Mechanical aspects of the thermal shielding for the gas-cooled fast breeder reactor

Heat transfer, hydrodynamics, and structural analysis methods relevant to the gas-cooled fast breeder reactor (GCFR) shielding design are reviewed and evaluated, and results of heat transfer and hydrodynamic analyses are presented. Owing to uncertainties in pressure loss correlations and the complexity of the flow field upstream of and around the upper axial shield assembly, a flow test for this region is recommended to verify analytical pressure loss calculations. Results of heat transfer and hydrodynamic analyses for the 300-MW(e) GCFR reference shielding design are discussed. Preliminary heat transfer analyses indicate that the inner radial shield design should be changed to provide adequate cooling. By providing an additional coolant passage in the inner radial shield, the predicted shield temperatures were reduced to acceptable levels. Current technical literature on structural methods is also reviewed, and fracture mechanics methods are described. Structural analysis methods discussed in the report include simplified stress analysis and stress analysis based on fracture mechanics. Stress analysis of the shield assemblies will be preceded by simplified stress analysis which will be used to size some of the structural componentss of the shield assembly. Fracture mechanics analysis is required for the final calculations