ITER is an international project at the forefront of the search to create nuclear fusion, the process that powers our sun, on earth. Its goal is to generate a ratio of fusion power to input power >= to 10. To do this the ITER machine will generate high energy neutrons that will activate the machine making manned maintenance impossible. The ITER project therefore relies on full remote handling both in-vessel and ex-vessel for future upgrades and maintenance.
Oxford Technologies has been involved with the ITER project since its inception as a result of our heritage at the EFDA-JET fusion project, Culham.
Oxford Technologies was tasked under a Remote Handling Framework to develop an engineered concept for an In-Vessel robot device capable of carrying and installing in-vessel components up to 4.5 tons in weight and carrying out remote tasks such as in-service inspection, leak localisation & testing, dust & tritium control and maintenance of in-vessel diagnostics. This work was broken down into several sub tasks:
- MPD Concept design including Manipulator Systems, End-Effector, Tool Interface and Hoist / Viewing System. Design of ‘In-Cask Equipment’ was also required comprising tools, deployment trolleys and storage boxes.
- MPD System Analysis
- MPD Remote Vacuum Cleaner
- MPD RH Operations Task Assessment
- Concept Design Review (CDR) support.
The challenges in designing a remote handling system for remote maintenance of the ITER in-vessel machine were considerable. The system had to be deployed remotely by large Casks that dock onto the ex-vessel ports through port cells and be able to reach all in-vessel surfaces (when deployed from one of several ports). Specific design requirements included:
- Minimum lifetime of 30 years (with replacement / consumable parts)
- Lifetime radiation of 1MGy and continuous operation under gamma radiation dose rate of ~ 250Gy/h
- Recoverable in the event of failure either by self recovery or rescue.
- Design should allow for SL-1 seismic events and be recoverable after SL-2 event.
- Materials selection compliant with ITER Vacuum Handbook
- RAMI – system availability not less than 90%
- Modular design for ease of maintenance
Oxford Technologies heritage included the design and build of the in-vessel Boom used for remote maintenance of the EFDA-JET fusion machine based at Culham, UK. That device had to carry up to 1 tonne at the end of a cantilevered 10m long rectangular robotic boom or be fitted with a bilateral Manipulator to be able to perform dexterous maintenance tasks in-vessel. The ITER MPD is on a significantly larger scale working in a volume 10 times that of the JET machine and carrying more than 5 times the load. This required a radically different kinematic concept to be able to reach the upper and lower section of the 10m in-vessel when deployed via the equatorial ports. The solution was a snake like device with a cylindrical cross section of ~ 750mm diameter with alternate pivoting and rotational joints, deployed from a linear sliding joint. This arrangement allowed for both toroidal deployment up to 50 degrees each side of a port and poloidal deployment throughout the 10m in-vessel height. Careful analysis of the required in-vessel remote tasks was completed using virtual reality simulations. A suite of tools and support systems were developed to facilitate all task and system requirements.
The MPD design as produced by Oxford Technologies successfully passed its Concept Design Review and is now part of the specified ITER baseline remote handling equipment.