The research reactor TRIGA Mark II in Mainz with pulse operation mode

The feature of the TRIGA reactors are their special fuel elements, being a combination of fuel and zirconium hydride as moderator, providing a prompt negative temperature coefficient and therefore a very high level of security. On the basis of this fact, the TRIGA reactors are the most used research reactors in the world. The TRIGA research reactor Mainz (FR MZ) exclusively utilizes uranium with a degree of enrichment below 20%,
so-called non-weapon grade uranium.

The TRIGA reactor in Mainz can be operated continuously at a maximum power of 100 kWtherm. Furthermore, a pulse operation mode allows inserting an excess reactivity for a short time interval. For a period of 30 ms the reactor reaches a peak power of 250 MW and an energy release of about 10 MWs.

With its entire shielding, the TRIGA Mark II reactor is erected above ground. Four horizontal beam tubes and a thermal column penetrate the concrete shielding, reaching the reflector and the core, respectively. The thermal column is closed by a mobile concrete shielding.

At the FR MZ a rotary specimen rack at the upper part of the graphite reflector allows to simultaneously irradiate up to 80 samples at 40 positions. The central experimental tube provides the maximal flux density for thermal and fast neutrons. Additionally, with a pneumatic transport system samples can be inserted into and unloaded from the reactor core within a few seconds, without disturbing the reactor operation.

Currently two cold sources are available for experiments with ultra-cold neutrons (UCN) at the FR MZ. They are provided for several weeks of two-shift operation in the framework of a UCN-user facility.

Licensee of the FR MZ: the president of the Johannes Gutenberg University Mainz,
Prof. Dr, G. Krausch