Today the Hungarian Atomic Energy Authority issued a manufacturing license for the core catchers of Units 5 and 6 of the Paks Nuclear Power Plant. The core catcher is one of the many new technical solutions for the improved third generation VVER-1200 units, which will increase safety, and is a special container located under the reactor pressure vessel, capable of containing the corium in case of damage.
This long lead item will be installed at an early stage of the implementation, thus this recently acquired license is another major milestone in the successful progress of the project.
The core catcher is used to contain the corium in the event of core meltdown of the reactor’s active zone. It can be used to prevent the corium from interacting with the concrete of the baseplate, reduce hydrogen evolution reaction and reduce the release of radioactive materials into the environment. The total weight of the core catcher elements is 732,7 tons, the total height is 15,24 metres, and the largest element, with a diameter of 11 metres, is the support ring.
The core catcher contains filler blocks containing alumina and iron oxide, which, when mixed with the corium, reduces the specific heat of the corium. Gadolinium is also added to the filler blocks to prevent nuclear chain reactions in the corium due to its neutron absorbing properties. The steel vessel of the core catcher can be cooled from the outside with boron water in the event of a severe accident.