Identification and quantification of a 60Co radiation source under an intense 137Cs radiation field using an application-specific CeBr3 spectrometer suited for use in intense radiation fields

Abstract

ABSTRACT Passive γ-ray spectroscopy is a useful technique for surveying the radioactive wastes and spent nuclear fuels under nuclear decommissioning. However, this method depends on material properties such as the activity, density, element, scale, and (especially) for low-energy γ rays from 235U and 239Pu. The γ-decay lines of 134Cs, 137Cs, 60Co, and 154Eu occur at greater energies (than those of 235U and 239Pu), and these nuclides provide significant information on spent nuclear fuel and radioactive wastes. A CeBr3 spectrometer with a small-volume crystal has been previously developed for use in intense radiation measurements. We exposed the spectrometer to radiation dose rates of 0.025, 0.151, 0.342, 0.700, and 0.954 Sv/h under a standard 137Cs radiation field. A 6.38 MBq 60Co calibration source was placed in front of the detector surface. Identification of the full energy peak at 1173 keV was impossible at dose rates higher than 0.700 Sv/h. However, subtraction of the 137Cs radiation spectra from the γ-ray spectra enabled the identification of the full energy peaks at 1173 and 1333 keV at dose rates of up to 0.954 Sv/h; the relative energy resolution at 1173 and 1333 keV was only slightly degraded at this dose rate.