Beneficiary Organization Details

Nuclear Regulatory Agency (Bulgaria)
http://www.bnsa.bas.bg
Project Aims

The main objectives of the project were:

• To train Bulgarian scientists to use the TRANSURANUS (TU) code, with the extensive assistance of the ITU, Karlsruhe which released also the code;
• To develop of a specific VVER version of the TU code through the development of 10 TU data drawers including VVER correlations from original data;
• To validate the TU VVER version with SOFIT 1.1, Bulgarian PIN-micro code and Kola-3 experiments.

Project Results

• The major achievement of this project was the creation of a team of Bulgarian specialists trained to work on up-to-date nuclear fuel behavior and modelling;
• Regarding the development of a specific VVER version of the TU code through the development of 10 TU data drawers including VVER correlations from original data, the key difference compared to Western fuel pins was found in the N1 cladding swelling, growth and elongation. Because of the anisotropic behavior of the cladding, it leads predominantly to axial elongation, and thus, to a decrease of the operational life of a cladding;
• The validation of the TU VVER version with SOFIT 1.1 and Kola-3 experiments looked rather good except for the fission-gas release predictions for the fuel assembly 222 of the Kola-3 data. However, this appeared to be due to a systematical experimental error. Also the comparison calculations with the Bulgarian PIN-micro code were of value for the validation of TU VVER.

The project was completed according to the specified Terms of Reference.
Further Project Results
Further information on the project results could be sought from the beneficiary organizations.