Neutronics and safety parameters study of an SMR concept

Sammanfattning

The design of an integrated boron-free PWR SMR raises a significant number of challenges. All existing knowledge from large size PWRs can be used used as a basis but shall be verified. The boron-free design allows to eliminate the risk of a boron dilution accident as well as the concern linked to boric acid corrosion in the primary loop. This work presents margins under normal conditions of the safety-related neutronics and thermal-hydraulics parameters of a core design currently under study at Framatome. The quantifying studies are performed using coupled deterministic codes for neutronics and subchannel thermal-hydraulics. The results presented in this work show that the power peaking factors increase, and the boiling crisis risk are mainly a consequence of an axially peaked power distribution in the core. This result differs from usual similar studies performed on large size PWRs where the latter mentioned risks are mainly driven by a radially peaked power distribution. This result offers new possibilities for optimizing the core design and operation. Some of the possible improvements are presented in the last part of this work.