IEC 62118 pdf download

IEC 62118 pdf download Nuclear reactor instrumentation – Pressurized water reactor (PWR) of VVER design – Monitoring adequate cooling within the core during shutdown
1 Scope and object
This International Standard applies to pressurized water reactors (PWRs) of VVER designwith configurations similar to those shown in figures 1 and 2, and presents the requirementsfor monitoring adequate cooling within the core during hot and cold shutdown conditions.Annex B provides more information on vVER operating states.
Good international practices to be used when designing new or upgrading existing corecooling monitors for VVER systems are summarized in this standard.This standard does notconsider the design details of the different VVER technological systems designs,except to theextent that the design affects the monitoring of core cooling.
Requirements are given for core cooling monitoring instrumentation to ensure the safeoperation of VVERs during abnormal operation and during and after design basis accidents(DBA). Requirements for core cooling monitoring during conditions beyond a DBA,whichcould be a specific national requirement or consideration, are not covered here.
The core cooling monitoring instrumentation has to function under widely different conditions.The circumstances underwhich this instrumentation needs to function are described.Descriptions of diverse measuring principles and suitable devices are given along withrequirements for the following:
operational conditions;. installation;
. operator displays;
testing, calibration and maintenance;equipment qualification;
. documentation;
redundancy.
Normative references
The following normative documents contain provisions which，through reference in this text,constitute provisions of this International ‘Standard. For dated references,subsequentamendments to, or revisions of, any of these publications do not apply. However,parties toagreements based on this International Standard are encouraged to investigate the possibilityof applying the most recent editions of the normative documents indicated below.For undatedreferences,the latest edition of the normative document referred to applies. Members ofIEC and lSo maintain registers of currently valid International Standards
IEC 60050(393):1996, International Electrotechnical Vocabulary (EV) – Chapter 393:Nuclearlnstrumentation – Physical phenomena and basic concepts
IEC 60737:1982，In-core temperature or primary envelope temperature measurements innuclear power reactors -Characteristics and test methods
3 Definitions and abbreviations
For the purpose of this International Standard, the following definitions apply. For terms
defined elsewhere, the source is given in square brackets.
3.1
ALARA
as low as reasonably achievable
3.2
coolant
water and/or steam for heat removal from the core
3.3
DBA
design basis accident
3.4
diversity
the existence of redundant components or systems to perform an identified function, where such components or systems collectively incorporate one or more different attributes
[IAEA 50-SG-D8]
3.5
downcomer
annular volume between reactor vessel wall and internals that directs coolant flow to the bottom of the core