Retrospective Fast Neutron Dosimetry of Nuclear Power Plants by Means of Scraping Samples Using the Nb(n,n') Nb Reaction
SourceSteel samples from a core component of a boiling water reactor have been investigated in order to determine the accumulated fast neutron fluence. The study was performed by means of the reaction 93Nb(n,n')93mNb. For this examination, the steel samples were taken after having been irradiated during normal operation for about 20 years. Starting with chemical separation methods, the specific activity of 93mNb in the steel samples was measured by a) inductively coupled plasma mass spectrometry, and b) total reflection X-ray fluorescence technique. From these results, the fast neutron fluence for neutron energies above 1 MeV were calculated. The fluence values determined using inductively coupled plasma mass spectrometry are in good agreement with earlier 54Mn measurements.