactor containment pressure below 100 psi. Since no traceable release of radioactive elements to the surrounding environment, it could be concluded that fully functional plant safety systems are key to avoiding a release of radioactive elements. PCTRAN-HTR calculated results were satisfactorily consistent with ABWR final safety assessment report.