IEEE 308:2020 pdf free download – IEEE Standard Criteria for Class 1E Power Systems for Nuclear Power Generating Stations
nuclear power generating station (station): A plant where electric energy is produced from nuclear energyby means of suitable apparatus. The station may consist of one or more generating units.
passive reactor design: A reactor design that uses forces of nature, such as fluid density differences andheat transfer, to create natural circulation cooling on a scale sufficient to replace large active components foraccident and operational event response.This eliminates the need for forced coolant circulation and associatedactive components requiring Class 1E ac power for accident and operational event response.
power sources: The electrical and mechanical equipment and interconnections necessary to generate orconvert power.
NOTE—Electric power source and power supply are interchangeable within the context of this document.
preferred power supply: The power supply from the transmission system to the Class 1E distribution systemthat is preferred to furnish electric power under accident and post-accident conditions.
programmable digital device: A device that can store instructions and is capable of executing a systematicsequence of operations performed on data that is controlled by internally stored instructions.
protection system: The part of the sense and command features involved in generating the signals usedprimarily for the reactor trip system and engineered safety features.
protective action: The initiation of a signal within the sense and command features, or the operation ofequipment within the execute features, to accomplish a safety function.
redundant equipment or system: A piece of equipment or a system that duplicates the essential function ofanother piece of equipment or system to the extent that either may perform the required function regardless ofthe state of operation or failure of the other.
NOTE—Redundancy can be accomplished by using identical equipment, cquipment diversity, or functional diversity.
safety class structures: Structures designed to protect Class 1E equipment against the effects of design basisevents.
safety function: One of the processes or conditions (e.g., emergency negative reactivity insertion, post-accident heat removal, emergency core cooling, post-accident radioactivity removal, containment isolation)essential to maintain plant parameters within acceptable limits established for a design basis event.
NOTE—A safety function is achieved by the completion of all required protective actions by the reactor trip system andthe engineered safety features, or both,concurrent with the completion of all required protective actions by the auxiliarysupporting features.
safety group:A given minimal set of interconnected components, modules, and equipment that can accomplisha safety function.
NOTE—A safety group may include one or more divisions. In a design where each division can accomplish a safetyfunction, each division is a safety group.However, a design consisting of three 50% capacity systems separated into threedivisions would have three safety groups; any two out of three divisions are required to be operating to accomplish thesafety function.
4.2 Relationship between the safety system and Class 1E power system
The portions of the Class 1E power system that are required to support safety systems in the performance oftheir safety functions shall meet the requirements of IEEE Std 603IM.
Other components, equipment, and systems within Class 1E power systems that have no direct safety functionand are provided only to increase the availability or reliability of the Class 1E power system shall meet therequirements in IEEE Std 603 to confirm that these components, equipment, and systems do not degrade theClass 1E power system below an acceptable level.
The safety system criteria that these elements would not have to meet, for example,include the criteria asdefined in IEEE Std 603 for operating bypass, maintenance bypass, and bypass indication.An analysis shallbe made to confirm that when these components, equipment, or systems are utilized, the consequences of anyoperation or failure are acceptable to the Class 1E power system.