Sodium-water reaction is a design-basis accident of a sodium fast reactor. A breach of the heat transfer tube in a steam generator (SG) results in contact of liquid sodium with water. The typical phenomenon is that the pressurized water blows off and is mixed with the liquid sodium surrounding SG tubes. The design and safety concern is a possibility of the secondary failure of nearby heat transfer tubes that could cause undesirable development of the accident. One needs to evaluate the temperature transients of the heat transfer tubes in the reaction region for safety evaluation. In the present study, a computational method is developed for this purpose. It solves the sodium thermal hydraulics and the heat conduction in the adjacent heat transfer tubes. An experiment performed at the Japan Atomic Energy Agency is analyzed with the method developed in this study. It is found that analyzed temperatures are in good agreement with the experimental data. Based on the experimental and computational results, multiphase multicomponent flow characteristics are depicted. Furthermore, the heat transfer coefficient is evaluated using the instantaneous heat flux and temperature obtained from the numerical simulation.