HKED uses X-rays to determine the U and Pu concentration in liquids with typical combined uncertainties of 0.2% and 0.7%, respectively.
The JRC operates the HKED systems used for EURATOM safeguards.
The JRC’s research and development on HKED aims to reduce calibration work, improve robustness, and solve hardware and software issues.
Overview
Hybrid K-edge / K-XRF densitometry (HKED) can simultaneously determine the uranium (U) and plutonium (Pu) concentration in actinide solutions of any radiation level. Today it is difficult to imagine safeguarding nuclear reprocessing plants without HKED.
HKED is also used for measuring the U and Pu content of pellets and powders from nuclear fuel production plants. HKED is faster, simpler and cheaper than other analytical methods which provide the same or just slightly better combined measurement uncertainty than HKED. That is why it is the main analytical technique used for safeguarding reprocessing pants and fuel production, the safeguards workhorse.
The first HKED system of the present kind, using an X-ray tube as radiation source, was set up in the 1980s in Karlsruhe (Germany). Since then, a total of about 20 systems have been installed and worked reliably worldwide. The basic design and performance have not changed significantly. However, several challenges and possibilities for improvements have been identified.
HKED is safeguarding more plutonium than all other analytical techniques altogether.
HKED is a combination of two techniques: X-ray transmission around the K-edge energies (KED) and X-ray fluorescence (XRF) measurement. The liquid sample is placed in an X-ray beam and two gamma spectrometers are used to measure the transmitted and the fluorescent X-ray radiation. Solid samples (pellets, powders) need to be dissolved before analysis.
The KED measurement is used for determining the concentration of the major element (usually U), while XRF is for the concentration of the minor element (usually Pu).
Challenges and research
The JRC, together with its international partners, works on addressing challenges of the HKED technique, arising from recent technological and societal changes.
- Ensuring sustainability of hardware and software: A new hardware-software interface was designed and implemented by the JRC. The JRC advocates common access to source codes and avoiding that a single commercial entity has control.
- Improving analytical performance: New algorithms are being developed at the JRC to improve HKED performance and robustness and to reduce calibration efforts.
- Keeping continuity of knowledge: The JRC co-organizes HKED workshops, disseminates publications and data, provides trainings.