Light Water Breeding with Nitride Fuel

This scoping study proposes using mixed nitride fuel in Pu-based high conversion LWR designs in order to increase the breeding ratio. The higher density fuel reduces the hydrogen-to-heavy metal ratio in the reactor which results in a harder spectrum in which breeding is more effective. A Resource-renewable Boiling Water Reactor (RBWR) assembly was modeled in MCNP to demonstrate this effect in a typical high conversion LWR design. It was determined that changing the fuel from (U,TRU)O2 to (U,TRU)N in the assembly can increase its fissile inventory ratio (fissile Pu mass divided by initial fissile Pu mass) from 1.04 to up to 1.17.

► RBWR assembly modeled in MCNP/MCODE with oxide and nitride fuels to calculate breeding ratios.
► Using high density nitride fuel can increase the breeding ratio from 1.04 to 1.14.
► Results should encourage further investigations to overcome materials challenges of nitrides.