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ACT experimental station at the CAT-ACT beamline

Background

INE / ACT - experimental stations

The INE Beamlines  (INE-Beamline and the ACT station at the CAT-ACT Beamline) at the KIT-synchrotron are dedicated to actinide research with X-ray spectroscopic techniques. Both are operated by the Institute for Nuclear Waste Disposal (INE).

INE Fig1 Immobilisation

Schematic sketch visualizing some of the actinide mobilization / retention processes possibly following actinide release from corroded HAW.

Research and development at INE are largely aimed at long term safety assessment of proposed deep geological repositories for high-level, heat producing nuclear waste (HAW) disposal. To ensure sound safety assessment, a molecular understanding of processes determinant in the fate of radionuclides, notably the actinides, and thermodynamic quantification is essential. Of central importance in such investigations is determination of actinide speciation (i.e., their chemical and physical form). X-ray spectroscopic methods have proved to be valuable tools for actinide speciation research. Investigations on non-fissile radioisotopes up to 106 times the legal exemption limit and fissile radioisotopes (Pu-239, U-235) up to 200mg, contained within two layers of protection, are possible.

The synchrotron-based activities at the INE-Beamline are embedded in INE’s in-house research, thereby allowing a combination of analytical and instrumental methods, notably laser techniques and microscopic methods.

 

In situ X-ray spectroscopic investigations on radioactive samples are routinely performed at the INE Beamlines for studying, e.g., actinide containing solid-water interface chemical reactions, not possible at other facilities. A special protocol for working with radioactive samples at both INE beamlines exists and is supervised by INE’s own radiation protection officers. The unique aspect of the INE Beamlines is its close proximity to INE’s active laboratories on-site KIT north campus. The design is for a multi-purpose beamline, where a number of methods are possible on one and the same sample.

 

The INE Beamlines serves three general functional areas:

  • Research = user facility (INE in-house, HGF NUSAFE program, via strategic research cooperation with KIT-INE)
  • Education and dissemination (maintaining nuclear competence)
  • Development & upgrades (adaption of methods, serving user needs)

 

Layout

 

Layout of the CAT-ACT facility with optic hutch adjacent to the storage ring wall, two in-line experimental stations and separate control cabin in the ANKA east hall extension.

 

Schematic beam path (not to scale) from the source (left) to the experiments (right)

CAT-ACT optical components designed and manufactured by FMB Oxford (Oxford, United Kingdom). From right to left: frontend components (intensity absorber, X-ray beam position monitor, white beam slit), collimating mirror, double crystal monochromator, diagnostics module, toroidal focusing mirror, beam shutter separating ACT hutch from optics section. Inset: focusing mirror coating scheme.

Experiment

Detectors

 

Detector Type Main specs
Fluorescence

5 element LEGe (Canberra-Eurisys)

 

Ketek SDD

140 eV at 6 keV; 50 mm2 active area/element; 25 µm Be window

 

Absorption

3 ionization chambers (Poikat / Hamburg

low-energy set-up with single entrance window (Oken Ltd. ionization chambers, Japan)

window 12.5 or 25 µm KAPTON, FEMTO low current amplifiers DLPCA-200

ionization chambers and sample chamber form windowless volume – gas tight insertion of SDD into sample chamber for high quality fluorescence spectra


 

Sample holder (HUBER stage, combined with HRXES spectrometer):

 

Movement Range
z stage 90 mm; 50 nm/step
phi circle 360°; 0.001°/step
x stage 80 mm; 100 nm/step
y stage 80 mm°; 100 nm°/step



                   
                   Experimental setup for XAFS and XES measurements at the ACT station. The photo shows the high energy detection setup without He containment.

 

 

Sample environment

 

Standard holder for transmission and fluorescence measurements of radioactive and non-radioactive samples, e.g., 400 µl and 2 ml PE-tubes, pellets.

Liquid sample cell for the investigation of redox labile systems under electrochemically controlled conditions

Environment: atmosphere, inert gas (existing supplies: He, N2, Ar)

 

 

Methods

 

 

XAFS characterization of bulk species by XANES/EXAFS
XAFS/XRD characterization of phase - pair distribution relationships
XRF measure elemental concentrations
High energy resolution (Johann spectrometer) HRXES: high resolution X-ray emission spectroscopy
RIXS:    resonant inelastic X-ray scattering
Combination of methods combined X-ray methods or X-ray method combined with other techniques, e.g., laser, Raman or UV/VIS spectroscopy

 

Characteristics

Radioactive work Infrastructure and licensing for activities 106 times the legal exemption limit as well as Pu-239 and U-235 up to 200mg.
Energy range 3.4 keV - 55 keV (wavelength range: 3.6 – 0.2254 Å)
Source 2.5 T superconducting multipole wiggler (Ec=10.2keV, K=11.2, 15mm vacuum gap, 4.7kW radiated power)
Optics

• fixed-exit DCM with  LN2 cooled crystals and piezo-driven detuning / feed-back system for second crystal, direct drive Bragg axis goniometer with maximum speed of 4°/s and exchangeable crystal pairs Si(111) and Si(311)
• two mirrors for beam collimation, focusing and rejection of higher harmonics:

  • Vertically collimating Si 1st mirror with bare Si/Rh/Pt coated stripes (bend radius 5 km < R < 40 km),
  • focusing 2nd mirror with bare Si zone (bend radius 2.4 km < R < 10 km, 37 mm sagittal radius) ,  Rh-coated zone (bend radius 2.4 km < R < 10 km, 25.2 mm sagittal radius) and Ir-coated zone (bend radius 2.4 km < R < 10 km, flat)

• Diagnostic modules

Beam size at sample position

~1mm × 1mm (standard beam size with mirror)

mirrorless operation above 45keV

Flux at sample position ~1011  photons/s/100mA  at 20keV, Si(111)
Experimental set-up/ sample positioning

• Standard sample holders for radioactive samples, other dimensions can be accommodated
• High precision HUBER sample positioning system
• High Resolution X-ray Emission Spectrometer
• 1.2 × 3 m2 breadboard optical table
• Sealed media feed-through chicanes and separate ventilation / filter system for experimental hutch
• Access through lock-room with hand / foot-contamination monitor

Experimental set-up/ detectors • Ionization chambers for nominally high energies (transmission mode)
• Ionization chambers for nominally low energies (Oken Ltd, Japan)
• XRD-setup using image plates (autoradiography films)
• 5 pixel high purity germanium solid state fluorescence detector (Canberra Ultra-LEGe)
• Silicon drift detector (Ketek)
• Fully digital fluorescence detector read-out (XIA Xmap)
 

Further detailed information is available in:

Zimina, A.; Dardenne, K.; Denecke, M. A.; Doronkin, D. E.; Huttel, E.; Lichtenberg, H.; Mangold, S.; Pruessmann, T.; Rothe, J.; Spangenberg, Th.; Steininger, R.; Vitova, T.; Geckeis, H.; Grunwaldt, J.-D.; CAT-ACT—A new highly versatile x-ray spectroscopy beamline for catalysis and radionuclide science at the KIT synchrotron light facility ANKA, Review of Scientific Instruments 2017, 88, 113113.

doi:10.1063/1.4999928

 

Team INE / ACT Beamline
Name Tel. E-Mail
kathy dardenneVxx2∂kit edu
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