The concept of TRIGA reactors was developed in early 50's. This reactor is not designed to produce energy (like nuclear power plant) but to produce neutrons. For this reason it is small in size (cylinder, 40cmx40cm) and in power (250kW). It is cooled by water at normal pressure and room temperature. It is inherently safe: no operator mistake or equipment failure can result in fuel damage. Even if the fuel was damaged (e.g. cladding rupture) only a small fraction (10-5 or one thousandth of a percent) of radioactive products would escape due to special, highly resistant fuel material (zirconium hydride).
There have been more than 40 TRIGA reactors operating all over the world for 40 years without a single reactor accident. Reactors like ours are normally built as part of university laboratories in the campuses. Even in Austria, where perception of nuclear energy is highly critical, a twin reactor to ours is located in the middle of Vienna, in Prater.
Before we answer, we should ask ourselves:
"Do you know any country that has a nuclear power station but no research reactor?"

However, to make an appropriate well founded answer we have to compare costs and benefits.


The reactor is not a big economic burden to the country, as until now we succeeded to cover all major investments by the help of foreign sponsors. Construction costs were mainly covered by the IAEA technical assistance funds. Fuel elements are donation (free of charge) of the German Government. Spent fuel shipment and disposal in USA was paid by the US Government. Actual costs include only maintenance, material costs (including electricity, water, physical protection, etc) and cost of work.

Yearly budget of the TRIGA reactor is approximately equal to the price of electricity produced in Krško NPP in one day.


General meaning:

The reactor has played important role in developing nuclear technology and safety culture in Slovenia It has been one of a few centres of modern technology in the country. Its international cooperation and reputation is important for promotion of J. Stefan Institute, Slovenian science and Slovenia in the world.


  • Practically all nuclear professionals in Slovenia started their career or attended practical training courses at TRIGA reactor (including all professors of nuclear engineering and reactor physics at Ljubljana and Maribor University, as well as directors and key personnel of Krsko NPP, Slovenian Nuclear Safety Administration and Agency for Radioactive Waste).
  • All reactor operators and other technical staff in Krsko NPP pass training courses on TRIGA reactor.
  • The reactor is used in regular laboratory exercises for graduate and post graduate students of physics and nuclear engineering at Faculty of Mathematics and Physics, Ljubljana University.
  • On-the-job training for IAEA trainees from developing counties (in average 2 per year). Reactor has been used in several international training courses.
  • Reactor is open to the visitors, more than 200 per year, mainly schools.


  • Reactor has been used in research work published in approx. 300 scientific (SCI) papers and more than 600 published conference reports.
  • More than 20 Ph. D. research works, more than 30 M. Sc. degree works and more than 100 Diploma works have been performed using the reactor.

Isotope production:

  • Total number of patients treated with radio-isotopes produced in the reactor is more than 50.000 (mainly radioactive technetium).
  • 10-20 industrial sealed sources per year (mainly cobalt), in total several hundred.
  • Several special radioactive sources (e.g. radioactive sodium in soluble compound for turbine testing in Krsko NPP).
  • dopiranje polprevodnikov.

Posredni učinki:

Vzdrževanje tehnološkega nivoja pri obratovanju reaktorja že od vsega začetka spodbuja uvajanje najnovejših tehnoloških dosežkov, ki se kasneje široko uveljavijo:

  • za potrebe reaktorskih preračunov smo na IJS že v šestdesetih letih nabavili prvi elektronski računalnik (ZUSE), s čemer se je začel tudi razvoj računalništva
  • na reaktorju smo med prvimi uporabili mikroprocesorje za vodenje procesov
  • že v začetku sedemdesetih let smo uvedli računalniško zajemanje podatkov in nadzor nad eksperimenti
  • na Odseku za reaktorsko fiziko (F8) so za potrebe preračunov reaktorja TRIGA nabavili prvi zmogljiv osebni računalnik na IJS (IBM PC XT)