Estimation of Design Basis Tornado Parameters for the Zone around the Fuqing Nuclear Power Plant

Based on the investigation data of tornadoes in the Fuqing Nuclear Power Plant area from 1959 to 2017, the probability distribution of exceeding a specific wind speed is calculated using the Rankine model. The design basis tornado wind speeds are derived from the probability values, and the pressure drop of tornadoes is calculated using the pressure drop model. Results show that the design basis wind speed of an F3 category tornado is 71.4 m/s, with a probability of 1 × 10⁻⁸. Moreover, the total pressure drop of an F3 category tornado is 4.29 kPa, the translation speed is 13.8 m/s, the maximum rotating wind speed is 57.6 m/s, and the maximum pressure drop rate is 1.18 kPa/s. Furthermore, the collision velocity and momentum of the projectile produced by the tornado in two different scenarios are calculated. These two scenarios involve an air penetrator with a weight of 125 kg and a solid steel ball with a radius of 2.5 cm. The maximum horizontal collision velocity of the projectile caused by the tornado is 24.99 m/s in both scenarios. The collision momentum is 3123.75 kg m s⁻¹ in the air penetrator with a weight of 125 kg and 1.615 kg m s⁻¹ in the solid steel ball with a radius of 2.5 cm. From the perspective of these scenarios, the calculations will provide the scientific and theoretical bases for the planning and construction of the Fuqing Nuclear Power Plant.