IEC 62765-2:2019 pdf download

IEC 62765-2:2019 pdf download.Nuclear powers plants – Instrumentation and control important to safety – Management of ageing of sensors and transmitters
1 Scope
This part of IEC 62765 identifies minimum requirements and applicable practices for correcting and preventing any potential impacts on nuclear power plant (NPP) safety due to the ageing of temperature sensors, such as NPP resistance temperature detectors (RTDs) and thermocouples (TCs). This document provides strategies, technical requirements, and recommended practices for the management of the ageing of temperature sensors important to safety in nuclear power plants (NPPs) to ensure that ageing can be identified and that suitable remedial actions are undertaken as necessary to demonstrate that the safety of the plant will not be impaired. This document is aligned with IEC 62342, which provides guidance on ageing management for instrumentation and control (I&C) systems important to safety in NPPs. IEC 62765 standard series covers pressure transmitters (Part 1 ) and temperature sensors (Part 2). Part 1 covers pressure transmitter (PT), level transmitter (LT) and flow transmitter (FT). Part 2 consists of resistance temperature detector (RTD) and thermocouple (TC) with respect to instrumentation and control (I&C) important to safety. Detector of neutron power (Part 3) will be covered in a separate standard. Interfaces of temperature sensors with processes such as thermowells, seals, sheathes, extension/compensating cables, and connectors are within the scope of this document. Ageing management of temperature sensors used as M&TEs are beyond the scope of this document.Temperature units of this document are in terms of International Temperature Scale-1 990 (ITS- 90), because of consistency with normative references. IAEA SSR-2/1 and SSR-2/2 address the requirements of ageing management in the design, as well as in the operation of the lifetime of the plant.SSG-39 recommends design consideration for ageing management specific to I&C system. The requirements of temperature sensors for industrial and nuclear application in the normative references are indispensable to this document whereas this document focuses on the ageing management of temperature sensors to meet the requirements.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.3.1 adjustment <of a measuring instrument> set of operations carried out on a measuring instrument in order that it provides given indications corresponding to given values of the measurand Note 1 to entry: An adjustment can be carried out during cross-calibration of temperature sensors in the temperature measurement channel. [SOURCE: IEC 60050-31 1 :2001 , 31 1 -03-1 6] 3.2 calibration set of operations that establish, under specified conditions, the relationship between values of quantities indicated by a measuring instrument or measuring system, or values represented by a material measure or a reference material, and the corresponding values realized by measurement standards [SOURCE: IAEA Safety Glossary, edition 201 6] 3.3 calibration diagram portion of the co-ordinate plane, defined by the axis of indication and the axis of results of measurement, which represents the response of the instrument to different values of the measurand [SOURCE: IEC 60050-31 1 :2001 , 31 1 -01 -1 0] 3.4 compensating cables manufactured from conductors having a composition different from the corresponding thermocouple. They are designated by the letter “C” following the designation of the thermocouple, for example “KC”. In some cases different tolerances apply for the same thermocouple type over different temperature ranges. These are distinguished by additional letters such as, for example, KCA and KCB [SOURCE: IEC 60584-3:2007, 3.1 .2]3.5 cross-calibration procedure of inter-comparing the indications of redundant instruments (e.g., temperature sensors) to identify outlier sensors as a means of verifying calibration or identifying calibration changes. A more appropriate term for this definition is “cross-validation,” although cross- calibration is more commonly used Note 1 to entry: A calibration test of temperature sensors in some NPPs can be different from this definition mainly because an adjustment of the temperature channel during cross-calibration may be allowed within a predetermined allowable value. [SOURCE: IEC 62385:2007, 3.6]