Application of Semiconductor Logic Components in Reactor Safety and Regulating Systems

A prototype of reactor trip logic for a CANDU reactor shutdown system, implemented with field programmable logic arrays (FPLAs), was developed as a step towards the phasing out of relays in this application. The prototype uses continuous self-testing to detect and locate faults. A design for control rod interlock logic, based on FPLAs, was also produced. The main design features of both systems are explained. The experience gained in this application of FPLAs is discussed. The potential application of this technology is in complex logic systems where a relay design is too inflexible and time consuming to fabricate, and a programmable controller or computer is impractical or undesirable.