Abstract: The invention relates to a precision positioning device comprising a base, moveable stage and four double parallelograms connecting the stage to the base. Each double parallelogram comprises six deformable vertices forming six pivots so that the stage can move in translation in a reference plane. Thanks to the four double parallelograms, the moveable stage is over-constrained so that the undesired rotational motions are very limited. The precision positioning device can further comprise a moveable platform connected to the moveable stage thanks to flexure strips. The moveable platform is over-constrained to only move in translation according to the Z axis.

Abstract: A device for measuring the flow rate of a fluid in the annular space of a steam generator; having within a probe housing, kept fixed relative to the outer wall of the steam generator, a probe. A seal between the probe and the probe housing is formed by an elastic bellows fitted in such a way that it constantly applies one end of the probe against the inner wall of the generator.