last modified: 01-MAR-1975 | catalog | categories | new | search |

NEA-0448 MATTEO.

MATTEO, BWR Subchannel Steady-State and Transient Thermohydraulics

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1. NAME OR DESIGNATION OF PROGRAM:  MATTEO.
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2. COMPUTERS
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Program name Package id Status Status date
MATTEO NEA-0448/01 Tested 01-MAR-1975

Machines used:

Package ID Orig. computer Test computer
NEA-0448/01 IBM 370 series IBM 370 series
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3. NATURE OF PHYSICAL PROBLEM SOLVED

Enthalpy, flow and vapour concentration distributions in all the sections and subchannels of a nuclear BWR or of an experimental loop simulating thermohydraulic behaviour are calculated in steady state and transient assuming that heat fluxes to the coolant and total mass flow into the channel are  known functions of time. The general pressure of the system is also  a known function of time as well as the inlet enthalpy.
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4. METHOD OF SOLUTION

Open channel model - the diverted volume flows are calculated at each node by imposing equal pressure drops for each subchannel. The problem specification for intersubchannel volume exchange is obtained by imposing zero net recirculation in all independent recirculation closed paths among subchannels in the  channel layout. The diverted cross flows are split up into vapour and liquid cross flows by specific models for transversal slip and vapour-liquid volume per volume exchange between pairs of connected  subchannels. The numerical model is finite backwards differences in  space and time. The diverted flows at each axial node are obtained by an iterative procedure with underrelaxation. The tangent method is utilized for diverted volume flows with renormalization to enforce the total volume continuity. The convergence is said to be achieved when the pressure has been achieved and the pressure drops agree within one tenth of percent with their weighted average. The calculation scheme sweeps the bundle from inlet to outlet iterating to convergence at each axial node in succession in steady  state and at each time step.
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5. RESTRICTIONS ON THE COMPLEXITY OF THE PROBLEM

Relatively slow pressure transient as no sound wave propagation is considered and thermodynamic equilibrium is assumed in the saturated region.
Relatively low inlet enthalpy subcooling as liquid water properties  are considered at the saturation point corresponding to the general  pressure level. The pressure drop into the channel should be small relative to the general pressure level as the spatial variation of pressure is neglected in evaluating liquid and vapour properties.
All these limitations allow the calculation of every practical transient in BWR analysis with exclusion of blowdown. Transients with complete flow reversal are also excluded as no provision for coolant inlet from two directions is made. Local flow reversal in some subchannels is permitted in principle even if the correlations  utilized are questionable in this event.
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6. TYPICAL RUNNING TIME

No general statement can be made since it is a dynamical program with an iterative procedure. A typical transient for BWR will take around 5 minutes.
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7. UNUSUAL FEATURES OF THE PROGRAM

The single subchannel model is a separate flow model with subcooled boiling model including vapour generation and recondensation - Zubee's concentration parameter and  drift velocity slip model.
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8. RELATED OR AUXILIARY PROGRAMS: RELATED AND AUXILIARY PROGRAMS
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9. STATUS
Package ID Status date Status
NEA-0448/01 01-MAR-1975 Tested at NEADB
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10. REFERENCES
NEA-0448/01, included references:
- G. Forti:
The Computer Programme MATTEO for Subchannel Analysis of BWR Rod
Bundles in Steady State and Transient
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11. MACHINE REQUIREMENTS:  No disks, no tapes.
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12. PROGRAMMING LANGUAGE(S) USED
Package ID Computer language
NEA-0448/01 FORTRAN-IV
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13. SOFTWARE REQUIREMENTS: OPERATING SYSTEM OR MONITOR UNDER WHICH PROGRAM IS EXECUTED
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14. OTHER PROGRAMMING OR OPERATING INFORMATION OR RESTRICTIONS

ANY OTHER PROGRAMMING OR OPERATING INFORMATION OR RESTRICTIONS
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15. NAME AND ESTABLISHMENT OF AUTHOR

     Joint Research Centre EURATOM
     Ispra Establishment
     Ispra, Italy
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16. MATERIAL AVAILABLE
NEA-0448/01
File name File description Records
NEA0448_01.001 SOURCE PROGRAM (F4) 1949
NEA0448_01.002 SAMPLE PROBLEM INPUT DATA 41
NEA0448_01.003 SAMPLE PROBLEM PRINTED OUTPUT 1184
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17. CATEGORIES
  • H. Heat Transfer and Fluid Flow

Keywords: BWR reactors, coolants, enthalpy, flow rate, heat transfer, steady-state conditions, thermodynamics, transients, vapors.