Optical fibre sensors (OFS) can bring substantial
advantages over conventional sensing approaches for in- situ
measurement in fission Material Testing Reactors (MTRs) and
other nuclear research or industrial facilities: easy remote sensing,
possibilities of multiplexing, passive operation, low sensitivity to
electromagnetic interference, compact size, high resolution and
accuracy even under high radiation dose and high temperature,
once necessary adaptations have been achieved. In this paper
firstly we remind the three undesired effects of high level of
irradiation on OFS: radiation induced attenuation, radio luminescence
and compaction due to fast neutrons. Then we present two
types of sensor that we develop: elongation Fabry Perot sensor
- jointly with SCK.CEN- and Michelson type displacement
sensor; they both rely on white light interferometry to retrieve
the desired measurement.