Development of a method for pre-activity and dose rate calculations of components in the reactor vicinity based on neutron fluence distributions (EMPRADO)
The aim of the collaborative project is to develop a standardized method that calculates the specific and temporal progression of activation for reactor components and near-reactor concrete or construction elements based on the power history of a nuclear reactor. A non-destructive and early radiological characterization in the region of the reactor core is thus possible, which is required for an optimal planning of the decommissioning. This can make a significant contribution to minimize the radioactive waste and the radiation exposure of personnel during the decommissioning. The method will be developed using the example of a "Vor-Konvoi" pressurized water reactor and validated with experiments.
In the HZDR subproject, the required exact 3D neutron fluence calculations and the experimental activation determination will be carried out. The Monte-Carlo method is a recognized method for such simulations with complicated geometries. Therefore, the international widely-used program MCNP6 is mainly used in the project. For the geometry model, original design documents are used to represent the geometry as accurately as possible in the calculations. The neutron sources will be specified as external source. These are based on corresponding power histories. Due to the large spatial dimensions, one focus of the work will be the optimization of the simulation. The using of variance-reducing methods will be indispensable.
For validation of the calculation results neutron flux measurements on the basis of activation foils will be carried out at certain NPPs. Different metal films are installed at selected locations near the reactor and irradiated during an operating cycle. The generated activities will be measured by Gamma spectroscopy and Liquid Szintillation Counting (LSC) and compared with the calculation results.