Definition of the Fifth Dynamic AER Benchmark Problem - A Benchmark for Coupled Thermohydraulic/ Three-Dimensional Hexagonal Neutron Kinetic Codes

The fifth dynamic benchmark defined in this paper is the first benchmark for coupled thermohydraulic system/three-dimensional neutron kinetic core models. In this benchmark the interaction between the components of a VVER-440 NPP with the reactor core should be investigated.

The initiating event is a symmetrical break of the main steam header (MSH) at the end of the first fuel cycle and hot shutdown conditions with one stuck out control rod group. The main purpose is the investigation of recriticality. For this reason, the calculation should be continued until the power excursion is eventually terminated by high-borated water from the high pressure injection system.

The participants of the benchmark should use own input data decks developed according to the needs of their own codes. The main geometrical parameters and characteristics of control and safety systems to be considered in this benchmark will be given to bring into agreement the data decks. Own best estimate nuclear cross section data should be used in the calculation. Only the initial subcriticality at the beginning of the transient will be given to made the results more comparable.