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Contact: Dominic Rhodes (email Dominic)
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National Nuclear Laboratory

National Nuclear Laboratory – Central Laboratory

Material processing:
Low throughput of higher active materials

Sample Preparation:
FIB & sample preparation suite

Material characterisation:
On-site Post–irradiation Examination (PIE) of active materials (prototypic materials and radiation levels)

Material transfer:
Transfer of lower active materials for off-site PIE


Manchester University Characterisation of AGR Core Moderator Graphite

  • Characterise porosity, including open/closed porosity
  • Evaluate density profiles through samples

NNL IR&D Carbonaceous deposit on AGR Fuel Pins

  • Measure thickness, porosity and density
  • Characterise structure
  • Use above results to assist the evaluation of impairment of heat transfer from fuel pin to coolant caused by deposit


Focussed Ion Beam

An FEI Helios instrument has been installed in our Central Laboratory. It is currently capable of handling trace active samples. An airlock and sputtered material shields are fitted and following fully active commissioning in 2015 the instrument will be able to handle more highly irradiated structural materials and fuels.

This instrument combines the imaging and analysis capabilities of an SEM with the ability to use an ion beam as a nano-to- micron scale “scalpel”, thus allowing cross-sectioning of samples and preparation for analysis in the Transmission Electron Microscope or Atom Probe Tomography.

Cross-sectioning is destructive so work with highly radioactive material will be carefully assessed to minimise issues with deposition of active material within the instrument. Examples of applications include examination of stress corrosion cracking and oxidation and preparation of non-conductive materials not suitable for electropolishing.

The very small size of the TEM and APT samples means that they can more easily be transported to universities or other research facilities, although NNL can currently provide access to its active TEM (JEOL 2100 fitted with 80mm2 Oxford Instruments EDX detector) and will be installing a FEGTEM as part of the NNUF facility (see below). The current TEM is capable of 5-10nm spatial resolution for the analysis of irradiated samples and is typically used to characterise irradiated cladding. An electron energy loss spectroscopy (EELS) upgrade (Gatan Quantum 965ER) is in progress.

Field Emission Gun – Transmission Electron Microscope (FEGTEM)

In mid-2015, NNL is due to install a JEOL ARM200CF. This is the highest resolution analytical S/TEM currently available and provides atomic resolution composition mapping. It has 80pm probe size, a 0.98Sr EDX detector and will be fitted with the Gatan Quantum system.

X-Ray Microtomography

A Bruker Skyscan 1172 is currently installed and working in an active lab. This provides computerised CT scanning with micron scale resolution, with ~1µm voxel resolution, up to 8000X8000 pixel images for each slice and resolution limit of ~0.8µm. Samples up to 27mm (or 50mm using multiple scans) can be accommodated. The instrument provides detail of internal structure non-destructively including quantitative measurements of porosity and measurement of relative density. Initial work has been carried out on active graphite and carbonaceous materials.

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