Two-Phase Flow Measurement in the Upper Plenum of a PWR (Pressurized Water Reactor) during Reflood.

摘要

In order to study the two-phase hydrodynamics of a pressurized water reactor during emergency reflood, a group of four instruments has been developed for installation at the core and upper plenum interface. These instruments are a drag body, a cut-out portion of the end-box tie plate; a turbine meter located above one of the tie-plate holes; a differential pressure measurement across the tie plate; and a collapsed liquid level measurement above the tie plate. A single-module air and water apparatus simulates the PWR during reflood. Tests are done with the upper plenum empty, and with it containing simulated control rod guide tubes and baffle plates. The flow regimes studied are flood and unflood countercurrent flow, upflow, and combined injection. The upper plenum internals have a significant effect on the behavior of the two-phase flow. An algorithm to determine the individual mass flowrates of gas and liquid is presented. The algorithm depends on the drag body force measurement, the differential pressure measurement, the collapsed liquid level, and the flooding line.