Abstract: The γ dose-rate monitor system is mainly used to monitor the absorbed dose rate of γ radiation in the loss of coolant accident or coolant leakage accident of nuclear power plant. Because of the particularity and complexity of the application situation, and the difficulty of developing technology, domestic nuclear power plants rely on imports at present. How to break the technology monopoly of foreign countries and realize the localization of the equipment is a problem worthy of study. The local processing box provides working voltage and signal processing for the detector of γ dose-rate monitor system, and the electrometer module is the core component of the local processing box. The combination of current-frequency (I-F) and voltage-frequency (V-F), and the combination of current-voltage (I-V) and V-F are put forward. By comparing the two kinds of electrometer module design schemes, and combining with the experience of design and test verification for many times, the advantages, disadvantages and key technology design methods are given, which have a certain guiding significance for product research and development and selection of electronic components.

Key words: γ dose-rate monitor system, loss of coolant accident, local processing box, electrometer