REFERENCE MATERIALS FOR MEASURING NUCLEAR SIGNATURES IN THE ENVIRONMENT

The increased interest in measuring small amounts of nuclear material in environmental samples, techniques called ‘Environmental Sampling’, or ‘High Performance Trace Analysis’, has arisen following the extended protocol of the IAEA and the need to implement this in Safeguards. Parallel to this, the control of the Non-Proliferation Treaty (NPT) requires in its turn analysis of environmental samples for first hints of nuclear signatures which could point to weapons production or testing. The need for reference materials to support these activities has become very clear and one can say categorically that without adequate reference materials any measurements of nuclear signatures in the environment become worthless. There is a problem of availability and also of correct application, but the basic need for coverage by nuclear RMs is an urgent matter and needs to be addressed now. At IRMM we have an extensive range of nuclear RMs for conventional Safeguards and Nuclear Material Control and Accountancy (NMC&A). More than 2 years ago, foreseeing the need for equivalent materials which could be applied to the analysis of samples containing sometimes very small amounts of uranium or plutonium, we began a programme to extend the present set of isotopic ratio and isotopic amount content RMs specifically to provide coverage in this area. At the same time we began the external QC programme NUSIMEP (Nuclear Signatures Inter-laboratory Measurement Evaluation Programme), again specifically designed for laboratories measuring small amounts of U or Pu in the environment. The campaign NUSIMEP-2 was completed early in 2001 and NUSIMEP-3, uranium isotopic abundances in saline solutions, is presently underway.