BWR-HD: An Optimized Boiling Water Reactor with High Power Density

Increasing the economic competitiveness of nuclear energy is vital to its future. One way to reduce the cost of the plant is by extracting more power from the same volume. A scoping study is conducted to maximize the power density in boiling water reactors (BWRs) under the constraints of using fuel with traditional materials and cylindrical geometry, and enrichments below 5% to enable its licensability with no changes to present facilities. An optimization search over all other design parameters yields a BWR with high power density (BWR-HD) at a power level of 5000 MW(thermal), equivalent to a 26% uprated Advanced BWR (ABWR), the most recently built version of BWR. The BWR-HD utilizes about the same number of wider fuel assemblies, with 16 × 16 pin arrays and 35% shorter active fuel than the 10 × 10 assemblies of the ABWR. The fuel rod diameter and pitch are also reduced to just over 70% of the ABWR values. Thus, it is possible to increase the power density and specific power by 65% while maintaining the nominal ABWR minimum critical power ratio margin. The optimum core pressure is found to be the same as the current 7.2 MPa. The core exit quality is increased to 19% from the ABWR nominal exit quality of 15%. The pin linear heat generation rate is 20% lower, and the core pressure drop and mass of uranium are 30% lower. The BWR-HD’s fuel, modeled with FRAPCON 3.4, showed similar performance to the ABWR pin design. This results in 20% reduced operations and maintenance and capital costs per unit energy, but total fuel cycle cost similar to that of the 18-month ABWR fuel cycle.