The establishment of a MELCOR/SNAP model of Chinshan (BWR/4). MELCOR/SNAP model was used to estimate the effectiveness of URG for Chinshan. The MELCOR results were compared to MAAP, TRACE and PCTRAN. URG is a new method to prevent a Fukushima-like accident. The low raw water (150 GPM) can make the cladding temperature below 1088.7 K.