In our atmosphere, carbon-14 is continuously generated from nitrogen (about 80% of air) and is incorporated into all living things. When a species die, the incorporation of this cosmogenically generated carbon-14 stops and its content decreases by radioactive decay. The degree of carbon-14 decay in material from once living things allows archaeologists to determine how old their findings of biological origin (e.g. a wooden tool) are. Carbon-14 is also generated in nuclear reactors e.g. during irradiation of metals containing nitrogen or carbon additions. These materials are considered radioactive waste for which special safety measures are and will be taken. The CAST project (CArbon-14 Source Term) aims to develop understanding of the potential release mechanisms of carbon-14 from radioactive waste materials under conditions relevant to waste packaging and disposal to underground geological disposal facilities. The expected increase in understanding should decrease uncertainties in the long-term safety assessment and increase confidence in the safety case.
The CAST consortium brings together 33 partners with many different skills and competences both in geological disposal of difference waste types, but also in developing safety cases and on planning and implementing experimental programmes on gas generation. The consortium includes national waste management organisations (WMOs), research institutes, universities and commercial organisations working in this field. The involvement of the waste management organisations (the end-users of the outcome in the form of process understanding, data and competence) ensures that the project is focused on important and outstanding issues. It also ensures that the project is aligned to European national programmes and thus that results are used as intended. Organisations from three countries outside the European Union also particpitate in CAST– Ukraine (SI IEG NASU), Japan (RWMC) and Switzerland (NAGRA and MCM). This offers a unique extension of scientific basis to the project, as well as an insight into how other national programmes manage the issue of 14C.
CAST started operating 1st October 2013 and is coordinated by Steve Williams from RWM (NDA).