Methoden der Untersuchung von Reaktormaterialien nach Heißdampf-Korrosion in Versuchskreisläufen und Kernreaktoren

Methods for investigation of reactor materials after corrosion in superheated steam in test circuits and nuclear reactors If it is impossible to make gravimetric determinations one may use planimetric measurements under the optical microscope; the mean thickness of the oxide layer enables the metal losses to be calculated. A combined method involves the descaling of corroded specimens with subsequent determination of the alloy constituent concentration in the surface layer of the descaled metal; this method is suitable in particular when – as is the case during corrosion in steam under heat transfer conditions – part of the oxide is lost to the steam system. The alloy constituents are determined by the microprobe or by X-ray fluorescence. A semi-quantitative method is used for fuel elements; in this case the dimensions of the material are measured prior to use and changes are determined by optical microscopy after use. If the values thus obtained are compared with values determined in out-of-reactor experiments one may even assess the influence of the neutron radiation.