THE BIG PICTURE: Small Modular Reactors

Interest in small modular reactors (SMRs) has ramped up of late owing to applications in niche electricity or energy markets where large reactors would not be viable—such as for cogeneration in countries with small grids, remote and off-grid areas, and for nuclear/renewable hybrid projects.

Modular attributes may also enable SMRs to target the economics of serial production, offering shorter construction timeframes. But though significant advancements have been achieved for more than 50 key SMR technologies worldwide in recent years, most continue to crawl through the development pipeline. Source: International Atomic Energy Agency’s (IAEA’s) Advanced Reactors Information Systems (ARIS) database 

Technology Development

Per the ARIS glossary:

Conceptual design: When the key components and layout drawings as well as single line diagrams are available; Brief descriptions of key components and systems are provided; Identification and preliminary analysis of concept relevant incidents and accidents have been performed.

Basic design: When the system descriptions for all plant systems are provided; Safety analyses needed for a design approval have been completed; Licensing documents for certification is available; Procurement specifications and documentation for major components, systems, and structures have been developed; Itemized cost estimate and master schedule for the construction phase have been prepared.

Detailed design: When a largely completed design and a complete construction schedule are available; Manufacturing, procurement specifications are completed; Commissioning specifications are completed.

Under construction: 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.

Technology Types

Land-based water-cooled SMRs: Designs that adopt integral light water reactor (LWR) technologies.

Marine-based water-cooled SMRs: Concepts that can be deployed in a marine environment.

High temperature gas-cooled (HTGR) SMRs: Modular-type designs that provide heat of more than 750C.

Fast neutron spectrum SMRs: Designs with fast neutron spectrum and an assortment of coolant options. These include sodium-cooled fast reactors (SFRs), heavy liquid metal-cooled (HLMC) fast reactors, and gas-cooled fast reactor (GFRs).

Molten salt SMRs. Designs that are fueled and cooled with molten salt.

Other SMRs. SMRs that cannot be classified in other categories.


—Copy and artwork by Sonal Patel, a POWER associate editor (@sonalcpatel, @POWERmagazine)

Corrected (November 2018): Order of columns under technology development reordered to reflect definitions in ARIS glossary: 


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