Compare spent fuel computed with Nuclear Fuel Cycle Simulation System (NFCSS) with real world data

The Nuclear Fuel Cycle Simulation System (NFCSS) has been developed by the International Atomic Energy Agency (IAEA) to track nuclear material during nuclear fuel cycles. The NFCSS has been used in several studies for the estimation and analysis of accumulated spent fuel from nuclear power plants, but this system has not yet been validated using real data. In this study, the computed estimates of spent fuel for boiling water reactors (BWRs) and pressurized water reactors (PWRs) in the island of Taiwan from 1977 to 2014 were compared to official data from 2002, 2012, and 2014. Taiwan was chosen for the relative simplicity and availability of its data. There are four BWRs and two PWRs in commercial operation. MOX fuel is not used, and all of the spent nuclear fuel is stored in a spent fuel pool within each unit. Data after 2014 was not used because the insufficient space within the spent fuel pools has affected the number of removed fuel bundles and the cycle length. Electricity produced from nuclear power from 1977 to 1988 taken from Taipower was used to estimate the load factor and thermal efficiency values, which were the input parameters for the computation. The load factor and thermal efficiency from 1989 to 2014 taken from the IAEA were used as the input parameters for the computation, which also used a constant discharge burnup value for each BWR and PWR despite the actual discharge burnup varying over the investigation period. The fuel residence time was approximately 4 years for each unit. The results of the NFCSS show fairly good agreement with the official data, though the system overestimates the amount of spent fuel in the long run. In addition, this study suggests that the use of four parameters—approximate load factor, thermal efficiency, discharge burnup, and fuel residence time—may be sufficient to predict the accumulated spent fuel over 40 years of operation for BWR-4 and BWR-6 units. (author)