Subchannel thermal hydraulic analysis of 5 × 5 rod bundle with CRUD layer

摘要

? 2023 Elsevier B.V.This paper studies the thermal–hydraulic behaviors difference with or without the Chalk River Unidentified Deposits (CRUD) layer by using subchannel analysis code COBRA-EN. Based on similar structure characteristics, the EPRI CHF prediction model is improved and applied in a 5 × 5 rod bundle. Three different species transient scenarios are calculated for comparing different hydraulic behaviors with or without the CRUD layer. The results show that the heat transfer enhancement is limited under high pressure because the improved CHF model is mainly affected by local pressure. But when the pressure came low, the enhancement became more obvious, such as heat flux and minimum departure from nucleate boiling ratio (MDNBR). Under serious accidents, the influence can be mitigated with the CRUD layer, and recovery from the accident with the CRUD layer was faster than bare cladding when considering the effect of the CRUD layer.