Glossary of Terms in PRIS Reports


A

Advanced Gas-cooled Reactor
AGR An advanced gas-cooled reactor (AGR) is a type of nuclear reactor. The second generation of British gas-cooled reactors, using graphite as the neutron moderator and carbon dioxide as a coolant.  

 

B

Boiling Water Reactor
BWR Boiling light water cooled and moderated reactor. In a BWR, the reactor core heats water, which turns to steam and then drives a steam turbine.  

 

C

Capacity Factor
CF Capacity factor: The actual energy output of an electricity-generating device divided by the energy output that would be produced if it operated at its rated power output (Reference Unit Power) for the entire year. Generally expressed as percentage. In PRIS a term Load Factor (LF) is used for CF.  

 
Commercial Operation
In PRIS a commercial operation of a reactor is from its Commercial Date. A period from the first grid connection to the Commercial Date is called 'trial operation'. Performance Indicators in PRIS reports are calculated for commercial operation. Electricity production is calculated from the...  

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Commercial Operation Start
The date when the plant is handed over by the contractors to the owner and declared to be officially in commercial operation.  

 
Construction Start Date
The date when first major placing of concrete for the base mat of the reactor building is made. For floating NPP the construction start date is the beginning of platform construction. From this date the reactor is considered to be under construction.  

 
Country Nuclear Power Profiles
CNPP The CNPP compile background information on the status and development of nuclear power programmes. It consists of organizational and industrial aspects of nuclear power programmes and provides information about the relevant legislative, regulatory, and international frameworks in each country.  

 

D

Design Net Capacity
The original Design Net Capacity (electrical power) is the unit electrical output after deducting the self-consumption power assumed by the original unit design, no matter if it has ever been routinely achieved during operation. This value does not reflect possible power changes during subsequent...  

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E

Electricity Supplied
Net electrical energy produced during the reference period as measured at the unit outlet terminals, i.e. after deducting the electrical energy taken by unit auxiliaries and the losses in transformers that are considered integral parts of the unit. Also called Net Energy Generated. Measured in...  

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Energy Availability Factor
EAF The energy availability factor over a specified period, is the ratio of the energy that the available capacity could have produced during this period, to the energy that the reference unit power could have produced during the same period. The energy availability factor is determined for each...  

  More info: http://www-pub.iaea.org/MTCD/Publications/PDF/TRS428_web.pdf Full Description
Energy Unavailability Factor
EUF Energy unavailability factor can be calculated from the relationship: EUF = 100 - EAF over a specific time period Where: EAF = energy availability factor  

 

F

Fast Breeder Reactor
FBR Fast neutron reactors use fast neutrons to cause fission in their fuel. They do not have a neutron moderator, and use less-moderating coolants  

  More info: http://www-pub.iaea.org/MTCD/Publications/PDF/te_1531_web.pdf
First Criticality Date
The date, when the reactor is made critical for the first time.  

 
Forced Loss Rate
FLR Operating period forced loss rate is defined as the ratio of the unplanned energy losses during a given period of time, considering only the operating period, to the reference energy generation minus energy losses corresponding to planned outages and their possible unplanned extensions, during the...  

  More info: http://www-pub.iaea.org/MTCD/Publications/PDF/TRS428_web.pdf Full Description

G

Gas Cooled Reactor
GCR A gas-cooled reactor is a nuclear reactor that uses graphite as a neutron moderator and carbon dioxide (helium can also be used) as coolant.  

 
Gigawatt
GW The gigawatt is equal to one billion (10^9) watts or 1 gigawatt = 1000 megawatts. In the electric power industry, gigawatt electrical (abbreviation: GWe or GW(e) is a term that refers to electric power, while megawatt thermal or thermal megawatt (abbreviations: GWt, GW(th) refers to thermal power.  

 
Gigawatt-hour
GWh A gigawatt hour (GWh or GW.h) is a unit of electrical energy equal to 1000 megawatt hours (MWh) and equal to one billion (10^9) watt hours, 3.6 terajoules, or 3.41 billion British thermal units (Btu).  

 
Grid Connection Date
The date on which the plant is first connected to the electrical grid for the supply of power. After this date, the plant is considered in operation.  

 
Gross Capacity
Reference gross electrical power of the plant expressed in MW(e). The maximum (electrical) power that could be maintained continuously throughout a prolonged period of operation under reference ambient conditions. The gross electrical power is measured at the output terminals of the turbine...  

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L

Light Water Cooled Graphite Moderated Reactor
LWGR Light water cooled graphite moderated reactor. Also known as RBMK. Using light water for cooling and graphite for moderation, it is possible to use natural uranium for fuel.  

 
Load Factor
LF Load Factor, also called Capacity Factor, for a given period, is the ratio of the energy which the power reactor unit has produced over that period divided by the energy it would have produced at its reference power capacity over that period. Reference energy generation (net) is the energy that...  

  More info: http://www-pub.iaea.org/MTCD/Publications/PDF/TRS428_web.pdf Full Description

M

Megawatt
MW The megawatt is equal to one million (10^6) watts. In the electric power industry, megawatt electrical (abbreviation: MWe or MW(e) is a term that refers to electric power, while megawatt thermal or thermal megawatt (abbreviations: MWt, MWth) refers to thermal power.  

 
Megawatt-hour
MWh A megawatt hour (MWh or MW.h) is equal to 1000 kilowatt hours (KWh). It is an energy equal to 1000 kilowatts of electricity used continuously for one hour.  

 

N

Non-electrical Application
Some power reactor units produce a portion of their output energy in the form of heat/steam for non-electrical applications (desalination, district heating and industrial heat). This energy is also reported into PRIS.  

 
Nuclear Power Plant
NPP A nuclear power plant is a thermal power station in which the heat source is one or more nuclear reactors. As in a conventional thermal power station the heat is used to generate steam which drives a steam turbine connected to a generator which produces electricity.  

 
Nuclear Share
Percentage share by country of electricity generation mix for nuclear power. The ratio of the nuclear electricity production, to the total electricity production from all sources in a country.  

 
Nuclear Steam Supply System
NSSS The NSSS consists of a nuclear reactor and all of the components necessary to produce high pressure steam, which is used to turn the turbine for the electrical generator.  

 

O

On-line Hours
Total number of hours in the reporting period during which the unit was operated with at least one main generator connected to the grid.  

 
Operation Factor
OF Operation factor is defined as the ratio of the number of hours the unit was on-line to the total number of hours in the reference period, expressed as a percentage. It is a measure of the unit time availability on the grid and does not depend on the operating power level (UNIPEDE denote it as a...  

  More info: http://www-pub.iaea.org/MTCD/Publications/PDF/TRS428_web.pdf Full Description
Operational Reactor
In PRIS a reactor is considered as 'operational' or 'in operation' from its first grid connection to permanent shutdown. Thus, when a reactor is temporarily not generating electricity because of outages for, e.g. refuelling, maintenance, repair, large refurbishment or political decision, the...  

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Operator
It is the company which currently operates the nuclear power plant  

 
Outage
For the purpose of PRIS coding, the 'outage' is defined as any status of a reactor unit, when its actual output power is lower than the reference unit power for a period of time. By this definition, the outage includes both power reduction and unit shutdown.  

 
Outage Coding System
The PRIS outage coding is primarily focused on reporting power production losses. The coding includes only those aspects of the outage events that can be useful in analyses focused on elimination of unnecessary power losses. The coding consists of three major codes: • The first code identifies...  

  More info: http://www-pub.iaea.org/MTCD/Publications/PDF/TRS428_web.pdf Full Description
Owner
It is the company which owns a nuclear power plant majority.  

 

P

Permanent Shutdown Date
The date, when the plant is officially declared by the owner to be taken out of commercial operation and shut down permanently without any intention to re-start the unit.  

 
Power
The rate of producing, transferring, or using energy, most commonly associated with electricity. Power is measured in watts and often expressed in kilowatts (kW) or megawatts (MW).  

 
Power Reactor
A nuclear reactor is a device to initiate and control a sustained nuclear chain reaction. In a power reactor, the energy released is used as heat to make steam to generate electricity.  

 
Pressurized Heavy Water Reactor
PHWR A pressurised heavy water reactor (PHWR) is a nuclear power reactor, commonly using unenriched natural uranium as its fuel, that uses heavy water (deuterium oxide D2O) as its coolant and moderator.  

 
Pressurized Water Reactor
PWR Pressurized light water moderated and cooled reactor. In a PWR, the reactor core heats water, which does not boil. This hot water then exchanges heat with a lower pressure water system, which turns to steam and drives the turbine.  

 
PRIS-Statistics
PRISTA A web-based reporting application used by registered users to produce reports and statistics from PRIS.  

  More info: prisweb.iaea.org

R

Reactor Model
The reactor model identifies a specific reactor design series (e.g. Magnox, AGR, VVER V-213, Konvoi, EPR, BWR-6, etc.) within a particular reactor type (GCR or PWR respectively). All models of the same reactor type usually have the same basic design charactersitics (moderator and coolant type and...  

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Reactor Status
One of the stages of a power reactor during its lifecycle: - Under construction - Operational - In long-term shutdown - Permanently shut down  

 
Reactor Type
Classification of power reactors by coolant and moderator material: BWR -- Boiling Light-Water-Cooled and Moderated Reactor; FBR -- Fast Breeder Reactor; GCR -- Gas-Cooled, Graphite-Moderated Reactor; HTGR -- High-Temperature Gas-Cooled, Graphite-Moderated Reactor; HWGCR...  

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Reference Energy Generation
REG Reference energy generation (MWh or GWh) for the period is the net electricity output that would be produced if a reactor unit is operated at its rated power output for the entire period.  

 
Reference Unit Power
RUP The reference unit power expressed in units of megawatt (electrical) is the maximum (electrical) power that could be maintained continuously throughout a prolonged period of operation under reference ambient conditions. The power value is measured at the unit outlet terminals, i.e. after deducting...  

  More info: http://www-pub.iaea.org/MTCD/Publications/PDF/TRS428_web.pdf Full Description

S

Scram
The reactor scram is defined as a reactor shutdown achieved by rapid insertion of negative reactivity into the reactor core, which can be performed either manually or automatically by actuation of the reactor protection system.  

 
Suspended Operation
Susp. Op A reactor is considered in the suspended operations status, if it has been shut down for an extended period (usually more then one year) and there is the intention to re-start the unit but: 1. restart is not being aggressively pursued (there is no vigorous onsite activity to restart the...  

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T

Terawatt-hour
TWh A terawatt hour (TWh or TW.h) is a unit of electrical energy equal to 1000 gigawatt hours (MWh).  

 
Thermal Capacity
The Reference thermal power of the plant expressed in MW(th). The reactor thermal power is the net heat transferred from the fuel to the coolant.  

 
Trial Operation
In PRIS a reactor is in trial operation from its first grid connection to the date when it is offically declared in commercial operation (Commercial Operation Date)  

 

U

Unit Capability Factor
UCF Unit capability factor is defined as the ratio of the available energy generation over a given time period to the reference energy generation over the same time period, expressed as a percentage. Both of these energy generation terms are determined relative to reference ambient...  

  More info: http://www-pub.iaea.org/MTCD/Publications/PDF/TRS428_web.pdf Full Description
Unplanned Capability Loss Factor
UCL The ratio of the unplanned energy losses during a given period of time, to the reference energy generation, expressed as a percentage. Unplanned energy loss is energy that was not produced during the period because of unplanned shutdowns, outage extensions, or unplanned load reductions due to...  

  More info: http://www-pub.iaea.org/MTCD/Publications/PDF/TRS428_web.pdf Full Description

W

Web-Enabled Data Acquisition System
WEDAS Web based application used by PRIS data providers for on-line data entry to the PRIS database.  

  More info: prisweb.iaea.org/wedas