Core design options of an ultra‐long‐cycle sodium cooled reactor with effective use of PWR spent fuel for sustainable energy supply

Summary In this work, 350MWe ultra‐long‐cycle sodium‐cooled reactor cores are designed to supply electric energy over ~60 Effective Full Power Years (EFPYs) without refueling and with an effective use of Transuranics (TRU) and uranium from large pressurized water reactor (PWR) spent fuel stocks. The core employs the axial blanket‐driver‐blanket (ABDB) burning strategy, which was recently proposed by the authors to achieve an ultra‐long‐cycle length with self‐controllability under unprotected accidents. In particular, a thorium–uranium fuel cycle is considered to remove the heterogeneity of the fuel assemblies for design simplification and to improve the core performance parameters by selectively adding thorium into both blanket and driver fuels. The results show that the use of TRU nuclides from PWR spent fuel leads to significant extension of the fuel cycle length, but considerable increase of burnup reactivity swing. In addition, these results also indicate that the uranium–thorium mixed fuels both in the lower blanket and driver considerably improve the inherent safety of the ultra‐long‐cycle core by reducing burnup reactivity and sodium void worth; this makes it possible to simplify the previous heterogeneous fuel assembly design with improved core performances. Copyright © 2016 John Wiley & Sons, Ltd. Key Findings: 350MWe ultra‐long‐cycle sodium cooled fast reactor core was successfully designed to supply electric energy over ~60 Effective Full Power Year (EFPYs) without refueling and with an effective use of Transuranics (TRU) and uranium from large PWR spent fuel stocks. The design optimization with thorium addition led to the improvement of core performances with fuel assembly design simplification. The reactor can be utilized as an effective long‐term intermediate storage of PWR spent fuels with sustainable and safe electricity generation.