Splitting up an atomic reactor
The AVR Jülich atomic power station operated for 22 years, from 1966 until 1988. The decommissioning of the German plant, which had an output of 13 MW, has proved difficult, time-consuming and expensive. A technical addition, a so-called material transfer lock, had to be constructed first, before the decisive phase of decommissioning the plant could finally begin.
On 11 November, after extensive preparations, experts started lifting out the pressure container of the atomic power plant called the Arbeitsgemeinschaft Versuchsreaktor Jülich (working group for a test reactor in Jülich). For this unique project the reactor container vessel (weighing about 2,100 t and 26 m high and 7.6 m wide) had to be lifted into the protective environment of a so-called material transfer lock, using four special lifting devices (so-called strand jacks). They were lifted the vessel from its former position in the reactor building, moved it and then placed it exactly in a storage rack.
A special annular structure will be welded onto the lower part of the container over the next few months, the lower lifting tackle. A further three turning strand jacks will be fastened to this which, together with the lifting strand jacks, will then be used to lift the reactor vessel and swing it into a horizontal position. Following this, it will be placed in a horizontal position onto the transportation and storage frame.
After the cranes an SPMT will be used
The highlight of the operation next year will be moving the vessel to an intermediate storage site about 600 m away. Before this can be done, however, the container must first be pivoted and then, after further preparations, placed on its transportation and storage frame. Only then can the frame and vessel be transported as a unit to the intermediate storage site, using SPMT modules.
Each of these SPMT units can handle a weight of 180 t. A total of 15 modules will be combined and used to transport the reactor pressure vessel. Their simple handling and bearing capacity, as well as their exceptional manoeuvrability, mean that these modules are ideal for use as transport equipment for delicate tasks such as this one. Their use reduces the time the journey will take to just four hours, whereas the lifting and alignment process will take many days of concentrated work.