Comparative Analysis of CTF and Trace Thermal-Hydraulic Codes Using OECDNRC PSBT Benchmark Void Distribution Database

Abstract EN

The international OECD/NRC PSBT benchmark has been established to provide a test bed for assessing the capabilities of thermal-hydraulic codes and to encourage advancement in the analysis of fluid flow in rod bundles.

The benchmark was based on one of the most valuable databases identified for the thermal-hydraulics modeling developed by NUPEC, Japan.

The database includes void fraction and departure from nucleate boiling measurements in a representative PWR fuel assembly.

On behalf of the benchmark team, PSU in collaboration with US NRC has performed supporting calculations using the PSU in-house advanced thermal-hydraulic subchannel code CTF and the US NRC system code TRACE.

CTF is a version of COBRA-TF whose models have been continuously improved and validated by the RDFMG group at PSU.

TRACE is a reactor systems code developed by US NRC to analyze transient and steady-state thermal-hydraulic behavior in LWRs and it has been designed to perform best-estimate analyses of LOCA, operational transients, and other accident scenarios in PWRs and BWRs.

The paper presents CTF and TRACE models for the PSBT void distribution exercises.

Code-to-code and code-to-data comparisons are provided along with a discussion of the void generation and void distribution models available in the two codes.