Document: NRC Regulatory Guide
Document ID: 82021804-a487-471b-a76c-095315525b53
Document Type: regulatory_guide
Title: Guidelines for Evaluating Electromagnetic and Radio-Frequency Interference in Safety-Related Instrumentation and Control Systems (Rev. 2)
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML1628/ML16281A531.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.180
CFR Part: 
CFR Title: 

Content:
wn for little load or capacitor switching and limited power surge activity, while elevated withstand levels are appropriate for locations where primary power is provided through connection to external lines or there are sources of significant switching transients present. Table 23 lists the withstand levels that are acceptable for nuclear power plant application. Interior locations where safety-related I&C systems either are or are likely to be installed include control rooms, remote shutdown panels, cable spreading rooms, equipment rooms, auxiliary instrument rooms, relay rooms, and other areas (e.g., the turbine deck). Most locations where safety-related I&C systems are likely to be installed can be characterized as having low surge conditions. However, locations where primary power is provided through direct connection to external lines or there are sources of significant switching transients present (e.g., switchgear, large motors) should be treated as being subject to elevated surge conditions. A determination of the exposure conditions that characterize a location is necessary to select instances where the elevated withstand level should be met. DG-1333, Page 27 Table 23 Surge Withstand Levels for Power Lines Surge Waveform Low Withstand Level Elevated Withstand Level Ring Wave 2 kV 4 kV Combination Wave 2 kV / 1 kA 4 kV / 2 kA EFT 2 kV 4 kV 5.1 IEEE Std. C62.41 Ring Wave and IEC 61000-4-12 The Ring Wave simulates oscillatory surges of relatively high frequency on the ac power leads of equipment and subsystems and is represented by an open-circuit voltage waveform. The waveform, a 100-kHz sinusoid, has an initial rise time of 0.5 µs and continually decaying amplitude. A plot of the waveform is shown in Figure 5.1. The rise time is defined as the time difference between the 10% and 90% amplitude points on the leading edge of the waveform. The amplitude of the waveform decays with each peak being 60% of the amplitude of the preceding peak of the opposite