The Mainz research reactor TRIGA Mark II with pulse device
The special feature of the TRIGA reactors are the fuel assemblies, which, by bringing the fuel together with the moderator in the form of zirconium hydride, ensure a prompt negative temperature coefficient of reactivity, thus guaranteeing a very high level of safety. Due to this feature, TRIGA reactors are the most widely used research reactors in the world. The TRIGA Mainz research reactor uses only uranium with an enrichment level of less than 20%, so-called non-weapons-grade uranium.
The Mainz TRIGA reactor can be operated continuously with a maximum output of 100 kWtherm. In addition, a pulse device allows the additional introduction of excess reactivity in a short time interval, whereby the reactor achieves a peak power of 250 MW and an energy release of 10 MWs for 30 ms.
The TRIGA Mark II reactor is built above ground with the entire shielding structure. Four horizontal radiant tubes and a thermal column penetrate the concrete shield and reach up to the reflector or reactor core. The thermal column is closed off by a mobile concrete radiation protection gate.
A rotating irradiation carousel in the upper part of the graphite reflector allows the irradiation of up to 80 samples in 40 positions. In the central irradiation tube, samples can be irradiated at maximum thermal and fast neutron flux. Furthermore, there are three pneumatic tube systems with which samples can be introduced into or removed from the reactor core in a few seconds without interrupting reactor operation.
Currently, two sources for experiments with ultracold neutrons (UCN) are available at the TRIGA-Mainz research reactor, which are available in multi-shift operation as part of a "user facility".
As part of the safety analyses of all nuclear facilities in Germany following the Fukushima accident, the TRIGA research reactor in Mainz was also examined. An expert opinion by the TÜV (in german only) has shown that even in the covering accident scenario (plane crash with kerosene fire with simultaneous complete destruction of the reactor core), the possible effects on the environment of the reactor are so low due to the low nuclear inventory that no evacuation measures or disaster control measures are to be expected according to current radiation protection guidelines.
Licence holder of the FR MZ: the President of Johannes Gutenberg University Mainz,
Prof. Dr. G. Krausch