Results are discussed from an investigation into a system for the physical monitoring of energy release in the core of the VK-50 boiling water reactor. Movable self-powered detectors are used in this system as energy-release neutron detectors. Rhodium serves as the emitter in these detectors. A number of parameters for these detectors were experimentally measured; they include the ratio of the instantaneous current to the activation current, the coefficients of relative sensitivity of the detectors to neutrons, and the effective cross sections for the interaction of /sup 103/Rh with thermal and epithermal neutrons. Computer simulation of the system and detectors is discussed. The system can monitor absolute energy distribution in the fuel assemblies under reactor conditions. The system is independent of thermotechnical measurements with an instrument to determine energy release in the reactor core.