Experimental estimation of neutron fluxes from niobium impurities in the pressure vessel steel of nuclear power reactors

Bruno Bärs, Erkki Häsänen

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Abstract

Nb impurities in samples from radioactive pressure vessel material have been chemically separated and purified twice by liquid ion exchange chromatography. The 93mNb activity from the fast neutron induced reaction 93Nb(n, n′)93mNb was measured by liquid scintillation counting (LSC). The remaining interference from 54Mn in the LSC spectra was subtracted based on LSC spectra from pure 54Mn.
The corresponding Nb masses in the purified solutions were measured with an inductively coupled plasma mass spectrometer (ICP-MS). The specific activity of 93mNb in the pressure vessel material studied was 5–30 Bq/μg Nb and was further used to estimate the corresponding reaction rates, neutron fluxes and doses. Due to the long half-life (16.1 yr) and low threshold energy (about 1 MeV) Nb is an excellent dosimeter material.
Since steel with Nb impurities is a common construction material e.g. the 54Mn(n,p)54Mn (312.2 d, about 3 MeV) and 93Nb(n, n′)93mNb reactions can be used to experimentally estimate the neutron doses and check some shape index for the neutron spectra in radioactive samples from pressure vessels and reactor structure materials.
This work is a novel application of Nb for dosimetric purposes.
Original languageEnglish
Pages (from-to)577-580
JournalNuclear Instruments and Methods in Physics Research. Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
Volume317
Issue number3
DOIs
Publication statusPublished - 1992
MoE publication typeA1 Journal article-refereed

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Keywords

  • nuclear reactors

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