"Preparations for the construction of our second reactor have been underway since 2014. This year, we are already in the final stages, having received the permit for the construction of the VR-2 nuclear reactor from the State Office for Nuclear Safety (SÚJB) at the end of March. However, in the meantime, we have been preparing everything necessary to build the reactor as quickly as possible," explains Jan Rataj, Head of the Department of Nuclear Reactors at FJFI. "We are now assembling the reactor vessel and will subsequently retrofit it with all the necessary elements so that we can thoroughly test the entire assembly and will put the reactor into operation later this year. Everything is going exactly as planned," adds Jan Rataj.
Key components of the VR-2 reactor
- Control and management system - used to control and manage the VR-2 reactor technology. Supplied by ŠKODA JS a.s. in cooperation with dataPartner s.r.o.
- Reactor vessel and radial channels - the fuel will be placed inside the reactor vessel during operation. Supplied by Witkowitz Group - VÍTKOVICE ENERGETICÉ STROJÍRENSTVÍ a.s.
- Storage vessel - used for storage and drying of the internal fuel basket. Supplied by Witkowitz Group - VÍTKOVICE ENERGETIC ENGINEERING a.s.
- Water management storage tank - used to store demineralised water outside the reactor vessel. Supplied by BeHo spol. s r.o.
- Radiation monitoring system - supplied by VF a.s.
- Fuel - brought from Aalto University, Finland.
- Demineralisation station - used to produce demineralised water. Supplied by Watek s.r.o.
- Heating and cooling technology - used to adjust the temperature of demineralised water, supplier not yet tendered.
The Witkowitz Group manufactured the reactor vessel as well as the storage vessel for FJFI. "We are pleased to be able to participate in the construction of a new nuclear reactor that will help educate professionals for the nuclear industry. It is inspiring for the Witkowttz Group to be able to work with such an important academic institution as the FJFI. The cooperation of experts from research, development and practice is very important," says Milan Mercl, Director of VES of the Witkowitz Group. VES has recently become a member of the alliance of Czech technology suppliers for nuclear sources - CPIA.
"The Czech Republic has an extraordinary competitive advantage in the field of nuclear energy. The Witkowitz Group is aware of the importance of maintaining it. That is why we have been working on the development of the David modular nuclear reactor for a long time," adds Martin Groch, Project Director of the David SMR and Vice-Chairman of the Board of Witkowitz Atomica.
A subcritical reactor needs an external neutron source to function
The new VR-2 reactor is a subcritical reactor that does not have enough fuel to sustain a fission chain reaction. It needs an external source of neutrons to keep the fission reaction going. The reactor is based on a pool reactor vessel design, which also contains an internal fuel rod assembly that forms the core. The moderator is demineralised water.
The reactor vessel itself is cylindrical with a flat bottom. It is made of AISI 316L grade stainless steel with a wall thickness of 8 mm and a bottom thickness of 10 mm. The vessel will have a diameter of 1 300 mm and a height of 1 710 mm. The vessel has two symmetrical holes with a diameter of 128 mm for the installation of radial channels made of aluminium. One radial channel will be a permanent part of the reactor vessel and will be used to house the neutron source for the reactor control. The other radial channel will be experimental and will be installed according to the actual experimental needs. The channels will be mounted in the reactor vessel using a flanged joint.
The active zone will contain a combination of enriched and natural uranium fuel in the form of fuel rods. The enriched fuel is UO2 with 10% of 235U enrichment, while the natural uranium is in the form of uranium metal. The moderator will be light water. The core configuration will be subcritical under all conditions, so an external neutron source will be required to sustain the fission reaction. The external neutron source will be provided by a D-D type neutron generator, an electronic device that can be easily shut down immediately. When switched off, fission in the reactor core will stop immediately. The neutron generator also allows the neutron generation parameters to be changed, e.g. to increase or decrease the neutron emission or to operate in continuous or pulsed mode.
This type of reactor is relatively small and can easily fit into the existing reactor hall where the school's VR-1 Sparrow reactor is already located. "Thanks to the possibility of using the existing infrastructure, we could afford to build a second reactor at all. Otherwise, the investment would have been many times higher," adds Jan Rataj.
For educational and experimental use
The VR-2 subcritical reactor will be a very flexible facility that the faculty will use primarily for teaching, but also for some experiments. The main part of the activities will be teaching of nuclear engineering students. The equipment will be used for teaching laboratory tasks. It will also be used for experiments in the framework of students' bachelor, master and doctoral theses. Apart from teaching activities, it will also be used for research experiments. "The teaching and experimental requirements of the existing reactor have been at the edge of capacity for several years. With the second reactor we can better distribute activities and we are ready for a larger number of students - not only ours, but also from foreign universities or various training and practice for employees of other institutions and companies. We also have a lot of high school students and other interested people coming to us, and finding a free date for their visit was sometimes not easy. With the new reactor our possibilities are much better," explains Ondřej Novák from KJR.
The project for the construction of the new school reactor was mainly financed by the Operational Programme Research, Development and Education of the Ministry of Education and Science - Modernization of Large Research Infrastructure VR-1 - School Reactor for Research Activities CZ.02.1.01/0.0/18_046/0015833. Excluding the cost of fuel and the time of the Department's staff, the cost of construction can be estimated at approximately eight million crowns, of which 6.6 million was covered by the above project.
Further information about the FJFI reactors, study programmes and scientific activities can be found on the website of the Department of Nuclear Reactors.