Microradiographic fuel investigation in thin layers

R. Neider, P. De Meester

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The fuel elements of most high-flux MTR-reactors are assemblies of rolled plates or coextruded tubes. A typical case are me BR-2 elements which consist of an enriched Al-U24% alloy core and are clad with aluminium. Besides a sufficient bond integrity between core and cladding the should be homogeniously distributed over the whole area of the core. Bad bonding or inhomogenious distribution of fuel may give rise to hot spots which may cause a failure of the fuel element. The distribution and location of fuel within the plates or tubes is checked by radiographic, gamma-graphic and scintillation scanning methods. Except for marked uranium inclusions, little attention has been given to fuel homogeneity on the micro-scale, though this may help in a better understanding of many fuel hetorogenity phenomena, However the methods mentioned can hardly detect small inhomogeneities with a diameter less
than 0.5 mm. Therefore a contact microradiographic method was developed, which yields a maximum resolution of about 30 pm. The plates or tubes are radiographed with 60-keV X-rays while fine-grained photographic emulsion
is in intimate contact with the investigated area. The fuel distribution is checked qualitatively by 10- to 30-fold enlargements of the film on paper and quantitatively by photometric density measurements. For calibration purposes a wedge step of clad Al-U24% is radiographed under the same conditions as the
test pieces and developed simultaneously. Exposure data for the used fine-grained emulsions as well as qualitative and quantitative test results are given for rolled plates and coextruded tubes.
Original languageEnglish
PublisherSCK CEN
Number of pages24
StatePublished - May 1965
Externally publishedYes

Publication series

NameSCK CEN Reports
PublisherSCK CEN

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