NUCLEAR

The Alemnis Standard Assembly (ASA) can be installed in “hot” chambers which handle radioactive materials and is especially suited to the study of mechanical properties of nuclear materials because of its ability to test extremely small volumes of material. For a given radioactive substance, the intensity of radiation that it produces is directly proportional to the rate of decay of the substance and the amount of the substance. This means that the smaller the sample to be tested, the lower the level of radiation. The ASA can handle very small volumes (e.g. micropillars, beams, particles) which typically fall within the range 20 – 200 µm3. Provided that such samples can be adequately manipulated, they can be handled and tested with much less radiation protection than if they were in larger bulk form.

The ASA can be installed in most types of radioactive “hot” chamber, including glovebox types (left) and more sophisticated types with remote manipulators (right).

One of the most common types of installation for studying radioactive materials is the integration of the ASA into a Scanning Electron Microscope (SEM) which has itself been already integrated into a hot chamber. One of the restrictions with such installations is that the SEM is often placed inside a chamber which only has access via a glovebox which can make sample and indenter installation/removal more complicated, as well as reducing general access to the ASA. In addition, the SEM chamber door may be constrained and thus cannot be opened completely, again making access more difficult. In some installations, the ASA and SEM may be operated for certain periods of time after which the chamber can be fully accessed by personnel equipped with suitable protective clothing for maintenance and improvements.

The ASA has already been used for many studies of radioactive materials, as well as proposed replacement candidate materials for existing fission reactors and future fusion reactors. These include materials for reactor cladding, fuel rods (both new and spent), recycled waste, cooling pipes and coatings. Some examples: Zirconium alloys, MAX phases (e.g., Ti2AlC, Ti3SiC2, Ti2AlN, etc.), alumina, SiC, TiO2 and CeO2. The example shows the load-displacement curve for a crush test performed on an alumina particle with a 100 µm diameter diamond flat punch indenter. The advantage of true displacement control is plainly evident after the yield point when the particle suddenly fails and then densifies.

Typical load-depth curve for crush testing of an alumina particle for nuclear fuel reprocessing