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
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CFR Title: 

Content:
ready accessibility for monitoring and maintenance in mild environments, the need to establish a qualified life does not apply. Nonetheless, the qualification criterion of 10 CFR 50.55a(h)(2) shall be addressed for safety-related computer-based I&C systems. This regulatory guide describes a method that the NRC staff considers acceptable for determining the environmental qualification procedures for safety-related computer-based I&C systems for service within nuclear power plants. In so doing, this guide endorses certain practices in the current national standard, and it incorporates guidance to address specific issues posed by the application of microprocessor-based technology. Adherence to these qualification practices contributes to ensuring that a computer-based I&C system can perform its safety-related function under all anticipated service conditions. This guide complements Revision 1 of Regulatory Guide 1.89, “Environmental Qualification of Certain Electric Equipment Important to Safety for Nuclear Power Plants,” issued June 1984, which addresses compliance with 10 CFR 50.49, “Environmental Qualification of Electric Equipment Important to Safety for Nuclear Power Plants,” for harsh environments that are subject to design-basis accidents. The NRC staff accepted the Electric Power Research Institute (EPRI) Topical Report (TR) 107330, “Generic Requirements Specification for Qualifying Commercially Available PLC for Safety-Related Applications in Nuclear Power Plants,” in a safety evaluation report (SER) by letter dated July 30, 1998. The EPRI report includes guidance on an acceptable method for addressing mild-environment qualification of programmable logic controllers (PLCs). The mild-environment qualification practices endorsed in this regulatory guide are equivalent to, and consistent with, those described in the EPRI TR. The primary distinctions between the two methods are that the scope of this regulatory guide focuses exclusively on