Radiation Protection Today - Winter 2022 Issue 4 - Page 18

Autonomous Systems for Radiological Characterisation during Decommissioning

Richard McGrath is Principal Technical Leader , Radiation Safety at the Electric Power Research Institute ( EPRI ), an independent American non-profit organisation that conducts research and development related to the generation , delivery , and use of electricity . In this article , he describes the findings of a recent project to demonstrate prototype autonomous systems for the radiological characterisation of walls and floors .
A substantial effort is applied in performing radiological characterisation of structures and land areas during the decommissioning of nuclear and similar facilities . This includes multiple surveys to support release of the site from radioactive regulatory controls . These surveys are repetitive in nature and typically performed using manually delivered systems , which is time consuming and labour intensive .
Characterisation and final verification surveys performed during decommissioning intentionally follow a prescribed protocol with respect to areas covered , scan speeds , responses to elevated readings , required detector offsets , and the need for repeat measurements . Based on these attributes , combined with the repetitive effort of performing surveys over large areas , automation of radiological characterisation techniques has a high potential to be successful and could provide substantial benefit .
EPRI recently completed a project to demonstrate prototype systems developed by two industry suppliers ( Createc Ltd and Gamma Reality Inc ) that can autonomously perform radiological surveys of walls and floors . These systems can be used as part of characterisation and final status surveys during the decommissioning of a nuclear facility .
Demonstrations conducted in early 2022 yielded the following results :
• Both systems were able to survey the test area surfaces autonomously .
• Both systems were able to analyse the detector data to provide results in terms of radionuclide specific concentrations for Co-60 and Cs-137 , as opposed to the simple gross gamma counts provided by conventional survey techniques .
• Both systems were able to achieve minimum detectable concentrations that were well below those typically required for final status surveys ( i . e . 50 % of site release limits ).
• Both systems detected sources that were a fraction of typical site release limits while : o Scanning at a rate up to :
• 36 times faster than conventional manual scanning using hand-held
2
100 cm survey meters .
• 8 times faster than in-situ gamma spectroscopy , which typically scans
2 up 28 m at a time . o Locating elevated areas of activity and displaying them on 3D images of the survey area created by the system .
• The GRI system was also able to show the source locations on a photo of the scanned area created by the system .
Createc Ltd System
Gamma Reality Inc System
18 Radiation Protection Today www . srp-rpt . uk