code 2006 CRITEX final by iW5Nyk





                             GENERAL INFORMATIONS
                                      ( 1 )

Designation of      CRITEX
the code
                    Models the transient criticality of a fissile solution contained in an open
Summary             cylindrical vessel with vertical walls, so that the solution is able to
(General purpose)   expand vertically (thermal dilatation, production of radiolytic gas
                    bubble). The solution vertical extent is divided with axial meshes into a
                    number of volumes that allows to calculate the axial movement of the
                    solution and the following reactivity effect.
                    The energy deposited in the volumes is calculated based on the power
                    profile (assuming fundamental neutronic mode), coupled with the
                    central power calculated with the point kinetic equation.

                    Name(s)                             D. J. MATHER , A. M. BICKLEY,
                                                        A. PRESCOTT.
                                                        P. FOUILLAUD, P. GIROUD,
                                                        P. GRIVOT.

                                                        UK/AEA (United Kingdom Atomic
                    Organization                        Energy Authority).
Authors                                                 CEA (Commissariat à l’Energie
                                                        CEA Centre de Valduc
                    Post mail address                   DRMN/SRNC
                                                        21120 IS-SUR-TILLE Cedex
                    e.mail address            

                    First version released              CRITEX V4.3 (1993).
                    (date and reference number)

                    Current version released            CRITEX V6.1 (2001).
                    (date and reference number)

                    Current development
Status of code
                    Language program / Modularity       Fortran 90.

                    Operating system                    Windows.
                    (windows, linux, unix,…)

                    Software requirements               Fortran 90 compiler.
                    (fortran compiler,…)

           Portability                                 Workstation.
           (PC / Workstation/Supercomputer))

           Availability / web site
           (executable, source files, data files, …)

           Typical running time                        10 s  10 min.
           (for one calculation)


                                GENERAL INFORMATIONS

User Interface                 Input data file for a CRITEX run can be built by INITAL code or

                               Time, central specific power, inverse period, total power, total
Calculated Standard            energy released.
Outputs / and Units            Reactivity inserted, reactivity feedback (doppler, solution
                               expansion), total reactivity of the solution.
Time step output : power,
energy, pressure,              Solution temperature at top/mid/bottom level of the vessel.
temperature, …
Main characteristics : first
                               First peak power, first minimum, secondary peak powers and
peak power, total energy
release, maximum pressure,     minimums.
temperature, time of
boiling,…                      Time of radiolytic gas bubble formation (nucleation).

                               Gas inverse time constant (diffusion).

Graphic editor

                               Description of code modeling (report).
                               Code production (report).
Quality Assurance              Selection of Experimental Benchmarks (reports).
(data and code package)
                               Code qualification synthesis (report).

                               C. LAVARENNE
Contact Person                 BP 17
(name of the contact for the
                               92262 FONTENAY-AUX-ROSES Cedex


                                   GENERAL DESCRIPTION

                                                                Physical Forms

Fissile Materials
                                        Solution                Powder             Metal          Fuel rods   …
                              (nitrate,fluorure, sulfate,…)   (dry, wetted,…)   (dry, wetted,…)

                              Nitrate (93%, 5%,
Uranium                       3.5%).
(isotopic content %)          Fluoride (1%  8%).

                              (239Pu/240Pu/241Pu =
Plutonium                     95/5/0, 80/20/0,
(isotopic content %)
Mixed Plutonium /                  Pu
                              (           10 ou 30% ).
Uranium                           U  Pu
(isotopic content %)          Fluoride.

                              Cylindrical 1D with
                              free upper surface
Geometry description          allowing solution
Cylindrical, spherical,…      expansion.
Space Dimension (1D, 2D,…),
Meshing / Region,
Finite Element Method, …      Axial meshing.


                              DESCRIPTION OF MODELS USED

                           Point kinetic equation,                      Point kinetic equation.
Neutronic Power / Kinetics transport or diffusion theory

                                      Transport or diffusion                 Reactivity inserted by step,
                                      theory, mathematical                   ramp or buckling formula.
                                      formulas,                              Reactivity feedback of the
Reactivity and Reactivity             input or calculated data               solution expansion is calculated
feedback                              (reactivity insertion, temperature     with one group perturbation
                                      coefficients : Doppler, dilatation,..)
                                                                             Doppler coefficients are
                                                                             tabulated internal data.

                                      Thermal (heat conduction,         Axial meshing, heat conduction,
                                      convection, boiling…) / Meshing   natural convection.
                                      and region

                                      Multi-phase flow                  Radiolytic gas bubble formation
Thermal – hydraulics
                                                                        and migration.

                                      Fluid motion / Meshing and

                                      Pressure modeling
                                                                        Radiolytic gas bubble migration
                                      Radiolytic formation and          is modeled by means of a
Radiolysis                            migration models                  conservation equation with
(for solutions)
                                                                        bubble migration velocity and a
                                                                        source term.

                                      Neutronics – kinetics             k , neutron lifetime, delayed
                                      (cross sections libraries, k ,   neutron constants and doppler
                                      neutron lifetime, delayed
                                      neutrons)                         coefficients are tabulated internal
Data libraries :                                                        data , they have been calculated
External or/and Internal                                                with WIMS or APOLLO
(constants, calculated / tabulated,                                     deterministic neutronic codes.
experimental, bibliography, …)
…                                                               Internal data determined from
                                      Thermal and hydrodynamics laboratory measurements.
                                      (heat capacity, conductivity,…)
                                                                        Internal data determined from
                                      Radiolysis (yield, threshold      CRAC and SILENE experiments.
                                      formation, velocity,…)

                             VALIDATION BASE OF THE CODE

                                      The power is calculated with point kinetic equation and a
                                      power profile assuming fundamental neutronic mode. The
                                      reactivity feedback takes into account solution expansion
Summary of the main
                                      (thermal dilatation , void effect of bubbles) and doppler effect.
assumptions in the code
                                      Solution temperature is calculated using a thermal balance
                                      equation with heat capacity and natural convection.
                                      Bubble migration is calculated using a conservation equation
                                      with bubble migration velocity and a source term.

                              Aqueous solution of fissile media.
Limitations to the use of the
                              No treatment of the boiling phase.

                                      CRAC, SILENE: Uranyl nitrate (93%, 22 g/l  218 g/l,
                                      =30 cm, 80 cm, 36 cm).
Experimental benchmarks               SHEBA: uranium fluoride (5%, 979 g/l, =49 cm).
(reactor : fissile media, geometry,
reactivity insertion, duration,…)     Reactivity pulse or ramp from 0.035 to 3 $.

                                      Tokai-Mura (JCO , 1999).
Past Accidents

                                      Validation of the modeling
                                      with standard codes
                                      (neutronics, thermal,…)

Codes comparison
                                      Accidents code

Domain of validation and              Comparison with experimental benchmarks from SILENE ,
level of confidence                   CRAC and SHEBA experiments show correct agreement for
                                      first peak power and total energy released (within 20 to 40%).

                            D. J. MATHER, A. M. BICKLEY, A. PRESCOTT
                            “CRITEX – a code to calculate the fission release arising from
                            transient criticality in fissile solutions”
                            AEA/CS/R1007/R (1994)
                            D. J. MATHER , A. M. BICKLEY, A. PRESCOTT
                            F. BARBRY, P. FOUILLAUD, J.P. ROZAIN
                            “Validation of the CRITEX code”
                            Proceedings of the ICNC'91
References                  P. GRIVOT, P. FOUILLAUD
(reports, communications,
                            “Description du code CRITEX”
                            CEA/IPSN/DPEA/SRSC n°96.02 (1996)
                            P. GIROUD
                            “Mise en production du code CRITEX version 6”
                            CEA/IPSN/DPEA/SRSC n°01.09 (2001)
                            P. GIROUD, P. GRIVOT
                            “Accident de criticité en solution – Synthèse de la qualification
                            du code CRITEX“
                            CEA/IPSN/DPEA/SRSC n°00.05 (2000)


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