01 Feb An Extended Arm in the Water

The team responsible for decommissioning research reactor DR 3 must not only focus on dismantling the reactor block itself but also manage all elements that were part of the experiments. In this context, a pool plays a crucial role.

NSome of the employees have recently been engaged in emptying two storage blocks – one situated directly next to the reactor block and another in an adjacent hall – of pipes. This involves approximately 200 pipes that were utilized in various capacities while the reactor was operational.

Forty of the tubes are the so-called Flux Scan Absorbers. They were placed inside the fuel element tubes to regulate fission, and therefore must be handled with particular care.

The team has meticulously removed the 'absorbers' themselves (thin steel rods that have absorbed neutrons) from the aluminum tubes that encased them. The steel rods were then transferred to a large basin, where they are now being cut into smaller pieces one by one. This nearly 5-meter-deep basin has historically been used for both storage and treatment of irradiated elements, as water provides radiation shielding.

A remote-controlled heavy-duty shear is positioned at the bottom of the basin. A research technician slowly lowers the cord with the steel rod using one hand, while operating the heavy-duty shear with the other. Slowly but surely, the steel rod is transformed into a pile of 15 cm long fragments.

Subsequently, the research technician grasps a long rod equipped with mechanical grippers at its end. Using this extended arm, he now retrieves each fragment from the basin's bottom and lifts it through the water into a metal basket. Once all 40 absorbers are fragmented within the basket, the basket is lifted using a lead-lined transport container and, after draining, transferred to a shielded container.

To minimize radiation risk, a health assistant continuously monitors all work processes.