Unattended NDA Systems

Modern nuclear facilities are increasingly automated with the aim of decreasing both personnel exposure and production costs. Owing to automation, direct access to nuclear material maybe limited for both the operator and the inspectorate. Unattended NDA systems generate measurement data without requiring the presence of an inspector. The data acquired are routinely collected from measurement cabinets after a certain period or are transmitted remotely to an external location (such as an inspector s office). Main attributes of various unattended NDA systems are listed in Table 63.6. 

A combination of containment and surveillance (C/S) data with synchronized NDA data is a very powerful tool to monitor nuclear processes while C/S or NDA data in isolation have less 

System Detector Main measurement task Typical performance values (%)  

VIFM VIFB solid state Si Counts SF bundles (fuelling machine SF pond) Attribute 

SEGM Si-Pin Monitors cask loading into dry storage silo Attribute 

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The main drawback of these automated systems is their predictability. In most safeguards approaches, this drawback is compensated for by unannounced or short-notice inspections on a random basis. Most unattended NDA systems are part of the HLNC family. Other systems use low-resolution gamma detectors either in combination or as a stand-alone application. 

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