Fast neutron dose measurements at the pressure vessel of a WWER-440 pressurized water reactor by the use of ⁹³Nb(n, n')^93mNb

The reaction Nb(n, n')^93mNb with low threshold energy was used to obtain experimentally both absolute and accurate relative estimates for the fast neutron fluence (> 0.9 MeV) at the inner surface of the pressure vessel of a WWER-440 type PWR. The scraped samples from the cladding (which contains niobium) of the pressure vessel and niobium dosimeters from the surveillance chains were treated destructively for measuring weak X-rays with a Si(Li) detector and conversion electrons using liquid scintillation counting.