| As a transitional and temporary method of storing spent fuels, thesecurity of spent fuel pool has caused widespread concern as a new issueafter the Fukushima nuclear accident on March,2011, in Japan. Thereforeit is necessary to do meticulous research on spent fuel pool loss ofcooling accident.In this paper, a model of spent fuel pool in nuclear power plant isdeveloped by using the system code RELAP5/MOD3and it simulates thehot water behavior of the whole spent fuel pool. The nodalization in themodel is based on the cycles of spent fuels. The model analyzes rackscontaining the latest cycle in a much more meticulous way and theradiation heat transfer model is considered here. The ABS-92formula isused to calculate the decay power of the spent fuels.Based on the model, normal operation of the spent fuel pool and itscooling system is simulated. The spent fuel pool loss of cooling accidentis simulated after that. Fuel uncovery time and the time exceeding2200°F for fuels’ PCT after loss of cooling accident were predicted. The effects ofradiation heat transfer mode, spray before leakage of radioactive materialand the nodalization of hot channel and bypass outside of rack ontemperature response are analyzed.It is shown in the calculation that the model is able to simulate thenormal operation of the spent fuel pool and its cooling system andsucceeds in establishing the mechanism of natural convection cooling.The fuel uncovery time is17.87days and it takes19.14days for fuels’PCT to exceed2200°F; the heat transfer mode takes more8.97days forfuels’ PCT to exceed2200°F; the200gpm spray cooling recommendedby NEI06-12takes8630s（2.4hour）to reduce the temperature of the fuelsto100°C from726.9°C, and it takes36170s（10.05hour）to do so; amore complicated nodalization of highest power density zone takes less6.3hours for fuels’ PCT to exceed2200°F and a more complicatednodalization of bypass outside of rack takes more0.89hour for fuels’PCT to exceed2200°F. |
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