Experimental and analytical investigations were made to examine the flow and temperature characteristics of the heating, ventilating, and air-conditioning (HVAC) system installed on the operation floor in the Boiling Water Reactor building. A 2.62 ft x 2.13 ft x 1.31 ft. (0.8 m x 0.65 m x 0.4 m) apparatus and a one-twentieth reduced-scale model of an operat ional floor were used to measure velocity and temperature distributions. Experimental conditions for the former and latter were a Reynolds number of Re=8.2X10⁴ and Richardson number of Ri=4.37, respectively. Airflow patterns were visualized by balloons filled with helium gas. A three-dimensional thermal hydraulic program using a laminar flow model of incompressible viscous fluid was applied. Experiments showed that an ascending flow occurs over the spent fuel pool due to natural buoyancy, which is well predicted by the program within the range of experimental error. An alternative design concept for the HVAC system is proposed, which is equipped with exhaust ducts on the ceiling in place of the pool’s side wall. The temperature above the center of the reactor refueling pool with the new HVAC system is lower than with the conventional one by 0.56 F (1 °C) (25% the conventional increase in temperature). The performance of the new HVAC system in a 1.043 MBtu/s (1100 MW) power plant is evaluated. It estimated that its capacity to remove heat from the pools is 53.5 Btu/s (56.4 kW), twice that of the conventional HVAC system.

Units: Dual