Experimental and analytical studies for the jetting mode condensation effects on the CMT delivery have been performed. The computer code simulation for the experiment is performed using the RELAP5/MOD3 code and the results are compared against the experimental data. In addition, a transient case of small break LOCA has been simulated for a typical CE type plant replacing high pressure safety injection pumps with CMTs. The experimental results of show that the steam jetting occurs when the CMT actuation valve is opened and it prevents water from adquate discharging from the CMT. This fact is due to the abrupt condensation resulting in a large pressure drop. The steam flow rate entering into CMT is equal to the critical flow rate if steam jetting occurs. It is confirmed by simple analytical work that all the steam may be condensed if the steam flow rate is critical. The current RELAP5/MOD3 code cannot properly predict the jetting mode in the CMT. A multiplier is introduced to the interfacial heat transfer coefficient in the RELAP5/MOD3 to simulate the jetting mode. The calculation results of the modified RELAP5/MOD3 show a good agreement with the experimental results. With the modified RELAP5/MOD3, a transient case of small break LOCA has been simulated for a typical CE type plant with CMTs. The simulation results show that the water in CMTs is not properly discharged into the Reactor Vessel. Based on the results, it is concluded that more comprehensive studies are needed in order to apply the CMT design to the nuclear power plant.