Hydraulics and Thermo-hydraulics

Abstract

In nominal conditions, areas do coexist, with hot sodium (545 °C) and cold sodium (395 °C on primary and 345 °C on secondary sides), which will create thermo-hydraulics issues that have to be resolved in different locations of the reactor:

• Fluctuation and thermal stripping risks, in the mixing zones with flows at different temperatures.

• Complex zone between the core and the core cover plug and interaction with the inter sub-assembly flow.

• Stratification in the pools and consequences on the structures and the inner vessel.

• The intermediate heat exchanger and steam generator thermo-hydraulics.

• Role of the cold pool as a mixer towards the flows coming from the eight intermediate heat exchangers.

• Cold shocks or hot shocks during transient conditions.

In-gas thermo-hydraulics are complex too, with argon convective movements, generating thermal asymmetries and aerosol deposits. Furthermore, there are specific issues with the structures having thermal evolutions different between the part immersed in sodium and the part in gas. Finally, a section is devoted to the risks of gas entrainment, in particular passing through the reactor core.