Steel 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.