The silo entry gamma monitor (SEGM) monitors the loading of dry storage containers into a final silo storage location. The SEGM has a pair of pin diode γ silicon detectors located at different levels in the verification tubes available for each silo. The detectors provide direction sensitive verification of the silo loading and are installed before the start of a transfer campaign. The cables from several silos (up to eight) are routed to a common electronics cabinet, where the resulting data are logged. The data can be extracted either locally or remotely via a standard Ethernet link. After each silo has been completely filled, the detectors are removed by inspectors and replaced with seals, and the top cover is welded.

(Source: IAEA Safeguards Techniques and Equipment)