Document: NUREG-0800
Document ID: f2ddec6c-0cce-4223-b813-233678ee07d0
Document Type: srp
Title: DIVERSE INSTRUMENTATION AND CONTROL SYSTEMS
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML1515/ML15159B171.pdf
Revision Date: 2023-06
Chapter: 7
Section ID: 7.8
CFR Part: 
CFR Title: 

Content:
ptable methods of compliance with the NRC regulations. 1. For plants with a digital RTS or ESFAS, the NRC position on D3 should be especially noted. This position is contained in Item II.Q, “Defense against Common-Mode Failures in Digital Instrument and Control Systems,” of the Staff Requirements Memorandum on SECY-93-087, “Policy, Technical, and Licensing Issues Pertaining to Evolutionary and Advanced Light-Water Reactor (ALWR) Designs.” SRM requirements applicable to diverse I&C functions are as follows: • “If a postulated common-mode failure could disable a safety function, then a diverse means, with a documented basis that the diverse means is unlikely to be subject to the same common-mode failure [as the safety system], shall be required to perform either the same function [as the safety system function that is vulnerable to common mode failure] or a different function [that provides adequate protection]. The diverse or different function may be performed by a non-safety system if the system is of sufficient quality to perform the necessary functions under the associated event conditions.” • “A set of displays and controls located in the main control room shall be provided for manual system-level actuation of critical safety functions and monitoring of parameters that support the safety functions. The displays and controls shall be independent and diverse from the safety computer system[s]…” 2. SRP Appendix 7.1-B provides guidance for evaluating conformance to the requirements of IEEE Std 279-1971. 3. SRP Appendix 7.1-C provides guidance for evaluating conformance to IEEE Std 603-1991. 4. SRP Appendix 7.1-D provides guidance for evaluating conformance to the acceptance criteria contained in RG 1.152, “Criteria for Digital Computers in Safety Systems of Nuclear Power Plants,” which endorses IEEE Std 7-4.3.2, “IEEE Standard Criteria for Digital Computers in Safety Systems of Nuclear Power Generating Stations.” 7.8-6 Draft Revision 6