RADIATION MONITORING & ALARA | The measurement protocol calls for four spectrum


Feedback from Bohunice Installation of efficient and reliable NDA equipment for different waste types in box pallets and FIBCs was a mandatory component of the waste management strategy adopted by the decommissioning project at Jaslovské Bohunice NPP V1. The end user, JAVYS a.s., defined stringent technical requirements for the provision and operation of a characterisation facility for the enormous amount of material expected to be generated by the dismantling activities. Jacobs Slovakia s.r.o. procured and supplied the RoboCountTM


and has been operating it since. It optimised the measurement process because of its compatibility with both waste package types and ability to address diverse measurement requirements. The biggest advantages of RoboCountTM


2020 are an efficient measurement


process, high level of safety, and fully automatic operation. The system is in operation five days a week in 8-hour shifts with an average throughput of 20 box pallets or 10 FIBCs per shift. In total, about 1900 box pallets and 160 FIBCs have been measured so far. The box pallets contain contaminated carbon-steel and stainless-steel fragments which, after characterisation, are suitable for decontamination. FIBCs are used for contaminated and/or activated crushed concrete. We are planning to upgrade the system to be able to characterise material in 200l drums, making it suitable for all waste package types currently used here. Jacobs Slovakia s.r.o. will operate the facility until the end of the project in 2023. RoboCountTM


2020 has exceeded our quality, reliability, and safety


expectations. Our application of an industrial robot to NDA is a much-needed example of the good practice of implementing proven technology (COTS) in the nuclear industry. ■ Helena Mrázová, Project Manager, Jacobs Slovakia s.r.o.


acquisitions per package — one from each side of an FIBC or two from each long side of a pallet. With the 20% relative efficiency HPGe detector installed, both crates and FIBCs can be measured in 4 x 60= 240s with the 90o


collimator


across most of the activity range. For activities approaching the top limit of 109


2020 facility in 2018 package, the 30o Bq per waste collimator and the increased detector to


package distance will lower the integral count rate to below the hardware limit of 100,000 cps and allow the assay time to be cut by half to 4 x 30 = 120s. The assay time limited throughput is thus 15 to 30 packages per hour. The actual throughput, taking loading and unloading into account (estimated 300s), is 7 to 8 WPs per hour. An upgrade to allow 200-l drum assay — not practicable with a typical NDA system but only entailing adaptations to RoboCount™


2020


software — is under preparation. Industrial robots are available essentially off-the-shelf


from several major manufacturers, each offering very similar wrist load categories, work areas, and features. Prices have also come down as a result of strong competition. Robot selection for upcoming projects will depend on customer preference, pricing, and the willingness of the supplier to accommodate special requests peculiar to the NDA application. Some manufacturers, spoiled by large orders of standard


V case, the robot will switch to a 30o collimator before


performing a regular measurement. The collimators are stored in a tray and the coupling is by a bayonet mechanism without electrical or pneumatic actuators. Collimators of other sizes and aperture types, matched


to specific waste types and activities, could be integrated in an enlarged tray. For package identification, a 1D bar code reader is mounted above the collimator (it can be upgraded to 1D/2D image based code reader or an RFID reader). The system also has an automatic liquid nitrogen refill,


performed by the robot via a docking station at predefined time intervals. The docking station is connected to a supply Dewar (vacuum flask). The vent coupling of the docking station exhausts into the atmosphere through a platinum resistance sensor connected to the Dewar mounted nitrogen pump. Liquid flow is interrupted as soon as the sensor detects the change from gaseous to liquid nitrogen. Depending on the size of the supply Dewar, the 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 platform balance, the bar code reader, the Lynx®


multi-channel


analyser and the nitrogen pump. For gamma spectrometer data acquisition and analysis, the application relies on the Mirion Technologies Genie™


2000 software suite. Personnel safety is of utmost importance in industrial


settings involving heavy automated machinery such as an industrial robot. There are emergency stop buttons on the control unit and the teach pendant, while 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 prototype system is currently configured to measure pallets (1200 x 800 x 800 mm) and 1m3 activity range is 105 137 as key nuclides.


FIBCs. The expected –109 Bq per package with Co-60 and Cs- 36 | November 2021 | www.neimagazine.com


units from the automotive industry, will not entertain any such wishes. Some will even void their warranty and decline to service units installed in controlled areas, even though the chances of an NDA robot getting contaminated are near zero. This attitude should change as more and more industrial robots are successfully employed in nuclear applications. Already, at least one of the major players is showing keen interest in entering the NDA market. The impressive capabilities of robotic NDA systems such 2020 can be further extended in a number of


as RoboCount™


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


● For free release a second or even a third detector and field-of-view shielding can be installed.


● NDA system throughput is more often limited by package manipulation than by spectrum acquisition time. It can be increased by batch operation with the platform integrated into an automatic conveyor. Alternatively, one robot might serve two or more stations. In a true NDA facility of the future, autonomous ground vehicles will transport waste packages to and from the robotic NDA system and rotate them in lieu of the current platform.


● An SGS-TC/TGS capable system would employ a second robot, 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 tool changers, eg, dose rate measurement, swabbing, marking and sampling.


● The ultimate development goal is the integration of LiDAR coupled with real-time mathematical efficiency calibration, ushering in the era of fully-robotic NDA.


We believe the future of NDA belongs to industrial robotic systems on account of their flexibility, zero maintenance, attractive price/performance ratio, standardisation potential, and the promise of total automation. ■


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