Spent fuel elements are currently stored in four-seat racks located in the east and west clean pools, adjacent to the HFIR reactor pool. The storage racks are designed to allow pool water to cool the spent-fuel elements by natural convection. One of the design criteria for the new storage racks is that the surface temperature of the fuel plates not exceed the boiling point of the pool water. The resulting nonlinear boundary conditions are applied to the fuel-plate heat conduction problem.
Iterative cycling is required to produce a converged steady-state solution.
Representative inner and outer fuel plates are depicted for each of the three fuel elements. It is assumed that the water-filled volumes between the tiers are able to communicate freely with the external pool water. The maximum fuel-plate temperature of 195.2 F occurs near the top of the outer fuel element stored in the top tier. Other assumptions can be made regarding thermal and hydrodynamic coupling between the tiers to provide additional bounding calculations.