Wireless, Invessel Neutron Monitor for Initial CoreLoading of Advanced Breeder ReactorsResearch sponsored by the Division of Research and Technology, U.S . Department of Energy under contract W7405eng26 with the Union Carbide Corporation.

An experimental wireless, in-vessel neutron monitor is being developed to measure the reactivity of an advanced breeder reactor as the core is loaded for the FIRST time to preclude an accidental criticality incident. The environment is liquid sodium at a temperature of ?>220°C, with negligible gamma or neutron radiation. With ultrasonic transmission of neutron data, no fundamental limitation has been observed after tests at 230°C for >2000 h. The neutron sensitivity was ?>l count/s-nv, and the potential data transmission rate was ?>10⁴ counts/s