IEC 61031:2020 pdf download – Nuclear facilities – Instrumentation and control systems – Design, location and application criteria for installed area gamma radiation dose rate monitoring equipment for use during normal operation and anticipated operational occurrences.
3 Terms and definitions For the purposes of this document, the terms and definitions given in IEC 60050-395 as well as the following apply. ISO and IEC maintain terminological databases for use in standardization at the following addresses: • IEC Electropedia: available at http://www.electropedia.org/ • ISO Online browsing platform: available at http://www.iso.org/obp NOTE Specific terminology for the radiation monitoring system is given in IEC 62705 and specific terminology for the area radiation monitor is given in IEC 60532 3.1 anticipated operational occurrence deviation of an operational process from normal operation that is expected to occur at least once during the operating lifetime of a facility but which, in view of appropriate design provisions, does not cause any significant damage to items important to safety or lead to accident conditions [SOURCE: IAEA Safety Glossary, 201 8 edition]
3.2 area radiation monitor equipment designed for continuously monitoring local gamma radiation dose rates in a fixed position in a nuclear facility Note 1 to entry: The equipment usually consists of a gamma radiation sensitive detector, a signal processing unit, interconnecting cables for signal transmission and a power supply. It is used to measure and display, locally and/or at some remote location, the radiation dose rate present at the detector location. 3.3 calibration check calibration procedure which is followed periodically on each area radiation monitor to ensure that the response of the equipment remains within specified limits 3.4 local dose rate dose rate at the detector location measured in whatever radiation dose rate quantity approved under national regulations and displayed on the instrument in appropriate units Note 1 to entry: See also IEC 60532. 3.5 normal operation operation within specified operational limits and conditions [SOURCE: IAEA Safety Glossary, 201 8 edition] 4 Abbreviated terms EMC Electromagnetic Compatibility HPD HDL (hardware description language) – Programmed Device I&C Instrumentation and Control IAEA International Atomic Energy Agency IEC International Electrotechnical Commission ISO International Organization for Standardization KERMA Kinetic Energy Released per unit MAss NPP Nuclear Power Plant NSLR National Standardizing Laboratory of a country for Radioactivity measurement RMS Radiation Monitoring System 5 Design principles 5.1 Function and application criteria The primary purpose of area radiation monitors is to protect personnel by alerting them to significant changes in radiation levels. To this end, the monitors measure continuously the gamma radiation dose rate in defined areas of a nuclear facility, and inform plant personnel by audible and/or visual alarms when predetermined dose rate levels are exceeded.
NOTE Area radiation monitors are not normally used for personnel dosimetry purposes, except as a source of backup information, nor are they normally used for the determination of the length of time which personnel are permitted to remain within radiation fields. They complement rather than replace operational health physics measurements and procedures including use of portable equipment. Nevertheless, they can also provide information on the effectiveness of such procedures. Because of their location, area radiation monitors may also be capable of indicating changes in plant parameters which are of interest to the plant operator. Where this is the case, monitor output functions shall be available at a remote location, usually the plant control room or an associated area. Area radiation monitors may also be used for interlocks and/or for initiating protective actions. In some cases, they may even be considered as inputs to reactor safety systems, although this would not normally be regarded as good practice. Area radiation monitors may also be used under accident conditions if the range of measurement is appropriate to the defined purpose and all sub-assemblies are qualified for the accident environmental conditions at their locations. This application is covered in more detail in IEC 60951 -1 and IEC 60951 -3. 5.2 General requirements 5.2.1 General characteristics and lifecycle The design of the area radiation monitor shall meet the requirements of IEC 60532. Furthermore, the additional specific requirements given in IEC 61 031 shall be met. If signals from area radiation monitors are used as inputs to interlock systems or plant and/or reactor safety systems, the design of such monitors shall also meet the appropriate requirements of such systems (for example, in respect to interface requirements, classification, reliability, qualification, etc.).