BASSIST: an applied thermodynamic database for radionuclide chemistry

BASSIST (Base Applied to Speciation in Solution, at Interfaces and SolubiliTy) is an applied thermodynamic database (TDB) for chemistry of long-lived radionuclides. This TDB is developed at the French Atomic Energy Commission (CEA) and concerns solution, sorption and dissolution equilibria. The order of the different steps necessary to elaborate this TDB are presented, from a critical review of experimental acquisitions until to a database compilation. Important concepts such as the heterogeneity of data, the coherence of database and the use of chemical analogies between elements are discussed by using an example of application of the TDB in speciation calculation. The TDB BASSIST is built by using "certified" data, such as selected values of the Nuclear Energy Agency (NEA) and some uncertified data from literature. In the last part of this article, the choice of chemical analogies between elements, the impact of different sets of data on uranium(IV) speciation calculations are discussed.