Document: NRC Regulatory Guide
Document ID: e16da529-b6b4-4fdf-bc3f-7490180363f3
Document Type: regulatory_guide
Title: Environmental Qualification of Certain Electric Equipment Important to Safety for Nuclear Power Plants (Rev. 2)
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML2018/ML20183A423.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.89
CFR Part: 
CFR Title: 

Content:
CFR 50.49(b)(3) requires that certain post-accident monitoring equipment also be environmentally qualified. RG 1.97 includes regulatory guidance for post-accident monitoring equipment. While the above describes the electric equipment that is within the scope of 10 CFR 50.49, the NRC, in the introduction to 10 CFR Part 50, Appendix A, also states that “important to safety” SSCs are those SSCs that provide reasonable assurance that the facility can be operated without undue risk to public health and safety. c. The following definition of “qualified life” should be used instead of the definition in Section 3.20 of IEC/IEEE Std. 60780-323, Edition 1, 2016-02: “period for which an equipment has been demonstrated, through testing, analysis and/or experience, to be capable of remaining functional during and following design basis events to ensure that the criteria specified in 10 CFR 50.49(b)(1)(i)(A), (B), and (C) are satisfied.” 10 CFR 50.49(b)(1)(i) addresses the EQ functional requirements and states as follows: This equipment is that relied upon to remain functional during and following design basis events to ensure— (A) The integrity of the reactor coolant pressure boundary; (B) The capability to shut down the reactor and maintain it in a safe shutdown condition; or (C) The capability to prevent or mitigate the consequences of accidents that could result in potential offsite exposures comparable to the guidelines in 10 CFR 50.34(a)(1), 50.67(b)(2), or 100.11 of this chapter, as applicable. d. The term “service life,” as defined in Section 3.22 of IEC/IEEE Std. 60780-323, Edition 1, 2016- 02, implies that aging effects are insignificant unless the equipment is in service. However, the period before the operational phase of the SSC (i.e., shelf life) could also adversely impact the qualified life. DG-1361, Page 11 Therefore, the following definition of “service life” should be used instead of the definition in Section 3.22 of IEC/IEEE Std.