Differences between analog and digital I&C

Björn Wahlström*

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

1 Citation (Scopus)

Abstract

Fifty years ago instrumentation and control (I&C) systems at nuclear power plants (NPP) were analog and relied on a mixture of mechanical, pneumatic and electric components. Today analog technology has been replaced with digital technology. Digital I&C has over the years experienced difficulties in the licensing process, which has delayed and escalated costs of both NPP and I&C projects. In the paper it is argued that some of the difficulties are connected to misunderstandings regarding differences between analog and digital I&C. These misunderstandings have led to unrealistic expectations regarding proofs that selected I&C systems can be considered acceptable. To ensure a successful licensing process it would be necessary to agree on evidence for safety that can be considered sufficient. Such evidence should be collected both from the I&C design process and from testing intermediate and final I&C solutions. By a combination of evidence from different sources it should be possible to build a safety case that can be agreed to give sufficient proofs for acceptability. The first component in building the safety case is to make use of safety principles to provide structural evidence that certain classes of design errors have been avoided. The second component is to use simulators and targeted testing to demonstrate functionality of the I&C in different plant situations.

Original languageEnglish
Title of host publication9th International Topical Meeting on Nuclear Plant Instrumentation, Control, and Human-Machine Interface Technologies, NPIC and HMIT 2015
PublisherAMERICAN NUCLEAR SOCIETY
Pages2560-2569
Number of pages10
Volume3
ISBN (Electronic)9781510808096
Publication statusPublished - 2015
MoE publication typeA4 Article in a conference publication
EventInternational Topical Meeting on Nuclear Plant Instrumentation, Control, and Human-Machine Interface Technologies - Charlotte, United States
Duration: 22 Feb 201526 Feb 2015
Conference number: 9

Conference

ConferenceInternational Topical Meeting on Nuclear Plant Instrumentation, Control, and Human-Machine Interface Technologies
Abbreviated titleNPIC and HMIT
Country/TerritoryUnited States
CityCharlotte
Period22/02/201526/02/2015

Keywords

  • Analog
  • Digital
  • I&C functions
  • Safety principles
  • Verification and validation

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