A new log-linear safety channel for reactor power measurement

At Pakistan Research Reactor 1(PARR-1) the safety channels measure reactor power from few kW to 150% of full reactor power and provide reactor scram in case of high neutron flux or malfunctioning in the electronics of the channels. The channels are linear and they cover only three decades of reactor power level. So, the channels can not provide any information about the reactor power and channel operating condition at low reactor power up to few kW. A new log-linear safety channel has been developed for reactor power measurements in logarithmic and linear mode. The channel also measures reactor period. Due to the logarithmic mode of operation the channel can cover from startup range up to 200% of full reactor power. The new channel with one ion chamber has complete functionality of existing safety channels and intermediate power range logarithmic channels. So, on the replacement of existing safety channels with the new log-linear channels the existing logarithmic dc channels will not be required. The new channel will reduce the number of channels, improve fault capabilities and, hence, improve safety and availability of the system. The new channel will also be used in nuclear power plant. The log-linear safety channel has been tested at PARR-1 and the results are found in very good agreement with the designed specifications. This paper presents design and construction of the channel and field test results. (author)