The development and operation of the protection system for a TRIGA Mark III nuclear research reactor is presented. This system was designed as an integral component of the new control console for the Mexican National Institute for Nuclear Research's reactor and is based on modern digital and optical electronics. In compliance with the normative applicable to the safety aspects of this kind of nuclear facility, the new protection system was designed to maintain its computer-free operational characteristics, while the rest of the new console's systems were allowed to incorporate digital computers and processors to control the normal operation of the reactor. The new protection system, compared to the original, enhances the scram functions and improves the safety and operability features of the system's circuits.