Computer Programs

NAME OR DESIGNATION OF PROGRAM, COMPUTER, DESCRIPTION OF PROGRAM 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 AUTHORS, MATERIAL, CATEGORIES

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Program name | Package id | Status | Status date |
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HARPHRQ | NEA-1345/01 | Tested | 06-JAN-1994 |

Machines used:

Package ID | Orig. computer | Test computer |
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NEA-1345/01 | IBM PC | PC-80486 |

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3. DESCRIPTION OF PROGRAM OR FUNCTION

HARPHRQ is a program based on the code PHREEQE and is designed to model geochemical reactions. Like PHREEQE, it can calculate the pH, redox potential and mass transfer as a function of reaction progress and the composition of solution in equilibrium with multiple phases. In addition, HARPHRQ includes options to allow the composition of a solution at a fixed pH to be calculated and to automatically add or remove mineral phases as they become saturated or exhausted. A separate module can also be interfaced to give a choice of sorption models including the triple-layer model.

HARPHRQ is a program based on the code PHREEQE and is designed to model geochemical reactions. Like PHREEQE, it can calculate the pH, redox potential and mass transfer as a function of reaction progress and the composition of solution in equilibrium with multiple phases. In addition, HARPHRQ includes options to allow the composition of a solution at a fixed pH to be calculated and to automatically add or remove mineral phases as they become saturated or exhausted. A separate module can also be interfaced to give a choice of sorption models including the triple-layer model.

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4. METHOD OF SOLUTION

The code solves a reduced set of simultaneous non-linear equations. The conceptual model embodied in PHREEQE and HARPHRQ is the ion-association model of Pearson and Noronha to obtain values for a set of key independent variables. These results are then used to solve for all other unknowns sought. The key independent variables in PHREEQE are:

1. aH+ the activity of the hydrogen ion in solution;

2. ae- the activity of the electron in solution;

3. the activity of a single aqueous (master) species for each element;

4. the amount of mass transferred between each mineral phase and solution to achieve equilibrium.

From these data, the code calculates the dependent variables, including activities of all other aqueous species specified. The equations used to solve for key independent variables are:

1. Electrical neutrality;

2. Electron balance;

3. Mass balance;

4. Mineral equilibrium.

Where a constant pH is to be maintained, the electrical neutrality equation is removed from the refinement procedure in HARPHRQ. The equations are solved using:

1. a continued-fraction approach for the mass-balance equations; and

2. a modified Newton-Raphson approach for the remaining equations.

The activity coefficient can be calculated in HARPHRQ using the Debye-Huckel and Davies corrections from PHREEQE, and also a modified Davies correction. The modified Davies option uses the Davies expression up to ionic strength 0.3 mol dm-3 and then maintains the magnitude of this correction at ionic strengths above the cut-off value.

The code solves a reduced set of simultaneous non-linear equations. The conceptual model embodied in PHREEQE and HARPHRQ is the ion-association model of Pearson and Noronha to obtain values for a set of key independent variables. These results are then used to solve for all other unknowns sought. The key independent variables in PHREEQE are:

1. aH+ the activity of the hydrogen ion in solution;

2. ae- the activity of the electron in solution;

3. the activity of a single aqueous (master) species for each element;

4. the amount of mass transferred between each mineral phase and solution to achieve equilibrium.

From these data, the code calculates the dependent variables, including activities of all other aqueous species specified. The equations used to solve for key independent variables are:

1. Electrical neutrality;

2. Electron balance;

3. Mass balance;

4. Mineral equilibrium.

Where a constant pH is to be maintained, the electrical neutrality equation is removed from the refinement procedure in HARPHRQ. The equations are solved using:

1. a continued-fraction approach for the mass-balance equations; and

2. a modified Newton-Raphson approach for the remaining equations.

The activity coefficient can be calculated in HARPHRQ using the Debye-Huckel and Davies corrections from PHREEQE, and also a modified Davies correction. The modified Davies option uses the Davies expression up to ionic strength 0.3 mol dm-3 and then maintains the magnitude of this correction at ionic strengths above the cut-off value.

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5. RESTRICTIONS ON THE COMPLEXITY OF THE PROBLEM

The conceptual and numerical limitations of PHREEQE are also applicable to HARPHRQ. In addition, it should be noted that if the pH is fixed the resulting solution will not be charge balanced. The selection of the pH-fix option in HARPHRQ limits the number of types of reaction that can be modelled. For example, if a second solution is defined for mixing with the initial solution they should have the same pH. Similarly, a titration with either protons or hydroxide ions is not possible. However, a stepped pH, pe or both pH and pe have been included to simulate a titration with protons or hydroxide ions, or other similar experiments. These restrictions only apply when the option for calculating a solution at fixed pH is chosen.

The conceptual and numerical limitations of PHREEQE are also applicable to HARPHRQ. In addition, it should be noted that if the pH is fixed the resulting solution will not be charge balanced. The selection of the pH-fix option in HARPHRQ limits the number of types of reaction that can be modelled. For example, if a second solution is defined for mixing with the initial solution they should have the same pH. Similarly, a titration with either protons or hydroxide ions is not possible. However, a stepped pH, pe or both pH and pe have been included to simulate a titration with protons or hydroxide ions, or other similar experiments. These restrictions only apply when the option for calculating a solution at fixed pH is chosen.

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NEA-1345/01

The six test cases included in this package were run by the NEA-DB on a PC/80486 with 66 MHz. Running times were in the range between a tenth of a second and 1.3 seconds.[ top ]

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10. REFERENCES

- P.L. Brown, A. Haworth, S.M. Sharland and C.J. Tweed,

HARPHRQ: A geochemical speciation program based on PHREEQE.

Nirex Safety Studies Report NSS R.188 (to be published 1991).

- C.J. Tweed,

A guide to PICKER - A Data Selection Program for the Geochemical

Code PHREEQE

Nirex Safety Studies Report NSS R.132 (1988).

- P.L. Brown, A. Haworth, S.M. Sharland and C.J. Tweed,

HARPHRQ: A geochemical speciation program based on PHREEQE.

Nirex Safety Studies Report NSS R.188 (to be published 1991).

- C.J. Tweed,

A guide to PICKER - A Data Selection Program for the Geochemical

Code PHREEQE

Nirex Safety Studies Report NSS R.132 (1988).

NEA-1345/01, included references:

- NEA Data Bank:Note to Users of HARPHRQ (NEA 1345/01)

(June 1990)

- P.L. Brown et al.:

HARPHRQ - A Geochemical Speciation Program Based on PHREEQE

User's Guide

(October 1991).

- D.L. Parkhurst, D.C. Thorstenson and L.N. Plummer:

PHREEQE - A Computer Program for Geochemical Calculations.

USGS/WRI-80-96 (Rev. January 1985)

- G.W. Fleming and L.N. Plummer:

PHRQINPT - An Interactive Computer Program for Constructing Input

Data Sets to the Geochemical Simulation Program PHREEQE

USGS/WRI-83-4236 (1983)

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NEA-1345/01

The program was tested at NEA-DB under MS-DOS 6.0 using the Lahey F77L-EM32 FORTRAN-77 version 5.11 compiler.[ top ]

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NEA-1345/01

File name | File description | Records |
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NEA1345_01.001 | HARPHRQ Information File | 330 |

NEA1345_01.002 | HARPHRQ Source Code File | 3281 |

NEA1345_01.003 | HARPHRQ PC-executable code | 0 |

NEA1345_01.004 | UO2 Dissolution - Input Test sample | 15 |

NEA1345_01.005 | UO2 Dissolution - Output data file | 1390 |

NEA1345_01.006 | Library data for a set of uranium minerals | 288 |

NEA1345_01.007 | Iron dissolution - Fix PH test sample | 10 |

NEA1345_01.008 | Iron dissolution - Fix PH output data file | 152 |

NEA1345_01.009 | Iron dissolution - Floating PH test sample | 10 |

NEA1345_01.010 | Iron dissolution - Floating PH output data | 152 |

NEA1345_01.011 | Iron dissolution-Finite minerals test sample | 16 |

NEA1345_01.012 | Iron dissolution-Finite minerals output data | 1003 |

NEA1345_01.013 | Fe01 test case | 14 |

NEA1345_01.014 | Fe01 output data file | 161 |

NEA1345_01.015 | Fe002 Test case | 16 |

NEA1345_01.016 | Fe002 Output data file | 429 |

NEA1345_01.017 | Library data to run the Iron Test samples | 88 |

NEA1345_01.018 | PHRQINH Source Code File | 2801 |

NEA1345_01.019 | PHRQINH PC-executable code | 0 |

NEA1345_01.020 | Thermodynamic library (PHRQINH input data) | 579 |

NEA1345_01.021 | Library of Minerals (PHRQINH input data) | 82 |

NEA1345_01.022 | DOS file-names | 21 |

Keywords: aqueous solutions, chemical reactions, geochemistry, geothermal, ground water, mass transfer, solubility, sorption.