were so highly activated by neutron radiation during the operation that a manual dismantling, as it is realized for other components, is impossible.
Either these components have to be cut remotely and packed behind shieldings (concrete, steal or water) under video monitoring or they have to stay uncut and shielded in decay storage until the radiation will have decayed as far as it will be possible to cut the components under easier conditions. Depending on the activation, the decay storage can take decades.
In the EWN GmbH both is being realized or in preparation. The reactor components (core basket, protecting tube unit, reactor cavity with core bottom) of the reactors 1 and 2 as well as the annular water tanks of the reactors 1 and 4 are being dismantled remotely. The reactor pressure vessels 1, 2 and 5 as well as the reactor components of the reactors 3, 4 and 5 have been taken uncut into the ISN for decay storage and will be manually cut later.
There are two cutting places for the remote dismantling of the components from the reactors 1 and 2. The highly activated components (core basket, lower parts of the reactor cavity and protecting tube unit) are cut under water on a wet cutting place. The less activated parts (upper parts of the reactor cavity and protecting tube unit) are cut on a dry cutting place. There are applied thermal cutting methods (plasma cutting, contact arc metal cutting) as well as mechanical cutting methods (e.g. by band saws). The facilities are equipped with different kinds of manipulators to carry the tools and to pack up the cut components. For remote monitoring radiation resistant video technique is used.
The components of the reactors 1 and 2 were cut on wet and dry cutting places inside unit 1. In July 2007 the reactor cavity of unit 2 was cut as the last component. All components of the reactor 5 were taken uncut to the ISN for decay storage. The disposal of the reactor pressure vessels of the units 1 and 2 was completed in November 2007. The cutting of the annular water tanks will follow after the reactor pressure vessels are removed.