Conceptual Design of a (Pu,U)O2Core with a Tight Fuel Rod Lattice for an Advanced Pressurized Light Water Reactor

The work performed at the Karlsruhe Nuclear Center for the neutron physics and thermohydraulic design of an advanced pressurized water reactor is described. Investigations have been restricted to the uranium/plutonium fuel cycle and to light water as coolant/moderator. The idea is to replace the core of a Kraftwerk Union 1300-MW(electric) pressurized water reactor (PWR) with a high-converting core with only minor changes in the internals of the reactor pressure vessel. Two reference designs are presented, a homogeneous one and a heterogeneous (seed and blanket) one, which satisfy the requirement of having a negative reactivity coefficient in case of complete water loss from the core region. With the assumed plutonium vector (PWR discharge and 10-yr ex-core time), the conversion ratios for the homogeneous and the heterogeneous reactor are 0.90 and 0.96, respectively. The net electrical plant output is only marginally lower than that of the PWR (1 to 2%). The target discharge burnup of 50000 MWd/ton can be achieved by increasing the number of fuel element cycles to more than three.