Pre-conceptual design assessment of DEMO remote maintenance

Abstract

EDFA, as part of the Power Plant Physics and Technology programme, has been working on the preconceptual design of a Demonstration Power Plant (DEMO). As part of this programme, a review of the remote maintenance strategy considered maintenance solutions compatible with expected environmental conditions, whilst showing potential for meeting the plant availability targets. A key finding was that, for practical purposes, the expected radiation levels prohibit the use of complex remote handling operations to replace the first wall. In 2012/13, these remote maintenance activities were further extended, providing an insight into the requirements, constraints and challenges. In particular, the assessment of blanket and divertor maintenance, in light of the expected radiation conditions and availability, has elaborated the need for a very different approach from that of ITER. This activity has produced some very informative virtual reality simulations of the blanket segments and pipe removal that are exceptionally valuable in communicating the complexity and scale of the required operations. Through these simulations, estimates of the maintenance task durations have been possible demonstrating that a full replacement of the blankets within 6 months could be achieved. The design of the first wall, including the need to use sacrificial limiters must still be investigated. In support of the maintenance operations, a first indication of the requirements of an Active Maintenance Facility (AMF) has been elaborated.

Overview of EU DEMO design and R&D activities

“…Conceptual designs for a set of remote handling equipment for the vertical maintenance scheme are being developed incorporating designs for in-vessel transporters, to detach and attach the blanket segments and divertor cassettes, and cask-housed vertical maintenance devices to open and close access ports, cut and weld service connections, and extract blanket segments from the vessel [18]. Further study is needed in order to comprehensively establish the feasibility and evaluate the efficiency of the proposed maintenance system however it is clear from the outset that the design of in-vessel components and the vessel itself is intrinsically linked the design of the remote maintenance system.…”

Continuous maintenance and the future – Foundations and technological challenges

“…Use of remote controlled robots for maintenance is widely used in Nuclear [106], space and any hazardous industries. Fig.…”

“…Section of proposed DEMO vertical maintenance system architecture with remote controlled manipulators[106].…”

Initial DEMO tokamak design configuration studies

“…1, and vertically handled through large upper ports. This concept had also been adopted in the European Power Plant Conceptual Study [10] and has been further developed for DEMO [11]. Cantilevered RH tools carrying the blanket weight as e.g.…”