An apparatus for venting an annular space between a liner and a pipeline of a subsea riser used for conveying hydrocarbons, the apparatus comprising a permeate recovery device for recovering permeate passing through the liner into the annular space. Since the implementation is continuous, the tracking is more accurate than traditional techniques. Power supply to the dimming control section is performed by an insulated auxiliary power supply. The memory device comprises a plurality of memory cells, an access transistor gate being connected to a word line and a memory transistor gate being connected to a write line. The spectroscopic sensor is a semiconductor device in which the angle limiting filters, the light band-pass filters, and the photodiodes are integrated, and, assuming that the surface on which impurity regions for the photodiodes are formed is a front surface of a semiconductor substrate, holes for receiving lights are formed in the impurity regions from the rear surface side. The recesses and magnets can be of essentially any compatible shape.