IEC 62887:2018 pdf download

IEC 62887:2018 pdf download.Nuclear power plants – Instrumentation systems important to safety – Pressure transmitters: Characteristics and test methods
1 Scope
This document is applicable to general aspects of design, manufacturing and test methods for pressure transmitters used in instrumentation systems important to safety in all nuclear power plants (PWR, BWR, FBR, etc.). The conditions imposed by reactor use are often different from those which occur in non-nuclear applications. Exposure to radiations (mainly neutron, gamma, even beta) is liable to cause alterations in the measurements. Mechanical and electrical properties of transmitters can be affected by nuclear transformations, heating and structural changes. Particular attention is paid to the adoption of standards for the choice of materials and installation. Furthermore, design consideration is given to the effects of high environmental pressure, high temperature, chemical spray, temperature gradients and temperature cycling as well as to the way in which the temperature and pressure measuring system could influence the safety or economic performance of the reactor. The consequences of nuclear conditions for pressure transmitters lead to onerous requirements regarding qualification. This document deals with specific requirements for nuclear applications of pressure transmitters including design, materials, manufacturing, testing, calibration and inspection. For applications in non-nuclear areas of a NPP, IEC standards used for industrial products apply. This document deals only with transmitters, the boundaries are: – Sensing elements. – Electronics converters. – Electrical connection. – Process connection. – Sealed systems. Instrumentation systems using pressure transmitters as components (such as flowmeter, level measurement) or other components connecting to transmitters (such as sensing lines, valves) are not in the scope of this document. Remote seals are considered as components of transmitters and are treated.
3 Terms and definitions
For the purposes of this document, the following terms and definitions 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 3.1 absolute pressure sensor sensor which makes the measurement with vacuum as reference EXAMPLE: Examples of associated units: kPa abs, MPa abs, bar abs. 3.2 accident conditions deviations from normal operation that are less frequent and more severe than anticipated operational occurrences EXAMPLE: Examples of such deviations include a major fuel failure or a loss of coolant accident (LOCA). Note 1 to entry: Accident conditions comprise design basis accidents and design extension conditions. [SOURCE: IAEA safety glossary, 201 6 edition] 3.3 accident management the taking of a set of actions during the evolution of a beyond design basis accident: a) to prevent the escalation of the event into a severe accident; b) to mitigate the consequences of a severe accident; c) to achieve a long term safe stable state.Note 1 to entry: The second aspect of accident management (to mitigate the consequences of a severe accident) is also termed severe accident management. [SOURCE: IAEA safety glossary, 201 6 edition] 3.4 accuracy <of a measuring instrument> quality which characterizes the ability of a measuring instrument to provide an indicated value close to a true value of the measurand Note 1 to entry: This term is used in the “true value” approach. Note 2 to entry: Uncertainty is all the better when the indicated value is closer to the corresponding true value. [SOURCE: IEC 60050-31 1 :2001 , 31 1 -06-08] 3.5 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 EXAMPLE: Examples of anticipated operational occurrences are loss of normal electrical power and faults such as a turbine trip, malfunction of individual items of a normally running plant, failure to function of individual items of control equipment, and loss of power to the main coolant pump.