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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Content:
ew and, therefore, they do not represent official NRC staff positions. This regulatory guide contains information collections that are covered by the requirements of 10 CFR Part 50 which the Office of Management and Budget (OMB) approved under OMB control number 3150-0011. The NRC may neither conduct nor sponsor, and a person is not required to respond to, an information collection request or requirement unless the requesting document displays a currently valid OMB control number. DG-1142, Page 4 B. DISCUSSION Both Regulatory Guide 1.89, “Environmental Qualification of Certain Electric Equipment Important to Safety for Nuclear Power Plants,” issued November 1974, and Revision 1 of Regulatory Guide 1.89 (1984) endorse IEEE Std. 323-1974, “IEEE Standard for Qualifying Class 1E Equipment for Nuclear Power Generating Stations.” Regulatory Guide 1.89 specifically limits its scope to compliance with 10 CFR 50.49 “with regard to qualification of electric equipment important to safety for service in nuclear power plants to ensure that the equipment can perform its safety function during and after a design-basis accident.” Thus, Regulatory Guide 1.89 focuses on the environmental qualification of equipment intended for use in harsh environments that are subject to design-basis accidents. The IEEE Std. 323 definition of qualification is “generation and maintenance of evidence to ensure that the equipment will operate on demand to meet system performance requirements.” In effect, environmental qualification is verification and validation that a design adequately accommodates the effects of, and is compatible with, the environmental conditions associated with the normal, abnormal, and accident conditions that the equipment or system might encounter. The Code of Federal Regulations defines a mild environment as one “that would at no time be significantly more severe than the environment that would occur during normal plant operation, including anticipated