Prior to the start of the present cycle 33 a longer maintenance interval of 45 days was completed, in which a number of works has been performed.
The company Kraftanlagen München built with the support of the operating crew of the FRM II in the primary cooling circuit an additional, second major non-return valve. In 2009, the main check valve did not fully close and had caused a reportable event. Therefore, the installation of an additional second check valve had already been planned back then. The installation of this more than 500 kg valve, which was associated with extensive preparations, extensive conversion work on the primary cooling circuit and various examinations could be completed in the maintenance break.

In addition, the previously only 2t carrying freight elevator was replaced by a new hydraulic lift with a lifting capacity of 10t in the reactor building. The higher capacity of the elevator is imperative in order to transport the radiation shielding for the targets of the future molybdenum-99 production. 700 special dowels had to be put in order to attach the new rails in the elevator shaft.

Another measure in preparation for the molybdenum-99 production line was the welding of additional pipes in the secondary cooling circuit for the connection of the future cooling cycle of the Mo-99 irradiation facility.

The compressor motor the cold source was equipped with a frequency converter to compensate for fluctuations and interpret brief failures in the external power supply.

The evaluation of the measurements for the C-14 charges for the first half of 2013 has shown that the very low annual limit for C-14 has been exhausted only to about 15%. Since during this period also the cleaning resins of the moderator cycle were dried, this value shows that the measures taken to reduce the C-14 charges are effective and an approach to the annual limit for 2013 is not expected. The 33 cycle will run until 21 September, then a short break until the 15th October is intended.