Final report of ENTHALPY
A. De Bremaecker (SCK.CEN-Mol detached at IRSN), M. Barrachin, F. Jacq (IRSN), F. Defoort (CEA/DRN), M. Mignanelli (AEA-T), P.Y. Chevalier B. Cheynet (Thermodata), S. Hellmann, F. Funke (Framatome-ANP), C. Journeau, P. Piluso (CEA/DRN/DTP), S. Marguet (EdF), Z. Hózer (AEKI), V. Vrtilkova, L. Belovski (SKODA), L. Sannen, M. Verwerft (SCK.CEN-Mol), P-H. Duvigneaud, K. Mwamba (ULB), H. Bouchama, C. Ronneau (UCL), Rapport technique SAM-ENTHA(03)-P-018, juin 2003.
The calculation of fuel degradation, melting, relocation, and ex‑vessel spreading, and of fission products retention/release are based on the physical properties of the corium (viscosity, heat conductivity, density, solid/liquid fraction, etc.). These properties can be deduced from the phase diagrams of the elements and systems present in the in- and ex-vessel scenarios. Phase diagrams are obtained directly by experiments or indirectly by thermodynamic measurements and models.
The general objective of the ENTHALPY project performed by 12 partners, was to obtain one unique European commonly agreed thermodynamic database for in- and ex-vessel applications, well validated and to develop methodologies to couple the database to Severe Accident codes used by end-users i.e. at least utilities, Safety Authorities and nuclear designers.
In this quest the most outstanding issue was to compare, critically assess and merge the two existing databases existing in Europe, and to extend them to new elements.
Separate Effect tests (SET) were done to get information on unknown or badly known phase diagrams such as FeOx-B2O3 ; ZrO2 - B2O3 ; UO2 - B2O3 ; in the quinary system UO2 - ZrO2 – BaO - MoOx ; in the hyperstoichiometric domain ZrO2-UO2+X ; in the ternary system Zr-Fe-O (solubility of ZrO2 in Zr-Fe) ; and in 10 typical ex-vessel mixtures. Global tests were used to validate the database (Precalculations of ZrO2-UO2+X tests, VERCORS 4 & 5, Hofmann tests, VULCANO VE-U3 and VE-U7, COMETA/NRI).
Methodologies of coupling between the database and SA codes were studied and applied to a 4-elements system (U-Zr-Fe-O). An application of the database to a reactor case (TMI2) was also performed.
Finally the “NUCLEA” data base was issued, validated against several in- and ex-vessel tests, is documented and is now commercially available. It contains the following elements O-U-Zr-Fe-Cr-Ni-Ag-In-Ba-La-Ru-Sr-B-C-Al-Ca-Mg-Si + Ar-H; the multi-component (15) oxide system UO2-ZrO2-FeO-Fe2O3-Cr2O3-NiO-In2O3-BaO-La2O3-SrO-B2O3-Al2O3-CaO-MgO- SiO2 is also a subset of the whole database.
Future work in this field will comprise a further extension to other elements (Mo, Pu, Cs for instance) and efficient coupling methods between the bigger subsets of the database and SA codes.