Document: NRC Regulatory Guide
Document ID: 26c3e31f-c018-4aee-b926-6db849b72a5a
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:
ds focus on a preventive approach, employing isolation and detection practices. In addition, postevent recovery procedures can mitigate the extent of smoke damage. Moreover, certain design choices and construction practices, such as chip packaging and conformal coatings, can reduce equipment susceptibility to smoke exposure. In the absence of acceptable methods and practices for smoke-tolerant design and installation, the most effective approach for addressing smoke susceptibility is to minimize the likelihood of smoke exposure by rigorously adhering to the fire protection guidance in Appendix R, “Fire Protection Program for Nuclear Power Facilities Operating Prior to January 1, 1979,” to 10 CFR Part 50. The safety goal of qualification is to avoid a common-cause failure of the safety-related system when it is needed to perform its safety function. The unique functional and hardware characteristics of computer-based I&C systems suggest that qualification guidance should explicitly state special considerations. These special considerations constitute good engineering practices that the industry generally follows. Nonetheless, the NRC staff developed this regulatory guide to promote clarity and avoid uncertainty, encourage the retention of the qualification records, and endorse the most appropriate standard. This guide does not intend to imply that a qualified life should be established for I&C systems in mild environments. Therefore, for the purposes of this guide, qualification is a validation of design to demonstrate that a safety-related computer-based I&C system is capable of performing its safety function under the specified environmental and operational stresses. DG-1142, Page 7 C. REGULATORY POSITION The procedures described in IEEE Std. 323-2003 are appropriate for satisfying the environmental qualification of safety-related computer-based I&C systems for service in mild environments at nuclear power plants. The standard can be applied subject to the