Device for shielding the neutron flux of a nuclear reactor arranged in a reactor cavern

摘要

The annular space between the reactor pressure vessel and the concrete wall of the reactor cavern (2) is provided at the level of the reactor pressure vessel flange (13) with a rigid shielding structure. In order to compensate the thermal expansions which occur, a specific annular gap must remain free between the rigid shielding structure and the reactor pressure vessel. In order, in addition, to be able to shield this remaining annular gap (7) effectively, shielding segments (8) are provided which are displaceably arranged below the rigid shielding structure (4). Running rails (22) are mounted on the sheet-metal housing (10) by holders (21). Guided in these running rails are rollers (20) which are connected to the shielding segments via holders (19). The shielding segments are displaceable in the horizontal direction, and thus form a sealed shield when the reactor is operating. When the reactor is shut down, the shielding segments can be retracted for the purpose of in-service inspections on the outer surfaces of the reactor pressure vessel. IMAGE