Category Archives: Licensing Basis

Class 1E Definition

Class 1E Definition

The Class 1E definition is found in IEEE 308. It is associated with electrical power systems found in nuclear power plants.

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IEEE 323 – Qualifying electrical equipment to the harsh environments of nuclear power plants

Cherenkov Radiation in the Advanced Test Reactor core, Idaho National Laboratory

IEEE 323 is the standard used to qualify electrical equipment for safety-related use in nuclear power plants. Here, we explore that standard and its requirements. Continue reading

Technical Requirements Manual

Unlocking productivity

The NRC made some rule changes in the mid-1990’s that simplified a critical component of a nuclear power plant’s licensing basis. This reduced the paperwork burden on both the NRC and the sites. It also gave birth to a new kind of licensing basis document. Continue reading

Class 1E circuit independence – a summary of IEEE 384-1992


Class 1E circuits must be independent from circuits of other categories. Understanding IEEE 384-1992 is vital to understanding the NRC’s circuit separation and isolation requirements. . . .  Continue reading

Diversity and common-mode failures

“Diversity” means using a different kind of technology, equipment, or methodology to perform the same function. Put another way, it’s taking different approaches to solving the same problem . . . .

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Redundancy and the single-failure criterion

“Redundant” means having a second source of power or piece of equipment that acts as a backup in case the first fails to operate properly. . . .

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Redundancy and Diversity

Here are two basic concepts that should be understood by every electrical engineer in the nuclear power industry: redundancy and diversity. They are closely related, but not the same thing . . . .

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Environmental Qualification

Environmental qualification has to do with Class 1E equipment installed in a harsh environment. But it may not be as intuitive as it at first appears . . . .

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