System message

The VR-2 reactor is a new nuclear facility built at the Faculty of Nuclear Sciences and Physical Engineering, CTU in Prague. This is a subcritical assembly controlled by a neutron generator. It is based on the pool arrangement of the reactor vessel, in which there is also an internal installation with fuel rods forming the reactor core. The moderator is demineralized water. The VR-2 subcritical reactor project is completely managed by the Faculty of Nuclear Physical Engineering, CTU in Prague, ie it prepares documentation for the national regulatory body and prepares technical documentation for the supply and production of reactor components. Several departments from other CTU faculties in Prague also play an important role here, providing invaluable feedback within their specialties. Individual components are gradually supplied based on tenders to a wide range of domestic companies.

VR 2 kompletni sestava

Project schedule

  • 2014 - start of the project
  • 2018 - fuel transport
  • 2020 - obtained permission to locate a nuclear facility
  • 2022 - construction permit
  • End of 2022 - commissioning


Description of the device

The fuel stored in the internal installation (basket) will be placed in the reactor vessel or in the storage vessel. The storage vessel will be located near the reactor vessel. There will be several baskets in the reactor inventory, which will vary in type and grid spacing.

The actual reactor vessel will have a cylindrical shape with a flat bottom, it will be made of stainless-steel class AISI 316L with a wall thickness of 8 mm and a bottom of 10 mm. The diameter of the container will be 1,300 mm and the height 1,710 mm. The vessel will be provided with two symmetrical holes with a diameter of 128 mm for the installation of radial channels. The radial channels with a diameter of 128 mm will be made of aluminum. One radial channel will be permanently part of the reactor vessel and will serve to house a neutron source to control the reactor. The second radial channel will be experimental and will be installed according to current experimental needs. The channels will be secured in the reactor vessel using a flange joint.

The core will contain a combination of enriched and natural uranium fuel in the form of fuel rods. In the case of enriched fuel, it is UO2 with 10% enrichment of 235U, natural uranium is in the form of uranium metal. The moderator will be light water. The core configuration will be subcritical under any conditions, so an external neutron source will be required to maintain the fission reaction. The external neutron source will be provided by a neutron generator type D-D. It is an electronic device that can be turned off very easily. If it is switched off, the fission in the reactor core also stops. The neutron generator also allows you to change the parameters of neutron generation, such as increasing or decreasing neutron emissions or operating in a continuous, resp. pulse mode.

 VR 2 zamestnanec ležérní

Key components

  • 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 - fuel will be placed inside the reactor vessel during operation. Supplied by the Witkowitz - VÍTKOVICE group ENERGETICKÉ STROJÍRENSTVÍ a.s.
  • Storage container - used to store and dry the inner fuel basket. Supplied by the Witkowitz - VÍTKOVICE group ENERGETICKÉ STROJÍRENSTVÍ a.s.
  • Water management storage tank - used to store demineralized water outside the reactor vessel. Supplied by BeHo spol. s r.o.
  • Radiation monitoring system - supplied by VF a.s.
  • Fuel - brought with Finland from Aalto University.
  • Demineralization station - used to produce demineralized water. The delivery company Watek s.r.o
  • Heating and cooling technology - used to adjust the temperature of demineralized water, the supplier is not yet competed.


The VR-2 subcritical reactor will be a very flexible facility that will offer a range of experimental and training opportunities. The main part of the activities will consist of teaching nuclear engineering students. The equipment will be used in the teaching of laboratory tasks. It will also be used for experiments in student bachelor's, master's and doctoral theses. In addition to teaching activities, it will also be used to carry out research experiments. Thanks to the detachable construction of the internal installation, it will be possible to easily change the type of grille (square vs. triangular) and its spacing (optimal moderation vs. undermoderated and remodeled layout). Sophisticated water management will allow the reactor to increase (up to 50 ° C) or decrease (up to 4 ° C) the temperature of the moderator and its level. Selected vertical channels, resp. experimental radial channels offer space for the installation of other experimental equipment, such as neutron detectors, other neutron sources (AmBe, Cf-252 or D-T generator) or a reactivity oscillator.



The project for the construction of a new school reactor was financed mainly from the Operational Program Research, Development and Education of the Ministry of Education, Youth and Sports - Modernization of the 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 8 million crowns, of which 6.6 million were covered by the above project.