Prior to 1962, the 50.59 process for modifying a nuclear plant without requiring prior Commission approval did not exist. There was no UFSAR. There were only Technical Specifications, the Hazards Summary Report, and license amendments. This is a summary of the 50.59 rule’s evolution, from 1961 to today…Continue reading “10 CFR 50.59 – A history of the rule’s development”
Category: Licensing Basis
50.59 – Why 10% is the criterion for determining “more than a minimal” increase
It’s given as guidance in NEI 96-07 without a basis, and 10% is not mentioned in the regulations at all. But the basis isn’t arbitrary. Here is the reason…Continue reading “50.59 – Why 10% is the criterion for determining “more than a minimal” increase”
Class 1E Definition
The Class 1E definition is found in IEEE 308. It is associated with electrical power systems found in nuclear power plants.
IEEE 323 – Qualifying electrical equipment to the harsh environments of nuclear power plants
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 “IEEE 323 – Qualifying electrical equipment to the harsh environments of nuclear power plants”
Technical Requirements Manual
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 “Technical Requirements Manual”
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 “Class 1E circuit independence – a summary of IEEE 384-1992”
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 . . . .
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. . . .
Continue reading “Redundancy and the single-failure criterion”