AutoISO: a new acquisition and data review software for the use of isotopic composition analysis codes (MGA++, PC/FRAM and IGA)

In the framework of French domestic safeguards, inspectors from IRSN/DEND perform gamma spectrometric measurements to verify operator's declaration on uranium and plutonium. For this purpose, isotopic composition codes have been used for many years by the inspectors to measure uranium enrichment and plutonium isotopic composition. This paper presents new acquisition and data review software developed by IRSN/DEND that integrates automatically MGA++, PC/FRAM and IGA analysis (uranium and plutonium). The feedback gained from isotopic composition measurements showed that the duration of the measurement to obtain a good gamma ray spectrum is a key factor for the accuracy of the result. The developer of the code provides a simple criterion to decide when to stop the acquisition, based on the total count in the spectrum with a recommended value greater than 106. This criterion is just a general indication and in many cases, it is not appropriate. For instance, the MGA++ analysis may be accurate with less count than 106. On the other hand, for spectra with high Compton scattering, it may be necessary to increase the total count in the spectrum. Keeping in mind that the total count is directly related to the duration of the measurement, the main objective of AutoISO is to optimize the duration of the measurement as regard with results provided by isotopic composition code. The basic idea is to perform a cumulative acquisition, based on Gamma-Vision software from ORTEC and to perform periodically a isotopic composition analysis. AutoISO enables to perform this process completely automatically with the saving of all data. In order for the user to decide when to stop the process, a graphical view of isotopic composition results is available. Other features are available in AutoISO in order to ensure the quality of the data acquired, by looking graphically at information in the cumulative spectra: region of interest, total counts. Since its development, AutoISO has been used intensively. It is not only a powerful tool to optimize acquisition duration (and subsequently to improve the quality of the measurements) but also an adequate software for the testing of the code performance. At that stage, only isotopic composition routines are integrated but it is intended to extent its capabilities for other codes like PLUM, FUNE which are dedicated to the measurement of plutonium mass in waste drum