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Technical Working Groups on Advanced Technologies for Light Water Reactors and Heavy Water Reactors (TWG-LWR and TWG-HWR)

The Technical Working Groups on Advanced Technologies in Light Water Reactors (TWG-LWR) and Heavy Water Reactors (TWG-HWR) are groups of international experts who provide advice and support IAEA programme implementation in the area of advanced technologies for water cooled reactors (WCRs) utilized for the production of electricity and/or heat.

The IAEA has been serving interested Member States as a focal point for information exchange and collaborative research and technology development for WCRs. The TWG-LWR was established in 1987, with the TWG-HWR following in 1997.  Both Working Groups address advances in national programmes, systems analyses and fuel utilization, including research and development, design, performance and cost related aspects of the reactor core, plant systems and components, and reactor and plant structures and containment.

The members of these Technical Working Groups are appointed by the IAEA Deputy Director General, Head of the Department of Nuclear Energy, following consultation with the respective national authorities or organizations.

Scope and Functions

The scope of both TWGs, which hold joint meetings, covers:

  • Design and technology development for current and advanced WCR concepts;
  • Economics, performance and safety for current and advanced WCRs; and
  • Infrastructure specific to the development and deployment of WCRs.

The TW-LWR and TWG-HWR provide advice and guidance and marshal support in Member States for the implementation of the IAEA's programmatic activities in advanced technologies for WCRs. They act as a forum for information and knowledge sharing on national and international projects in WCRs and advise on preparatory actions in Member States and the IAEA to plan and implement coordinated research programmes, collaborative assessments and other activities. They also review results of projects on advanced technologies for LWRs and HWRs. The TWGs develop and/or review selected documents for publication in the IAEA Nuclear Energy Series, assess existing gaps in IAEA literature and advise on the preparation of new publications.

The TWG-LWR and TWG-HWR coordinate their activities with other IAEA activities in interfacing areas, as well as with the work of other international organizations to avoid any duplications. Specifically, activities in areas common to both reactor technologies are conducted jointly by the Working Groups.


Full Members of the TWG-LWR include:

Argentina, Brazil, China, Czech Republic, Finland, France, Germany, India, Italy, Japan, Republic of Korea, Russian Federation, South Africa, Spain, Sweden, Switzerland, UK, USA and the OECD Nuclear Energy Agency (OECD/NEA)

Observer: Mexico

Full members of the TWG-HWR include:

Argentina, Canada, China, India, Republic of Korea, Pakistan, Romania.


The TWG-LWR and the TWG-HWR meet at regular intervals but not more than once a year, with each meeting lasting up to five working days. Extraordinary meetings may be called when required.

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