BNEN Design of a labyrinth seal to limit the free surface level difference in a Lead Fast Reactor

At SCK CEN, we currently design a lead cooled pool type fast test reactor called LEANDREA. This reactor will be the reactor to test the fuel assemblies and other components for the power LFR SMR EAGLES.

The pressure difference between plena in a pool type lead cooled reactor creates a separation between the free surface levels of the plena. The reactor core is responsible for the largest pressure drop in the coolant flow path. Typical pressure differences are in the order of 2 bar, which result in a separation of levels of about 2 meters.  This level difference compared to ‘no flow’ conditions adds up to the height of the reactor vessel.

The goal of this thesis is to investigate ways to avoid the free surface level separation by design in a lead cooled pool type reactor.  

The current LEANDREA design looks at an option to use a labyrinth or seal to create a significant pressure drop between the main vessel and the cylindrical diaphragm in combination with a back flow to limit the level separation and in such a way to reduce the height of the reactor vessel.

First a literature review should be performed to learn about experience in past reactor designs or in other industrial applications with similar challenges.

The student should analyze options based on thermal hydraulic evaluation and structural mechanical calculations to create a safe and reliable solution.

The final design proposal shall be compatible with the lead coolant, high temperature conditions and thermal gradients as also applicable to the large dimensions of the diameter of the reactor vessel.

Possible tools: CFD, Finite element simulations