G. Caffrey¹ , W. Alston¹ , A. Egger¹ , K. Krebs¹ , B. Milbrath² , S. Padgett³ , G. Warren² , M. Wetzel¹ , J. Wharton¹ , N. Wimer³ , M. Zalavadia²

¹Idaho National Laboratory, Idaho Falls, ID, USA
²Pacific Northwest National Laboratory, Richland, WA, USA
³Laurence Livermore National Laboratory, Livermore, CA, USA

Abstract:

We have conducted extensive system tests of the On-Site Inspection RadioIsotopic Spectroscopy (OSIRIS) system, a spectrum-blind instrument for the acquisition and analysis of high-resolution gamma-ray spectra during on-site inspections under the Comprehensive Nuclear-Test-Ban Treaty (CTBT). Unlike most other spectrometers, the OSIRIS system does not display actual gamma-ray spectra, and its software filter limits the display of spectral information to just seventeen CTBT-relevant fission-product isotopes, for example, 131I. The OSIRIS tests include environmental chamber measurements of energy-calibration accuracy and electronic-gain stability of the mechanically-cooled high-purity germanium gamma-ray spectrometer over the range measured from -12 °C (10 °F) to 50 °C (122 °F). Other measurements have followed the decay of calibrated uranium fission-product sources for over a year at Idaho National Laboratory (INL) and Pacific Northwest National Laboratory (PNNL). Many of the fission-product measurements at INL and PNNL were conducted outdoors under a broad range of ambient conditions.