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
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.