Page 34 - Thermal Hydraulics Aspects of Liquid Metal Cooled Nuclear Reactors

Introduction to liquid metal cooled reactors 9

Full name: Advanced Lead Fast Reactor European Demonstrator
Designer: Ansaldo nucleare
Reactor type: Lead fast reactor
Electric capacity: 125MW(e)
Thermal capacity: 300MW(th)
Coolant: Pure lead
System pressure: 0.1MPa
System temperature: 400°C/480°C (core inlet/outlet)
No. of safety trains: 4 trains
Emergency safety systems: No injection safety systems needed
Residual heat removal Two DHR systems, four loops each—passive
systems:
Design status: Conceptual design
New/distinguishing features: Pool type, lead-cooled, passive safety, and high safety
margins

1.5.2.1 Introduction

The Advanced Lead Fast Reactor European Demonstrator (ALFRED) conceptual
design has been originally developed in the frame of the Lead-cooled European
Advanced Demonstration Reactor (LEADER) project coordinated by Ansaldo
Nucleare. ALFRED is a 300MW(th) pool-type system developed to demonstrate the
viability of the European LFR technology for the deployment of next-generation com-
mercial power plants. The ALFRED design integrates prototypical design options
intended to be used in the industrial-size plants, using proved and available technical
solutions to the maximum extent possible, in order to ease qualification and licensing.

1.5.2.2 Description of the primary cooling system

The ALFRED primary system is based on a pool-type configuration allowing the
removal of all internal components. The flow path of the primary system, driven by
internal structures, is maintained as simple as possible, aiming at minimizing pres-
sure losses to achieve an efficient natural circulation. The primary coolant leaving
the core flows upward through the primary pumps and then downward, through the
steam generator, to a cold plenum before feeding the core. The volume between the
primary coolant free levels and the reactor roof is filled with inert gas. The reactor
vessel is cylindrical with a torospherical bottom head, and it is anchored to the
reactor cavity from the top using a Y-junction. The inner vessel structure provides
a radial restraint to the core to preserve its geometry and is connected to a bottom
grid in which fuel assemblies are inserted. The free gap surrounding the reactor
vessel is sized to maintain the main circulation flow path also in case of leakage.
The core is constituted by 171 wrapped hexagonal fuel assemblies, 12 control rods,
and 4 safety rods, surrounded by dummy elements. Hollow pellets of MOX fuel
with maximum plutonium enrichment of 30% are used. Eight steam generators
and primary pumps are located in the annular space between the inner vessel
and the reactor vessel walls.