Determination of boron in borated concrete by means of a simplified prompt gamma activation analysis at the HOTNES facility

The prompt gamma activation analysis (PGAA) is an elemental analysis based on the gamma-ray emission following neutron radiative capture by nuclides. A simplified and compact PGAA for the determination of boron in borated concrete was setup at the HOTNES neutron facility, relying on common laboratory equipment. The thermal neutron field has fluence rate of about 20 cm-2 s-1 and is obtained from a moderated americium-boron neutron source. The gamma-ray detector is a common 3 '' x 3 '' NaI(Tl) scintillator. Samples of borated resin with the same geometry of the concrete samples were manufactured and used as standards. A specific "blank sample" correction was developed to isolate the boron contribution in the spectra obtained by irradiating the concrete samples. Boron quantities in the order of 1.5-2.0 g were measured in the concrete samples with uncertainty in the order of +/- 6%, in agreement with manufacturer's expectations. The Detection Limit of this simplified and compact boron analysis is in the order of 0.3 g in terms of boron mass, in line with values given in literature for PGAA-based boron analysis performed at research fission reactors.