Examples

GUARDYAN is capable of simulating neutron transport in complex geometries, but is has yet to be further developed in order to provide quantitative results fit for intercomparisons with other codes. Here we only provide some illustrations for the capabilities regarding neutron transport, time evolution and the geometrical complexity.

BME OR

The pool-type nuclear reactor of the Budapest University of Technology is in operation since 1971. The core is built of EK-10 fuel assemblies with 10% enrichment. The maximum thermal power is 100 kW, the maximum thermal neutron flux is 2.7•10¹² n/cm²s. The main purpose of the facility is to support education in nuclear engineering and physics; however, extensive research work is carried out as well. Neutron and gamma irradiation can be performed using 20 vertical irradiation channels, 5 horizontal beam tubes, two pneumatic rabbit systems and a large irradiation tunnel. The facility has physical and radiochemical laboratories and a hot cell too.

The geometry model was input to Guardyan and a neutron transport calculation was initiated from a homogeneously distributed neutron source usng 10²⁶ neutrons. Fig. 1 shows the photograph of the core in operation, the model geometry and a snapshot of the neutron population. On the geometry model figure the light blue indicates the position of the fuel pins, light green stands for water and dark blue is for the reflector.

BME Training Reactor Image of the Core

BME Training Reactor Geometry

Neutron density distribution in the BME Training reactor calculated by GUARDYAN

Figure 1.: BME Training Reactor image of the core, model geometry and simulated neutron density

The right-hand-side image of the neutron population is a snapshot of particles after exactly 10^-6 seconds. Most of the neutrons are in the water due to their lower speeds. Note that the geometry image is not superimposed here, the material changes are only visible in accordance with the neutron population change.

Time evolution in a critical assembly

VVER-440 a Geometry input check