Outer annulus imbalance study: Mark I fuel

摘要

Results of an investigation of fuel element outer annulus enthalpy imbalance are reported and analytical results of suggested methods to limit this imbalance are presented. Also included are comparisons of calculated and experimental enthalpy imbalance ratios along with other quantities. Results indicate that tightening fuel tolerances and clearances can substantially reduce the present outer annulus imbalance thereby increasing power capability. A basic pre-requisite to reduction of clearance between fuel support diameter and process tube diameter is a test establishment of the minimum allowable clearance compatible with charging requirements. Matching fuel elements to process tube diameters will also reduce the imbalance but is in general not feasible at the present time.