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NEA-0587 UTSG.

UTSG, Steady-State and Transients of Vertical U-Tube Steam Generator

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1. NAME OR DESIGNATION OF PROGRAM:  UTSG.
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2. COMPUTERS
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Program name Package id Status Status date
UTSG NEA-0587/01 Tested 01-MAR-1980

Machines used:

Package ID Orig. computer Test computer
NEA-0587/01 IBM 3033 IBM 3033
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3. DESCRIPTION OF PROBLEM OR FUNCTION

The code is based on a non- linear theoretical model describing the steady-state and transient behaviour of a vertical natural-circulation U-tube steam generator together with its main steam system. The steam generator is con- sidered to consist of a heat exchange section, a top plenum, a down- comer region and a main steam system (with a sequence of relief and/ or safety valves, isolation, bypass, turbine-trip and turbine- control valves and a steam turbine). Possible perturbations from outside can be: inlet water temperature, inlet water mass flow and system pressure on the primary side, feedwater temperature, feed- water mass flow and outlet steam mass flow disturbed by actions of the different valves within the main steam system on the secondary side.
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4. METHOD OF SOLUTION

The theoretical model consists of a set of ana- lytical state and nonlinear ordinary differential equations of first order:

- The steady state (= starting) values are determined by putting in   the set of equations the time derivatives equal to zero and sol-  ving the resulting set of nonlinear algebraic equations by using  the solution method of a linear algebraic equation system in a    recursive way.

- Eliminating the steady state parts from the differential equation   system and regarding the variables as (absolute) difference  values (with respect to its steady state) the calculation of the  transient behaviour of the system is performed in a normal-  precision way, thus avoiding the more capacity and time-consuming  double-precision procedure. The solution of the non-linear  ordinary differential equation system of first order is obtained  by applying the digital DIFSYS method, an explicit integration    procedure based on a method established by Bulirsch and Stoer.
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5. RESTRICTIONS ON THE COMPLEXITY OF THE PROBLEM

Max. number of hori- zontal nodes of the heat exchange region < equal 7. Max. number of radial layers of the heat exchanging tubes < equal 3. Max. number of time points to be printed out < equal 501.
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6. TYPICAL RUNNING TIME

(AMDAHL 470/V):
Test case:      3.0 sec. real time = 4.6 sec CPU time.
Actual case:   50.0 sec. real time = 74.1 sec CPU time.
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7. UNUSUAL FEATURES OF THE PROGRAM

Calculations of the transient be-  haviour of a U-tube steam generator. ATWS-studies. Part of the comprehensive nonlinear transient code. ALMOD-2 for PWR nuclear power plants.
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8. RELATED AND AUXILIARY PROGRAMS:  No special relations.
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9. STATUS
Package ID Status date Status
NEA-0587/01 01-MAR-1980 Tested at NEADB
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10. REFERENCES

- A. Hoeld:
  A Theoretical Model for the Calculation of Large Transients in
  Nuclear Natural-Circulation U-Tube Steam Generators (Digital Code
  UTSG)
  Nucl. Eng. and Design 47, 1-23 (1978).
NEA-0587/01, included references:
- A. Hoeld:
  USTG - A Digital Code for Calculating the Nonlinear Transient
  Behaviour of a Natural-Circulation U-Tube steam Generator with ITS
  Main Steam System. Program Description.
  GRS-A-426 (March 1980).
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11. MACHINE REQUIREMENTS:  No special requirements.
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12. PROGRAMMING LANGUAGE(S) USED
Package ID Computer language
NEA-0587/01 FORTRAN-IV
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13. OPERATING SYSTEM UNDER WHICH PROGRAM IS EXECUTED:  AMDAHL 470/V6 with MVS, version 3.7.
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14. OTHER PROGRAMMING OR OPERATING INFORMATION OR RESTRICTIONS

If
no plots are needed (for which special plot routines are necessary)  use instead of the actual subroutine PLTFCT a dummy routine. (The routine SCALST is then surplus.)
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15. NAME AND ESTABLISHMENT OF AUTHOR

          Dr. Alis Hoeld
          Gesellschaft fuer Reaktorsicherheit (GRS) mbH
          Forschungszentrum
          D-8046 Garching
          West Germany.
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16. MATERIAL AVAILABLE
NEA-0587/01
File name File description Records
NEA0587_01.001 INFORMATION 9
NEA0587_01.002 SOURCE 6401
NEA0587_01.003 INPUT FOR S.P. 31
NEA0587_01.004 OUTPUT OF S.P. 193
NEA0587_01.005 JCL 11
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17. CATEGORIES
  • H. Heat Transfer and Fluid Flow

Keywords: heat exchangers, ordinary differential equations, steady-state conditions, steam generators, steam turbines, transients.