Hybrid K-Edge Densitometer (HKED)0 pages

ORTEC

®

Hybrid K-Edge Densitometer (HKED)
LATEST GENERATION (2009)

• Available for laboratory use or as an input solution instrument.
• Latest (2009) version of PC-Based Los Alamos Advanced
HKED software.
• Turnkey-complete HKED system packages available.
• Retrofits available for ALL other HKED systems.
• Custom configurations available to match HKED equipment to
existing hot cell with suitable failsafe sample handling
methods.
• Physics and Engineering consulting design support available.
• Flexible choice of standards for calibration purposes, including
ability to use suites of standards with different enrichment
factors.
• Superior attenuation correction algorithm permits good
calibrations with small numbers of calibration standards.
• Measurement range from 100 mg/L to 100’s of g/L for six
Actinides (U, Pu, Th, Np, Am, Cm), with ratios of major to minor
to 100’s.
• Ease of sample preparation, especially when compared to
destructive methods.
In a K-edge densitometer (KED), a continuous-energy beam of photons from
a tungsten-anode x-ray tube is transmitted through a liquid sample. Photon
transmission through the sample is measured at two photon energies which closely bracket the K-absorption edge energy of the
element of interest. The concentration (grams per liter) of the measured element is a simple function of the photon transmission below
and above the absorption edge, and the path length of x-rays through the sample.
KED can be extremely accurate, and is typically applied to concentrated solutions (>10 g/L). For samples in a 2-cm path length vial,
the best KED precision (0.15%) is obtained for samples with a concentration of about 200 g/L.
In a hybrid K-edge/x-ray fluorescence densitometer (HKED), KED is augmented by a simultaneous x-ray fluorescence (XRF)
measurement of the specimen. The concentration of the most-abundant actinide is determined by KED, and the XRF detector
measures fluoresced x-rays emitted from sample face.
Concentrations of other actinides are derived from
attenuation-corrected ratios of XRF peak areas.
This combined technique (thus the term “Hybrid”) allows
measurement of dissolver solutions in reprocessing
plants having typical U concentrations of 150–250 g/L
and Pu concentrations of 1–3 g/L. In this case, U is
measured by K-edge densitometry, and the Pu/U ratio is
measured by XRF.
K-edge densitometry (or hybrid K-edge densitometry,
HKED) is applicable to all U, Th and Pu materials and to
mixed U-Th or U-Pu (MOX) samples containing at least
0.2 g/L of the analyte. A precision and accuracy of about
0.2% for uranium and 0.75% for Pu may be achieved
when the concentration of the analyte ranges from 50 to
150 g/L in a typical measurement time of 1000 seconds.
A typical schematic view of an HKED is shown in figure
2.
1
Reilly D., Ensslin N., Smith H., Kreiner S., Passive
Nondestructive Assay of Nuclear Materials LA-UR-90-732 P302.

HPGe Detector

Cu. Cd Filter
Lead Shielding
Tungsten
Collimators

Filter

Solution Cell for Pu
Isotopic Analysis
HPGe
Detector

Cu
Anode

K-XRF Analysis

157°

W
Target

Shielded XRay Tube

K-Edge
Densitometer

Alpha Containment
Be Window

Filter

Solution Cell for Pu
Isotopic Analysis

Leaded Glass

Figure 2. Schematic View of Typical HKED.1