Background

The overall objective of this project was to improve the capabilities of the Ukrainian Safety Authority and its Technical Support Organisation (SSTC) for independent safety review and assessment of the on-site radiological situation at Ukrainian nuclear power plants. This project concerned the transfer of codes and training in the use of these codes.

The specific objectives were:

• Task 1: Evaluation of the behaviour of radioactive matter in systems and of resulting activity concentration
• Task 2: Transfer of codes, adaptation to VVER type of reactors and training of experts in the calculation of gamma dose rate fields, radiation by beta sources and the decay characteristics of a complex nuclide.
• Task 3: Transfer of codes, adaptation to VVER type of reactors and training of experts in the calculation of the three-dimensional distribution of neutron streams in a selected point and their shielding.

Project Results

• Task 1: This task was modified during the inception phase of the project and focused on the calculation of the distribution of radioactivity in the secondary circuit and in the containment following a steam generator tube rupture and a steamline break, and on the calculation of radiological consequences of radioactive release in the environment. The code ACARE (transport of radioactive material and activity concentration) was transferred to SSTC.
• Task 2: The codes ORIGEN (source term calculation), QAD (3D gamma shielding calculation on point kernel integration) and SAS3 (3D Monte-Carlo gamma field calculation including scattering) were transferred.
• Task 3: The codes MCNP (radiation transport calculation using Monte-Carlo methods) and TORT (radiation transport calculation using discrete ordinates method) were provided.

For these three tasks, 8 experts of SSTC were trained in Germany with calculation examples reflecting VVER problems and passed successfully the prepared tests. The related training material was provided.