Construction of the Mo-99 irradiation facility

Schematic drawing of the future molybdenum-99 irradiation facility within the reactor pool. In the thimble, the cooling unit is composed of 2 cooling water supplies and 2 irradiation channels (returning cooling water) (Drawing: P. Jüttner, FRM II).

Following the decision to install a Mo-99 irradiation facility in the moderator tank of the FRM II, in February 2011, the thimble for future Mo-99 production was successfully mounted. The thimble is made of the durable and irradiation-resistant reactor material Zircaloy 4. With a diameter of nine centimeters and a length of five meters, in future it will include 2 independently loadable, identical irradiation channels and enable the simultaneous irradiation of 2 x 8 so-called plate targets. The targets are positioned at a distance of about 45 cm from the fuel element, and thus close to the thermal neutron flux maximum. Each target contains 20 g of low-enriched Uranium (19.75 % enrichment of U-235).

In 2013, a 10 tons freight elevator was installed to transport the irradiated targets within the reactor building. Currently, loading, unloading and cooling of the targets are tested in a 1:1 scale mock-up.

The manufacturing and installation as well as the commissioning of the future Mo-99 irradiation facility are planned for 2018. The total cost for the construction of the Mo-99 facility amounts to approximately € 5.4 million. Additionally, the necessary research and development activities for the optimization of Mo-99 irradiation are supported by the Federal Ministry of Health through a € 1.0 million contribution.