A Reactivity Meter Using Passive Networks for Delayed-Neutron Groups

An instrument for measuring the net reactivity input to a reactor system has been designed and used at the Halden Boiling Water Reactor (HBWR), Norway, and at the Ågesta power reactor R3, Sweden. The design is based upon extensive use of passive networks. The instrument has been carefully tested. Test results are presented as gain and phase curves for reactivity to power transfer functions and are compared with the theoretical ones. The agreement is quite satisfactory. The operational experience is good.