Temperature sensor for a pressurized water nuclear reactor coolant circulation

Claim 1

A temperature sensing instrument for direct mounting in a wall of a structure traversed by a primary coolant of a pressurized water reactor, comprising: a thermally conductive finger-shaped sheath closed at one end and extending through said wall so that a closed end of said sheath is disposed within said structure in direct contact with said coolant, said closed end being formed with a frustoconical blind bore tapering generally toward said closed end and having an internal surface; and a temperature sensor received in said sheath and having a frustoconical tip with an external surface tapered substantially to match said frustoconical bore and lodged therein in surface contact therewith at said surfaces, both of said surfaces being treated to limit the roughness of the surfaces in surface contact, said sensor comprising: an elongated body of pure silver formed with a central hollow, a platinum sensor element wire received in said hollow, and a packing of high thermal conductivity boron nitride received between said wire and an inner wall of said tip and in contact with said wire and said inner wall.