Boron in zircaloy and aluminium for nuclear purposes

Materials used in nuclear watercooled reactors are first of all, zircaloy which is preferentially used as cladding material for nuclear fuel elements and pure aluminium which may be used for certain constructional units near the reactor core. For both metals, at present, a boron content of maximum 0.2 g/g is tolerated, but one is inclined to lower this limit to 0.1 or even to 0.05 Mg/g. The reason why this step has not yet been taken is that no generally accepted and reliable analytical techniques are available to determine these low concentrations. 

Aluminium-magnesium alloys are grain refined by small boron additions together with titanium and seldomly with zirconium. They obtain thereby considerably improved physical properties. Moreover, the casting properties and surface finishing are also improved to a great extent. 

The concentrations of interest are significantly higher (10 to 20 iug/g) than in nuclear reactor materials. Accurate analysis for boron are required to control the grain refining treatment. 

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