NUCLEAR FAILED FUEL DETECTION SYSTEM

摘要

A system is disclosed which utilizes multiple radiation detectors to establish the isotopic or pseudo isotopic (weighted average of several isotopes) content of radiation sources on a continuous on-line basis. A specific application which utilizes this principle is a failed fuel monitor which continuously monitors the delayed neutron and gamma activity emanating from the primary coolant of a nuclear reactor. Employing two neutron detectors, the system has the ability to distinguish between activity from failed fuel and from fuel rod surface contamination. Applying a technique to compensate for activity build-up in the primary coolant loop, the system makes it possible to interpret the signals even during power transients. The provision of a third detector responsive to the gamma radiation emitted from the primary coolant in the reactor coolant loop enables the system to distinguish between enlarged cladding failures in already failed fuel rods and additional fuel failures.