The method, developed in JRC Karlsruhe, streamed from the need to have a portable instrument able to measure both uranium content and uranium enrichment in field.
The analyses are performed with mobile equipment, in fuel fabrication plants during Physical Inventory Verification (PIV) activities of the international nuclear safeguards authorities (EURATOM, IAEA). The samples are selected by the safeguards inspectors and measured by COMPUCEA analysts directly in-field during the PIV.
With COMPUCEA the analytical results are immediately available to the safeguards inspectors in field. This allows a timely conclusion of the PIV and any observed discrepancies can be investigated immediately. With this approach, there is no need to send the samples to the safeguards laboratories.
The method
COMPUCEA is based on radiation measurements. However, the complete analysis procedure is a combination of chemistry and radiation spectrometry. The analytical steps include, i.a., quantitative sample dissolution, solution density measurement, quantitative aliquoting, before the radiation measurements.
The solid samples are first dissolved, as COMPUCEA can measure samples only in liquid form. U concentration is measured by X-ray transmission measurement at the L-absorption edge of uranium (LED).
For 235U enrichment, absolute gamma measurement of the 186 keV peak of 235U in well-defined geometry by LaBr3(Ce) detector is used (ENR). The instruments are calibrated with certified reference material and daily quality control measurements are done.
The instrument
COMPUCEA is owned by DG-ENER and operated by JRC analysts.
Since its development, the technique continued to be used successfully in European fuel fabrication plants to support EURATOM and IAEA inspections during PIVs
In 2011 the International Atomic Energy Agency (IAEA) adopted the use of COMPUCEA for international safeguards in non-European countries. It is being successfully used since then.
Recent developments
In 2017 the scope of COMPUCEA has been extended with the validation of the technique for the analysis of uranium hexafluoride samples (UF6).
The purpose of the extension was to support the IAEA in the verification of uranium conversion and enrichment facilities worldwide. The procedure adds a critical new step in the sample preparation to transfer the uranium from UF6 to a nitric-acid solution, from where the well-established and validated COMPUCEA procedure can be followed.
Several versions of COMPUCEA were developed to meet the evolving needs and changing requirements. The current version has been finalized in 2023.