BS IEC 62765‑2:2019 pdf download – Nuclear powers plants – Instrumentation and control important to safety – Management of ageing of sensors and transmitters Part 2: Temperature sensors.
c) Recommendations and limitations regarding the application of this standard It is important to note that this standard establishes no additional functional requirements for safety systems. Ageing mechanisms have to be prevented and thus identified by performance measurements in order to minimize their impact on sensor reliability. Aspects for which special recommendations and limitations have been provided in this standard are: • criteria for the evaluation of ageing of temperature sensors in NPPs; • steps to be followed to establish the temperature sensor testing requirements for an ageing management program for NPP instrumentation systems; and • relationships between on-going qualification analysis and ageing management program with regard to temperature sensors. It is recognised that testing and monitoring techniques used to evaluate the ageing condition of NPPs’ sensors and transmitters are continuing to develop at a rapid pace and that it is not possible for a standard such as this to include references to all modern technologies and techniques. This standard identifies minimum requirements aimed at ensuring that any potential impacts on NPP safety due to the ageing of temperature sensors of NPPs can be identified and that suitable actions are undertaken to demonstrate that the safety of the plant will not be impaired. To ensure that this standard will continue to be relevant in future years, the emphasis has been placed on issues of principle, rather than specific technologies.
A fourth level extending the IEC SC 45A standard series, corresponds to the Technical Reports which are not normative. The IEC SC 45A standards series consistently implement and detail the safety and security principles and basic aspects provided in the relevant IAEA safety standards and in the relevant documents of the IAEA nuclear security series (NSS). In particular this includes the IAEA requirements SSR-2/1 , establishing safety requirements related to the design of nuclear power plants (NPPs), the IAEA safety guide SSG-30 dealing with the safety classification of structures, systems and components in NPPs, the IAEA safety guide SSG-39 dealing with the design of instrumentation and control systems for NPPs, the IAEA safety guide SSG-34 dealing with the design of electrical power systems for NPPs and the implementing guide NSS1 7 for computer security at nuclear facilities. The safety and security terminology and definitions used by SC 45A standards are consistent with those used by the IAEA. IEC 61 51 3 and IEC 63046 have adopted a presentation format similar to the basic safety publication IEC 61 508 with an overall life-cycle framework and a system life-cycle framework. Regarding nuclear safety, IEC 61 51 3 and IEC 63046 provide the interpretation of the general requirements of IEC 61 508-1 , IEC 61 508-2 and IEC 61 508-4, for the nuclear application sector. In this framework IEC 60880, IEC 621 38 and IEC 62566 correspond to IEC 61 508-3 for the nuclear application sector. IEC 61 51 3 and IEC 63046 refer to ISO as well as to IAEA GS-R part 2 and IAEA GS-G-3.1 and IAEA GS-G-3.5 for topics related to quality assurance (QA). At level 2, regarding nuclear security, IEC 62645 is the entry document for the IEC SC 45A security standards. It builds upon the valid high level principles and main concepts of the generic security standards, in particular ISO/IEC 27001 and ISO/IEC 27002; it adapts them and completes them to fit the nuclear context and coordinates with the IEC 62443 series. At level 2, IEC 60964 is the
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.