The thermal hydraulic and SFD (Severe Fuel Damage) best estimate computer modelling code SOCRAT/V3 has been used for the calculation of QUENCH-16 experiment which was performed in the frame of the EC supported LACOMECO programme.
The QUENCH-16 test conditions simulated a representative scenario of LOCA (Loss of Coolant Accident) nuclear power plant accident sequence in which the overheated up to 1800K core would be reflooded from the bottom by ECCS (Emergency Core Cooling System). The QUENCH-16 experiment included the following phases: first heat-up phase, pre-oxidation phase, slow cool-down phase (preparatory to air ingress), air ingress phase and bottom water flooding phase.
The test QUENCH-16 was successfully conducted at the Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany, on July 27, 2011. The primary objective of this test was to investigate the oxidation of Zircaloy in the air following a limited pre-oxidation in the steam and to achieve a long period of oxygen starvation to promote the interaction with the nitrogen. Unexpectedly high cladding oxidation rate was detected during flooding phase which resulted in huge hydrogen production in QUENCH-16. It was due to zirconium nitride (ZrN) formation in a cladding which induced a diffusion transparency of zirconium dioxide layer.
QUENCH facility is designed for studies of the PWR fuel assemblies behaviour under conditions simulating design basis, beyond design basis and severe accidents.
SOCRAT/V3 computer modelling code was used for estimation of basic thermal hydraulic, oxidation and air ingress parameters in QUENCH-16.
The calculated results are in a reasonable agreement with experimental data which justifies the adequacy of modeling capabilities of SOCRAT code for application to such a complicated test as QUENCH-16.
