CODE-TO-CODE VERIFICATION OF THERMAL HYDRAULIC SUBCHANNEL CODE LINDEN

The subchannel code LINDEN is developed as a dedicated numerical tool for thermal-hydraulic analyses of a pressurized water reactor (PWR) under varying operating conditions. To fully achieve the development goals of LINDEN, rigorous verification and validation (V&V) work should be included in preparation for its intended applications in engineering practice. This research focuses on a code-to-code verification of the code, where a top-down verification strategy has been adopted. The main features and basic models of LINDEN were first introduced. In order to verify the concerned models, a verification matrix for separate-effect test and integral-effect test with different typical thermal-hydraulic scenarios was designed. The test cases involved a typical single channel in a PWR primary circuit and a 5x5 rod bundle under both steady-state and transient conditions. The simulation results of several key thermal-hydraulic parameters were then compared with those from the state-of-the-art subchannel code CTF. The calculation results of LINDEN were in good agreement with those of CTF under different test cases, and only the void prediction of LINDEN is on the lower side compared to CTF's, which could be attributed to different interface mass exchange models taken in the two codes. In summary, the code-to-code based assessment work in this study has confirmed that the basic models are correctly implemented and performed as expected.