Deuterium Permeability of the Austenitic SS AISI 316

THE PERMEABILITY AND DIFFUSIVITY OF DEUTERIUM IN MEMBRANES OF STAINLESS STEEL AISI 316 HAVE BEEN DETERMINED AT DIFFERENT MEMBRANE TEMPERATURES AND UPSTREAM DEUTERIUM DRIVING PRESSURES. THE RESULTS ONTAINED ARE IN GOOD AGREEMENT WITH OTHERS REPORTED IN THE LITERATURE, AND THEY WERE USED TO ESTIMATE THE TRITIUM PERMEATION AND INVENTORY IN SOME STRUCTURAL PARTS OF A FUSION REACTOR. THE SAME KIND OF MEASUREMENTS HAVE BEEN PERFORMED WITH A STEEL MEMBRANE HAVING THE UPSTREAM SURFACE COVERED WITH A LAYER OF ABOUT 4X10-2 M OF THE LIQUID EUTECTIC ALLOY PB-17LI, TO REPRESENT THE INTERFACE PB-17LI/STEEL OF A COOLING TUBE IN THE BLANKET OF A FUSION REACTOR. IN THIS CASE THE VALUES OF THE PERMEABILITIES HAVE DECREASED BY A FACTOR OF 1 TO 4 WITH RESPECT TO THE ABSENCE OF PB-17LI, AND ALSO THE ACTIVATION ENERGY OF THE PERMEATION HAS DECREASED FROM 52000 TO 34000 J/MOL. THIS MEANS THAT THE PERMEABILITY HAS BECOME LESS TEMPERATURE-DEPENDENT. THIS BEHAVIOUR COULD BE EXPLAINED BY THE FACT THAT THE SOLUBILITY OF DEUTERIUM IN PB-17LI IS LOWER THAN IN AISI 316, AND NEARLY INDEPENDENT OF TEMPERATURE, ACTING THEREFORE AS A KIND OF PERMEATION BARRIER FOR THE DEUTERIUM. IN A REAL BLANKET THIS WOULD NOT BE THE CASE BECAUSE THE TRITIUM IS BRED WITHIN THE PB-17LI.

GAUTSCH Othmar;  HODAPP Guenter; 

1995-03-15

JRC5257