A pair of linear arrays of gamma thermometer (GT) sensors arranged in a nuclear reactor core including: a first linear array of GT sensors, wherein the GT sensors are arranged asymmetrically along a length of the first linear array; a second linear array of GT sensors, wherein the GT sensors are arranged asymmetrically along the second linear array and wherein the second linear array of GT sensors is asymmetrical with respect to the first linear array of GT sensors, and the first linear array positioned in the reactor core at a first core location and the second instrument housing positioned at a second core location, wherein a line of symmetry of the core extends through a center of the core and the first core location is the same horizontal distance from the line of symmetry as the second core location.