IEC 61504 pdf download.Nuclear power plants – Instrumentation and control systems important to safety – Plant-wide radiation monitoring
1 Scope and object
This International Standard provides guidance on the design principles and performance criteria for computer-based radiation monitoring systems (RMS). Such systems are provided to integrate the monitoring of plant-wide processes, effluent streams, and area radiation. This standard describes the integration of functions including equipment such as those described in standards IEC 60761 -1 , IEC 60761 -2, IEC 60761 -3, IEC 60761 -4, IEC 60761 -5, IEC 60768, IEC 6091 0, IEC 60951 -1 IEC 60951 -2, IEC 60951 -3, IEC 60951 -4, IEC 60951 -5, IEC 61 031 , and IEC 61 250 into a plant-wide digital system. The requirements of system-level components (central computer, subsystem computers, operator consoles, and inter- connections) are discussed. For detection assemblies, processing units and alarm units, this standard contains only the requirements needed to allow connection into the centralized system. The standards referenced above contain the specific requirements for these components. This standard provides criteria for the interface between monitors of different safety classes. This standard integrates data processing, storage, optimization, and correlation of data flow and displays. This standard defines the communication criteria to link distributed radiation monitoring equipment in the plant with an open architecture configuration. This standard does not apply to the design and testing of detection and measurement assemblies and subassemblies except as necessary to define the interface with the plant-wide system. Certain RMS functions, or a complete centralized radiation monitoring system may be entirely implemented with direct-connected analogue/relay technology. This standard does not apply to such functions or systems.
For the purpose of this International Standard, the general terminology concerning detection and measurement of ionizing radiation and nuclear instrumentation given in IEC 60050(393) and IEC 60050(394) applies, together with the following specific additional definitions. 3.1 category A category A is used to denote those functions and associated systems and equipment (FSE) which play a principal role in the achievement or maintenance of nuclear power plant safety. These FSE prevent postulated initiating events from leading to a significant sequence of events, or mitigate the consequences of postulated initiating events (see IEC 61 226). RMS functions that might be assigned to category A include, for example, radiation monitor inputs that initiate containment isolation. 3.2 category B FSE those FSE that play a complementary role to the category A FSE in the achievement or maintenance of nuclear power plant safety. The operation of a category B FSE may avoid the need to initiate a category A FSE. Category B FSE may improve or complement the execution of a category A FSE in mitigating a postulated initiating event so that plant or equipment damage or activity release may be avoided or minimized. Category B also denotes FSE whose failure could initiate or worsen the severity of a postulated initiating event (see IEC 61 226). RMS functions that might be assigned to category B include, for example, the radiation monitors used to alert control room operators to releases under post-accident conditions.3.3 category C FSE those FSE that play an auxiliary or indirect role in the achievement or maintenance of nuclear power plant safety. Category C includes FSE that have some safety significance, but are not category A or B. They can be part of the total response to an accident, but not directly involved in mitigating the physical consequences of the accident (see IEC 61 226). RMS functions that might be assigned to category C include, for example, area radiation monitoring functions.3.5 FSE functions and the associated systems and equipment. Functions are carried out for a purpose or to achieve a goal. The associated systems and equipment are the collections of components and the components themselves that are employed to achieve the functions (see IEC 61 226) 3.6 interlocks equipment used to prevent unsafe operation, protect personnel, and prevent hazards (see IEC 61 497)