BS IEC 62765-2:2019

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-1990 (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.