1. Nuclear Safety Standards Committee 35th Meeting 24 – 28 June 2013
Agenda item 2.8
DS431 Safety Guide on Digital Instrumentation and Control Systems
A.Duchac, SAS-NSNI

2. Background (1)

3. Background (2) The update also includes: Areas of new consensus, e.g.,
Systems programmed with Hardware Description Languages
Criteria for identifying need for diverse protection systems
Industrial digital devices
Software tools
Guidance on applying human factor principles to human machine interface
Reference to GS-R-3, GDS-R-4 and supporting guides
More extensive reference to NS-G and NSS series guides
A particularly strong relationship with DS-430 (draft guide on electrical power systems important to safety)

4. Changes since previous version “J” (Nov 2012)
Changes agreed by CM convened in Feb to consider:
Areas of non-consensus (SW reliability, and CCF vulnerabilities)
Fukushima lessons
Requests for reassessing resolution to specific MS comments
Consistency with latest MDEP DICWG common positions

5. Fukushima Implications
Revised sections on accident monitoring and communications facilities
Inserted fundamental points concerning accident monitoring from draft IAEA publication on Accident Monitoring Systems for Nuclear Power Plants ( )
Brought emergency facility terminology into line with that agreed for addendum to SSR 2/1 ( )

6. NUSSC Members comments to “K” version
41 comments received (CA,FI, FR, IEC, CH)
Positive review result in general
Sections affected:
2 - Management system for I&C (add GS-R-Part 4)
5 - Safety Classifications
6 - General recommendations for all I&C systems important to safety
7 - System and equipment specific design guidelines
9 - Software
Annex III - Areas where MS practices differ

7. NUSSC Members comments resolution
38 comments accepted; helped improving document quality and clarity
2 comments (FI, CH) on section 6.72 resolved by IEC 9 (removed examples of SW failures)
1 comment (CA 1) on DS 431 applicability to SMR not addressed: SMR are considered nuclear power plants?
One major comment (FI):
Section 5 “Classification” replaced by new wording in line with DS 367 “Classification safety guide”

8. Other fixes to “K” version
Document check and fix:
Paragraph numbering
References order (smallest to largest)
Consistency of cross references