MATERIAL CONTROL AND ACCOUNTABILITY

摘要

The research performed in common these last 3 years by the French Atomic Commission CEA, COGEMA andEurisys Mesures had for main subject the realization of a complete tool of modelization for the largest range ofrealistic cases, which could be encountered in gamma spectroscopy measurement. The main purpose of themodelization was to calculate the global measurement efficiency, which delivers the most accurate relationshipbetween the photons emitted by the nuclear source in volumic, punctual or deposited form and the germaniumhyper pure detector, which detects the received photons.It has been stated since long time that experimental global measurement efficiency becomes more and moredifficult to address especially for complex scene as we can find in decommissioning and dismantling or in caseof high activities for which the use of high activity reference sources become difficult to use for both healthphysics point of view and regulations.The choice of a calculation code is fundamental if accurate modelization is searched. MCNP represents thereference code but its use is long time calculation consuming and then not practicable in line on the field.Punctual nut of attenuation in straight line codes as the French Atomic Commission 3D analysis Mercure code orthe 3D analysis Microshield code can represent the practicable compromise between the most accurate MCNPreference code and the realistic performances needed in modelization.The comparison between the results of these three codes are presented in this paper, Mercure code beingsupported in line by the recent Pascalys 3D representation scene software.