N16 Power Control System of the Livermore Pool-Type Reactor

A power level indicating and control system that is independent of rod position and gamma background was developed for the Livermore Pool-Type Reactor (LPTR). This system, based on the N16 decay in the primary coolant water, avoids the errors in ion-chamber measurements caused by changes in leakage flux, related to fuel loading, fuel burnup, xenon buildup, and rod position. A scintillation detector was placed near the coolant outlet. A dual differential discriminator monitors the output and drives a counter in the control room. The numerical readout is directly in watts. The counter output provides a control signal that can override the ion-chamber control when an error exists. The system operates from 2 MW down to 2 kW under automatic control.