NEA-1158 NEARSOL.

1. NAME OR DESIGNATION OF PROGRAM:  NEARSOL.

3. DESCRIPTION OF PROGRAM OR FUNCTION

NEARSOL models the aqueous speciation and solubility of actinides under near-field conditions for disposal using a simple thermodynamic approach.

4. METHOD OF SOLUTION

The program draws information from a thermodynamic data base consisting of solubility products and complex formation constants for all known species, and standard electrode potentials, at 25 C, corrected for ionic strength effects. By minimising the free energy of the system through a series of iterations, a precipitating solid phase is predicted which limits the solubility, and the concentration of the main aqueous species are calculated as a function of pH.
Initially the program evaluates only hydroxide and carbonate species, but the effect of sulphate, phosphate and fluoride anions can also be included.
The program is simple to use, requiring inputs of:
  1. Actinide(s)
  2. pH range
  3. Ionic strength
  4. Redox conditions
  5. Ligand concentrations
Functions are included to calculate the distribution of the protonated and unprotonated forms of carbonate and phosphate and the value of Eh as a function of pH under disposal conditions as required.
The program can further evaluate the role of free calcium ions.

5. RESTRICTIONS ON THE COMPLEXITY OF THE PROBLEM:  None.

6. TYPICAL RUNNING TIME

The program is executed interactively. The compile and link steps to create an executable module required about two minutes on an IBM 3090 computer.

7. UNUSUAL FEATURES OF THE PROGRAM:

8. RELATED AND AUXILIARY PROGRAMS

Subroutine ON01B from Harwell Subroutine Library and GHOST-80 graphics package are required.

10. REFERENCES:

- S.J. Leach:
  Notes on NEARSOL
  (Received November 1987)
- NEARSOL Test Problem (Input and Output)
  (Received November 1987)
- S.J. Leach:
  Equations and Constants used in NEARSOL
  AERE Report  (July 9, 1986)
- S.J. Leach and D.C. Pryke:
  NEARSOL - A Simple Program to Model Actinide Speciation and
  Solubility Under Waste Disposal Conditions: A User's Guide.
  AERE-R 12066  (May 1986)

11. MACHINE REQUIREMENTS:

13. OPERATING SYSTEM UNDER WHICH PROGRAM IS EXECUTED:

MVS/XA with compiler VS FORTRAN LEVEL 2.1.1 and time- sharing system TSO.

14. OTHER PROGRAMMING OR OPERATING INFORMATION OR RESTRICTIONS:

15. NAME AND ESTABLISHMENT OF AUTHORS

               S.J. Leach, D.C. Pryke
               Chemistry Division
               Harwell Laboratory
               UK Atomic Energy Authority

File name	File description	Records
NEA1158_01.001	INFORMATION FILE	73
NEA1158_01.002	NEARSOL FORTRAN PROGRAM	1911
NEA1158_01.003	NEARSOL AUXILIARY INPUT DATA	44
NEA1158_01.004	NEARSOL COMMAND PROCEDURE (TSO/MVS)	11
NEA1158_01.005	NEARSOL2 FORTRAN SOURCE	2017
NEA1158_01.006	NEARSOL2 COMMAND PROCEDURE (TSO/MVS)	11