Document: NRC Regulatory Guide
Document ID: 086612c4-a8a7-4f50-a166-6f1cb05bcdaf
Document Type: regulatory_guide
Title: Guidelines for Environmental Qualification of Safety-Related Computer-Based Instrumentation and Control Systems in Nuclear Power Plants
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML0630/ML063040591.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.209
CFR Part: 
CFR Title: 

Content:
pplicants, and licensees to benefit from the existing national consensus standard. Toward that end, the staff compared different versions of qualification standards to determine how the latest updates have identified new qualification issues. In particular, the staff conducted a comparative analysis of IEEE Std. 323-1974 and IEEE Std. 323-1983 (reaffirmed in 1991 and 1996). A subsequent review of IEEE Std. 323-2003 revealed consistency with previous findings. The following significant findings resulted from the analysis of the original and latest versions of this standard: • The qualification methods (type testing, operating experience, and analysis) are identical in both versions. However, digital I&C generally undergoes more rapid evolutions than equivalent analog components. Thus, obtaining sufficient documentation on operating experience under identical environmental conditions for a particular I&C system for qualification purposes may be difficult. Therefore, type testing should be the preferred qualification method. DG-1142, Page 12 • IEEE Std. 323-2003 refers to standards for testing the EMI/RFI as an environmental condition, but the standard does not specifically prescribe the conduct of tests within the type-test sequence. Nonetheless, Revision 1 of Regulatory Guide 1.180 provides specific guidance on EMI/RFI susceptibility tests. • Both versions provide the same essential details on qualification by operating experience. • Both versions provide essentially the same procedures for qualification by analysis. 4. Values and Impacts This section analyzes the values and impacts for each of the three identified approaches. In this analysis, the probability of an alternative approach having a positive effect on qualification is not known quantitatively, nor is the probability of achieving the overall safety goals. However, on the basis of a qualitative assessment of existing literature, experience with military applications of digital I&C, commercial