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

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

 
Construction Start Date
The date, when first major placing of concrete, usually for the base mat of the reactor building, is done. From this date the reactor is considered to be under construction.  

 
Country Nuclear Power Profiles
CNPP The CNPP compiles background information on the status and development of nuclear power programs. It consists of organizational and industrial aspects of nuclear power programs and provides information about the relevant legislative, regulatory, and international framework 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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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 operation.

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 as Net Energy Generated. Measured in...  

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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 as Net Energy Generated. Measured in MWh.
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
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Energy Availability Factor

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 period as shown below:
EAF (%) = (REG - PEL - UEL - XEL) / REG x 100
Where:
- REG = reference energy generation for the period
- PEL = total planned energy losses
- UEL = total unplanned energy loss
- XEL = total external energy losses (beyond the plant management control)
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...  

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Forced Loss Rate

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 same period, expressed as a percentage.

Unplanned forced energy loss during the operating period is energy that was not produced during that period because of unplanned shutdowns, or unplanned load reductions due to causes under plant management control.

FLR (%) =FEL/( REG - (PEL+EPL)) x100 %

Where:
- FEL = operating period unplanned forced energy losses for one year
- REG = reference energy generation for one year
- PEL = planned energy losses for one year
- EPL = unplanned extensions of planned outages energy losses for one year

This indicator reflects the effectiveness of plant programs and practices in maintaining systems available for safe electrical generation when the plant is expected to be at the grid dispatcher disposal.

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, GWth) 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, when 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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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 generator.

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 as 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...  

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

Load Factor, also called as 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 could be produced during a given time period if the unit were operated continuously at reference unit power.

The unit load factor is calculated for each period as shown below:
LF (%) = EG / REG x 100%
Where:
- EG = net energy generation (MW.h) for the period
- REG = reference energy generation (net) (MW.h) for the period.

This indicator reflects the actual energy utilization of the unit for electricity roduction.
Long Term Shutdown
LTS Reactor is considered in long-term shutdown status from the Long-term Shutdown date to the Restart Date, if it has been shut down for an extended period (usually more than one year) and any of the following conditions has occurred in early period of shutdown: 1. restart is not being...  

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Long Term Shutdown

Reactor is considered in long-term shutdown status from the Long-term Shutdown date to the Restart Date, if it has been shut down for an extended period (usually more than one year) and any of the following conditions has occurred in early period of shutdown:

1. restart is not being aggressively pursued (there is no vigorous onsite activity to restart the unit) or
2. no firm restart date or recovery schedule has been established, but there is the intention to re-start the unit eventually.

This status may be for example due to technical, economical, strategic or political reasons. This status does not apply to long-term maintenance outages, including unit refurbishment, if the outage schedule is consistently followed, or to long-term outages due to regulatory restrictions (licence suspension), if restart (licence recovery) term and conditions have been established. Such units are still considered "operational" (in a long-term outage).
If an intention not to restart the shutdown unit has been officially announced by the owner, the unit is considered "permanently shut-down".

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 clock 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
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Operation Factor

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 time utilization factor).

On-line hours are the total clock hours in the reference period during which the unit operated with breakers closed to the unit bus. Reference period hours are the total number of hours in the pre-defined calendar time.

The Operation Factor is calculated as shown below:
OF (%) = t/T x 100%
T
Where:
- t = number of hours on-line (h)
- T = reference period in hours (h)
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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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 reactor is still categorized as operational. The only exception to this classification is when the reactor’s status is declared as 'long-term shutdown', then it is excluded from operational reactors even though it has not yet reached permanent shutdown.
Operator
It is the current company that 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
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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 outage date and duration and amount of energy lost due to the outage.
• The second code (Type Code), identifies the kind and extent of the outage and provides technical information about the outage.
• The third code (Cause Code), covers the causes of the outage and the system that was significantly involved in the outage.

To include supplementary information of the outage, a description field is also provided.

The outage coding system clearly refers to a statistical (with “codification” and figures) and not to an event approach (with descriptions and root cause analysis). It constitutes a first level tool for plant performance benchmarking.
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.  

 
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... or VVER V-213, Konvoi , EPR, BWR-6,...) 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...  

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Reactor Model

The reactor model identifies a specific reactor design series (e.g. Magnox, AGR... or VVER V-213, Konvoi , EPR, BWR-6,...) 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 form).
Reactor Status
One of power reactor stages during its lifecycle: - Under construction - In 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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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 -- Heavy-Water-Moderated, Gas-Cooled Reactor
HWLWR -- Heavy-Water-Moderated, Boiling Light-Water-Cooled Reactor
LWGR -- Light-Water-Cooled, Graphite-Moderated Reactor
PHWR -- Pressurized Heavy-Water-Moderated and Cooled Reactor
PBMR -- Pebble Bed Modular Reactor
PWR -- Pressurized Light-Water-Moderated and Cooled Reactor
SGHWR -- Steam-Generating Heavy-Water Reactor
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
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Reference Unit Power

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 the power taken by unit auxiliaries and the losses in the transformers that are considered integral parts of the unit.

The reference unit power is expected to remain constant unless following design changes, or a new permanent authorization, the management decides to amend the original value.

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.  

 

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
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Unit Capability Factor

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 conditions.

Available energy generation is the energy that could have been produced under reference ambient conditions considering only limitations within control of plant management, i.e., plant equipment and personnel performance, and work control.

Reference energy generation is the energy that could be produced if the unit were operated continuously at full power under reference ambient conditions.
Reference ambient conditions are environmental conditions representative of the annual mean (or typical) ambient conditions for the unit.

The unit capability factor is determined for each period as shown below:
value for a unit: UCF (%) = (REG - PEL - UEL)/REG x 100 %

Where:
- REG = reference energy generation for the period
- PEL = total planned energy losses for the period
- UEL = total unplanned energy losses for the period

The purpose of this indicator is to monitor progress in attaining high unit and industry energy production reliability. This indicator reflects effectiveness of plant programs and practices in maximizing available electrical generation, and provides an overall indication of how well plants are operated and maintained.
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
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Unplanned Capability Loss Factor

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 causes under plant management control. Energy loss is considered to be unplanned if it is not scheduled at least four weeks in advance.

Reference energy generation is the energy that could be produced if the unit were operated continuously at full power under reference ambient conditions throughout the period.

The unplanned capability loss factor is determined for each period as shown below:
UCL(%) = UEL / REG x 100%
Where:
- UEL = total unplanned energy losses for the period
- REG = reference energy generation for the period

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