Feasibility of lead cooled breed and burn reactors

The objective of the present work is to assess the feasibility and achievable performance of a large Breed-and-Burn (B&B) reactor core that is cooled with heavy-liquid-metal (HLM), such as lead or lead-bismuth eutectic (LBE), relative to a sodium-cooled B&B core. With the exception for the initial critical fissile fuel loading the B&B reactor systems are to be fuelled only with fertile material. When the fuel reaches its radiation damage limit it is reconditioned and recycled without separating the actinides from most of the fission products.It was found that in order to get a total power of 3000 MWth as of the reference sodium-cooled B&B core, core pitch to diameter ratio needs to be increased from the 1.112 value of the reference sodium-cooled core to 1.3 for Pb and LBE coolants and to 1.24 for PbLi coolant. As a consequence, the minimum burnup required to sustain the B&B mode of operation is approximately 29% FIMA for the LBE and PbLi cooled cores – larger than the 21% FIMA required for the reference sodium cooled B&B reactor. Had the Pb been enriched to nearly 100% 208Pb, the minimum required burnup would be 22.5%; less than 10% higher than for Na-cooled core. The maximum possible accumulated burnup in the LBE-cooled B&B core is ∼45% FIMA – smaller than the 55% FIMA possible to achieve in the reference sodium cooled core. For the same core volume HLM-cooled cores require 26% smaller mass of fissile material to establish initial criticality.

► The feasibility of cooling a breed and burn reactor with LBE, Pb or PbLi is studied.
► Both the thermal-hydraulics and neutronics feasibility are discussed.
► Same core power level as with sodium can be achieved by reducing the P/D ratio.
► The minimum required burnup is 29% FIMA with LBE and PbLi.
► The minimum required burnup is 22.5% FIMA with 208Pb.