At the beginning of November, the State Office for Nuclear Safety (SÚJB) issued a permit for the location of the VR-2 subcritical reactor to the Faculty of Nuclear Sciences and Physical Engineering of the Czech Technical University in Prague (FNSPE). Preparations are proceeding according to schedule, and the new reactor should be launched in 2022.

FJFI KJR VR2 01"With our existing VR-1 Vrabec reactor, we are already facing capacity limits, because the interest in both educational and research activities is great. That was the main reason why years ago, we started thinking about the idea of building a second reactor, "explains Jan Rataj, head of the FNSPE department of nuclear reactors.

The VR-2 reactor is classified as a subcritical reactor. It is therefore a specific nuclear research facility that needs an external source of neutrons to sustain the fission chain reaction. To shut it down, all you have to do is turn off this neutron source. The fission chain reaction alone is not sustainable in itself. Thanks to this, the construction of the reactor is very simple: it consists of a cylindrical vessel about 1.7 meters high with a volume of about 2,200 liters. Inside the container there is a removable installation with a grid for placing fuel rods. Fuel rods, both enriched and natural, can have different configurations depending on the type of the grid. Light water will be used to moderate the neutrons. Water and concrete provide radiation shielding. The new reactor will be located in the reactor hall, where the faculty now operates the VR-1 school reactor.

The faculty received nuclear fuel as a gift from Aalto University in Finland, where it was part of a subcritical reactor in the 1970s. The Faculty participated in the transport of fuel to the Czech Republic in close cooperation with Alta Group, and the containers for transport were lent by ČEZ Group. The fuel part consists of a dispersion of UO2 with magnesium in an aluminum coating. Rods with 10% 235U enrichment or rods with natural uranium (0.72% 235U) are available.

The design of the reactor is based on inherent safety, which prevents the development of an uncontrolled fission chain reaction. The radiation situation in the vicinity of the facility is favorably affected by the minimum power of the reactor and thus allows the movement of students in the immediate vicinity.

Project schedule:

2019-20 - placement
2021-22 - construction
2022 - start
2023 - start of operation

FJFI KJR VR2 02In the Czech Republic, there are six power reactors in two power plants and three research reactors in two other locations: two in Řež research facility near Prague and one belonging to CTU in Troja, Prague. "Our university is one of the few in the world to have its own fission and fusion reactor. In just three years, we will even have two fission reactors, which will increase our potential for educating key nuclear experts, "says the dean of the faculty, prof. Igor Jex.

The first school reactor VR-1 Vrabec is celebrating 30 years since reaching the so-called critical state this year - on 3 December, 2020 at 16.25. There are now around 450 fission energy reactors worldwide and additionally almost 250 research ones.

The Department of Nuclear Reactors of the FNSPE uses the VR-1 Vrabec reactor for both teaching and research. In addition to their own students, students from other universities also go to Troja, as well as employees of various companies or organizations from the Czech Republic and abroad. For example, firefighters are regularly trained here, and a nuclear submarine crew also trained at the reactor. "Nuclear power plant operators from aboread can test the behavior of the reactor here and re-examine the rules of reactor physics experimentally," describes the contribution of Ondřej Novák from the Department of Nuclear Reactors of the FNSPE. This year, the VR-1 reactor became part of an international network of reactors, which, in cooperation with the International Atomic Energy Agency, were equipped with the Internet Reactor Laboratory system for distance learning.

Detailed information about the school nuclear reactor can also be found at the National Technical Museum (NTM) in Prague, where until 28 February 2021, an exhibition is being held to mark the 30th anniversary of operation.

Additional information

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