[en] In the framework of the code assessment and maintenance program (CAMP) of the US NRC the reflood model of the RELAP5 code is being validated at Forschungszentrum Karlsruhe (FZK) using data from the test PKL-IIB.5. The primaerkreislauf-(PKL) test IIB.5 simulates a double-ended break of the cold leg of a German 1300 MWe PWR with emphasis on the reflood heat transfer phenomena. The PKL-facility includes all major primary coolant circuit components and some secondary components, and a containment. After transient initiation the coolant is dumped to the containment while the ECC-systems (accumulators and low pressure injection systems) inject a large amount of cold water leading to a progressive core rewetting. Under such conditions complex heat transfer mechanisms take place in the core region. A novel reflood model, developed at PSI, was implemented in the code version RELAP5/MOD3.2.2Gamma (322G). The heat transfer coefficient in the film and transition boiling flow regime is dependent on the distance from the quench front. The transition boiling heat transfer is predicted by the empirical Weisman correlation. The post-test calculation of the PKL-IIB.5 test showed that the PSI-reflood model is able to describe the reflooding process in an reasonable manner. But the empirical Weisman correlation tends to over-predict the transition boiling heat transfer. Hence the semi-mechanistic FZK-transition boiling model was implemented in RELAP5 instead of the Weisman correlation. The resulting code version was named RELAP5/MOD3.2.2G+FZK (322G+FZK). Based on the re-calculation of the PKL-test with the modified RELAP5-version it can be concluded that the rewetting temperature predicted by the FZK-transition boiling model is much closer to the experimental data than that obtained using the Weisman approach. Results of these investigations are presented and discussed in this report. (orig.)