Interactive visualization developed by World Nuclear Industry Status Report (WNISR) and Visionscarto
for the Bulletin of the Atomic Scientists with support of the Pulitzer Center on Crisis Reporting.

Frequently Asked Questions (FAQ)


The information in this data visualization is based on the World Nuclear Industry Status Report (WNISR) Database, a Mycle Schneider Consulting Project, updated to 1 January 2017. Additional updates will be made as needed. The database covers commercial nuclear power reactors for which construction has or had started and does not include “planned” or “projected” power reactors. It also excludes research, heating or military reactors that do or did not generate power.

Sources of Data

The Worldwide Nuclear Power Reactor Construction Data Visualization is based on the WNISR Nuclear Reactor Database. Historic data are often drawn from the International Atomic Energy Agency's (IAEA) Power Reactor Information System (PRIS), from the World Nuclear Association's (WNA) online database, and from WNISR’s own research. The annual WNISR provides hundreds of bibliographical references, all of which are available on the WNISR website.

Information on reactor characteristics (type, model, capacity, provider, operator) are mainly drawn from IAEA-PRIS. Provider groupings by country or international consortia have been established by WNISR.

The main discrepancies between IAEA and WNISR data relating to reactor constructions:

• IAEA data depends on information provided by Member States; WNISR research attempts to establish which construction projects can be considered "active." If several credible sources—either in the open literature or from the WNISR's international network of contacts—corroborate a given status, a project will be either added to or withdrawn from the IAEA's list of reactors "under construction."

• The IAEA sometimes creates "new" construction-start dates, when there has been a significant interruption in the building of a nuclear power plant. WNISR tries to document these interruptions, but does not modify the original construction start date.

• Construction data in IAEA-PRIS have not only changed over the years for some reactors; some reactors have simply disappeared from the system. Not all of those changes are reflected in the WNISR database.


Construction Start

The date of a construction start is considered to be the moment the concrete base slab of the reactor building is being poured. Site preparation and excavation work are not included. For floating reactors (Russia and China), as no concrete is being poured, WNISR uses the “keel laying ceremony” of the barge as the construction start date.

Construction Suspension or Abandonment

Over the years, in many cases reactor construction has been suspended or abandoned. Suspension and cancellation apply only to “construction” and not to “projected” or “planned” reactors. Reactors enter the WNISR statistical database only when construction has started.

• Temporary Suspension

A reactor construction project that was once suspended but has resumed.

• Indefinite Suspension

A construction declared “suspended”—by the operator, authorities, regulators, etc., or listed as “suspended” in the IAEA-PRIS—that has not resumed as of January 1, 2017, and has no date or real prospect of restart. This includes non-official suspensions, for which WNISR has determined that there is de facto no active construction and no prospect of timely restart.

• Abandoned Construction

A construction declared cancelled, by the operator, authorities, regulators, etc. or through any other official decision, or listed as “cancelled” in IAEA-PRIS. Some cancellations have been listed in the IAEA publication series “Nuclear Power Reactors in the World,” that are not yet included in the WNISR database. This includes non-official abandonments, for which WNISR has determined that there is de facto no active construction and no prospect of restart.

Reactor Startup (or Grid Connection)

The WNISR definition of reactor startup is its grid connection. In the case of reactor construction, the expected startup date is not always expressed in terms of grid connection, but often as "commissioning," “completion,” “commercial operation,” or other, similar terminology. Expected startup is not always connected to a precise date; rather, it can be general, as in "early 2017," or "second semester 2018." WNISR uses “best estimates,” based on a variety of sources, when providing expected startup dates.

Construction Time

The total construction time is the entire length of a reactor's construction period, from construction start until it is (or is expected to be) connected to the grid or its construction is abandoned (canceled or indefinitely suspended). Temporary suspension periods are included in the total construction time.


Current Status

The “Current Status” of reactors is given as of the latest update of the data visualization. The status is currently as of January 1, 2017.

Under Construction

The status of a reactor is “Under Construction as of January 1, 2017” when:

The number of reactors “Under Construction” by year refers to the total number of reactors that met the “Under Construction” criteria as of December 31 of the respective year:

“Delayed Startup”

“Delayed Startup” applies to reactors under construction, for which the expected startup is later than the expected startup date at construction start.


A reactor is considered Abandoned (Cancelled or Indefinitely Suspended) as of January 1, 2017 when:

Cancelled Constructions and Indefinite (not resumed) Suspensions are grouped under the term “Abandoned” constructions.

Completed Constructions

Completed Construction applies to all reactors that have reached grid connection, i.e., they are actually operating, in long-term outage (LTO), or in shutdown

In Operation (or Operating)

A reactor is considered in operation:

A reactor can be retroactively withdrawn from “In Operation” status from the day it was disconnected from the grid (either to enter the LTO status or to be considered as in permanent shutdown).

In Long-Term Outage (or LTO)

A nuclear reactor is considered in long-Term outage or LTO:

Permanent Shutdown

A nuclear reactor is considered as in permanent shutdown:

Reactor Characteristics

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 (IAEA-PRIS Manual). The NSSS is also called the nuclear island.

Nuclear Provider

The indicated nuclear provider is mainly based on the Nuclear Steam Supply System (NSSS) provider, as in IAEA-PRIS as of December 2016. In some cases, the nuclear provider has changed during construction. The WNISR database does not yet account for all of these changes.


WNISR generally uses the net electricity generating capacity as in IAEA-PRIS.

For the construction data visualisation, it refers to the design net capacity.


This interactive visualization was built for The Bulletin of the Atomic Scientists by the core team of the World Nuclear Industry Status Report (WNISR) (data & analysis) and (design & programming). We are grateful for assistance and funding provided by The Bulletin and the Pulitzer Center on Crisis Reporting.


For any question, remarks or corrections regarding the content of this visualization, please get in touch with contact@worldnuclearreport; for all technical issues please inquire with