VTT plays an important role in developing maintenance for future fusion reactors
VTT Technical Research Centre of Finland's research results indicate that
joint planning of the reactor structure and remote maintenance system can
significantly improve the utilisation rates of future fusion power plants.
Designing a reactor with the simplest structure possible can reduce
maintenance periods, as well as building expenses and overhead costs. Since
1995, VTT Technical Research Centre of Finland has participated in two
international projects aimed at building a full-scale fusion reactor and
commercialising fusion as an energy source.
ITER and DEMO (DEMOnstration Power Plant) are international programmes
targeting the harnessing of fusion energy for energy production. VTT Technical
Research Centre of Finland plays an important role in both programmes by
developing remote handling systems for critical reactor parts.
ITER is an experimental nuclear fusion reactor currently being built to test
various technologies and materials for use in fusion reactors. If ITER proves
successful, the next step is DEMO – short for Demonstration Power Plant –
which will be the first prototype of a commercial fusion power plant.
Together with the European Fusion Development Agreement, EFDA, VTT Technical
Research Centre of Finland has studied how to apply the maintenance and
equipment designed during ITER, and avoid the problems encountered during the
programme, in a DEMO reactor.
The resulting concept plan provides for the planning of fusion reactor
maintenance alongside other structural design work at a sufficiently early
stage. Designing remote handling and reactor structure in parallel would
prevent major errors that hamper compatibility. This would mean fewer
alterations during the building process and minimised downtime in the finished
power plant, resulting in lower construction and overhead costs.
Several maintenance issues have been encountered during the ITER experiment.
Installation of service equipment and the required maintenance ports sizes
were not considered sufficiently in the original plans, for example, limiting
the opportunity for remote maintenance.
Because the objective of DEMO is to build a commercially viable reactor, the
maintenance requirements are significantly stricter than for ITER. Problems
discovered during ITER would mean extended downtime periods and considerable
additional costs if encountered in DEMO. The basic premise of DEMO design has
been to minimise maintenance periods through modular design and simple module
Fusion as a source of energy
Although a challenge, harnessing fusion for energy production is an attractive
option which would solve mankind's energy problems. A fusion reactor carries
no risk of a runaway reaction, and the production of fusion energy creates no
ITER's objective is to build a full-scale experimental reactor to demonstrate
the technical and scientific viability of fusion energy and achieve high
efficiency fusion. This project, initiated in the 1980s, is one of the world's
most ambitious scientific endeavours. In addition to the EU, there are six
other participants – Russia, Japan, China, India, South Korea and the United
An ITER reactor is currently under construction in Cadarache, France, due for
completion in 2020. VTT Technical Research Centre of Finland and the Tampere
University of Technology TUT, participate by developing the maintenance of the
most critical parts of the facility. In 2005, VTT Technical Research Centre of
Finland and Tampere University of Technology TUT established ROViR, an
international research centre located in Tampere, Finland, that hosts a
full-scale model of the fusion reactor base. On a global scale, VTT Technical
Research Centre of Finland is unique in its practical experience of the
functioning of fusion reactor maintenance equipment in the ITER reactor's
divertor area. A divertor is the bottom section of a reactor chamber, or
"sink", where the particles leaving the chamber are gathered.
Remote handling and virtual technologies are crucial in fusion reactor
maintenance because of radiation and limited space in the interior sections of
a reactor. These restrict accessibility and render remote handling the single
viable maintenance option. VTT Technical Research Centre of Finland's role in
designing and testing is crucial, as a failure in remote handling would lead
to extensive downtime.