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EFFECTS OF NATURAL ORGANIC SUBSTANCES ON THE GEOCHEMISTRY OF A RADIOACTIVE WASTE REPOSITORY.

Objective

A SIGNIFICANT PROPORTION OF THE DISSOLVED ORGANIC CARBON IN NATURAL GROUNDWATERS CONSISTS OF HUMIC AND FULVIC ACIDS. THERE IS EVIDENCE THAT THESE MAY FORM COMPLEXES WITH SOME RADIONUCLIDES WHICH MAY RESULT IN INCREASED AQUEOUS CONCENTRATION EITHER DUE TO INCREASED SOLUBILITY OR DECREASED SORPTION INTO SURFACES. PREVIOUS WORK IN THIS LABORATORY HAS INVOLVED THE COMPLETION OF A LITERATURE REVIEW/1/, AN INVESTIGATION OF POSSIBLE METHODS OF CHARACTERISATION AND SOME PRELIMINARY STUDIES OF THE EFFECT OF HUMIC ACID ON THE SORPTION OF AMERICIUM ON CEMENTITIOUS MATERIALS. THIS PROGRAMME IS FOR A CONTINUATION OF THAT RESEARCH IN THOSE AREAS RELEVANT TO A RADIOACTIVE WASTE REPOSITORY.

THERE ARE FOUR MAIN OBJECTIVES IN THE PROGRAMME. LIMITED HUMIC CHARACTERISATION FORMING PART OF THE "COCO" INTERCOMPARISON EXERCICE WILL BE MADE ON GROUNDWATER SAMPLES OBTAINED FROM GEOLOGICAL STRUCTURES WHICH ARE TYPICAL OF REFERENCE REPOSITORY SITES. THE EFFECTS OF HUMIC ACIDS ON THE SOLUBILITY OF PU, AM AND NP IN WATERS REPRESENTATIVE OF A CEMENTITIOUS REPOSITORY WILL BE INVESTIGATED AND THE INFLUENCE ON SORPTION STUDIED FOR EFFECTS OF NATURAL ORGANIC COMPOUNDS IN GEOCHEMICAL MODELLING CODES.

1. CHARACTERISATION OF HUMIC SUBSTANCES

2. EFFECTS OF HUMIC ACIDS ON PU, AM AND NP SOLUBILITIES

3. EFFECTS OF HUMICS ACIDS UPON THE SORPTION OF PU, AM AND NP ON CEMENT GROUTS.

4. MODELLING STUDIES.

Funding Scheme

CSC - Cost-sharing contracts

Coordinator

United Kingdom Atomic Energy Authority
Address
353,Harwell
OX11 0RA Didcot - Oxfordshire
United Kingdom