Rewetting Analysis of a Pressurized Water Reactor Fuel Slab Using Improved Lumped Models

Abstract

This work analyzes the rewetting of a pressurized water reactor (PWR) fuel slab using improved lumped parameter formulations based on Hermite approximations for integrals. The time-dependent two-dimensional rewetting problem is transformed into a quasi-steady heat conduction problem in a reference system moving with the rewetting front by assuming a constant rewetting velocity. The lumped parameter formulations are applied in the slab thickness direction, reducing the two-dimensional problem into a one-dimensional heat conduction equation in the longitudinal direction. The rewetting velocity is obtained by combining the analytical solutions of the average temperature distributions in the reflooded wet region and the liquid deficient dry region at the rewetting front. The Peclet number is obtained as a function of the Biot numbers, dimensionless internal heat generation rate, and dimensionless initial temperatures. The obtained solutions compare favorably with available solutions in the literature.