Pebble bed reactor core supported on graphite block structure - with hollow columns below discharging hot gas through numerous ducts

摘要

A support structure for the core of a gas-cooled, high-temp. reactor housed in a cylindrical pressure vessel vault, esp. a pebble bed reactor, consists of a bed of graphite blocks arranged in stacks, each supported on a circular column, the stacks of blocks are linked together to form a solid base for the pebble bed, while the support columns stand separate from one another in an open space beneath the core support structure. This open space serves as the hot gas header chamber leading to the gas discharge ducts. The graphite blocks of the core support structure contain a large number of ducts for hot gas flowing down from the core; each column is a hollow cylindrical column, the central duct of which receives the gas descending through the adjacent blocks from the core and discharges the gas through a large number of radial ducts uniformly distributed in different vertical planes. Due to the large number of outlets for the gas from the hollow support columns, thorough mixing of the hot gas within the header chamber takes place, partic. the hotter gas from the central region of the core with the cooler gas from the outer regions. In this way the gas is thoroughly mixed before it reaches the outlet ducts from the vessel.