Design guide on instrumentation and control system for an advanced research reactor

Instrumentation and control system is to regulate reactor power automatically and to perform protective functions to shut down the reactor safely in case of an accident threatening the reactor safety. If the protective action would not be properly activated, an abnormal situation might be connected to a significant radiation hazard, even though a research reactor is maintained at low pressure and low temperature condition. For this reason, the reactor protection system for the advanced research reactor will be designed as per the safety design requirements for nuclear power generating stations. System classification are suggested based on the HANARO concept. Considering an international growing tendency toward nuclear safety enhancement and supplement of the existing one, a revised classification system will be applied to the components, structures and systems for the advanced research reactor. The reactor protection system is classified to the safety class and the others are non-safety grade. Based on the HANARO experience, the design guide aims at the improvement of reliability of safety and achievement of automatic control and signal processing by digitalization. To satisfy functional diversity requirement, the first shutdown system adopts a concept of control rod with a stepping motor while the second shutdown system uses D2O dump system. The first shutdown system will use a PLC-type digital logic processor but the second shutdown system will use a conventional relay logic for the concept of equipment diversity. The reactor protective function for the advanced research reactor has a higher reliability by using two different shutdown mechanism. Although most of the instrumentation systems, except the reactor protection system are classified to non-safety grade, some systems like reactor regulation system or engineered safety feature actuation system selectively adopts the safety design requirements in order to ensure the safety-related function. All of the system control will be accomplished by a digital computer techniques and they are networked all together for comprehensive data display and management