Following the signature of the Comprehensive Nuclear-Test-Ban Treaty (CTBT) in 1996, the French government assigned the Atomic Energy Commission (CEA) to develop a Simulation Program to guarantee the safety and reliability of nuclear weapons.

At the core of the Simulation Program, the Megajoule Laser facility (LMJ) located in the region of Bordeaux (southwestern France) is designed to study the behavior of microscopic target materials under extreme temperature and pressure conditions (similar to nuclear weapons).

The LMJ building comprises 4 laser halls (each 128m long) sheltering 240 laser beams located at the four ends of the experimental hall. The experimental hall houses the experimental chamber positioned at the lasers’ focal point and consisting of a 350 ton aluminum sphere covered by a 40cm layer of borated concrete.


On behalf of the Bouygues Group, setec carried out the construction design of the experimental hall and the North and South buildings, including the finite element calculation models and concrete formwork and reinforcement design (1,150 drawings).

The six finite element calculation models developed for the experimental hall and the northern and southern buildings comprises over 125,000 nodes, including 92,000 nodes for the sole experimental hall. The project also comprised highly complex reserved spaces dedicated to cable ways and HVAC networks.

laser mégajoule - CEA


CEA (French Atomic Energy Commission)

Key figures

LMJ Building dimensions:

Length: 300m

Width: 100m

Height: 50m (35m above-ground)

150,000m3 of concrete

Period of services

Apr. 2003 - July 2008

Key challenges

A complex seismic calculation

The experimental hall was designed in compliance with the V.2.g seismic risk Fundamental Safety Rule (RFS): stress calculation in elastic range through dynamic multi-modal analysis.