Validation of the Subchannel Code SUBCHANFLOW Using the NUPEC PWR Tests (PSBT)

Uwe Imke,Victor Hugo Sanchez

doi:10.1155/2012/465059

Abstract

SUBCHANFLOW is a computer code to analyze thermal-hydraulic phenomena in the core of pressurized water reactors, boiling water reactors, and innovative reactors operated with gas or liquid metal as coolant. As part of the ongoing assessment efforts, the code has been validated by using experimental data from the NUPEC PWR Subchannel and Bundle Tests (PSBT). The database includes single-phase flow bundle outlet temperature distributions, steady state and transient void distributions and critical power measurements. The performed validation work has demonstrated that the two-phase flow empirical knowledge base implemented in SUBCHANFLOW is appropriate to describe key mechanisms of the experimental investigations with acceptable accuracy.

Highlights

The requirements for computational resources of highresolution computational fluid dynamics (CFD) are still large, so the thermal-hydraulic analysis of nuclear reactor cores is frequently performed using subchannel computer codes
The COBRA-TF family of subchannel codes [1, 2] extends this treatment to a different description of continuous liquid and entrained liquid droplets, which results in a set of nine conservation equations
A subchannel code based on the experience and empirical formulations of the last decades has been developed and validated using the PWR Subchannel and Bundle Tests (PSBT) benchmark data for typical bundle configurations used in pressurized light water reactors

Summary

Introduction

The requirements for computational resources of highresolution computational fluid dynamics (CFD) are still large, so the thermal-hydraulic analysis of nuclear reactor cores is frequently performed using subchannel computer codes. The COBRA-TF family of subchannel codes [1, 2] extends this treatment to a different description of continuous liquid and entrained liquid droplets, which results in a set of nine conservation equations. This kind of refinement needs additional constitutive relations which have to be derived from single-effect experiments. An alternative to the simulation of the processes on a microscale level is to use empirical correlations related to pressure drop, heat transfer, void generation, and so forth collected over the last decades These correlations are combined with liquid-vapor mixture equations for the conservation of mass, momentum, and energy as used by legacy codes. All results are obtained with the current version SUBCHANFLOW 2.1

Main Features of SUBCHANFLOW

Validation Using PSBT Benchmark Data

Standard deviation

Findings

Summary and Outlook