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NEA-1600 QUARK.

QUARK, 2-Group 3-D Neutronic Kinetics Coupled to Core Thermalhydraulics

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1. NAME OR DESIGNATION OF PROGRAM:  QUARK.
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2. COMPUTERS
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Program name Package id Status Status date
QUARK NEA-1600/01 Tested 09-DEC-1999

Machines used:

Package ID Orig. computer Test computer
NEA-1600/01 PC-80486 PC DELL OptiPlex
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3. DESCRIPTION OF PROGRAM OR FUNCTION

QUARK is a combined computer program comprising a revised version of the QUANDRY three-dimensional two-group neutron kinetics code and an upgraded version of the COBRA transient core analysis code (COBRA-EN). Starting from either a critical steady-state (k-effective or critical dilute Boron problem) or a subcritical steady-state (fixed source problem) in a PWR plant, the code allows to simulate the neutronic and thermal-hydraulic core transient response to reactivity accidents initiated both inside the vessel (such as a control rod ejection) and outside the vessel (such as the sudden change of the Boron concentration in the coolant).
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4. METHODS

The thermal-hydraulic model is based on three partial differential equations that describe the conservation of mass, energy and momentum for the water liquid/vapor mixture and the interaction of the two-phase coolant with the system structures. Optionally, a fourth equation can be added which tracks the vapor mass separately and which, along with the correlations for vapor generation and slip ratio, replaces the subcooled quality and quality/void fraction correlations, needed by the homogeneous model.

In each coolant channel, the one-dimensional (z) fluid dynamics equations in the vertical direction as well as the one-dimensional (r) equation in the horizontal direction that models the heat transfer in solid structures are approximated by finite differences. The resulting equations for hydrodynamic phenomena form a system of coupled nonlinear equations that are solved by the original upflow scheme (when no reverse flow is predicted) or by a Newton-Raphson iteration procedure. The heat-transfer equations in the solid structures are treated implicitly. Moreover, a full boiling curve is provided, comprising the basic heat-transfer regimes, each represented by a set of optional correlations for the heat-transfer coefficient between a solid surface and the coolant bulk.

The neutronic module is based on the Analytical Nodal Method (ANM) for two-group neutron diffusion equation in three-dimensional cartesian geometry, developed by A. F. Henry and his coworkers at MIT, which approximates the diffusion equation by analytical formulae that are exact in one dimension and solves the resulting nodal equations for node-averaged fluxes and directional leakages by a triple level of iteration.

The cross-sections and the discontinuity factors correcting for homogenisation errors are updated for thermal (fuel temperature) and thermal-hydraulic feedback (coolant temperature and density) and, also, for dilute Boron effect, either by applying temperature and density coefficients (quadratic at the most) or by interpolating in input multiple-entry libraries of reference values.
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5. RESTRICTIONS ON THE COMPLEXITY OF THE PROBLEM

The data-dependent arrays are contained in the named Common block BLANK whose standard length of 10106 bytes can be changed by modifying a PARAMETER statement in a include file (see the Installation Directions).
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6. TYPICAL RUNNING TIME

Sample problem 1 with 360 assembly-sized (20 cm) cubic nodes and 60 time steps (each 1 s long ) requires only 3 min of CP time on a PC-486/100 but typical problems concerning actual large LWR cores may require some thousands of nodes require and some hundred or thousand time steps. Therefore, the CP times can range from a few to some tens of minutes for a steady-state and rise to some hours for a transient.
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7. UNUSUAL FEATURES
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8. RELATED OR AUXILIARY PROGRAMS

NORMA-FP.
See E. Brega, R. Fontana, E. Salina, "The NORMA-FP Program to Perform a Subchannel Analysis from Converged Coarse-Mesh Nodal Solutions (Rev. 3)", ENEL-DSR-CRTN-N5/91/05/MI, Milan, September 1991.
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9. STATUS
Package ID Status date Status
NEA-1600/01 09-DEC-1999 Tested at NEADB
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10. REFERENCES
NEA-1600/01, included references:
- E. Salina, G. Alloggio, E. Brega:
  QUARK: a Computer Code for the Neutronic and Thermal-Hydraulic Space- and
  Time-Dependent Analysis of Light Water Reactor Cores by Advanced Nodal
  Techniques.
  Synthesis Srl, rep. 1034/1 prepared for ENEL-ATN/GNUM, Milan, September 1994
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11. HARDWARE REQUIREMENTS

A Personal Computer with 486 or Pentium processor and at least 16 Mb of RAM
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12. PROGRAMMING LANGUAGE(S) USED
Package ID Computer language
NEA-1600/01 FORTRAN-77
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13. SOFTWARE REQUIREMENTS

DOS or WINDOWS provided with MS FORTRAN Power Station Compiler version 1.0 or higher.
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14. OTHER PROGRAMMING OR OPERATING INFORMATION OR RESTRICTIONS
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15. NAME AND ESTABLISHMENT OF AUTHORS

E. Salina
Synthesis Srl
Via B. Garofalo 10
20133 Milano, Italy

E. Brega
ENEL SpA
Via Pozzobonelli 6
20162 Milano, Italy
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16. MATERIAL AVAILABLE
NEA-1600/01
INSTALL.DOC Installation procedure for QUARK
PKUNZIP.EXE Restoring utility
QUARKDOC.ZIP Compressed files of Code Abstract and User's Manual
QUARKFOR.ZIP Compressed files of the FORTRAN source (24 files)
QUARKSP1.ZIP Compr. input and output files (8 files) of sample problem 1 (3
cases)
QUARKSP2.ZIP Compr. input and output files (7 files) of sample problem 2 (2
cases)
QUARKSP3.ZIP Compr. input and output files (11 files) of sample problem 3 (5
cases)
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17. CATEGORIES
  • F. Space - Time Kinetics, Coupled Neutronics - Hydrodynamics - Thermodynamics
  • G. Radiological Safety, Hazard and Accident Analysis

Keywords: heat transfer, reactor kinetics, thermodynamics.