Adaptation of the gas gap simplified model in DYN3D code to new types of fuel

28th Symposium of AER on VVER Reactor Physics and Reactor Safety (2018, Olomouc, Czechia)
[1] Advances in spectral and core calculation methods


M.Ieremenko, Iu.Ovdiienko (SSTC NRS)


The new types of nuclear fuel introduction on Ukrainian NPPs for improve operational characteristic and diversification of nuclear fuel supplier are actual process.

A significant effort has been made to license alternative fuel designs for the VVER plants in Ukraine. As a technical support organization of the Ukrainian regulatory authority, SSTC NRS takes part in the licensing process for introduction of new FA types. For carrying out of independent confirmatory calculations of core characteristics the DYN3D code are used. Considering this adaptation of the DYN3D code to new types of fuel is a necessary part of state-of-art calculations. One of the DYN3D code models that need to be modernized for new types of fuel is the simplified model of the gas gap behavior at the fuel burnup. This model in code is represented as a function gap=f(bur) and calculated by TRANSURANUS code, which takes into account material and geometric characteristics of fuel pins. At present for Ukrainian NPPs actual the following fuel types (operated now or perspective): TVEL Fuel Company – FA Second Generation (VVER 440), FA with “slim fp” (VVER 440), TVSA-12 (VVER 1000); Westinghouse – TVS-WR (or RWFA, VVER 1000), FA with IFBA fuel (VVER 1000), “ESSANUF” FA (VVER 440).

Calculation result of change of fuel-cladding gap width depending on burnup by TRANSURANUS code are presented in this report.

The work was performed in the framework of the project BMU/GRS 4717R01520 under German BMU support. The report describes the opinion and view of the contractor – SSTC NRS – and does not necessarily represent the opinion of the ordering party – BMU/GRS and TÜV SÜD.