Radioisotope activity surveillance apparatus, system, and method

A radioisotope activity surveillance system, comprising:

• a fuel rod assembly comprising a plurality of nuclear fuel rods;
• a target assembly comprising:
• a top nozzle comprising an orifice plate;
• and
• at least one target material rod fixedly coupled to the orifice plate, wherein the target assembly is movable to slidably dispose the at least one target material rod within the fuel rod assembly, and wherein the fuel rod assembly is configured to irradiate the at least one target material rod to produce radioisotopes when the at least one target material rod is slidably disposed within the fuel rod assembly;
• and
• a sensing assembly defining an opening sized and configured to receive the target assembly therethrough, the sensing assembly comprising:
• a housing, wherein an outside surface of the housing defines the opening;
• and
• a self-powered detector assembly to detect radioisotope activity of the at least one target material rod, wherein the self-powered detector assembly comprises a spiral wound sensing portion disposed in the housing.