Expert Group on Physics of Reactor Systems (EGPRS)
View of an element being loaded into a ZEBRA (zero energy breeder reactor assembly).


Under the guidance of the Working Party on Scientific Issues and Uncertainty Analysis of Reactor Systems (WPRS), the Expert Group on Physics of Reactor Systems (EGPRS) will perform specific tasks associated with neutronics, radiation transport, reactor physics and nuclear fuel feedback along with uncertainty analysis of present and future nuclear power systems. The considered reactor systems that will be studied include but are not limited to:

  • current fleet of light-water and heavy water reactors (LWRs/HWRs) as well as present generation of fuel designs;
  • evolutionary and innovative LWRs/HWRs along with advanced and/or accident tolerant fuel designs;
  • next generation of core and fuel assembly designs,including water cooled small modular reactors (SMRs),micro-reactors, high temperature gas cooled reactors (HTGR) as well as advanced fast spectrum systems including sodium fast reactors (SFRs) and molten salt reactor systems (MSRs);
  • accelerator driven (sub-critical) and critical systems for waste transmutation as well as fusion systems.


The objective of the EGPRS is to provide expert advice to the WPRS and the nuclear/accelerator community on the development needs (data and methods, validation experiments, scenario studies) for neutronics and fuel feedback issues of different reactor systems.

The fulfilment of this objective notably entails providing specific technical information on:

  • core reactivity characteristics, including fuel depletion effects;
  • core power/flux distributions;
  • core dynamics and reactivity control;
  • fuel physics feedback modelling and effects;
  • fluence, shielding and dosimetry aspects of reactors, accelerators and target irradiation facilities;
  • uncertainty analysis of the above.

This technical information will generally be derived from a combination of direct experimental evidence and/or the results of theoretical benchmark analyses using accurate, validated modelling and simulation (M&S) methods. In either case, the availability of suitable experimental data is a fundamental requirement. The EGPRS will monitor gaps and steer development of the International Radiation Shielding Experiments Database (SINBAD) in collaboration with the United States’ Radiation Safety Information Computational Centre (RSICC).

Current Activities

EGPRS Organisation


Hakim Ferroukhi (SUI)

Robert Grove (USA)


All NEA member countries  EGPRS working area

Full participant European Commission (under the NEA Statute)

Observer (international organisation)

International Atomic Energy Agency (by agreement)



NEA Secretariat: Oliver Buss

Members' working area

EGPRS working area (password protected | reminder)

Related news
Publications and reports
Working Party Structure

Click on elements in graph above to jump directly to a specific WPRS activity.

Past activities

Previously completed or related activities

  • VHBuFC: Expert Group on very high burn-ups in LWRs (completed)
  • EGRPANS: Expert Group on Reactor Physics and Advanced Nuclear Systems  (completed)