Pressure Drop Correlations for Fuel Element Spacers

TLDR

Accurate prediction of hydraulic losses in multirod fuel bundles, particularly pressure drop at spacers, is essential for reactor design calculations. The study proposes pressure drop correlations derived from extensive experimental investigations of grid‑type spacers and wire‑wrapped rod bundles. These correlations are valid over a broad range of flow contractions in spacer grids (15–50 %) and a wide spectrum of geometrical parameters for wire‑wrapped bundles (P/D 1.125–1.417, H/dm 6–45, n 7–61) with Reynolds numbers from 10³ to 3 × 10⁵.

Abstract

An accurate prediction of the hydraulic losses in multirod fuel bundles is necessary for reactor design calculations. Correlations of the pressure drop at the spacers are important for these calculations. Pressure drop correlations are proposed on the basis of numerous experimental investigations, both with grid type spacers and wire wrapped rod bundles. These correlations are valid over a broad range of flow contractions in the case of spacer grids (15 to 50%) and a broad range of geometrical parameters with wire wrapped rod bundles, respectively, namely rod bundle parameter: pitch-to-diameter ratio P/D = 1.125 to 1.417, wire wrap parameter: lead-to-wrap diameter H/dm = 6 to 45, and number of rods in a rod bundle n = 7 to 61 rods. The Reynolds numbers of the investigations under consideration ranged between 103 and 3 × 105.