Critical flow velocities for involute parallel fuel plate assemblies

An analytical procedure was developed for the prediction of the critical flow velocity of involute fuel plates that will be used in the advanced neutron source (ANS) core design. The critical flow velocity is that flow velocity at which modifications of the local linear velocity, resulting from a deflection of the fuel plates, produce across the plates a pressure difference sufficient to maintain the deflection. The procedure for calculating critical velocity was used to analyze reported permanent large deformation or collapse of reactor fuel plates in tests conducted at Oak Ridge National Laboratory (ORNL) in the operating engineering test reactor and in the materials test reactor. For each of the observed fuel plate failures, analytical results were calculated by the procedure and the relations given by Miller in his paper. These comparisons show that the developed analytical procedure compares very well with Miller's relations for flat plates and circular curved plates. Experimental studies are planned to investigate the critical velocity for the involute fuel plates proposed for the ANS reactor design. Parametric studies were done to develop design graphs to compare the critical velocity and the size or volume parameters of the ANS core. The study shows that within the present assumed core limits of size and flow rates of interest, the critical velocity of the involute plates will not be exceeded. The procedure will be used in design studies until the ANS core design is finalized