Effects of radial heat flux gradients and flow regimes on the peak sodium temperature rise in wire wrapped rod bundles

The peak sodium temperature rise in a wire wrapped rod bundle was determined experimentally over a range of radial heat flux gradients under forced, mixed and natural circulation conditions. The bundle tested was a full size blanket assembly typical of the type to be used in current liquid metal breeder reactors (LMFBR). At a given radial heat flux gradient, the peak sodium temperature rise was constant in the fully turbulent flow regime; however, in the mixed and natural circulation regimes, the peak sodium temperature was decreased significantly by buoyancy. A study was made of the dimensionless parameters which influence the peak temperaure rise for the given geometry tested. The results were correlated using a dimensionless normalized peak temperature rise (T-T/sub in/)/(δT/sub avg/) and the ratio of rod bundle Grashof to Reynolds numbers. The peak temperature parameter ranged from 1.65 to 1.05. The forced, mixed and natural convection thermal-hydraulic regimes were identified