GB914380A - Improvements in or relating to nuclear reactors - Google Patents

Abstract

914,380. Nuclear reactors. UNITED KING- DOM ATOMIC ENERGY AUTHORITY. Oct. 19, 1961 [Jan. 23, 1961], No. 2684/61. Class 39 (4). Temperature measurement means for a fuel element channel of a nuclear reactor comprises a thermocouple stem adapted to be disposed within the channel, to extend outwardly from the fuel element intended to be nearest the reactor charge face when the fuel elements are in operative position within the channel, and to support a thermocouple hot junction for exposure to coolant in the channel. In Fig. 1 the thermocouple stem comprises an outer tubular member 3 and a telescoping inner tubular member 4, the outer member being supported by radial lugs 6 from a lip 5 in the fuel channel and the inner member terminating in a cone adapted for stacking arrangement with a cup at the upper end of the uppermost fuel element (not shown). The hot junction 7 of a thermocouple is clipped to the exterior surface of the wall of member 3 and is connected by a lead 8 to a remote indicator instrument outside the reactor core. In an alternative, Fig. 2 (not shown), the junction 7 projects radially outward from the wall of member 3 to make direct contact with the coolant gas. In a modification, Fig. 3 (not shown), the junction 7 is surrounded by an open-ended shield which screens it against heat radiated from the channel wall and provides some protection against damage during charging operations. In a further arrangement, Fig. 4 (not shown), apertures are provided in members 3 and 4 to allow coolant to flow inside the thermocouple stem, and the hot junction 7 is located inside the stem. Specification 907,735 is referred to.