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NEA-1368 ARIANNA-2.

ARIANNA-2, Sub-Compartment Thermo-Hydraulic Transients in LOCA

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1. NAME OR DESIGNATION OF PROGRAM:  ARIANNA-2.
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2. COMPUTERS
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Program name Package id Status Status date
ARIANNA-2 NEA-1368/01 Tested 21-OCT-1993

Machines used:

Package ID Orig. computer Test computer
NEA-1368/01 IBM 30xx series DEC VAX 6000
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3. DESCRIPTION OF PROGRAM OR FUNCTION

ARIANNA-2 allows to analyze the behaviour of a thermal-hydraulic transient following a LOCA in a
multicompartment containment system during short, medium and long term accidental sequences. The transient is described as a quasi- steady state: mass and energy flows, in each time step, are based on the thermodynamic conditions of the previous time step.. The mass and energy inventory in each volume may be modified by the contribution of heat transfer, junction flows and blow-down mass and energy inputs. The flow through the junctions can be evaluated by choosing one of the following three models: Moody, homogeneous inertial flow or orifice polytropic flow. Each control volume can be simulated as a homogeneous steam-water-air mixture or as a stagnant  mixture region (atmosphere) above a liquid pool (sumps); the pool region may or may not be in thermodynamic equilibrium with the atmosphere. In the blow-down volumes, isentropic or isenthalpic expansion of the mixture jet is possible together with associated de-entrainment of liquid in the water pool.
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4. METHOD OF SOLUTION

Mass and energy exchange between volumes, linked through junctions, are calculated according to the following  assumptions:
- inlet and outlet pressures for each junction are equal to those of   the two linked volumes;
- thermodynamic flow conditions are equal to those of the donor   volume;
- flow properties are constant during the time-step and mixture flow   is homogeneous.
The inertial flow is calculated on the basis of a numerical solution of the momentum equation while the orifice flow is calculated on the basis of Moody model (critical case) or ideal gas model. The heat transfer to structures is calculated solving the Fourier equation by a finite difference method; and various options make it possible to  calculate heat transfer coefficients.
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5. RESTRICTIONS ON THE COMPLEXITY OF THE PROBLEM

The ARIANNA-2 program provides up to 100 volumes, 200 junctions, 30 of which can have time-dependent areas, and 100 heat conducting structures which  can exchange with any combination of compartments or between any compartment and the outside atmosphere. Up to 101 mesh-points for each structure are allowed and up to 20 different material regions.
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6. TYPICAL RUNNING TIME

A 2-volumes, 1-junction problem requires 0.005 s per time step of CPU time on IBM 3090.
NEA-1368/01
NEA-DB compiled the source program and executed the two test cases included in this package on a DEC VAX-6000 computer in 5m10.54s and 18.36s, respectively.
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7. UNUSUAL FEATURES OF THE PROGRAM

The architecture of ARIANNA-2 is completely modular. Additional features such as restart, plotter file automatic time step control permit flexible use of available code features.
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8. RELATED AND AUXILIARY PROGRAMS

The ARIANNA-2 is the last in the ARIANNA series of programs originally developed at DCMN of Pisa University.
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9. STATUS
Package ID Status date Status
NEA-1368/01 21-OCT-1993 Tested at NEADB
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10. REFERENCES:
NEA-1368/01, included references:
- N. Cerullo, F. Oriolo and A. Pasculli:
  ARIANNA-2 , Un Nuovo Codice di Calcolo per l'Analisi di Transitori
  Termoidraulici in Sistemi di Contenimento a Piena Pressione
  (in Italian)
  RL 098(84).
- M. Cascioli, N. Cerullo, W. Flospergher, F. Oriolo and S. Paci:
  Implementazione e Qualifica dei Modelli di Salvaguardia
  Ingegneristica del Contenimento nel Codice ARIANNA-2 (in Italian)
  RL 305(87).
- N. Cerullo, A. Mandrefini, F. Oriolo and S. Paci:
  Validation of the ARIANNA-2 Code on the Basis of HDR V44 and T31.5
  Tests
  Second International Conference on Containment Design and
  Operation
  Toronto (October 14/17, 1990).
- N. Cerullo, W. Flospergher, F. Oriolo and A. Pacsulli:
  A Model for Thermal-Hydraulic Analysis of Transients in PWR
  Containment Systems the ARIANNA-2 Computer Code
  Reprint from Energia Nucleare/Anno 2/N. 3 (December 1985).
- NEA Data Bank:
  Graphical Comparison of the Original IBM Results (full line) with
  those Obtained on the DEC VAX 6000 (marks)
  NEADB (19/10/93).
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11. MACHINE REQUIREMENTS

4 MB of memory are needed for compilation and execution on IBM 3090.
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12. PROGRAMMING LANGUAGE(S) USED
Package ID Computer language
NEA-1368/01 FORTRAN-IV
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13. OPERATING SYSTEM UNDER WHICH PROGRAM IS EXECUTED:
MSV, VM (IBM 370).
NEA-1368/01
VAX/VMS V5.5-2 with VAX Fortran-77 compiler.
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14. OTHER PROGRAMMING OR OPERATING INFORMATION OR RESTRICTIONS:
Numerical output may show system-dependent variations.
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15. NAME AND ESTABLISHMENT OF AUTHORS

  N. Cerullo, F. Oriolo
  Dipartimento di Costruzioni Meccaniche e Nucleari
  Facolta di Ingegneria
  Via Diotisalvi, 2 - I - 56126 PISA (ITALY)
  Telefax 39-50-585265, Telex 500104 FINGPI I
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16. MATERIAL AVAILABLE
NEA-1368/01
File name File description Records
NEA1368_01.001 ARIANNA-2 information file 190
NEA1368_01.002 ARIANNA-2 source code 3764
NEA1368_01.003 ARIANNA-2 job control for installation 29
NEA1368_01.004 ARIANNA-2 test input file # 1 110
NEA1368_01.005 ARIANNA-2 test output file # 1 1892
NEA1368_01.006 ARIANNA-2 test input file # 2 34
NEA1368_01.007 ARIANNA-2 test output file # 2 2002
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17. CATEGORIES
  • G. Radiological Safety, Hazard and Accident Analysis
  • H. Heat Transfer and Fluid Flow

Keywords: accidents, containment, energy transfer, mass transfer, pressure, reactor safety, temperature distribution.