MYRRHA engineering

The major components of the design and development of MYRRHA are:

Rationale for the MYRRHA design characteristics

MYRRHA is designed as a flexible fast spectrum irradiation facility. This means that a fast neutron spectrum is present at every location in the reactor and that in every fuel assembly position a dedicated experimental fuel assembly can be loaded. In this way, the entire reactor volume offers possibilities of loading experimental fuel assemblies in conditions similar to the reactor conditions, being a fast neutron spectrum, and in contact with the flowing liquid lead-bismuth at reactor operating temperatures.

As BR2, MYRRHA will be able to host at least 8 in-pile sections (IPS) (representing a total volume of 8 x 3700 cm3) with a core loading pattern optimised to obtain the most appropriate irradiation conditions in the IPS. In these usually double-walled IPS, a different coolant (Na, NaK, He, H2O) can be present with temperature and pressure conditions optimised for the experimental fuel/material loaded in the IPS.

The IPS are usually instrumented to follow the irradiation conditions that have been optimised in the IPS by choosing the appropriate coolant (stagnant or loop-type) and a temperature independent from the MYRRHA environment. The content of some of these IPS can be loaded/unloaded during reactor operation. The presence of these IPS makes MYRRHA not only a fast spectrum irradiation facility, but also a very flexible one.

Main characteristics

MYRRHA

Unit

Core power

50-100

MWth

Active core average power density

250

W/cm3

Accelerator energy

600

MeV

Accelerator current

3.5

mA

Coolant type

LBE

-

Total flux (hottest pin)

4.7E+15

n/cm2/s

Fast flux above 0.75 MeV (hottest pin)

1.01E+15

n/cm2/s

Dpa(/350 EFPD's) (hottest pin)

45

-

Ppm He/dpa (hottest pin/target zone)

3.8/6.4

-

Irradiation volume (8 In-Pile Sections)

3700*8

cm3

Inlet temperature

270

°C

Coolant delta T

130

°C

Velocity (fuel rod)

1.9

m/sec

Temperature at cladding surface

500

°C

Maximum linear power

370

W/cm