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The Simulation Program

Simulation of the compression of a laser target.
Simulating the compression of a laser target.© CEA

Since France indefinitely halted nuclear testing in 1996, the Simulation Program has been the key element that allows physicists at CEA's Military Applications Division (DAM) to guarantee the reliability, safety and performance of the country's nuclear weapons. Its purpose is to use calculations to reproduce the various phases of operation of nuclear weapons to ensure their performance without having to resort to further nuclear testing.

The Simulation Program is a scientific approach applied to nuclear weapons. Its core elements are top-notch teams of scientists and key facilities for solving and validating equations used to model the operation of nuclear weapons: supercomputers, X-ray machine and the Megajoule Laser.

Simulation program diagram.
Simulation Program - © CEA

Weapons physics

The Simulation Program's summary tool is the "safeguard standard". It consists of a series of codes, each of uses calculations and physical models to reproduce the phases of operation of nuclear weapons.


LEFT - Particle accelerators for nuclear physics research. RIGHT - Dynamic mechanical tests being conducted to study shock-induced damage of materials. © CEA

The development of the safeguard standard requires linking together specific physical models (equations) and using powerful computational tools to solve these equations.

Numerical simulation


Le supercalculateur Tera 100, conçu, fabriqué et installé par Bull, dispose d'une capacité de calcul de plus de 1 Péraflops. Il est notamment utilisé pour développer et exploiter les codes numériques permettant de reproduire les différentes étapes de fonctionnement d'une arme. Crédit CEA
The Tera 100 supercomputer in Bruyères-le-Châtel.© CEA

The Tera 100 supercomputer at the DAM center in the Paris region is fully operational and has been used by weapons designers and physicists since early 2011. It can perform one quadrillion floating-point operations per second (1 petaFLOP, or 1015 operations per second). Since 2011, the Tera 100 has been used with the 2010 safeguard standard for all work guaranteeing the operation of nuclear weapons.

Computers with very high computing capacities are needed to process the complexity of the physical phenomena involved in nuclear weapons. It can take computers like the Tera 100, up to one month of continuous processing to work out some calculations.

Experimental validation


Générateurs haute tension, Airix. Crédit CEA

High-voltage generators at Airix. © CEA

Experimental validation is performed by comparing predictions of the standard with measurements collected during past nuclear tests and by validation experiments currently being performed in sections with the Airix X-ray machine and the Laser Integration Line. Starting in late 2014, these experiments will be conducted at the Epure facility and the Megajoule Laser.

The Airix X-ray machine has made it possible to validate the various models of the initial, non-nuclear stage of operation of a nuclear weapon. Initially at the PEM experiment center in Moronvilliers (MEP), it was moved to CEA's Valduc site and is the first arm of the Franco-British Epure facility.

The Megajoule Laser at the Cesta site is used to validate models relating to the nuclear operation of weapons. The first experiments are planned for late 2014.

MàJ: 18/11/2014
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