Zirconium Based Alloy Reactor Beds for Tritiated Water Handling

This paper addresses an important consideration in the application of a Zirconium based alloy reactor bed for tritiated water handling, namely the nature and extent of variation of the water vapour conversion rate of alloy during its use. Experimental results obtained from four different investigations are presented to summarily view the water vapour reduction behaviour and hydrogen isotope release by the alloy during the conversion. The ternary getter alloy -[Zr(V_0.5Fe_0.5)₂], commercially known as St 737 (SAES Getters), is found to have good sorption properties for water vapour even at moderate temperatures (400 °C and less), and attractive sorption – desorption characteristics for hydrogen over a large and convenient working pressure range (up to ≈ 4 kPa). The four different conversion experiments performed, namely, (i) by “Fill” method, where the interaction occurred between a defined water vapour quantity and the getter alloy in the absence of any flow; (ii) under continuous water vapour “Flow” conditions; (iii) by subjecting the alloy to high concentrations of oxygen up-take (“Poisoning”) under water vapour flow conditions, with periodic regeneration; and (iv) over nearly the “Full Usage” of alloy where both the conversion and interposed relaxation durations extended up to a few thousand hours, showed that the functional characteristics of the Zr-V-Fe alloy are relevant to “batch” as well as “continuous” handling modes of a reactor operation.