Budapest Research Reactor
The Budapest Research Reactor is one of the leading research infrastructures in Hungary and in Central-Europe. The basic scientific activity at BRR is the use of neutron beam lines for neutron scattering investigations. We have more than 50 years of tradition in this field. BRR is a VVR-type (water-cooled, water-moderated reactor) Soviet designed and built reactor: it went critical on March 25, 1959. Originally, the reactor power was 2 MW, but it was upgraded to 5 MW in 1967. A second full-scale reactor refurbishment was started in 1986, fully designed and performed by Hungarian companies. The project was supported by the International Atomic Energy Agency (IAEA) and the European Union. The reconstruction was completed by the end of 1990, but due to the political changes in the country, the license for reactor start-up was issued only in 1992. The reactor has been operated by the Centre for Energy Research (CER – one of the research centres of the Hungarian Academy of Sciences). In 1992, a consortium, named Budapest Neutron Centre (BNC), was formed as an association of the neutron-research based laboratories on the KFKI campus site.
KFKI Campus (reactor building is in middle)
BRR is a tank type reactor, moderated and cooled by light water. Until 2009 the reactor was fuelled with Russian type VVR-SM fuel with 36%, uranium enrichment and later due to the program of the core conversion, 20% enriched VVR-M2 type will be used. The core is surrounded by a solid beryllium reflector. The main technical data of the reactor are: thermal power 10 MW; mean power density: 39.7 kW/litre; approx. maximal thermal flux: 2.1 × 1014 n/cm2s, maximum cooling water outlet temperature: 60oC.
The reactor cycle is about 10 effective days, which is followed by a short break for a weekend. The Budapest Research Reactor is known for its reliable operation. About a 160 operational days per year are foreseen for the next years. However, the timetable is flexible accommodating the various requirements of the instrument developments.
Following the commitment to join the Russian Research Reactor Fuel Return (RRRFR) programme, BRR was prepared to change from HEU to LEU. The preparation for the core conversion has been running since 2007. The selected type of LEU was the Russian made VVR-M2 fuel: the geometric and thermo-hydraulic parameters are identical, whilst its nuclear features are similar to the previously used VVR-M and -M2 HEU fuel elements. In this way the core conversion scenario was including HEU and LEU fuels with gradually decreasing HEU fuel assembly numbers. During the core conversion 4 cycles with mixed HEU-LEU cores took place (over 8 months), then the utilisation of HEU fuel was finished in 2012 and since then only 20% enriched fuel has been used. According to neutronic calculations no more than a 10% loss in neutron flux is expected due to the core conversion.