Realistic scoping study of reactivity insertion accidents for a typical PWR and BWR core

Reactivity insertion accidents investigated include the rod ejection accident (REA) in a pressurized water reactor (PWR) core and the control rod drop accident (CRDA) in a boiling water reactor (BWR) core. These are highly energetic and rapid transients with an extremely small probability of occurrence; nevertheless, they are design basis accidents events that must be considered in the plant safety analysis. For safety analysis purposes, the RIA for PWRs has historically been analyzed with point kinetics model using core wide coefficients having a high degree of conservatism. The difference between treating a RIA transient with best-estimate (realistic) and conservative limiting assumptions is explored. The RIA analyses were performed using CORETRAN, which allows a full three-dimensional time-dependent RIA simulation for both PWR and BWR cores. (R.P.)