Thermal hydraulics of the fixed bed nuclear reactor concept

The thermo-hydraulics of the fixed bed nuclear reactor (FBNR), possessing spherical HTGR type fuel, is described. Its main characteristic is the variable fixed bed core in suspense and its “cold” fuel in case of a LOCA (< 400°C). A 40 MWel reactor has a pressure loss across the fixed bed of 9.5 bar and needs a pump power of 3.4 MWel – more than in a classical PWR but being the price for its excellent inherent safety characteristics.