Probably on one of the sunniest days of our IP-Programme so far, our group first assembled on the Marienplatz, enjoying the beautiful architecture in the centre of Munich. Afterwards we split in two groups, one that would visit the research reactor in Garching around lunch time and another which would head to Garching later in the afternoon.
After shifting away from the rest of the group, we really wanted to make the best of our free time, so we first strolled around the English Garden before making our way into the centre of Schwabing. There really was no way around the many Pinakotheken and after little time of contemplating about where we should go, we visited the Museum Brandhorst, where we enjoyed lots of wonderful works of art, the most prominent were maybe some works by Andy Warhol.
Afterwards, we comfortably sat down in one of Munich’s cozy cafés. Surprisingly, the café we randomly selected turned out to be a “cat coffee” which is a simple café where you are surrounded by numerous cats and are free to pat them as a customer. Some of us had heard of this café business model, but none of us had seen it in action, but every one of us loved it.
In the afternoon we went to the research reactor in Garching, near Munich. This is the second one in fact. The first one started operating in 1957. It was purchased from the United States. Within nine months the reactor was fully operative.
In 2000, the first research reactor was shut down. The second one began working in March 2004. While we were there, the reactor was not in operation, nevertheless experiments took place. Normally it has a 30-day-cycle with an active run of three weeks and a maintenance break of one week. Since the reactor is kind of a prototype, there is a big inspection necessary after ten years. By the way, normal power-reactors have this kind of an inspection yearly.
The core runs with highly enriched uranium with about 93% of U235. The reasons why this type of fissile material is used is simple: Highly enriched uranium allows it to build the reactor much more compact and to increase the output of Neutrons with less thermal losses. In other words: The reactor produces much more Neutrons in a smaller and easier way to cool the facility than a core with low enriched uranium could.
That is the purpose of the reactor. It‘s there to produce Neutrons. The heat it produces is a by-product. Also the reactor is no research facility for enhanced reactor technologies, it is only there to create Neutrons which are necessary for state-of-the-art fundamental research and to manufacture high-tech materials.
The neutrons are released during the nuclear fission in the core itself and are afterwards led to the experiments by neutron-conductors. These conductors use the physical effect of so called „total-reflection“, comparable with what happens in fibreglass-optics used for data-connections.
Depending on in which distance to the actual fission in the core the neutrons are led out, they have different energies. The energy the neutrons have is measured in eV (ElectronVolts), beginning with so called „UltraCold“ Neutrons with about less than 0,002 eV (Speed about 700km/h) up to „Hot“ neutrons with up to 14 MeV (14000000 eV) (nearly the speed of light)are produced and led to the experiments.
Maybe interesting to mention is the medical use of neutrons for cancer therapy. This rather new approach to tread cancer uses Neutrons instead of radiation to destroy the cancer cells, which causes less damage to the surrounding tissue.