Also, it was decided to develop and qualify a computation chain "evolution of the assessments materials and criticality" based on coupling the forms dedicated to calculations of assessments matters of the nuclides (DARWIN and CESAR) and CRISTAL. The DARWIN and CESAR packages come upstream of CRISTAL package, and help to calculate the evolution of the physical dimensions of interest, while taking into account the detailed history of the assembly (in the reactor and during cooling), in particular the abundance of each nuclide during fuel cycle, on any reactor type (PWR, BWR, LMFBR, ...)

From their site:

PHASE 1 : CRISTAL V0

"Le formulaire CRISTAL est élaboré et qualifié dans le cadre d'une collaboration entre l'IRSN (Institut de Radioprotection et de Sûreté Nucléaire), AREVA (à l'époque COGEMA : Compagnie générale des matières nucléaires) et la Direction de l'énergie nucléaire (DEN) du CEA, en tenant compte des besoins relatifs à l'ensemble des applications envisageables. Après quatre ans de développement, de validation et de qualification, la première version (V0.1) du formulaire est livrée aux utilisateurs depuis novembre 1999. "

PHASE 1 : CRISTAL V0

The CRISTAL package is developed and qualified within the framework of a collaboration between the IRSN (Institute of Protection against radiation and Nuclear Safety), COGEMA (general Company of the nuclear matters) and the Management of the nuclear energy (DEN) of the CEA, by taking account of the needs of the possible applications. After four years of development, validation and qualification, the first version (V0.1) of the form has been delivered to users since November 1999.

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Note added at 23 mins (2009-12-18 13:19:04 GMT)
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http://www.cristal-package.eu/GB/presentation.htm