No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
Radiation Tolerance of Commercial-Off-The-Shelf Components Deployed in an Underground Nuclear Decommissioning Embedded System
Abstract
Robotics and embedded systems are increasingly used and deployed in harsh environments such as nuclear decommissioning and radioactive waste handling. Development of new, low-cost, robotic solutions, requires commercial-off-the-shelf (COTS) components to survive radioactive exposure. Understanding the response of these components to γ-radiation is important for safe and reliable deployment. Power supply regulation and microcontrollers have been highlighted as sensitive to radiation and this study determines experimentally the characteristics of degradation for COTS voltage references, voltage regulators and a microcontroller. The findings lead to development of a discrete voltage regulator constructed with individual BJTs that exhibits increased radiation tolerance.
... Ducros et al. performed radiation tolerance testing, and found that power supply components were by far the most susceptible and had on average a tolerance of up to 210 Gray (Gy) total ionizing dose (TID) at a dose rate of 1.9 Gyh −1 . Other electronic components were found to be much more tolerant, surviving TIDs of 2200 Gy. Nancekievill et al. (2016) found similar results in their radiation tolerance testing of CoTS electronic components. ...
... For deployments into high dose areas an additional factor that needed to be considered was the effect of radiation on Vega. In particular, the electronic systems used in Vega will be damaged by gamma radiation (Nancekievill et al., 2016). ...
This paper presents the Vega robot, which is a small, low cost, potentially disposable ground robot designed for nuclear decommissioning. Vega has been developed specifically to support characterization and inspection operations, such as 2D and 3D mapping, radiation scans and sample retrieval. The design and construction methodology that was followed to develop the robot is described and its capabilities detailed. Vega was designed to provide flexibility, both in software and hardware, is controlled via tele-operation, although it can be extended to semi and full autonomy, and can be used in either tethered or untethered configurations. A version of the tethered robot was designed for extreme radiation tolerance, utilizing relay electronics and removing active electronic systems. Vega can be outfitted with a multitude of sensors and actuators, including gamma spectrometers, alpha/beta radiation sensors, LiDARs and robotic arms. To demonstrate its flexibility, a 5 degree-of-freedom manipulator has been successfully integrated onto Vega, facilitating deployments where handling is required. To assess the tolerance of Vega to the levels of ionizing radiation that may be found in decommissioning environments, its individual components were irradiated, allowing estimates to be made of the length of time Vega would be able to continue to operate in nuclear environments. Vega has been successfully deployed in an active environment at the Dounreay nuclear site in the UK, deployed in nonactive environments at the Atomic Weapons Establishment, and demonstrated to many other organizations in the UK nuclear industry including Sellafield Ltd, with the goal of moving to active deployments in the future.
... A common but mistaken assumption is that only radiation-hardened robotics should be used within the nuclear industry, hence hydraulically actuated robots [17][18][19][20][21][22] and platforms that feature radiation-hardened components [23] have traditionally been in favour. Although this may be true for operations within high-radiation environments such as hot cells, other typical nuclear environments exhibit radiological levels which may be too high for daily human exposure but are not sufficient to damage conventional hardware. ...
... For a worker to receive a dose of 1 mSv over the course of a day would be seen as very high and almost certainly not As Low As Reasonably Practicable (ALARP). However, this dose is virtually irrelevant to COTS electronic components, where radiation hardness testing tends to begin at around five or six orders of magnitude higher than this [23]. Thus, although commercially available robotic platforms may not be useable within the primary containment vessel of a nuclear reactor, for example, they may be useable within activities such as the categorisation of general waste. ...
A novel, semi-autonomous radiological scanning system for inspecting irregularly shaped and radiologically uncharacterised objects in various orientations is presented. The system utilises relatively low cost, commercial-off-the-shelf (COTS) electronic components, and is intended for use within relatively low to medium radioactive dose environments. To illustrate the generic concepts, the combination of a low-cost COTS vision system, a six DoF manipulator and a gamma radiation spectrometer are investigated. Three modes of vision have been developed, allowing a remote operator to choose the most appropriate algorithm for the task. The robot arm subsequently scans autonomously across the selected object, determines the scan positions and enables the generation of radiological spectra using the gamma spectrometer. These data inform the operator of any likely radioisotopes present, where in the object they are located and thus whether the object should be treated as LLW, ILW or HLW.
... Naturally, there is a significant interest in radiation hardened robotics within the industry, hence hydraulically actuated robots [6][7][8][9][10][11] and platforms that feature radiation hardened components [12] have traditionally been in favour. However, although operations within environments such as hot cells involve very high levels of radiation, other typical nuclear environments may exhibit radiological levels which, despite being too high for daily human exposure, are still far too low to damage conventional hardware. ...
... In terms of damage to commercially available off-the-shelf (COTS) electronic components, this is a low dose rate. Discussions of radiation hardness tend to begin at around eight orders of magnitude higher [12]. Thus, although commercially available robotic platforms may not be useable in very high radiation environments (e.g. ...
A novel, semi-autonomous radiological scanning system for inspecting uncharacterised objects is presented. The research utilises commercially available off-the-shelf (COTS) electronic components, intended for use in relatively low radioactive dose environments. To illustrate the concept, a Microsoft Kinect, a Universal Robots UR3 (6 degree of freedom) manipulator and a Kromek RadAngel gamma radiation spectrometer are utilised. The new control software allows the remote operator to select the required object, before the robot arm autonomously scans it, enabling the generation of various radiological spectra shapes. These data inform the operator of any likely radioisotopes present and where they are located in the object.
... Trapped charges accumulate over time and modify the transistor characteristics. The effect of radiation has been studied in many components commonly found in embedded systems: signal propagation changes within ICs [21], impact on voltage regulators [22], System-On-Chips and microcontrollers [23]- [25]. ...
Embedded digital devices, such as Field-Programmable Gate Arrays (FPGAs) and Systems on Chip (SoCs), are increasingly used in dependable or safety-critical systems. These commodity devices are subject to notable hardware ageing, which makes failures likely when used for an extended time. It is of vital importance to understand ageing processes and to detect hardware degradations early. In this survey, we describe the fundamental ageing mechanisms and review the main techniques for detecting ageing in FPGAs, microcontrollers, SoCs, and power supplies. The main goal of this work is to facilitate future research efforts in this field by presenting all main approaches in an organized way.
... Testing complete circuits may provide more data than testing individual components, due to potentially unexpected interactions between the components. While some studies have investigated the radiation effects on electronic components in the context of the nuclear industry [13,14], microprocessor testing in literature is predominantly focused on single event detection and heavy particle irradiation. This research is mostly focused on space applications, and the results cannot be directly correlated with performance in a gamma radiation environment more prevalent in nuclear decommissioning [15][16][17][18][19]. ...
The impact of gamma radiation on a commercial off the shelf microcontroller board has been investigated. Three different tests have been performed to ascertain the radiation tolerance of the device from a nuclear decommissioning deployment perspective. The first test analyses the effect of radiation on the output voltage of the on-board voltage regulator during irradiation. The second test evaluated the effect of gamma radiation on the voltage characteristics of analogue and digital inputs and outputs. The final test analyses the functionality of the microcontroller when using an external, shielded voltage regulator instead of the on-board voltage regulator. The results suggest that a series of latch-ups occurs in the microcontroller during irradiation, causing increased current drain which can damage the voltage regulator if it does not have short-circuit protection. The analogue to digital conversion functionality appears to be more sensitive to gamma radiation than digital and analogue output functionality. Using an external, shielded voltage regulator can prove beneficial when used for certain applications. The collected data suggests that detaching the voltage regulator can extend the lifespan of the platform up to approximately 350 Gy.
... The existing literature on the radiation damage of electronic components focuses particularly on military applications, aerospace applications [4] and on the experiments carried out at the European Organization for Nuclear Research (CERN) [5]. However the radiation and total dose levels associated with the nuclear decommissioning environments are not equivalent with these reported applications as pointed out by Nancekievill et al. [6]. ...
The use of Wireless Sensor Networks (WSN) is now widespread, with well-documented deployments across a diverse range of sectors including aerospace, agri-science and consumer electronics. In the nuclear industry there have been successful deployments of WSN technologies for instrumentation and control, however, there are significant challenges that need to be addressed before wireless sensing can be used in some nuclear decommissioning extreme environments.
This paper presents a concept design for a wireless sensor network capable of delivering wireless remote sensing and control capability through the reinforced concrete structures used in nuclear processing environments. The paper describes the deployment challenges, and how these are being addressed by the design methodology. These challenges include: difficult to reach areas with limited or no power sources; radiation tolerance of sensors and communication systems and delivery of secure and reliable communication in spaces exhibiting highly variable wireless propagation conditions.
Following the description of the design methodology, the paper focuses on recent work to characterise the wireless propagation through the reinforced concrete structures found in many decommissioning environments. Preliminary Radio Frequency (RF) propagation measurements undertaken in two buildings on the Sellafield site are presented. The paper demonstrates how analysis of these results enables potential transmission frequencies to be identified and the power budget of the wireless sensor nodes to be modelled.
... Studies presented in Ref. [27] have shown that electronic components in nuclear decommissioning environments are exposed to different dose rates and total dose rates compared to other industrial applications. These findings need to be taken into account during the selection of dose rate and total dose to evaluate the effects of TID on components deployed in nuclear decommissioning environments. ...
The effects of Total Ionizing Dose (TID) on electrical components is a key parameter to evaluate the life span of wireless sensor nodes for possible deployment in nuclear decommissioning environments. The aim of this study was to experimentally evaluate the effects of TID on capacitance, internal resistance and the self-discharge characteristic of 100 F supercapacitors. An automated test circuit was designed and assembled to charge and discharge the supercapacitors. The supercapacitors were irradiated using a Co-60 γ ray radiation source and the voltage across the supercapacitor terminals, charging current and discharging current were monitored and logged to calculate the capacitance during the irradiation process. Measurements of internal resistance and self-discharge characteristic were performed before and after the irradiation to examine the effects of exposure to γ radiation on these electrical properties. The experimental results show negligible effects on the capacitance of supercapacitors exposed to a maximum dose of 40 kGy. The internal resistance and self-discharge characteristics were not affected by TID up to 89 kGy. These results demonstrate that supercapacitors are a suitable technology to design an Energy Storage System to be deployed in the majority of nuclear decommissioning environments.
... Examples include undertaking irradiation tests on optical fibres (Coenen and Decreton, 1993), position sensing using laser systems (Decreton, 1995) Decreton, 1996;Sinclair and Chertov, 2015;Van Duy et al., 2015;Zhang et al., 2013). Similarly, high end computing is also regarded as greatly important (Bagatin et al., 2017;Lin et al., 2016;Nancekievill et al., 2016;Ostler et al., 2009;Schmidt et al., 2012;Sterpone et al., 2005;Wu et al., 2011). Furthermore, global advances have already proved to be beneficial for the robotic community. ...
The use of ground-based robotic systems for the characterization of nuclear environments is reviewed. Almost since the dawn of the nuclear energy industry, man has somewhat inadvertently created environments in which access has been constrained primarily due to the risk posed by extreme levels of radiation exposure but also due to space constraints, and because of toxic and combustible atmospheres. Robotic systems pose an ideal solution to some of these difficulties, removing the need for humans to access such places and frequently providing data on the state of such places that would not otherwise be available. However, each of these requirements are often very different in terms of the specification of a given robot, and the detailed characteristics of a given harsh environment can pose significant challenges even for the most robust of platforms. Furthermore, such developments can be expensive in terms of cost and development time. These issues notwithstanding, robotic solutions to nuclear challenges are reaching a level of maturity where their use is destined to add significant value. This paper considers the salient developments in ground-based solutions from the era preceding the Three Mile Island accident, through Chernobyl and on to the present day and, in particular, the needs of Fukushima Daiichi as attentions turn to this complex robotic suite of challenges. [OPEN ACCESS]
As robotics become more sophisticated, there are a growing number of generic systems being used for routine tasks in nuclear environments to reduce risk to radiation workers. The nuclear sector has called for more commercial-off-the-shelf (COTS) devices and components to be used in preference to nuclear specific hardware, enabling robotic operations to become more affordable, reliable, and abundant. To ensure reliable operation in nuclear environments, particularly in high-gamma facilities, it is important to quantify the tolerance of electronic systems to ionizing radiation. To deliver their full potential to end-users, mobile robots require sophisticated autonomous behaviors and sensing, which requires significant computational power. A popular choice of computing system, used in low-cost mobile robots for nuclear environments, is the UP Core single board computer. This work presents estimates of the total ionizing dose that the UP Core running the Robot Operating System (ROS) can withstand, through gamma irradiation testing using a Co-60 source. The units were found to fail on average after 111.1 ± 5.5 Gy, due to faults in the on-board power management circuitry. Its small size and reasonable radiation tolerance make it a suitable candidate for robots in nuclear environments, with scope to use shielding to enhance operational lifetime.
The utilisation of robots in hazardous nuclear environments has potential to reduce risk to humans. However, historical use has been largely limited to specific missions rather than broader industry-wide adoption. Testing and verification of robotics in realistic scenarios is key to gaining stakeholder confidence but hindered by limited access to facilities that contain radioactive materials. Simulations offer an alternative to testing with actual radioactive sources, provided they can readily describe the behaviour of robotic systems and ionising radiation within the same environment. This work presents a quick and easy way to generate simulated but realistic deployment scenarios and environments which include ionising radiation, developed to work within the popular robot operating system compatible Gazebo physics simulator. Generated environments can be evolved over time, randomly or user-defined, to simulate the effects of degradation, corrosion or to alter features of certain objects. Interaction of gamma radiation sources within the environment, as well as the response of simulated detectors attached to mobile robots, is verified against the MCNP6 Monte Carlo radiation transport code. The benefits these tools provide are highlighted by inclusion of three real-world nuclear sector environments, providing the robotics community with opportunities to assess the capabilities of robotic systems and autonomous functionalities.
In 2024, The Large Hadron Collider (LHC) at CERN will be upgraded to increase its luminosity by a factor of 10 (HL-LHC). The ATLAS inner detector (ITk) will be upgraded at the same time. It has suffered the most radiation damage, as it is the section closest to the beamline, and the particle collisions. Due to the risk of excessive radiation doses, human intervention to decommission the inner detector will be restricted. Robotic systems are being developed to carry out the decommissioning and limit radiation exposure to personnel. In this paper, we present a study of the radiation tolerance of a robotic finger assessed in the Birmingham Cyclotron facility. The finger was part of the Shadow Grasper from Shadow Robot Company, which uses a set of Maxon DC motors.
The effect of very low dose rate irradiation is investigated for
several linear bipolar devices that are sensitive to enhanced low
dose-rate damage, including one device with super-β input
transistors. New results are included at 0.001 and 0.002 rad(Si)/s.
Irradiations at elevated temperature at high dose rate are compared with
room temperature irradiation at very low dose rate. Possible mechanisms
for enhanced damage are discussed
The various phenomena occurring in bipolar transistors when they
are exposed to ionizing radiation are discussed. NPN transistors are
found to degrade more than PNP transistors. Devices with highly doped
base rings will be less susceptible to total-dose damage than devices
without base rings, especially in NPN devices. Devices with small
emitter perimeter-to-area ratios will be less susceptible than devices
with large perimeter-to-area ratios. Collector bias does not affect gain
degradation. Reverse bias on the emitter is the worst-case irradiation
bias condition. The increases in base current are larger at small
base-emitter voltages than at large base-emitter voltages. Poly-emitter
devices are initially harder than standard emitter devices, but may
become worse than standard devices at large total doses. Degradation is
worse at lower dose rates
With the announcement of the U.K. new nuclear build and the requirement to decommission old facilities, researchers require bespoke facilities to undertake experiments to inform decision making. This paper describes development of The University of Manchester’s Dalton Cumbrian Facility, a custom built research environment which incorporates a 5 MV tandem ion accelerator as well as a self-shielded 60Co irradiator. The ion accelerator allows the investigation into the radiolytic consequences of various charged particles, including protons, alpha particles and a variety of heavier (metal and nonmetal) ions, while the 60Co irradiator allows the effects of gamma radiation to be studied. Some examples of work carried out at the facility are presented to demonstrate how this equipment can improve our mechanistic understanding of various aspects of the deleterious effects of radiation in the nuclear industry. These examples include applications in waste storage and reprocessing as well as geological storage and novel surveying techniques. The outlook for future research is also discussed.
Vulnerability of a variety of candidate spacecraft electronics to total ionizing dose and displacement damage is studied. Devices tested include optoelectronics, digital, analog, linear bipolar devices, and hybrid devices
The First Generation Magnox Storage Pond (FGMSP) is located on the Sellafield Nuclear Site, housing legacy spent Magnox nuclear fuel. Some of which has since corroded, forming a layer of Corroded Magnox Sludge (CMS) creating one of the largest decommissioning challenges the UK has faced. In this work the composition, physical properties and potentially high hazard nature of CMS are discussed, as are the gamma emission spectra of spent Magnox fuel rods typical of the ilk stored. We assess the potential use of a RadLine gamma detector to dose rate map this area and provide fuel rod detection. RadLine consists of a small scintillator, fibre optic cable and photon counter. The probe has the unusual advantage of not being electrically active and therefore fully submersible underwater, with the option to deploy hundreds of metres in length. Our experimental method encompasses general purpose Monte Carlo radiation transport code, MCNP, where we describe the modelling of CMS and pond liquor in comprehensive detail, including their radiological spectrum, chemical composition data, and physical properties. This investigation concludes that the maximum energy deposited within the scintillator crystal due to ambient CMS corresponds to a dose rate of 5.65 Gy h−1, thus above this value positive detection of a fuel rod would be anticipated. It is additionally established that the detectable region is within a 20 cm range.
The total dose response of three bipolar low dropout voltage regulators is presented for a variety of irradiation and anneal test conditions. Two of the part types were chosen for their known enhanced low dose rate sensitivity (ELDRS) and the third for its known radiation tolerance. The two ELDRS parts show a dramatic sensitivity to irradiation bias with the all leads shorted being worst case at low dose rate. The responses at 10 mrad/s and 2.3 mrad/s are similar in magnitude, indicating that the low dose rate enhancement factor has leveled off below 10 mrad/s. Elevated temperature irradiation at 100degC and 5 rad/s does not simulate the low dose rate response
This paper presents the results of cobalt-60 response measurements made on a low dropout voltage regulator and a shunt reference for three different radiation test conditions: low dose rate, accelerated (elevated temperature irradiation) and standard (50-300 rad(SiO<sub>2</sub>)/s). The accelerated test is shown to correlate well with the low dose rate failure of the reference but not for the failure of the regulator.
Experiments and simulations are used to analyze the total-dose response of a linear voltage regulator. Degradation of the dynamic output range of the error amplifier is determined to be responsible for the regulator failure. We present a first-order model to reproduce total dose circuit and system response. Modification of the bias circuitry in the error amplifier using beta compensation techniques is shown to harden the system to a significantly higher total dose level.
A comparison is presented of ionizing-radiation-induced gain
degradation in lateral, substrate, and vertical PNPs. The dose-rate
dependence of current gain degradation in lateral PNP BJTs is even
stronger than the dependence previously reported for NPN BJTs. Various
mechanisms are presented and their relative significance for gain
degradation in the lateral, substrate, and vertical PNPs is discussed. A
detailed comparison of the lateral and substrate PNP devices is given.
The specific lateral and substrate devices considered here are
fabricated in the same process and possess identical emitters. Even
though these devices have identical emitters and undergo the same
processing steps, the lateral devices degrade significantly more than
the substrate devices