Remote Handling Equipment Research Articles

Research on the inverse kinematics of heavy-load manipulator and end-effector for fusion reactor

The environment in Tokamak fusion reactor is hostile to remote handling (RH) equipment that maintains in-vessel components. Many maintenance tasks include transferring components, pipe cutting, and welding in the vacuum vessel (VV). To fulfill these maintenance works, a 7- degree-of-freedom (DOF) heavy load manipulator and a 3-DOF end-effector are designed and connected together to form a 10-DOF redundant robot. The inverse kinematics for such a high redundancy robot, considering obstacle avoidance in the complex space of VV, is a challenge. To solve this problem, the Jacobian method is adopted, and a method specially designed for obstacle avoidance of redundant robots working in the VV is integrated to simplify algorithm calculation and improve inverse solution efficiency. The algorithm is applied to solve the inverse kinematics of the redundant robot for the maintenance of the divertor plasma facing components (PFC) in VV. The results show that the inverse kinematics of the redundant robot can be solved quickly with high positioning accuracy. The method can also be used for other fusion reactor maintenance robots with some adjustments. The maintenance efficiency of redundant robot can be improved with the method which can be valuable for the whole remote handling process.

An Intelligent Human–Machine Interface Architecture for Long-Term Remote Robot Handling in Fusion Reactor Environments

This paper addresses the intricate challenge posed by remote handling (RH) operations in facilities with operational lifespans surpassing 30 years. The extended RH task horizon necessitates a forward-looking strategy to accommodate the continuous evolution of RH equipment. Confronted with diverse and evolving hardware interfaces, a critical requirement emerges for a flexible and adaptive software architecture based on changing situations and past experiences. The paper explores the inherent challenges associated with sustaining and upgrading RH equipment within an extended operational context. In response to this challenge, a groundbreaking, flexible, and maintainable human–machine interface (HMI) architecture named MAMIC is designed, guaranteeing seamless integration with a diverse range of RH equipment developed over the years. Embracing a modular and extensible design, the MAMIC architecture facilitates the effortless incorporation of new equipment without compromising system integrity. Moreover, by adopting this approach, nuclear facilities can proactively steer the evolution of RH equipment, guaranteeing sustained performance and compliance throughout the extended operational lifecycle. The proposed adaptive architecture provides a scalable and future-proof solution, addressing the dynamic landscape of remote handling technology for decades.

Total ionizing dose estimation of ITER upper port remote handling equipment

This study delineates a comprehensive estimation of the integrated Total Ionizing Dose (TID) for the ITER Upper Port Remote Handling Equipment (UPRHE). The primary objective is to assess the radiation impact and devise strategies to attenuate its effects on the UPRHE components. Radiation levels in various operational zones are deduced from the ITER radiation map. This analysis includes a meticulous definition of operation sequences and corresponding durations for each maintenance task executed by the UPRHE. It is imperative to evaluate each subsystem of the UPRHE for its resilience against the maximum conceivable dose rate and the cumulative TID throughout its operational lifespan. The estimation of TID for the UPRHE encompasses both hourly rates and cumulative doses, calculated based on the identified dose levels and task durations. Additionally, this study computes the TID for all UPRHE subsystems over both a single long-term maintenance (LTM) cycle and the projected 20-year lifespan. Subsequently, the study justifies the derived TID values with the established nuclear radiation alert thresholds for ITER electronics. This comparison reveals that most UPRHE components remain within the safety margin. For components surpassing these thresholds, the paper proposes mitigation strategies to refine the system design in subsequent development phases.

Dust contamination of Divertor Remote Handling System in ITER Hot Cell: A novel approach to model complex superficial radiation sources

Activated dust produced by the erosion of plasma-facing components entails a significant radiation source for ITER and, generally, for all tokamaks aiming for operation under high neutron exposure. In-Vessel remote-handling operations will mobilise the dust, which will be deposited on the remote-handling tools used, for which hands-on maintenance is expected. To ensure safe maintenance of the remote-handling equipment, a dedicated decontamination process in the Hot Cell is required. Evaluating the radiation fields produced by the contaminated equipment is central to minimising radiation exposure to personnel. In this study, we present a nuclear analysis of the Divertor Remote Handling System during its transfer and decontamination process. Past computational limitations regarding superficial sources definition and high uncertainties on the dust model have been overcome by implementing a novel methodology and following an alternative approach. Two surface-dependent dust distributions over the complex geometry surfaces were considered to evaluate the dose rates according to the different contamination levels during the process phases. A scoping analysis was performed to determine the amount of dust that would comply with project requirements in each phase of the process. Improvement margins were identified in the quantification of the amount of dust and Hot Cell layout.

Kinematic Simulation of Divertor Remote Handling Equipment for DTT

Kinematic Simulation of Divertor Remote Handling Equipment for DTT

Preliminary architecture of the DTT remote handling test and training facility

The realization of a specific REMote HAndling Test and Training Facility (REMHAT) is necessary for the development and optimization of the Remote Handling (RH) system, to demonstrate the fulfilment of all its design requirements, for testing and validation of the RH maintenance procedures, for the qualification and acceptance testing of RH equipment and tooling. Furthermore, it provides training and certification to the RH maintenance operators, by making available to operators the knowledge, instructions and experiencing of the Virtual Simulator platform, the control room devices, the robots and tooling to be used for RH tasks. In this work, the preliminary architecture of the DTT REMHAT facility is described, with a focus on the added value of the adoption of Virtual Reality (VR) technologies enabling real-time alignment of virtual robots’ configuration with the real ones (Digital Twin). A first approach to the facility design is proposed, starting from the technical requirements: Environmental, Design, Physical, Functional, Operational, Human Factors and Product assurance and safety. The proposed logical architecture consists of four Sub-Systems (S/S): building and auxiliaries, mock-ups, robots and Control Room. In the present work, a particular attention is paid on the last one. The idea is to create a digital twin of the RH equipment mock-ups to be coupled with software of real-time structural simulation, in order to have at disposition and show in VR environment real-time additional information about the real environment, like robots’ deflections and/or vibrations, clearances and possible collisions detection. These data could be crucial for the operator’s decision-making process about a sudden intervention on the RH system, further to their employment for future studies and optimization. Therefore, for each subsystem of the facility, the components identification and a description of the software and hardware aspects are provided. In conclusion, an overview of the critical issues of such complex system is presented, in order to prepare the ground for future research works.

Decay Dose Shielding Analysis with Hybrid Unstructured Mesh/Constructive Solid Geometry Monte Carlo Calculation and ADVANTG Acceleration

The target segments of the Oak Ridge National Laboratory Second Target Station (STS) neutron production facility become highly activated due to spallation reactions or nuclei transmutation by primary protons and emitted neutrons. Once the target segments are removed from their location within the core vessel, decay dose rates must be accurately quantified to determine the shielding configurations of remote-handling tools and transport casks and to aid in planning maintenance activities. For this analysis, we utilized a hybrid unstructured mesh (UM)/constructive solid geometry approach for calculating spallation products and neutron fluxes, activation calculations using the AARE package that includes the CINDER2008 activation code to calculate the decay photon source at different cooling times, and the ADVANTG code to accelerate the final decay photon transport calculation. Both Type 316 stainless steel (SS-316) and lead were investigated as candidates for shielding materials. The decay photon transport calculation through the thick SS-316 or lead shields exhibited between 25 and 30 orders-of-magnitude attenuations in the radial direction, depending on the shield. Such a difficult shielding calculation required advanced variance reduction. ADVANTG has some missing features, which limits its usability in spallation neutron source applications. It does not support volumetric sources created for MCNP6.2 UM capability. An approximate source was created for this problem. Not only was this approximate source needed for running the ADVANTG calculation to generate the weight windows, but also it was essential to develop source biasing (SB) parameters that were crucial for dramatically accelerating the decay photon transport in this problem. With this approximate source, the analysis was completed in a very reasonable computational time, and the design of the STS remote-handling equipment was finalized. This paper compares the efficiency of Monte Carlo simulations with different weight window and SB parameters calculated using different approximate ADVANTG calculations.

Analysis of implementing a rail-based maintenance system into a HELIAS 5-B device

This paper reports on the analysis of potential rail-based maintenance systems when implemented into a Helical Advanced Stellarator (HELIAS) 5-B device. The main purpose of such a system would be to handle and exchange the internal vessel components, namely the breeding blanket segments, which are expected to be the largest and heaviest components within the vessel. Other rail-based maintenance systems for tokamak devices, particularly the ITER Blanket Remote Handling System (BRHS), were studied, and their suitability when introduced to the differing constraints of a HELIAS device was determined. Rail-based systems envisaged for DEMO and CFETR devices were also studied. An ITER-like handling system was shown to be unsuitable for a HELIAS device of this scale. This is due to significantly higher blanket masses with an in-vessel operating space no larger than that of ITER, but with the additional complication of longer toroidal lengths and non-uniform vessel geometry. Movement of large components on rails like those found in DEMO and CFETR was shown to be more applicable to the HELIAS device. The main obstacle to the implementation of such rails would be the non-uniform geometry which complicates the selection of a rail path that avoids collisions with other in-vessel components, remote handling equipment, or the vessel structure itself.

Logistics and maintenance research activities for DONES facility

DONES is planned to operate on a continuous basis with only two beam stop periods per year for maintenance. The planned operational availability is 70 %, which calls for a carefully analyzed preventive maintenance. The purpose of the research is to propose a realistic and comprehensive logistics and maintenance plan. All the maintenance activities are included in a Maintenance Matrix based on the Plant Breakdown Structure of the project. This is the basis for the creation of a maintenance plan that will lead to a Work Schedule. Special mention within this matrix will be given to those Maintenance operations that must be included in order to comply with regulation. The need of replacement of components impose some requirements on the dimensions of architectural features of the main building such as doors, airlocks, corridors and shipping bays. To enable these replacements, the flow of materials has been developed and analyzed by an intralogistics simulation with AnyLogic. The results of this simulation lead to modifications on either the building or the components such that the replacements are feasible. The periodic replacement of an activated component has been analyzed using FMEA methodology resulting in proposals for the plant equipment designers as well as the remote handling equipment designers. Virtual reality simulations are used for a staged approach to the maintenance operation. The simulation of the HEBT scraper helped to define in detail each step or the maintenance operation. This tool has proven to be very useful to prompt changes in both the plant equipment design and the remote handling equipment. Also, the procedure of the operation itself can be refined and optimized. The conclusion of the research activities is the contribution to the definition of the building, plant equipment and achievement of the target availability.

Digital assistances in remote operations for ITER test blanket system replacement: An experimental validation

Removal/reinstallation of all Test Blanket System (TBS) equipment present in the Port Cell is required during the ITER Long Term Shutdown. TBS shall be designed so that occupational radiation exposure can be As Low As Reasonably Achievable (ALARA) over the life of the plant to follow the ITER Policy. The expected level of radiation in this area still allows performing maintenance tasks hands-on. However, the cumulated dose could be significant for operators. Classical Dose Reduction Measure (DRM) is to deploy Remote Handling systems. Consequently, use of robotized equipment, remotely operated means or collaborative robotics, have been investigated. Taking advantage of new digital technologies such as digital assistances, is expected to help operators during complex remote operations under limited vision conditions. Experiments were performed on a set of three TBS maintenance representative tasks: remote visual inspection of DN80 pipe, dye penetrant testing operation on pipe and dexterity test. A panel of remote handling equipment operators of different skill level was selected and involved onto these tasks. The results prove without ambiguity that for all operators the quality of the task execution is significantly improved when using digital assistances

Conceptual study of the remote maintenance of the DEMO breeding blanket

The development of a remote maintenance concept to replace DEMO in-vessel components after completion of their lifecycle or in case of failure is fundamental to the successful implementation of the EU fusion roadmap. The replacement of the hot breeding blanket (BB), by far the largest in-vessel component, at the end of its lifecycle is particularly important. This includes the removal from the reactor, the transport to the active maintenance facility (AMF) where the BB is decontaminated and prepared for storage as radioactive waste and the preparation and installation of the new BB. Significant effort is made to control and minimize the spread of contamination. All operations are therefore carried out in sealed rooms and corridors.The high mass of the BB segments requires all remote handling equipment to be capable of handling high payloads of more than 100 tons. It must also operate within tight space and based on impaired feedback from control sensors in the radioactive environment. At the same time, it must be highly reliable in accordance with nuclear requirements and be recoverable in case of failure.Some concepts of BB lifting devices were investigated in the past [1] (Keep et al., 2017), but were discontinued due to insufficient payload capacity. Thus, the vertical maintenance of the BB was identified as one of DEMO's key design integration issues since failure to develop a feasible concept would potentially require major changes to the tokamak architecture [2] (Bachmann et al., 2020). A new study had been initiated with a focus on structural integrity and efficient load transfer from the BB through the RH equipment to the VV upper port. A concept of the BB transfer cask and the BB transporter resulting from this study is presented in this article together with a conceptual study of the layout of the tokamak building and the AMF. Studies of alternative concepts for in-vessel maintenance are conducted in parallel but will not be described here.

Concept design of the upper port remote handling equipment for ITER neutral beam cell maintenance

Among the eighteen upper ports of the ITER Tokamak, the upper ports #4, #5, #6 and #7 are located in the Neutral Beam (NB) cell. A roughing filter and an upper port plug are located inside each upper port. Vacuum Vessel (VV) in-service inspection and neutron flux monitor ports are located on the balcony area near the third Heating Neutral Beam (HNB). This paper describes the concept design of the Upper Port Remote Handling Equipment (UPRHE) that provides means to maintain the components at the upper ports and the balcony area within the NB cell. The UPRHE can move along the toroidal direction to access the upper ports and can deploy various remote handling (RH) tools into the upper ports to access the components that require maintenance. The UPRHE consists of permanent installations in the NB cell and removable equipment that is transferred from the Hot Cell Facility to the NB cell only when carrying out the maintenance activities. The permanent equipment is the cabling device mounted on wall. The removable equipments are the upper port trolley, manipulator transporter, end-effectors, manipulators, and other RH tools. The concept design and the RH compatibility assessment demonstrate that the proposed UPRHE can perform the identified tasks and is ready to move on to the next design phase.

EPICS application for ITER RH supervisory control system

The purpose of the Remote Handling System is to carry-out remote maintenance of the ITER machine and components where the environment radiation levels are greater than 100 μSv/hr. The general approach to the remote maintenance operations is to remove components from the ITER machine and to replace with new or refurbished components. The refurbishment and waste processing operations take place in the Hot-Cell, also using the RH System. Remote maintenance operations are man-in-the-loop. Trained RH operators, using specialized interfaces to remotely operated RH equipment, carry-out a maintenance activity in the hazardous location. A dedicated suite of control rooms, located in the Personnel Access Control Building (B24), is used to control the RH operations in the Tokamak and Hot-Cell.The Remote Handling (RH) Supervisory Control System provides the basic control infrastructure to integrate the RH equipment systems into a single ITER Plant System operating from the RH control room(s) under the authority of the ITER central control system. The RH Supervisory Control System (RHSCS) has six relatively independent sub-systems fulfilling three major functions: a) to provide basic control infrastructure of the RH maintenance system; b) to support central monitoring and coordination of RH maintenance activities; c) to support management of RH maintenance campaigns.The RHSCS, currently in Final Design phase, comprehends the RH Plant Controller System (RHPC), responsible to provide the functionalities to control RH plant activities at a level suitable for coordination with other ITER activities. This sub-system, developed using the EPICS framework, will allow the connection between the main control room (MCR) and the RH Plant Controller.The system implements the EPICS Channel Access Protocol and it uses a set of process variable to communicate RH Plant System operating states and ITER rooms states between MCR and RH System via CODAC interface. Behind the simple approach based on the HMI created in BOY, the sub-system implements a mechanism to allow the flow-down and application of MCR work program to the RH System.

Preliminary study and selection of CFETR in-vessel component tritium dust decontamination method in hot cell

Abstract Decontamination is a necessary and effective way of radioactive contamination reduction in the IVC (In-Vessel Component) maintenance and decommissioning process for CFETR. Plasma unstable events that occur in the reactor produces a large amount of tritium dust in the vacuum vessel. Decontamination also plays an extremely important role in reducing the radioactive pollutants diffusion, cumulative radiation dose and staff occupational exposure level, controlling radioactive effluent of nuclear facilities and enhancing remote handling equipment life and reliability and even series environmental protection problems. In this study, we carry out selection and analysis of decontaminate method for CFETR hot cell, comparing to existing mature cleaning and decontamination methods for radioactive contaminated surface, with the comprehensive consideration of the characteristics of PFC (Plasma Facing Component) pollution and the limitation of hot cell remote handling operation, analyze the adaptability and requirements of the fusion facility, selecting the most suitable cleaning method satisfied with necessary requirements for CFETR hot cell. Establishment of PFC (Plasma Facing Component) decontamination method evaluation system provides technical support for the design of hot cell remote handling cleaning device.

EU-DEMO Breeding Blanket temperature evaluation before remote maintenance operation

In DEMO (the European proposal of demonstration fusion reactor) the Breeding Blanket (BB) segments shall be periodically replaced, at end of life or after failure. Any replacement of a BB segment shall be performed by Remote Handling Equipment (RHE) through the vertical upper port: any active action is executed by RHE that clamps a BB segment in the upper portion using a BB transporter. A driving requirement of DEMO commercial technology for RHE is the maximum operating temperature at the BB-RHE interface during BB replacement: the objective of this study is properly to assess this limit, being now the allowable value at 100 °C. This study deals with the Helium Cooled Pebble Bed (HCPB) concept.The initial configuration, with all sector segments (three in the outboard region and two in the inboard one) in their nominal position, has been considered; then the Finite Element model predicts if a natural convection cooling air flux inside vacuum vessel is adequate or if it is necessary a forced convection cooling system. The decay heat produced by the main blanket components (the BB modules caps and lateral walls, the backwalls, the supporting structures, the backplate manifolds, and so on) have been evaluated beforehand: the values applied as body loads in the thermal analyses have been selected within the set related to one month after shut-down. With the assumed geometrical and physical boundary conditions set for the natural and forced convection, the analyses indicate that a forced convection should be necessary to ensure compliance with the present RHE requirements. The obtained results, the analysis assumption and future analysis plan have been briefly discussed.

A stereoscopic eye-in-hand vision system for remote handling in ITER

The International Thermonuclear Experimental Reactor (ITER) maintenance is performed by means of remote handling (RH) systems and with aid of user interfaces such as haptic and joystick devices, virtual reality (VR) systems, and camera views. Many RH operations involving RH equipment, such as robotic manipulator arms, require millimeter accuracy, but camera views are often occluded or of poor quality, and might be unavailable during sensitive steps that require accurate, close-up views. Moreover, the VR system may not reflect the current scene accurately, as physical conditions may have changed under the harsh environment. The purpose of this research was to prototype and evaluate a novel software system, called 3D Node, that locates and detects the position and orientation of a piece of RH equipment or reactor element with respect to a stereo camera pair. The detection information is utilized to adjust the motion trajectories of a robotic manipulator arm. The 3D Node features stereo-camera calibration, target depth mapping, target position and orientation detection, and online target tracking. This paper reports on the 3D Node demonstration on the ITER Divertor RH use case and discusses the system applicability to other ITER RH systems.

Progress on reliability of remote maintenance concept for JA DEMO

JA DEMO selected the vertical maintenance scheme as the primary maintenance option. In order to improve reliability of Remote Handling (RH) and plant availability, update of in-vessel transferring mechanism of the segment, pipe unit structure on maintenance port were carried out. The RH equipment is composed of end-effectors (grippers) for the banana segment, a power manipulator, a telescopic guide and a carrier. The pipe structure in vertical maintenance port was updated considering the thermal expansion, easy handling (short maintenance time) and alignment of welding groove. Based on estimation of maintenance time, four works in parallel will be required for plant availability reachable for commercialization (>60%).

The remote handling system of IFMIF-DONES

The International Fusion Materials Irradiation Facility-DEMO Oriented Neutron Source (IFMIF-DONES) consists of complex systems and massive components that need to be on site assembled and maintained. For several of them it is required to perform maintenance, inspection and monitoring tasks over many years in a hostile environment and in efficient, safe and reliable manner. The maintenance of IFMIF-DONES’ systems and components, located mainly in the Test Systems (TS), in the Lithium Systems (LS) and in the Accelerator Systems (AS), is classified as a Remote Handling (RH) Class 1st activity and as such is considered a crucial and essential activity whose success will strictly depend on the IFMIF-DONES RH capability. According to this, a Remote Handling System (RHS) for IFMIF-DONES, which comprises the whole set of Remote Handling Equipment and tooling for the execution of maintenance tasks, has been designed. A wide range of technologies is involved: special cranes, manipulator arms, lift interface frames, special cameras, control systems and virtual reality. In this paper an overview on status of the design of the main robotic systems and tooling of the RHS of IFMIF-DONES, including design requirements, functions and maintenance tasks to be performed, is given.

Remote diagnostics application software for remote handling equipment

The ITER Remote Handling Control System (RHCS) controllers provide measurement and diagnostics data about the remote handling equipment and tools they control. This paper presents the Remote Diagnostics Application (RDA) software for the analysis and archiving of the RHCS diagnostics data.The RDA provides a basic set of diagnostics tools, including trends, spectra, histograms, scatter plots, cross-correlation plots, as well as archiving and retrieval of history data. The ITER RH operators can extend diagnostics capabilities for specific RH equipment needs by incorporating custom diagnostics functions. To facilitate customization, RDA implements an architecture with three nested levels: the RDA Framework, its Diagnostics Workbenches and their Diagnostics Primitives. The RDA Framework has a user interface that can load one or several special diagnostics cases implemented as custom Diagnostics Workbenches with custom or default Diagnostics Primitives, such as rules, analysis functions and filters.As a result, the RDA features a diagnostics framework to execute complex and dedicated diagnostics and prognostics for the RH experts to monitor performance data, to run diagnostics tests and rules on equipment systems and to analyse historical data. The RDA helps the RH operators reduce downtime of the Remote Handling systems by exposing failure conditions and maintenance needs.

Real-time volumetric rendering of radiation fields using 3D textures

The remote maintenance of nuclear fusion facilities must be carefully planned and monitored due to the potential damage to equipment caused by the ionising radiation that results from neutron activation of facility components. We present a method for visualising three-dimensional radiation dose fields in real-time. An interactive volumetric representation is achieved using view-dependent parallel ray casting of a scalar field in three dimensions. This enhances the planning of remote handling operations by allowing motion paths to be better optimised for the minimisation of dose to vital components, prolonging the lifetime of remote handling equipment.