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Pu. Ge detector. Cd screen (or other). iga nuclear database. Spectrum. Peak search from a uranium spectrum of CZT detector (simulated spectrum). Example of two Pu spectra, one measured with a Germanium dectector (top), the other with a CZT dectector (bottom).
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Pu Ge detector Cd screen (or other) iga nuclear database Spectrum Peak search from a uranium spectrum of CZT detector (simulated spectrum) Example of two Pu spectra, one measured with a Germanium dectector (top), the other with a CZT dectector (bottom) A NEW COMPUTER CODE FOR THE DETERMINATION OF THE ISOTOPE COMPOSITION OF ACTINIDES BY X- AND GAMMA-RAY SPECTROMETRY AND ITS APPLICATIONSAnne Catherine SIMON, anne-catherine.simon@cea.fr – Jean-Pierre BOTH – Isabelle ESPAGNON – Jean LEFEVRE – Vincent PICAUD – Alain PLUQUETCEA Saclay, France – DRT/LIST/DETECS AUTOMATIC DETERMINATION OF ISOTOPIC COMPOSITION OF ACTINIDES • Strong innovation in the development of igp, a new computer code of X- and gamma-ray spectra analysis for the determination of isotopic composition of Pu : • A generic design • The systematic and automatic exploitation of an atomic and nuclear database • Advanced constrained-optimisation techniques • The systematic use of all a priori physical knowledge • Extension of igp to uranium, MOX, and then to any actinides (Np, Cm…), possibly in presence of other nuclides (fission products…) • iga, a unique code with high ability to adapt automatically to: • Any experimental configuration (energy range, electronic gain, resolution…) • Any isotope present in the spectrum (U, Pu, minor actinides, fission products, pollutants…) Spectrum Simultaneous determination of efficiency / massic ratios X/g-ray spectrum Massic ratios (isotopic composition) Constrained fitting of a region of interest ACTIVITY MEASUREMENT ON WASTE PACKAGES Measurement of waste-package activity for the CEA – Fontenay-aux-Roses (SANDRA laboratory) • Unfavorable but known and fixed experimental conditions • iga/Sandra code • Same calculation core as iga • A specific nuclear database • Activity calculation according to two methods • From the absolute efficiency curve given by the user • From the relative efficiency curve determined by iga then normalised with the user's efficiency curve • Common caracteristics : • Emax ~ 2 MeV • gain ~ 0,5 keV/channel Normalisation of the relative efficiency curve calculated by iga with the user's absolute efficiency curve iga/Sandra nuclear database iga calculation core X/g-ray spectrum Activities Constrained fitting of a region of interest AUTOMATIC ANALYSIS FROM OTHER DETECTORS (CZT, NaI, LaBR3:Ce…) • Advantages • Ambient temperature spectrometry • More compact and less expensive device • Difficulties • Very degraded resolution compared with Germanium detector (typically 7 keV at 662 keV) • Particular peak form, strongly assymetric (tail) • Non-linear variance-energy relation (CZT) • Strong identified needs • Identification of isotopes • Activity measurement • Determination of isotopic composition of actinides