INTERIM STORAGE OF SPENT NUCLEAR FUEL IN THE UAE NUCLEAR POWER PLANTS

摘要

The interim storage options of spent nuclear fuel (SNF) in Barakah nuclear power plants in the UAE were studied in terms of costs and technical issues. Considering the capacity of the spent fuel pools in Barakah nuclear power plants, two scenarios for the interim SNF storage were established. Scenario 1 is 'minimum use of spent fuel pool' that SNF will be transferred to dry storage facilities as soon as SNF has been sufficiently cooled down in a pool for the dry storage. Scenario 2 is defined as 'maximum use of spent fuel pool' that SNF will be stored in a pool as long as possible till the amount of stored SNF in the pool reaches the capacity of the pools and, then, to be moved for dry storage. For these two scenarios, cost analysis was performed in terms of net present values (NPVs) and levelized unit costs (LUCs). The life cycle of the dry storage was divided into three phases: ⅰ) preconstruction phase, ⅱ) construction phase and ⅲ) operation phase. By using data available in literature for the three phases, the total costs were calculated and compared between the two scenarios. For a basic analysis, using the discount rate of 5 % and the required cooling period (T_(cool)) of 7 years before the SNF transfer to dry storage, LUCs were 184 and 192 $/kg HM for Scenarios 1 and 2, respectively, which were comparable to other analysis results in literature. Then, additional calculations were performed using two different values of the discount rate and the cooling period, respectively. The NPV 1 for Scenario 1 ranges between 175.7 and 413.5 million 2014 $, depending on the discount rate and the cooling period, T_(cool). For Scenario 2, NPVs of 85.2 and 237.3 million 2014 $ were obtained for discount rates of 7% and 3%, respectively. The comparisons of the NPVs between the two scenarios showed that Scenario 1 would cost 1.5 to 2.7 times Scenario 2. Technical issues of a dry storage system associated with the site specific conditions in the UAE were also studied. The higher ambient air temperature in the UAE than other countries could affect the cooling capacity of the dry storage by natural convection, which will affect the required cooling period (T_(cool)) in the spent fuel pool. Also, the harsh environments could have detrimental effects on the integrity of metallic components by degradation phenomena such as pitting, stress corrosion cracking (SCC). This discussion implies that the two aspects related to the harsh environment in the UAE should be studied as early as possible. The environmental and safety impacts associated with the dry storage of SNF were discussed. According to published reports in the USA it seems that there will be no significant environmental impacts of the dry storage for 60 years. However, it is judged that future studies should address the impacts for longer time period than 60 years.