RoboCount™ 2020

Robotic Non-Destructive Waste Assay System

DESCRIPTION

RoboCount™ 2020 is based on an industrial 6-axis articulating robot carrying a HPGe spectrometer module, combined with a dedicated WP platform and auxiliary components.

The robot is a Comau S.p.A. model NJ-220-2.7 with a CG5 control unit and TP5 teach pendant. The maximum wrist payload of 220 kg is significantly higher than the mass of the spectrometer module it is carrying. This is intentional because higher payload corresponds to a larger working area of approx. 5400 mm in diameter, enables the use of additional detectors and equipment as needed, and minimizes both wear and maintenance. Even if operated at maximum load, the wear and maintenance are expected to be minimal since the robot performs a few relatively leisurely motions during a typical assay compared to hundreds of high-speed cycles per day in manufacturing operations it was designed for. The robot is mounted on a massive steel pedestal which increases its effective maximum horizontal reach.

The WP platform is an optional system component. However, it significantly expands the system functionality providing WP weighing and positioning by rotation. The rotation motion is seamlessly integrated into the robot control architecture as a seventh axis. The integrated balance has a maximum load of 2,500 ± 1 kg.

The spectrometer module consists of a Mirion Technologies, Inc., liquid-nitrogen cooled, HPGe detector model GC2020, connected to a Lynx® multi-channel analyzer, and protected by a 5 cm modular ISOCS™ lead shield. The front shield segment features a collimating aperture defining the detector field of view. High-activity WPs could cause the detector incoming count rate to exceed the maximum throughput of the spectrometry chain, leading to increased detector dead time and, thus, underestimation of activity. A fast pre-measurement of the WP is therefore performed with a 90 o conical opening collimator. If the detector dead time preset is not exceeded, a regular measurement is performed. In the opposite case, the robot will switch to a 30 o collimator before performing a regular measurement. The collimators are stored in a tray and the coupling/uncoupling is performed by a bayonet mechanism without electrical or pneumatic actuators. Collimators of other sizes and aperture types, matched to specific WP types and activities, could be integrated in an enlarged tray. For WP identification, a 1D bar code reader is mounted above the collimator, upgradeable to 1D/2D image based code reader or an RFID reader.

The system also features an automatic liquid nitrogen (LN 2) refill, performed by the robot via a docking station at predefined time intervals. The docking station is connected to a supply Dewar. The vent coupling of the docking station exhausts into the atmosphere through a Pt resistance sensor connected to the Dewar mounted LN 2 pump. Liquid flow is interrupted as soon as the sensor detects the change from gaseous nitrogen to LN 2. Depending on the size of the supply Dewar, 50 l or higher recommended, the LN 2 autonomy can be well over a month.

The control PC runs a user application developed specifically for RoboCount™ 2020. The application communicates with the CG5 control unit, the WP platform balance, the bar code reader, the Lynx® multi-channel analyzer, and the LN 2 pump. For gamma spectrometer data acquisition and analysis, the application relies on the Mirion Technologies, Inc., Genie™ 2000 software suite.

Personnel safety is of utmost importance in industrial settings involving heavy automated machinery such as an IR. In addition to emergency stop buttons on both the control unit and the teach pendant, the perimeter of the system working area is protected by a light curtain which could be upgraded to a safety laser scanner in topologically more complex work environments.

The impressive capabilities of robotic NDA systems such as RoboCount™ 2020 can be further extended in a number of meaningful directions.

Use of electrically cooled HPGe detectors is possible and will probably become the norm in the future.

For free release (clearance), a second or even a third detector and field-of-view shielding can be installed.

NDA system throughput is frequently limited by WP manipulation rather than the spectrum acquisition time. It can be increased by batch operation with the WP platform integrated into an automatic conveyor. Alternatively, one robot might serve two or more WP stations. In a true NDA facility of the future, autonomous ground vehicles will not only transport the WPs to and from the robotic NDA system but also rotate the WP in lieu of the current WP platform.

An SGS-TC/TGS capable system would employ a second IR, carrying a transmission source module, and moving in sync with the spectrometer robot. Intriguingly, near 4π tomography would then become viable.

Additional functionality can be implemented via widely available IR tool changers, e.g., dose rate measurement, swabbing, marking, sampling, and LiDAR.

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