Mikko Siuko

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 pre-conceptual 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 2012/2013, 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.

Water hydraulic actuators for ITER maintenance devices

The characteristic advantages of hydraulics (high power density, simple construction and reliability) together with the characteristics of water as the pressure medium (fire and environmentally safe, chemically neutral, not activated nor affected by radiation) are highlighted in critical applications such as remote handling operations in international thermonuclear experimental reactor (ITER). However, lack of commercial selection of water hydraulic components, common design expertise and known application experiences prevents wide use of water hydraulics. Since 1994, IHA has designed and manufactured water hydraulic tools for ITER divertor maintenance and experiences have been good. Therefore, IHA is developing water hydraulic component selection to be applied in coming systems where water hydraulics is foreseen to provide an advantage. Aim of the still on going project is to develop a set of components like power units, control components and actuators. By that way designers are able to apply water hydraulics where advantageous. In the paper the component types, their design and characteristics and results obtained so far are presented.

R.H. divertor maintenance: the divertor refurbishment platform

The ITER divertor assembly consists in 60 cassettes located in the bottom region of the vacuum vessel. Because of erosion and damage during, reactor operations, their replacement is expected to be required eight times during the machine lifetime. The cassettes will be withdrawn from the vessel through dedicated ducts and they will be transported to a hot cell for refurbishment. The divertor refurbishment platform (DRP) simulates the arrangement in the divertor hot cell for cassette inspection, component replacement and repair, measuring, and testing. The DRP had to demonstrate the feasibility of divertor cassette refurbishment, procedures, and the use of conventional remote handling equipment in a hot cell, for the refurbishment of high heat flux components (also called plasma facing components PFC), cassette locking systems, water feeds and post-repair, integrity testing. The true environmental conditions (temperature, atmosphere, radiation, contamination) have not been replicated in the DRP, but they were taken into account in the development of the mock ups, the remote handling equipment, and the operating procedures. The results permit to validate the hot cell operations for the cassette refurbishment and to specify the hot cell requirements. This paper describes the objectives, lay-out, test programme, test results, and future activities of the divertor refurbishment platform.

Performance and remote maintenance of attachment schemes for Plasma Facing Components

The divertor design for the ITER-FEAT fusion reactor is based on cassettes which comprise a reusable body and three sacrificial Plasma Facing Components (PFCs) expected to be replaced in a hot-cell a number of times during machine lifetime. Central to this maintenance approach are the PFC-to-cassette attachments which must be readily assembled/disassembled by remote handling methods and withstand severe mechanical and thermal loading conditions during machine operation. This paper describes the facilities, equipment and methods used to carry out extensive testing of two attachment schemes, shear keys and multi-links, in order to assess their in-service performance and suitability to remote maintenance operations.

Utilization of virtual prototyping in development of CMM

The characteristic advantages of hydraulics (high power density, simple construction and reliability) together with the characteristics of water as the pressure medium (fire and environmentally safe, chemically neutral, not activated nor affected by radiation) are highlighted in critical applications such as remote handling operations in International Thermonuclear Experimental Reactor (ITER). However, component cost and lack of wide selection of water hydraulic components make it difficult to build and to test complex water hydraulic systems. The use of virtual prototyping for the development of water hydraulic tools can be used to address this problem. Rapidly increased computational power has created conditions for extensive numerical calculations, enabling computer aided virtual prototyping to replace physical prototype phases in product development.

Tool prototypes for replacing plasma facing components

The ITER divertor consists of replaceable cassettes, which consist of body element and replaceable plasma facing components. Connecting the plasma facing components to the cassette body is critical in order to minimise the amount of generated waste during maintenance. This paper presents tools for plasma facing component replacement, when using a multi-link type connection.

Using Digital Mock-Ups Within Simulation Lifecycle Environment for the Verification of ITER Remote Handling Systems Design

This paper is part of the EFDAs European goal oriented training program on remote handling (RH) GOT-RH. The program aims to train engineers for activities supporting the ITER project and the long-term fusion program. This paper is written based on the results of a project verification and validation (V&V) of ITER RH system using digital mock-ups (DMUs). The purpose of this project is to study an efficient approach of using DMU for the V&V of the ITER RH system design using a system engineering framework. This paper gives an overview of the current trends in product and simulation lifecycle management (PLM/SLM) in the industry. This paper suggests a design verification process centralized around a collaboration platform. The purpose of this paper aims at improving and formalizing the ITER RH design process together with the V&V process. The objective of the suggested process is to improve the cost efficiency and reliability of ITER RH systems.