Lead-cooled Fast Reactor Benchmark (LFR)
Design of the Advanced LFR European Demonstrator (ALFRED). Image: G. Grasso, ENEA (Italian National Agency for New Technologies, Energy and Sustainable Economic Development)


Lead-cooled Fast Reactors (LFR) are rather new concepts which have gathered increasing international attention after the Generation-IV International Forum (GIF) selected them as promising candidates for a new generation of nuclear energy systems.

Very limited operating experience exists to support the design, verification and licensing of LFRs. In particular, the lack of operating experience impacts the physics of the LFR core.

Under the guidance of the OECD NEA Working Party on Scientific Issues and Uncertainty Analysis of Reactor Systems (WPRS), the OECD NEA Expert Group on Physics of Reactor Systems (EGPRS ) is mandated to provide expert advice to the nuclear and accelerator community on the development needs in the domain of neutronics, radiation transport, reactor physics and nuclear fuel feedback along with uncertainty analysis of present and future nuclear power systems. EGPRS is currently monitoring benchmarks related to light-water cooled, molten-salt, sodium-cooled, and gas-cooled reactor systems and there is large interest to also address lead-cooled fast reactors.

Propaedeutic to further studies that will be proposed for assessing the impact of nuclear data uncertainties on integral parameters of design relevance, an introductory benchmark exercise under the auspices of EGPRS focuses on the physics of an LFR core.

The specific purpose of the LFR physics benchmark is to

·        familiarise with the physics of an LFR core,

·        practice with the neutronics of an LFR core,

·        assess confidence in the capability of simulating an LFR core.

Benchmark Description

The Advanced LFR European Demonstrator (ALFRED) is assumed as reference system for the LFR physics benchmark exercise. The ALFRED design is being carried out by the Fostering ALFRED Construction (FALCON) International Consortium, signed by Ansaldo Nucleare (IT), ENEA (IT) and RATEN-ICN (RO). Links with ENEA – the organisation responsible within FALCON for the core design of ALFRED – secure access to all the required information for the participants to the benchmark exercise.

The benchmark comprises three phases:

  • PHASE 1: Pin Cell
    • PHASE 1 consists of heterogeneous modelling of the cell of a fuel pin and of performing a criticality analysis of the cell in an infinite lattice. 
  •  PHASE 2: Sub Assembly/Super-Cell Simulations
    • For PHASE 2 of the benchmark, the simulation model is extended to the level of a whole Sub Assembly (S/A), or of a super-cell comprising several S/As.
  • PHASE 3: Whole Core Simulations
    • PHASE 3 addresses the modelling of the whole core, including control, shutdown and reflector/shield elements.
Benchmark Organisation

Benchmark coordinator: G. Grasso (IT)

Participants: All NEA member countries 

LFR Participants' working area (password protected)

Benchmark participation

Access to the benchmark is open to all OECD/NEA member countries and it requires only acceptance of the benchmark conditions.

Please sign the conditions form  and send it to the WPRS Secretariat.


  • 02/2022: Endorsement of Benchmark in EGPRS meeting
  • 05/2022:  Discussion of 1st draft specification during WPRS Workshop  


WPRS Secretariat