Simulation of xenon transients in the VVER-1200 NPP using the KARATE code system

Xenon transients in Russian VVER reactors have been studied in great theoretical and experimental detail. On the other hand, with an upgraded reactor design (including higher power density, modified safety systems and thermohydraulics), it is essential to study the relationship between reactor perturbations, reactor core geometry and feedback effects. Recently, some measurements have been published describing the interaction between xenon oscillations and power in the core of the newly developed VVER-1200 reactor. The construction of this type of reactor is planned in Hungary, so the simulation of these experiments using a Hungarian reactor physics code system is essential. In this paper, we introduce the core of the Novovoronezh reactor, which is the first VVER-1200 reactor, and present selected measurements from the physical start-up experiments of this new unit, including several xenon transients. We simulated these transients using our upgraded KARATE code system and found that the calculated and measurement results show reasonable agreement, which demonstrates the capabilities of our code. Similar trends to our results can be observed in the calculations performed by Russian design codes. (C) 2022 Elsevier Ltd. All rights reserved.