Code-to-Code Verification of COBRA-TF and TRACE
Open Access
- Author:
- Leandro, Adrian Michael
- Area of Honors:
- Nuclear Engineering
- Degree:
- Bachelor of Science
- Document Type:
- Thesis
- Thesis Supervisors:
- Justin Kyle Watson, Thesis Supervisor
Seungjin Kim, Thesis Honors Advisor - Keywords:
- COBRA-TF
TRACE
verification
simulation
model
point kinetics
turbine trip
sub-channel
reactivity feedback - Abstract:
- The purpose of this project is to perform code-to-code verification of the point kinetics models in both COBRA-TF and TRACE and to verify TRACE’s ability to perform sub-channel analysis. This is important to perform to ensure the validity and accuracy of these widely used codes. Additionally, the point kinetics model is relatively new to COBRA-TF and has not been completely verified. On the other hand, the point kinetics model is very mature in TRACE as it has been in place for more than 30 years. Furthermore, COBRA-TF is a sub-channel based code while TRACE is not; the channel component of TRACE only models entire BWR fuel bundles. This project is split into two main parts, analysis of a base model and a modified model. The base model includes nine components each representing a subsection of a quarter core. One of the smallest components represents the hottest channel in the core and the largest represents the entire quarter core. This base model showed substantial differences between COBRA-TF and TRACE, especially during a transient. These differences were exacerbated by inconsistent input between COBRA-TF and TRACE. Since the focus of this work was to verify the point kinetics model and sub-channel analysis, it was decided to create simplified models that contained strong feedback mechanisms. To complete the analysis, two new models were built based on this base model for COBRA-TF and based off of a simple, one pipe TRACE model of a pressure wave propagating through the primary side of a BWR. This means that only one sub-channel is used on COBRA-TF to mirror the single pipe on TRACE. Both of these models use identical point kinetics models. The new models also correct many of the modeling errors found on the base model, such as inconsistent fuel dimensions between both codes. Running these two models is still in progress since incomplete results have been gathered from both codes. Currently, TRACE does not have all reactivity feedback mechanisms turned on, and they must be activated in order to see changes to thermal hydraulic parameters. Additionally, COBRA-TF is not running any calculations with a transient pressure case as there may be issues with the FORTRAN source code of the COBRA-TF executable that is being used.