A discharge apparatus usable in a nuclear reactor includes an emitter apparatus in the form of a plurality of wire segments that emit electrons via beta decay to a collector. The rate at which the electrons are emitted is directly related to the neutron flux in the vicinity of each wire segment. The continual emission of electrons from the wire segments to the collector results in a charge imbalance, and an electrostatic discharge event in the form of a spark occurs between the wire segment and the collector. Time-of-flight techniques are used to analyze signals that result from the electrostatic discharge event to determine the position along the discharge apparatus where the electrostatic discharge event occurred. The electrostatic discharge events over time at various locations along the discharge apparatus where the wire segments are situated are employed in determining the neutron flux and thus the power generation at the locations.