33. A technique for the observation of micro-segregation of caesium in irradiated fuel pins

Developed from chemical spot tests, this simple technique enables caesium rich areas less than 1 Mrn in diameter to be detected on metallographic specimens using conventional optics. The spot

size is equivalent to about 10~^2 g^ cs.

s

Fission product migration in irradiated fuel elements has been studied by a number of techniques of which micro-gamma scanning and electron-probe micro-analysis have been most successful in relation to short range migration. These techniques require complicated and costly equipment and are not suited to routine moni toring work. It was thought that a chemical test analagous to 'sulphur printing', if it could be developed would be simple, cheap and applicable to large numbers of specimens. Such a test would be specific to one particular fis sion product, and for the preliminary develop ment work Caesium was chosen.