Definition of the Second Benchmark of AER

The first kinetic benchmark of AER was defined for comparison of different 3-dimensional kinetic codes developed for the hexagonal geometry of fuel assemblies in a VVER-reactor. The transient was assumed to be caused by ejection of nonsymetric control rod in a VVER-440 reactor. Feedback effects were neglected. The positive reactivity insertion not leading to prompt criticality results in a slower power increase and was compensated by insertion of shutdown rods.
The benchmark problem No. 2 discussed on the meeting of working group D in Budapest 1993 consists also of a control rod ejection accident in a VVER-440. The initial configuration is similar to benchmark No. 1. A nonsymetric control rod with a worth of 2 ßeff is ejected at hot zero power (HZP). The Doppler effect being the main feedback effect for this type of transients is the only feedback and is taken into account by an adiabatic model of fuel temperature. Therefore it is possible to calculate this type of transient with codes which do not contain a complete thermohydraulic model.
As in problem No. 1, the nuclear data are given to exclude at this step of comparison the effects caused by different nuclear data. A sharp and high power peak connected with large deformations of flux shape is expected to give a serious test for codes and methods of calculation.
The problem, the input data and the expected results which will be used for comparisons are specified.