NEA-1345 HARPHRQ

1. NAME OR DESIGNATION OF PROGRAM:  HARPHRQ.

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.

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.

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.

6. TYPICAL RUNNING TIME

The typical run times for HARPHRQ are similar to those for PHREEQE.

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.

7. UNUSUAL FEATURES OF THE PROGRAM

It is possible to interface HARPHRQ with a module that allows modelling of adsorption reactions  using models such as the triple-layer model. (This module is not available from the NEA, please contact authors for further information.)

8. RELATED AND AUXILIARY PROGRAMS

The program PICKER enables HARPHRQ  to be used in conjunction with the HATCHES database by selecting a
problem-related database from the much larger, fully documented HATCHES management system.

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).

- 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)

11. MACHINE REQUIREMENTS

540K bytes storage.
NEA 1345/01: The test cases included in this package have been executed by NEA-DB on a DELL 466/L 66-MHZ PC/80486 desktop computer.

13. OPERATING SYSTEM UNDER WHICH PROGRAM IS EXECUTED:  DOS (IBM PC), AIX

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

14. OTHER PROGRAMMING OR OPERATING INFORMATION OR RESTRICTIONS

HARPHRQ generally meets ANSI standards for Fortran. No problems have been encountered by the authors in porting the code, but extensive testing has not been carried out. See the PHREEQE entry for further  information.

15. NAME AND ESTABLISHMENT OF AUTHORS

      A. Haworth, C.J. Tweed and S.M. Sharland
      AEA Decommissioning and Radwaste
      Harwell Laboratory
      Oxon OX11 ORA
      UNITED KINGDOM

File name	File description	Records
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