Community Research and Development Information Service - CORDIS

Abstract

A VARIETY OF ELEMENTS AND COMPOUNDS SUCH AS FISSION PRODUCTS AND STRUCTURAL MATERIALS CAN CAUSE DIFFICULTIES IN THE IMMOBILISATION BY CEMENTATION PROCESSES. ELEMENTS SUCH AS CR, CU, FE, MN, MO, RU AND ZR, CONTAINED IN A MLW STREAM FROM A REPROCESSING PLANT EXHIBIT DIFFERENT VALENCE STATES. THEY CAN INFLUENCE THE REDOX POTENTIAL OF THE CEMENT MATRIX, LEADING TO AN INCREASE OF THE SOLUBILITY OF THE COMPOUNDS IN THE NEW VALENCE STATE. CEMENT SAMPLES CONTAINING VARIABLE AMOUNTS OF CR (III) OR NI (II) OR CD (II) AS CHLORIDE ADMIXTURES WERE PREPARED UNDER ESTABLISHED PROCEDURE. DUE TO THE HIGH PH GENERATED IN THE CEMENT CLINKER HYDRATION, RESPECTIVE METAL HYDROXIDES ARE FORMED AND IMPROVE THE PHYSICAL CHARACTERISTICS OF THE CEMENT MATRIX. AN INCREASE IN THE VALUE OF THE COMPRESSIVE STRENGTH WAS OBSERVED WHEN ABOUT 7% OF THE ABOVE ELEMENTS WERE BLENDED IN CEMENT. THE INCREASE DEPENDS ON THE NATURE OF THE ELEMENT IN THE SEQUENCE CR>NI>CD. THE LEACH TESTS CONFIRM THE FORMATION OF INSOLUBLE HYDROXIDE PRESENTING A LOW CONCENTRATION IN THE LEACHATE. ON THE OTHER HAND, THE HYDROLYZED CHLORIDE IONS SEEM TO REACT WITH CALCIUM WITH CONSEQUENT INCREASED DEGRADATION OF THE CEMENT MATRIX.

Additional information

Authors: ZAMORANI E, JRC-ISPRA;PAKISTAN ATOMIC ENERGY COMMISSION, ISLAMABAD, PAKISTAN;SERRINI G, JRC-ISPRA;PAKISTAN ATOMIC ENERGY COMMISSION, ISLAMABAD, PAKISTAN;MANARA A, JRC-ISPRA;PAKISTAN ATOMIC ENERGY COMMISSION, ISLAMABAD, PAKISTAN;SHEIKH I A JRC-ISPRA, JRC-ISPRA;PAKISTAN ATOMIC ENERGY COMMISSION, ISLAMABAD, PAKISTAN;PAKISTAN ATOMIC ENERGY COMMISSION, ISLAMABAD, PAKISTAN, JRC-ISPRA;PAKISTAN ATOMIC ENERGY COMMISSION, ISLAMABAD, PAKISTAN
Bibliographic Reference: PAPER PRESENTED: SCIENTIFIC BASIS FOR NUCLEAR WASTE MANAGEMENT, BERLIN/W, OCT. 10-13, 1988
Availability: Can be ordered online
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