Possible consequences of new actinide nuclides on criticality safety during transport
C. LAVARENNE1, D. MENNERDAHL 2, C. DEAN3, N. BARTON4, V. ROUYER1, F. JEAN5, PATRAM, Berlin, 20-24th sept. 2004
(1) IRSN; BP 17, 92262 Fontenay aux Roses, France
(2) EMS, Starvagen 12 -18357 TABY -Sweden
(3) SERCO, Winfrith Technology Center, Dorchester -Dorset -DT2 8ZE -UK
(4) Department of Transport Local Government, Radioactive Materials Transport Division - 2/33 Great Minister House -Marsham Street -London SWAP 4DR -UK
(5) APTUS, 77 rue des chantiers -78000 Versailles -France
Since 1998, there have been some speculations about future transport of significant quantities and concentrations of other actinide nuclides than the four currently listed in the regulation for the safe transport of the radioactive material. Therefore, it raised a need to specify exception limits for such actinides. Additionally, the number of packages per conveyance has changed and the proposed change of the mIes has to take this new element into account. ln order to define credible exception limits, it was necessary to have reasonably accurate data for all actinide nuclides. Then the DGTREN/participants decided to perfonn calculations with different code (MONK, MCNP, CRISTAL) and different cross-section libraries (JEF2.2, ENDFB, etc.). The parameters ofinterest (such as k-infinite, critical masses) were determined. This article will present the work achieved and the questions raised, e.g. related to the effect of the radioactive decay of the isotopes on the criticality risks. It will also point out the need for an evolution of the regulation of the safe transport of radioactive materials and give a proposition of modification for the IAEA requirements related to, firstly, the list of the fissile materials, secondly, the rule to detennine the quantities of actinide nuclides that can be excepted from the requirements for the packages containing fissile materials.