Document: NUREG-0800
Document ID: 6f2ffbec-a876-42d7-a247-d27c02ea9b4a
Document Type: srp
Title: DIVERSE INSTRUMENTATION AND CONTROL SYSTEMS
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML1602/ML16020A096.pdf
Revision Date: 2023-06
Chapter: 7
Section ID: 7.8
CFR Part: 
CFR Title: 

Content:
, RGs, and branch technical positions (BTPs). The SRP is not a substitute for the NRC’s regulations, and compliance with it is not required. However, an applicant is required to identify differences between the design features, analytical techniques, and procedural measures proposed for its facility and the SRP acceptance criteria and evaluate how the proposed alternatives to the SRP acceptance criteria provide acceptable 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 SRM on SECY-93-087. The 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, “Guidance for Evaluation of Conformance to IEEE Std 279,” provides guidance for evaluating conformance to the requirements of IEEE Std 279-1971. 7.8-6 Revision 6 – August 2016 3. SRP Appendix 7.1-C, “Guidance for Evaluation of Conformance to IEEE Std