شبیه‌سازی و ارزیابی نوترونیک و حفاظ استخر دوم یک رآکتور تحقیقاتی نوعی به‌عنوان استخر سوخت مصرفی

The design calculations of the spent fuel pool require the consideration of various parameters such as neutronic, thermal-hydraulic, safety, shielding, economic and operation. Considering the high cost of designing and building of a new spent fuel pool as well as the existence of empty spaces in the pool of some research reactors, neutronic and shielding calculations for the feasibility of using second pool of a typical research reactor as a spent fuel pool is done using ORIGEN2.1 and MCNP6 codes. The first step is the determination of the distance between fuels (grid pitch) in such a way that the effective multiplication factor for the worst possible case is less than 0.95, that 13 cm grid pitch fulfills this condition. Source term calculation for a fuel with the highest burnup (60%) is done as the most pessimistic condition. Continuous operation and 24 hours cooling are considered as the shortest possible time to transfer spent fuels to the storage rack in order to have the most pessimistic conditions in the design of spent fuel rack. For a rack with 100 spent fuels that is 87 cm away from the pool wall on each side, a 300 cm layer of water on top of the fuels and 85 cm thick concrete wall are enough for the possibility of using second pool as a spent fuel pool. It has been found that it meets the dose rate criteria of less than 1 and 10 μSv/h behind the wall and above the pool water level.