Computer Programs

NAME OR DESIGNATION OF PROGRAM, COMPUTER, DESCRIPTION OF PROBLEM OR FUNCTION, METHOD OF SOLUTION, RESTRICTIONS ON THE COMPLEXITY OF THE PROBLEM, TYPICAL RUNNING TIME, UNUSUAL FEATURES OF THE PROGRAM, RELATED AND AUXILIARY PROGRAMS, STATUS, REFERENCES, MACHINE REQUIREMENTS, LANGUAGE, OPERATING SYSTEM UNDER WHICH PROGRAM IS EXECUTED, OTHER PROGRAMMING OR OPERATING INFORMATION OR RESTRICTIONS, NAME AND ESTABLISHMENT OF AUTHOR, MATERIAL, CATEGORIES

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Program name | Package id | Status | Status date |
---|---|---|---|

COBRA-4I | NESC0432/11 | Tested | 18-MAY-1987 |

COBRA-4I | NESC0432/12 | Tested | 22-OCT-1997 |

Machines used:

Package ID | Orig. computer | Test computer |
---|---|---|

NESC0432/11 | IBM 3033 | IBM 3084 |

NESC0432/12 | DEC VAX series | DEC VAX 8810 |

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4. METHOD OF SOLUTION

The conservation equations of flow and energy are solved for interconnected subchannel control volumes via conventional finite differencing techniques. The steady-state calculations are solved by implicit finite differencing whereas the transient calculations are performed by either an implicit or explicit finite difference scheme. Internal rod temperatures are calculated by an orthogonal collocation approximation to the heat conduction equation.

The conservation equations of flow and energy are solved for interconnected subchannel control volumes via conventional finite differencing techniques. The steady-state calculations are solved by implicit finite differencing whereas the transient calculations are performed by either an implicit or explicit finite difference scheme. Internal rod temperatures are calculated by an orthogonal collocation approximation to the heat conduction equation.

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5. RESTRICTIONS ON THE COMPLEXITY OF THE PROBLEM

Using the COBRA4I code option to store variables on peripheral storage devices eliminates any practical limit as to maximum problem size. However, computer core requirements and code execution time is always a consideration when determining the complexity of the problem to be solved.

Using the COBRA4I code option to store variables on peripheral storage devices eliminates any practical limit as to maximum problem size. However, computer core requirements and code execution time is always a consideration when determining the complexity of the problem to be solved.

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6. TYPICAL RUNNING TIME

On a CDC 7600 running time is 0.004 seconds per cell-iteration using the implicit solution scheme and 0.00006 seconds per cell-iteration using the explicit scheme. The number of cells is determined as the number of subchannels times the number of axials nodes. The number of iterations required per time-step varies according to convergence criteria and complexity of physics; however, typical values are from 10 to 20 iterations for the implicit scheme and 10 to 50 iterations for the explicit scheme. The three sample problems run in less than 30 seconds on the CRAY1. The U-tube and fuel thermal sample problems each run in less than 2 minutes and the 7-pin sample problem in less than 1 minute on an IBM3033.

On a CDC 7600 running time is 0.004 seconds per cell-iteration using the implicit solution scheme and 0.00006 seconds per cell-iteration using the explicit scheme. The number of cells is determined as the number of subchannels times the number of axials nodes. The number of iterations required per time-step varies according to convergence criteria and complexity of physics; however, typical values are from 10 to 20 iterations for the implicit scheme and 10 to 50 iterations for the explicit scheme. The three sample problems run in less than 30 seconds on the CRAY1. The U-tube and fuel thermal sample problems each run in less than 2 minutes and the 7-pin sample problem in less than 1 minute on an IBM3033.

NESC0432/11

NEA-DB executed the three test cases included in this package on an IBM 3084 computer. The following CPU times were required: 7 seconds (7-pin problem); 47 seconds (fuel thermal model problem); 52 seconds (U-tube problem).NESC0432/12

NEA-DB executed the two test cases included in this package on a VAX 8810 computer. The following CPU times were required: 45 seconds (thermal model problem); 45 seconds (U-tube problem).[ top ]

7. UNUSUAL FEATURES OF THE PROGRAM

The improved capabilities of COBRA4I over its predecessor COBRA3C include:

(a) A new explicit solution scheme to calculate severe transients involving flow reversals, recirculations and expulsion and reentry flows with either a flow or pressure boundary condition specified.

(b) Improved storage allocation to reduce central memory requirements and improved running time.

(c) Improved fuel rod heat conduction model to calculate interior- rod temperatures with axial conduction and variable thermal conductivity included. Each rod may now consist of axially- varying materials.

(d) Addition of a set of correlations to calculate the properties of superheated steam and a set of heat transfer correlations covering the complete range of heat transfer from subcooled through boiling.

(e) Problem "Dump and Restart" capabilities which allow the solution to be saved for subsequent use either to continue calculations or to be used as an initial guess for a different problem which can result in significant time savings for similar problems.

(f) Auxiliary program to re-dimension COBRA based on user specified input defining problem size and code options desired, thus minimizing storage requirements.

(g) Auxiliary program to generate COBRA input for hexagonal rod- bundle geometry. Input for card groups 4, 7, and 8 can be generated, thus greatly reducing the amount of input required. (h) Line-printer plotting capability to display pressure drop, mass flux, enthalpy and crossflow versus axial position for all or a specified number of gaps and channels.

(i) A thermally-conducting wall model which can conduct heat between two channels on opposite sides of a wall.

The improved capabilities of COBRA4I over its predecessor COBRA3C include:

(a) A new explicit solution scheme to calculate severe transients involving flow reversals, recirculations and expulsion and reentry flows with either a flow or pressure boundary condition specified.

(b) Improved storage allocation to reduce central memory requirements and improved running time.

(c) Improved fuel rod heat conduction model to calculate interior- rod temperatures with axial conduction and variable thermal conductivity included. Each rod may now consist of axially- varying materials.

(d) Addition of a set of correlations to calculate the properties of superheated steam and a set of heat transfer correlations covering the complete range of heat transfer from subcooled through boiling.

(e) Problem "Dump and Restart" capabilities which allow the solution to be saved for subsequent use either to continue calculations or to be used as an initial guess for a different problem which can result in significant time savings for similar problems.

(f) Auxiliary program to re-dimension COBRA based on user specified input defining problem size and code options desired, thus minimizing storage requirements.

(g) Auxiliary program to generate COBRA input for hexagonal rod- bundle geometry. Input for card groups 4, 7, and 8 can be generated, thus greatly reducing the amount of input required. (h) Line-printer plotting capability to display pressure drop, mass flux, enthalpy and crossflow versus axial position for all or a specified number of gaps and channels.

(i) A thermally-conducting wall model which can conduct heat between two channels on opposite sides of a wall.

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8. RELATED AND AUXILIARY PROGRAMS

COBRA4I is an extended version of the COBRA3C computer program. The auxiliary program SPECSET re- dimensions COBRA4I according to user-specified problem size, and the auxiliary program GEOM calculates COBRA input for data groups 4, 7, and 8 for hexagonal rod bundles. The IBM version also contains auxiliary program CSPECS which replaces pseudostatements of the form *CALL SPECx in COBRA4I with the correctly sized set of FORTRAN declarative statements comprising COMDECKx.

COBRA4I is an extended version of the COBRA3C computer program. The auxiliary program SPECSET re- dimensions COBRA4I according to user-specified problem size, and the auxiliary program GEOM calculates COBRA input for data groups 4, 7, and 8 for hexagonal rod bundles. The IBM version also contains auxiliary program CSPECS which replaces pseudostatements of the form *CALL SPECx in COBRA4I with the correctly sized set of FORTRAN declarative statements comprising COMDECKx.

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Package ID | Status date | Status |
---|---|---|

NESC0432/11 | 18-MAY-1987 | Tested at NEADB |

NESC0432/12 | 22-OCT-1997 | Tested at NEADB |

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10. REFERENCES

- C.L. Wheeler, C.W. Stewart, R.J. Cena, D.S. Rowe, and A.M. Sutey,

COBRA-IV-I: An Interim Version of COBRA for Thermal-hydraulic

Analysis of Rod Bundle Nuclear Fuel Elements and Cores,

BNWL-1962, March 1976.

- C.W. Stewart, C.L. Wheeler, R.J. Cena, C.A. McMonagle, J.M. Cuta,

and D.S. Trent,

COBRA-IV: The Model and the Method,

BNWL-2214, July 1977.

- C.W. Stewart, C.A. McMonagle, M.J. Thurgood, T.L. George, D.S.

Trent, J.M. Cuta, and G.D. Seybold:

Core Thermal Model: COBRA-IV Development and Applications,

BNWL-2212, January 1977.

- D.M. Lister and P.A. Jallouk,

COBRA IV-I An IBM Compatible Version,

NUREG/CR-0519 (ORNL/NUREG/CSD-9), December 1978.

- COBRA4I, NESC No. 432.7600G, Tape Contents Description,

National Energy Software Center Note 77-37, Revised May 23, 1981.

- COBRA4I, NESC No.432.CRA1, COBRA4I Tape Description,

National Energy Software Center Note 82-108, August 20, 1982.

- COBRA4I, NESC No. 432.3033, COBRA4I Tape Description and

Implementation Information,

National Energy Softawre Center Note 86-05, October 25, 1985.

- C.L. Wheeler, C.W. Stewart, R.J. Cena, D.S. Rowe, and A.M. Sutey,

COBRA-IV-I: An Interim Version of COBRA for Thermal-hydraulic

Analysis of Rod Bundle Nuclear Fuel Elements and Cores,

BNWL-1962, March 1976.

- C.W. Stewart, C.L. Wheeler, R.J. Cena, C.A. McMonagle, J.M. Cuta,

and D.S. Trent,

COBRA-IV: The Model and the Method,

BNWL-2214, July 1977.

- C.W. Stewart, C.A. McMonagle, M.J. Thurgood, T.L. George, D.S.

Trent, J.M. Cuta, and G.D. Seybold:

Core Thermal Model: COBRA-IV Development and Applications,

BNWL-2212, January 1977.

- D.M. Lister and P.A. Jallouk,

COBRA IV-I An IBM Compatible Version,

NUREG/CR-0519 (ORNL/NUREG/CSD-9), December 1978.

- COBRA4I, NESC No. 432.7600G, Tape Contents Description,

National Energy Software Center Note 77-37, Revised May 23, 1981.

- COBRA4I, NESC No.432.CRA1, COBRA4I Tape Description,

National Energy Software Center Note 82-108, August 20, 1982.

- COBRA4I, NESC No. 432.3033, COBRA4I Tape Description and

Implementation Information,

National Energy Softawre Center Note 86-05, October 25, 1985.

NESC0432/11, included references:

- C.L. Wheeler et al.:COBRA-IV-I: An Interim Version of COBRA for Thermal-Hydraulic Analysis of Rod

Bundle Nuclear Fuel Elements and Cores. BNWL-1962, UC-32 (March 1976)

- C.W. Stewart et al.:

Core Thermal Model: COBRA-IV Development and Applications.

BNWL-2212, NRC-4 (Jan. 1977)

- C.W. Stewart et al.:

COBRA-IV: The Model and the Method. BNWL-2214, NRC-4 (July 1977)

- D.M. Lister and P.A. Jallouk:

COBRA-IV-I - An IBM-Compatible Version, NUREG/CR-0519 (December 1978)

- M. Birgersson:

COBRA4I Tape Description and Implementation Information

NESC Note 86-05 (Oct. 25, 1985)

NESC0432/12, included references:

- C.L. Wheeler et al.:COBRA-IV-I: An Interim Version of COBRA for Thermal-Hydraulic

Analysis of Rod Bundle Nuclear Fuel Elements and Cores.

BNWL-1962, UC-32 (March 1976)

- C.W. Stewart et al.:

Core Thermal Model: COBRA-IV Development and Applications.

BNWL-2212, NRC-4 (January 1977)

- C.W. Stewart et al.:

COBRA-IV: The Model and the Method

BNWL-2214, NRC-4 (July 1977)

- D.M. Lister and P.A. Jallouk:

COBRA-IV-I - An IBM-Compatible Version

NUREG/CR-0519 (December 1978)

- M. Birgersson:

COBRA4I Tape Description and Implementation Information

NESC Note 86-05 (October 25, 1985)

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11. MACHINE REQUIREMENTS

202,000 (octal) words and 4 scratch units besides the standard input/output units (CDC7600), 450K bytes and 6

units besides the standard input/output units (IBM3033).

202,000 (octal) words and 4 scratch units besides the standard input/output units (CDC7600), 450K bytes and 6

units besides the standard input/output units (IBM3033).

NESC0432/11

To run the test cases on an IBM 3084 computer, 560K bytes of main storage were required.[ top ]

Package ID | Computer language |
---|---|

NESC0432/11 | FORTRAN+ASSEMBLER |

NESC0432/12 | FORTRAN |

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13. OPERATING SYSTEM UNDER WHICH PROGRAM IS EXECUTED

SCOPE (CDC6600,7600), NOS (CDC CYBER175), COS (CRAY1), MVS (IBM3033), VM/CMS (IBM4331).

SCOPE (CDC6600,7600), NOS (CDC CYBER175), COS (CRAY1), MVS (IBM3033), VM/CMS (IBM4331).

NESC0432/11

MVS (IBM 3084).NESC0432/12

VMX V5.0-1 (VAX 8810).[ top ]

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15. NAME AND ESTABLISHMENT OF AUTHOR

7600 C.L. Wheeler, C.W. Stewart*, J.F. Cena,

D.S. Rowe, and A.M. Sutey

Pacific Northwest Laboratories

Battelle

P.O. Box 999

Richland, Washington 99352

CRAY1 T. Hosokawa

Century Research Center Corporation

No. 2, 3-Chome, Hon-cho

Nihonbashi, Chuo-Ku

Tokyo, Japan

IBM D.M. Lister and P.A. Jallouk

Oak Ridge National Laboratory

P.O. Box X

Oak Ridge Tennessee 37831

Elba Pezzoni

Comision Nacional de Energia Atomica

Buenos Aires, Argentina

* Contact

7600 C.L. Wheeler, C.W. Stewart*, J.F. Cena,

D.S. Rowe, and A.M. Sutey

Pacific Northwest Laboratories

Battelle

P.O. Box 999

Richland, Washington 99352

CRAY1 T. Hosokawa

Century Research Center Corporation

No. 2, 3-Chome, Hon-cho

Nihonbashi, Chuo-Ku

Tokyo, Japan

IBM D.M. Lister and P.A. Jallouk

Oak Ridge National Laboratory

P.O. Box X

Oak Ridge Tennessee 37831

Elba Pezzoni

Comision Nacional de Energia Atomica

Buenos Aires, Argentina

* Contact

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NESC0432/11

File name | File description | Records |
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NESC0432_11.001 | Information file | 154 |

NESC0432_11.002 | Assembly routines source file | 267 |

NESC0432_11.003 | COBRA4I master file | 8169 |

NESC0432_11.004 | Preprocessor for the COBRA4I master file | 225 |

NESC0432_11.005 | GEOM fortran program | 617 |

NESC0432_11.006 | SPECSET fortran program | 214 |

NESC0432_11.007 | COBRA4I unsized COMDECKs | 226 |

NESC0432_11.008 | CSPECS data | 1 |

NESC0432_11.009 | FT10 input | 2 |

NESC0432_11.010 | SPECSET data | 18 |

NESC0432_11.011 | Fuel thermal sample problem input | 118 |

NESC0432_11.012 | 7 pin sample problem input | 52 |

NESC0432_11.013 | U-tube sample problem input | 44 |

NESC0432_11.014 | GEOM sample problem input | 8 |

NESC0432_11.015 | Original JCL cards | 220 |

NESC0432_11.016 | NEA DATA BANK sample JCL cards | 541 |

NESC0432_11.017 | GEOM sample problem output | 49 |

NESC0432_11.018 | 7 pin sample problem output | 487 |

NESC0432_11.019 | Fuel thermal sample problem output | 1740 |

NESC0432_11.020 | U-tube sample problem output | 1693 |

NESC0432/12

File name | File description | Records |
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NESC0432_12.001 | Information file | 127 |

NESC0432_12.002 | Changes made in VAX conversion | 1148 |

NESC0432_12.003 | COBRA-4I FORTRAN Source | 6788 |

NESC0432_12.004 | VAX FORTRAN Include file | 9 |

NESC0432_12.005 | VAX FORTRAN Include file | 13 |

NESC0432_12.006 | VAX FORTRAN Include file | 26 |

NESC0432_12.007 | VAX FORTRAN Include file | 53 |

NESC0432_12.008 | VAX FORTRAN Include file | 32 |

NESC0432_12.009 | VAX FORTRAN Include file | 30 |

NESC0432_12.010 | VAX FORTRAN Include file | 13 |

NESC0432_12.011 | VAX FORTRAN Include file | 7 |

NESC0432_12.012 | VAX FORTRAN Include file | 5 |

NESC0432_12.013 | VAX FORTRAN Include file | 8 |

NESC0432_12.014 | VAX FORTRAN Include file | 5 |

NESC0432_12.015 | VAX FORTRAN Include file | 3 |

NESC0432_12.016 | VAX FORTRAN Include file | 10 |

NESC0432_12.017 | VAX FORTRAN Include file | 4 |

NESC0432_12.018 | VAX FORTRAN Include file | 15 |

NESC0432_12.019 | VAX FORTRAN Include file | 13 |

NESC0432_12.020 | VAX FORTRAN Include file | 6 |

NESC0432_12.021 | VAX FORTRAN Include file | 16 |

NESC0432_12.022 | VAX FORTRAN Include file | 8 |

NESC0432_12.023 | VAX FORTRAN Include file | 26 |

NESC0432_12.024 | VAX FORTRAN Include file | 3 |

NESC0432_12.025 | VAX FORTRAN Include file | 4 |

NESC0432_12.026 | VAX FORTRAN Include file | 2 |

NESC0432_12.027 | VAX FORTRAN Include file | 3 |

NESC0432_12.028 | VAX FORTRAN Include file | 2 |

NESC0432_12.029 | VAX FORTRAN Include file | 2 |

NESC0432_12.030 | VAX FORTRAN Include file | 2 |

NESC0432_12.031 | VAX FORTRAN Include file | 2 |

NESC0432_12.032 | VAX FORTRAN Include file | 77 |

NESC0432_12.033 | Command file for compilation | 14 |

NESC0432_12.034 | Command file for linking | 13 |

NESC0432_12.035 | Command file for running (brief) | 58 |

NESC0432_12.036 | Command file for running (complete) | 226 |

NESC0432_12.037 | Test case 1 input data Utube problem | 44 |

NESC0432_12.038 | Test case 2 input data thermal model problem | 118 |

NESC0432_12.039 | Test case 1 output | 1744 |

NESC0432_12.040 | Test case 2 output (original) | 1791 |

NESC0432_12.041 | Test case 2 output (NEADB) | 1791 |

NESC0432_12.042 | Command file to rename file names | 42 |

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- G. Radiological Safety, Hazard and Accident Analysis
- H. Heat Transfer and Fluid Flow

Keywords: LMFBR reactors, blowdown, enthalpy, fluid flow, heat transfer, hydraulics, reactor cores, reactor safety, rod bundles, transients, water cooled reactors.