CASL COBRA-TF improvements for PWR DNB analysis

Yixing Sung, Liping Cao, Vefa Kucukboyaci, Natalie Gordon, Robert Salko, Emre Tatli

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

Abstract

COBRA-TF (CTF) is a thermal hydraulic (T/H) subchannel code using either three-dimensional (3D) Cartesian or subchannel coordinate formulations for two-phase fluid flow and heat transfer solutions. CTF has been improved under the Consortium for Advanced Simulation of Light Water Reactors (CASL) program for Pressurized Water Reactor (PWR) applications, including software optimization, new closure models, pre- and post-processing and parallelization for modeling full reactor core T/H responses under normal operating and accident conditions. As a result of collaboration among CASL partners including the Westinghouse Electric Company, the Oak Ridge National Laboratory (ORNL), and the Sandia National Laboratories, additional modeling improvements were made to CTF specifically for PWR Departure from Nucleate Boiling (DNB) analysis, including a code option to evaluate fuel thermal margin in terms of DNB Ratio (DNBR) and an axial shape factor to account for effect of non-uniform axial power distribution on DNB. Multiple DNB correlations are now linked with CTF for different applications, including the Westinghouse proprietary WRB-1 correlation for fuel designs containing mixing vane grid spacers. The improved CTF code with the WRB-1 correlation (CTF/WRB-1) was validated using the DNB data from the PWR Subchannel Bundle Tests (PSBT). In addition to the comparison with the test data, the CTF/WRB-1 DNBR results and the associated local fluid conditions were compared to the results of the Westinghouse T/H design code, VIPRE-W, which is an enhanced version of the VIPRE-01 code originally developed by the Electric Power Research Institute (EPRI). The comparisons showed that CTF/WRB-1 DNBR predictions are in good agreement with the VIPRE-W results within the applicable range of the DNB correlation. A model sensitivity study was performed to confirm that the CTF void drift model had an insignificant effect on DNBR under the steam line break (SLB) low pressure condition.

Original languageEnglish
Title of host publicationTop Fuel 2016
Subtitle of host publicationLWR Fuels with Enhanced Safety and Performance
PublisherAmerican Nuclear Society
Pages1465-1474
Number of pages10
ISBN (Electronic)9780894487309
StatePublished - 2016
EventTop Fuel 2016: LWR Fuels with Enhanced Safety and Performance - Boise, United States
Duration: Sep 11 2016Sep 15 2016

Publication series

NameTop Fuel 2016: LWR Fuels with Enhanced Safety and Performance

Conference

ConferenceTop Fuel 2016: LWR Fuels with Enhanced Safety and Performance
Country/TerritoryUnited States
CityBoise
Period09/11/1609/15/16

Keywords

  • COBRA-TF
  • DNB
  • Subchannel analysis

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