Neutronic feasibility of a soluble Boron-Free PWR core design with the bigt burnable absorbers

Abstract

A soluble boron-free (SBF) pressurized water reactor (PWR) core potentially offers a number of significant operational improvements over commercial designs. Firstly, it eliminates risk of boric acid-induced corrosion on structural materials in reactor pressure vessel. Secondly, it is possibly simpler in plant design, operation and maintenance. Thirdly, it may have smaller accumulated volumes of crud and radioactive liquid waste. Fourthly, an SBF PWR core has consistently 'large negative' moderator temperature coefficients (MTC). All these are desirable advantages in term of economic and safety of a PWR. This paper extends authors' previous research on the SBF PWR core with BigT ("Burnable absorber-Integrated Guide Thimble") absorber. In particular, this research investigates use of the BigT in tandem with a commercial burnable absorber technology, namely integral fuel burnable absorber (IFBA) rods, to realize an SBF AP1000 equilibrium core. 3-D core analyses of the BigT-loaded and IFBA-rodded AP1000 core were simulated using Monte Carlo Serpent-2 code with ENDF/B-VII.0 library. The equilibrium core was directly searched via repetitive Monte Carlo depletion calculations until convergence. The analyses clearly demonstrate a promising SBF PWR design as burnup reactivity swing over the equilibrium cycle is reasonably small (~1,850 pcm). Fairly consistent albeit high radial power peaks (<2.0) with strongly negative MTC and sufficiently high shutdown margin (>2,600 pcm) are obtained throughout the cycle. In conclusion, an SBF AP1000 equilibrium core design is neutronically-feasible with BigT absorbers and IFBA rods.