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:
an 1 hour can be justified. This justification for each piece of equipment should include the following: (1) consideration of a spectrum of breaks, (2) the potential need for the equipment later in an event or during recovery operations, (3) a determination that failure of the equipment after performance of its safety function will not be detrimental to plant safety or mislead the operator, and (4) a determination that the margin applied to the minimum operability time, when combined with the other test margins, will account for the uncertainties associated with the use of analytical techniques in the derivation of environmental parameters, the number of units tested, production tolerances, and test equipment inaccuracies. For all other equipment (e.g., post-accident monitoring), the 10-percent margin for equipment operating time identified in Section 7.4.1.7 should be used. m. Section 7.4.1.9.3 of IEC/IEEE Std. 60780-323, Edition 1, 2016-02, should be supplemented with the following: “For insulating materials, a regression line (IEEE Std. 101, “IEEE Guide for the Statistical Analysis of Thermal Life Test Data” (Ref. 32)), may be used as a basis for selecting the aging time and temperature. Sample aging times of less than 100 hours should not be used.” n. Section 7.4.1.10 of IEC/IEEE Std. 60780-323, Edition 1, 2016-02, notes that a double peak test profile (with the same design-basis event temperature profile magnitude) is not required but may be used instead of one peak profile to increase the severity of the design-basis event test. The concept of applying a double transient test profile first appeared in the 1974 version of IEEE Std. 323. Item 7 in Section 6.3.1.5 of IEEE Std. 323-1974 specified that the initial transient and the dwell at peak temperature needed to be applied at least twice. Appendix A to IEEE Std. 323-1974 also included a figure that showed a representative test chamber profile for a combined PWR and BWR test. IEEE Std. 323-1974 stated,