FRAMATOME ANP France UO2 Fresh Fuel Transportation Criticality Application of the IAEA TS-R-1 Regulations

For more than 25 years, FRAMATOME ANP has been delivering fuel elements to various French and foreign NPP sites including Belgium, China, South Africa, and Sweden. With the FCC, its new fresh fuel transportation package, which completely satisfies the 1996 IAEA regulations, FRAMATOME ANP has a safe container to transport any type of PWR fuel assembly from the 14x14 to the 18x18 design with enrichments up to 5.0 w/o 235U. The new IAEA regulations (TS-R-1) in force since 2002 require that the criticality studies had to be validated against benchmarks to deduce uncertainties. These uncertainties are added to gross computer code results for comparison with the criticality safety criterion. The uncertainties described in the IAEA guidelines document are derived from both systematic bias and the different statistical uncertainties. FRAMATOME ANP uses the CEA/IRSN CRISTAL computer code system to perform criticality safety evaluations for transportation packages. Exhaustive efforts have been made to get a qualification report which covers the entire lifecycle of the fuel from the enrichment process through fuel transportation to the recycling backend. This qualification report is based primarily on information from the well known ICSBEP working group (International Criticality Safety Benchmark Evaluation Project). This group compares the main world criticality computer codes for different fissile media, shapes, spectra, etc. Among the various configurations several are for arrays of UO2 rods with various enrichments, rod pitches, and neutron absorbers. This subset provides a good qualification database to qualify the transportation package calculations. After a brief description of the CRISTAL chain, the paper shows our approach used to determine the uncertainties required by the IAEA regulations. The methodology is discussed and illustrated by numerical applications.