Bringing mythical electrical power to MITICA
The installation of the High Voltage Deck inside the MITICA High Voltage hall, October 2017. © Consorzio RFX.
To heat up ITER’s plasma at 150 million ˚ C, roughly ten times the
temperature at the core of the sun, we will need powerful heating systems using
high-energy beams. By raising the
temperature of the hot gas we accelerate the speed of the two nuclei (deuterium
and tritium) to make them crush in order to trigger off a fusion reaction. The principle
is simple. In practice, however, this requires the fabrication and testing of new
equipment before manufacturing the components for ITER. For this reason a facility
has been set up at the premises of Consorzio RFX in Padua (Italy) to develop and
test a Neutral Beam Injector (NBI) prototype.
MITICA, which stands for Megavolt ITER Injector and Concept Advancement,
relies on the in-kind contributions of F4E, ITER Organization, the ITER
Domestic Agencies of India and Japan, plus Consorzio RFX. And just like its
acronym suggests, in this ITER facility there will be tests performed with “mythical”
levels of beam energy and electrical power.
and Siemens started working together 3 years ago in order to develop three
units that will be part of the power supplies for the Neutral Beam Injection
system. Each unit is made of: i) an electrically insulated box, so-called “High
Voltage Deck”, that hosts the power supplies for the ion source of the
injector, ii) a gas-insulated bushing, called “High Voltage Bushing Assembly”,
bringing the electrical power through the transmission line all the way to the
ion source. To reach the required high voltage insulation levels of 1 MV they
are using SF6, a potent greenhouse gas, as electric insulator.
Flexible electrical conductors ensure the mechanical
decoupling between the top of the Bushing and the High Voltage Deck. Copyright
The insulated box is distributed over two floors covering a surface of
150 m2. Think of it as a
Faraday cage that can maintain a level of voltage of 1 MV isolating the power
supplies of the ion source from the ground. Inside its shiny metallic shell
there are transformers, power distribution systems, converters and control
cubicles weighing approximately 50 T. The box rests on eight insulated
“columns” which are more than 6 m high above the floor. The installation of the
High Voltage Deck has now been completed. It has successfully passed the electrical
acceptance tests in a factory, and has concluded the mechanical, structural
and seismic tests at the MITICA facility.
Meanwhile there has been excellent progress on the bushing assembly, supplied
by Siemens and its subcontractor HSP GmbH, which is connecting the power
supplies of the ion source to the transmission line. The equipment has been
fully installed and all tests required have been properly completed. It is now
ready to be connected to the transmission line supplied by Japan and then to
proceed with the final tests of the entire system.
the High Voltage Bushing during electrical tests, HSP GmbH high voltage
facility, Germany. ©SIEMENS
“The bushing is a-first-of-a-kind
equipment which was not available on the market at the time of
procurement. We collaborated closely
with our industrial partners to manufacture it and worked out together the challenging
logistics for its installation at the MITICA facility. The bushing assembly has
a height of 12 m and weighs approximately 19 T. This European equipment will be
connected to the transmission line which has been designed and built by Japan.
This is the outcome of strong international collaboration which is in line with
the spirit of the ITER project” explains Muriel Simon, F4E’s Technical
Responsible Officer following the contract with Siemens.
Installing the High Voltage Bushing inside the pit
of the MITICA facility with the help of
a remote control rolling platform and several cranes. © F4E.
Michael Krohn, Project Manager of Siemens, explains that “the
involvement of our company in this project offered us the opportunity to bring
in our experience in global business together with our excellent technical
expertise delivering standard and customised solutions. Thanks to our
collaboration with F4E, we have become familiar with the ITER project and
fusion for energy.”
Tullio Bonicelli, Head of F4E’s Neutral Beam and Electron Cyclotron, Power
Supplies and Sources, highlights that “the successful delivery and installation
of these “beyond the state-of-art” components at the MITICA facility paves the way
for more tests that will be performed during the second half of the year after the
equipment is connected to the transmission line. The operation of such
extensive system at 1 MV is not only challenging but also unprecedented. The
fusion community will be looking at us for answers in order to take our next
step towards the fabrication of the ITER Neutral Beam components.”