“Realisation of the becquerel”—reducing the impact of equipment failure

•The goals of the “Realisation of the becquerel” project of CCRI(II) are presented.•Reproducible source holder designed and tested.•New ionisation chamber design with better definition of sensitive volume proposed.•The advantages of the new design are discussed.

The goal of the CCRI(II) “Realisation of the becquerel” project is to design a reproducible radioactivity standard which will increase the robustness of the current international reference system for radioactivity measurements. Tests performed with a first prototype ionisation chamber of this project, built in 2005, are presented. Based on experience with the first prototype, a new design was proposed in 2010 aiming at achieving the very ambitious project goals. The article discusses the status of the project and the advantages of the new design.