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MODIFIED SULFUR CEMENT:A LOW POROSITY ENCAPSULATING MATERIAL FOR LOW,MEDIUM AND ALPHA WASTE

Objective

MODIFIED SULFUR CEMENT IS A MATERIAL COMPARABLE IN STRENGTH AND HARDNESS TO CONCRETE PRODUCTS WITH A LOW POROSITY AND RESISTANT TO ATTACK BY SALTS AND ACIDS. THE HANDLING OF MODIFIED SULFUR CEMENT IS COMPARABLE WITH BITUMEN : MELTING, AND SOLIDIFYING BY COOLING. THIS MATERIAL HAS PROMISING FEATURES REGARDING BETTER RETENTION OF MOBILE RADIONUCLIDES COMPARED WITH ORDINARY CONCRETE PRODUCTS BY LOW POROSITY. HIGH STRENGTH SHOULD PREVENT SWELLING OF ENCAPSULATED SALT WASTES AS IN THE CASE OF BITUMEN. THE RESTRICTIONS ON THE USE ARE ABOUT THE SAME AS FOR BITUMEN : HEAT PRODUCING WASTE IS TO BE AVOIDED; IT IS BURNABLE BUT DOES NOT SUSTAIN FIRE.

MODIFIED SULFUR CEMENT IS IN USE IN PLANTS AS FLOORS AND PONDS TO REPLACE OR PROTECT CONCRETE AGAINST ATTACK BY SALTS AND ACIDS. IT HAS BEEN PROPOSED AS A BACKFILL MATERIAL IN SHALLOW LAND BURIAL BUT IT HAS NEVER BEEN REALIZED.
Production rates and detailed chemical and physical characteristics of solid emissions from underwater plasma arc cutting of nonactive 304 grade stainless steel have been studied. Steel thicknesses of up to 40 mm have been cut in water depths of up to 10 m. A hyperbaric vessel and a deep water test colum and associated experimental equipment and techniques were developed for these studies. Concentrations and compositions of effluent byproduct gases were also investigated.

Quantitative data were collected and possible mechanisms investigated for the following aspect:
distribution, particle size and composition of solid emissions;
composition and flow rates of effluent gases;
effect of depth and other cutting conditions on solid and gaseous emmissions;
filtration resistance characteristics of water suspended particles; and
repeatability of cut quality and yields of emissions under standard cutting conditions.
FOR A CRITICAL JUDGEMENT FOR MODIFIED SULFUR CEMENT AS ENCAPSULATING MATERIAL DATA ARE LACKING FOR :

- RADIATION RESISTENCE,
- MAXIMUM LOADING CAPACITY OF MODIFIED SULFUR CEMENT WITH ASHES, SLUDGES, SPENT ION-EXCHANGERS REGARDING STRENGTH AND LEACHABILITY,
- POROSITY REGARDING TRITIATED WATER,
- REACTIONS WITH METAL COMPONENTS OF DISCARDED EQUIPMENT TO BE ENCAPSULATED.

Funding Scheme

CSC - Cost-sharing contracts

Coordinator

ENERGY RESEARCH CENTRE OF THE NETHERLANDS
Address
Westerduinweg 3
Petten
Netherlands