Thermodynamic database for nuclear applications,




a consistent database with 18 elements and more than 300 assessed binary or ternary systems.


O-U-Zr-Ag-In-B-C-Fe-Cr-Ni-Ba-La-Sr-Ru-Al-Ca-Mg-Si + Ar-H



Since 1990 some people in Europe were interested in the assessment of thermodynamical data for a number of compounds of reactor materials and fission products based on the recommendations of a specialists meeting held at JRC-Ispra, Italy in 1990 [*]. Critical assessments have been made on a very large number of compounds and systems. Today a Thermodynamic Data Base has been built, collecting all this knowledge. NUCLEA is a thermodynamic database for in and ex-vessel applications containing 18 + 2 elements and including the 15 oxide system :




This database has to cover the entire field from metal to oxide domains. It allows the user to calculate with the GEMINI2 code the thermochemical equilibrium state at any step of a severe accident and to use the results of the thermodynamic approach for improving the predictions of thermo-hydraulic or other accidents codes.


The Gibbs energy of all possible multicomponent condensed or gaseous substances and solution phases are modelled. The binary and ternary Gibbs energy parameters were critically assessed by means of sophisticated optimisation procedures.


Applications of a global thermodynamic approach, i.e. the simultaneous use of a high-quality thermodynamic database and an equilibrium calculation code, are numerous :


-          condensed state phase diagrams, transitions, liquidus/solidus, compositions and proportions,

-          coupling thermodynamics and thermo-hydraulic, viscosity, segregation, residual power distribution,

-          gaseous fission products release in any external conditions …



Such a database is much more than a compilation of thermodynamic data from various sources, its constitution needs a considerable work for self-consistency analysis, to ensure that all the available experimental information is satisfactorily reproduced.


Updating and improving the database has to be a regular task, tightly linked to the needs of end-users.



[*]     Fission Product Chemistry in Severe Nuclear Reactor Accidents, Specialist’s Meeting at JRC-Ispra, 15-17 January 1990, EUR 12989 EN (1990), A.L. Nichols ed.








The Nuclea Thermodynamic Database for In- and Ex-Vessel Applications contains the 18 + 2 following elements :


O-U-Zr-Fe-Cr-Ni-Ag-In-B-C-Ba-La-Ru-Sr-Al-Ca-Mg-Si + Ar-H,


Ar and H are not taken into account in condensed solution phases.






The condensed solutions (46 non-stoichiometric phases) were deduced from the analysis of the assessed sub-systems (binary, ternary, …) ; some of them present possible miscibility gaps.






511condensed substances are included in the database.


Hydrogen was added because it is a major component of the system, but the dissolution of hydrogen in condensed solid and liquid solutions is not taken into account at this time.






The gaseous species (203, ideal mixture) were extracted directly from the THERMODATA substance database and added to NUCLEA.





This package is constituted of :



the complete NUCLEA database for in and ex-vessel applications


a sub-database NUCLEA-iv for in-vessel applications only

(concrete elements are excluded)


a limited database with only 4 elements : Fe-O-U-Zr


the HANDBOOK of 300 calculated phase diagrams with experimental points


PAPYRUS : a bibliographic software with 8 000 references concerning the thermodynamics of NUCLEA.



Each part is independently available if you are interested.



A consistent thermodynamic database with a powerful thermochemical equilibrium calculation code.


********************************* GEMINI2 ************* V3.41




                  T/K : 2000.00      p/atm :   .100000E+01


                 INITIAL AMOUNT              MOLES

                 FE                         .10000000E+01

                 H                          .60000000E+01

                 O                          .11000000E+02

                 U                          .40000000E+01

                 ZR                         .20000000E+01





 SOLUTION(S)      Component                 mol            atomic fraction



 LIQUID                                  .150515E+01        .627147E-01


                    FE                   .999438E+00        .664011E+00

                    O                    .304879E-01        .202557E-01

                    U                    .135252E+00        .898595E-01

                    ZR                   .339975E+00        .225874E+00


 FCC_C1                                  .164943E+02        .687261E+00


                    O                    .109695E+02        .665049E+00

                    U                    .386474E+01        .234309E+00

                    ZR                   .166002E+01        .100643E+00



 GAS                  pressure (atm)        mol          volumic fraction



 H2(G)                 .998170E+00       .299753E+01        .998170E+00

 H1(G)                 .163831E-02       .491988E-02        .163831E-02

 FE1(G)                .188019E-03       .564625E-03        .188019E-03

 H2O1(G)               .357528E-05       .107367E-04        .357528E-05

 O1U1(G)               .214807E-06       .645071E-06        .214807E-06

 O2U1(G)               .116544E-06       .349984E-06        .116544E-06


                               BALANCE (mol)


     References    Solution(s) Substance(s)   Gas        Total       Activity


 FE  FE1(L)        .99944E+00  .00000E+00  .56463E-03  .10000E+01  .51830E+00

 H   H2(G)         .00000E+00  .00000E+00  .60000E+01  .60000E+01  .99908E+00

 O   O2(G)         .11000E+02  .00000E+00  .12138E-04  .11000E+02  .10397E-08

 U   U1(L)         .40000E+01  .00000E+00  .10048E-05  .40000E+01  .40845E-01

 ZR  ZR1(BCC_A2)   .20000E+01  .00000E+00  .42534E-07  .20000E+01  .60851E-01


 TOTAL             .17999E+02  .00000E+00  .60006E+01  .24000E+02

 GAS VOLUME (L)        .492834E+03







A bibliographic software with 8 000 references about the thermodynamics of the elements, compounds and solutions of NUCLEA.



 Chose the system you want by clicking the table and you obtain the references of interest.





the collection of the 300 phase diagrams assessed in NUCLEA.







Contact :



6, rue du Tour de l’Eau, 38400 Saint Martin d’Hères – France

Tel. (+33) 4 76 42 76 90    E-mail :