MYRRHA mechanical design of the primary system design and associated equipment

The mechanical design of the primary system and associated equipment of MYRRHA is driven by two basic requirements.

1. Since MYRRHA is to be a flexible irradiation facility that can host irradiation rigs, the capability of easy and frequent fuel reshuffling and flexible core access for (un)loading the irradiation rigs are very desirable features.

2. The irradiation objective, in particular the demonstration of transmutation, requires a high fast neutron flux which in turn implies a compact core, with high thermal loading on the fuel. Such fast and high flux consequently mandates liquid metal cooling.

The spallation target module and the core are immersed in a pool of lead-bismuth eutectic (LBE) that serves as coolant for both the spallation target and core; it also serves as a reflector/shielding for the fast neutrons and gamma rays.

A pool-type design for MYRRHA has not only been chosen from a safety point of view but also to provide an extremely flexible core management.

Reactor internals

1. Reactor vessel

2. Guard vessel

3. Cover

4. Diaphragm

5. Heat exchangers

6. Primary pumps

7. Fuel storage zone

8. Spallation target and core

9. Spallation loop

10. Fuelmanipulators

Overall view of the MYRRHA reactor with its main components.

General characteristics MYRRHA
Core barrel inner diameter 1,480 mm
Reactor vessel, inner diameter 6,030 mm
Height (cover not included)  8,860 mm
Primary coolant LBE
LBE volume  150 m³
Secondary coolant boiling water
Core inlet temperature 270 °C
Core average outlet temperature 400 °C
Maximum allowed bulk velocity 2.0 m/s
Nominal core power 50-100 MWth

More information: R&D programme > Material qualification
More information: R&D programme > Component qualification