Very High Temperature Reactor - Overview

Overview

The VHTR is a type of high temperature reactor that conceptually can reach higher outlet temperatures (up to 1000°C); however, in practice the term "VHTR" is usually thought of as a gas-cooled reactor, and commonly used interchangeably with "HTGR" (high temperature gas-cooled reactor).

There are two main types of HTGRs: pebble bed reactors (PBR) and prismatic block reactors (PMR). The prismatic block reactor refers to a prismatic block core configuration, in which hexagonal graphite blocks are stacked to fit in a cylindrical pressure vessel. The pebble bed reactor (PBR) design consists of fuel in the form of pebbles, stacked together in a cylindrical pressure vessel, like a gum-ball machine. Both reactors may have the fuel stacked in an annulus region with a graphite center spire, depending on the design and desired reactor power.

The Russian VHTR is also a HTGR.