Final report on rod cladding failure during SGTR

Achievements on modelling fission product release from defective rods during a steam generator tube rupture transient and iodine spiking have been obtained and presented in this deliverable

Third Yearly Activity Report

The calculation work performed during the 3rd project year in WP2 as well as the R&D activities carried out in WP3, WP4 and WP5 are described in this report. In addition, the work dedicated to the project management (WP1) as well as to WP6 regarding the dissemination/communication activities and the education/training program (e.g. the follow-up of the mobility program between different organizations in the consortium, training on simulation tools and activities accomplished by PhD/post-doctoral students) is also reported

The Application of the TRANSURANUS Fuel Performance Code to WWER Fuel: An Overview

The present review paper outlines the collaborative efforts for the establishment of the TRANSURANUS version for the simulation of VVER fuel pin behavior, which has been presented at this series of international conferences organized by the INRNE since 1994. The paper therefore starts with very briefly reviewing the development of the TRANSURANUS fuel performance code in collaboration with various organizations from EU member states operating VVER reactors. The development started with the application to normal operating conditions in the frame of different bilateral agreements supported by the European Commission and the IAEA (e.g. PHARE and PECO projects), followed by the specific project dedicated to its application to the loss of coolant type accidents (EXTRA). In the second part of the paper, a summary will be given of the verification, validation and benchmarking efforts, on the basis of the experimental data included in the IFPE database of the NEA, as well as in the frame of the co-ordinated research projects of the IAEA (e.g. FUMEX, FUMAC), and most recently also the Euratom project ESSANUF co-ordinated by Westinghouse Electric Sweden. Finally, we will outline the current plans for further improving the simulation capabilities of VVER fuels by means of TRANSURANUS

P2M Simulation Exercise on Past Fuel Melting Irradiation Experiments

This paper presents the results of the Power To Melt and Maneuverability (P2M) Simulation Exercise on past fuel melting irradiation experiments, organized within the Organisation for Economic Co-operation and Development/Nuclear Energy Agency Framework for IrraDiation ExperimentS (FIDES) framework by the Core Group (CEA, EDF, and SCK‧CEN) and open to all FIDES members. The exercise consisted in simulating two past power ramps where fuel melting was detected: (1) the xM3 staircase power transient [ramp terminal level (RTL) 70 kW‧m−1, average burnup 27 GWd‧tU−1], carried out in 2005 in the R2 reactor at Studsvik (Sweden), where the rodlet maintained its integrity, and (2) the HBC4 fast power transient (RTL 66 kW‧m−1, average burnup 48 GWd‧tU−1), carried out in 1987 in the BR2 reactor at SCK‧CEN (Belgium), where the cladding failed during the experiment. The exercise was joined by 13 organizations from 9 countries using 11 different fuel performance codes. In this paper, the main results of the Simulation Exercise are presented and compared to available postirradiation examinations (PIE) or on-line measurements during the power ramps (fuel and clad diameters, rod elongation, pellet-clad gap, and fission gas release). Since the focus of the Simulation Exercise is on fuel melting assessment, determination of the boundary between melted/nonmelted fuel and the consequent definition of a melting radius from PIE are first discussed. During the HBC4 ramp, fuel melting was predicted by most of the codes despite differences in the melting models. Higher discrepancies were observed for the xM3 rod that can be attributed partly to power uncertainty and partly to the limited capability of the models to describe partial melting of the fuel during this ramp. Finally, possible code developments to improve simulation results are presented.</p