NRG develops in core and Online submicron displacement measurement technology

After a multiyear development project, NRG has successfully demonstrated the capability to measure material expansion during irradiation in the High Flux Reactor Petten with micrometer accuracy, at temperatures beyond 750 C.

The technology, never adopted before in a reactor, allows high accuracy measurement of material deformation under load over time, thermal expansion, irradiation induced swelling and shrinkage, at high temperatures and during irradiation.

‘Measuring the dimensions of multiple material samples of a few millimeters thickness with 1 micrometer accuracy at 9 meters distance, during operation in a high flux nuclear reactor system, at temperatures beyond 750 C, is quite a challenge’.

After a number of laboratory test in which different concepts were developed, constructed, tested, dismissed and improved, a final concept was developed a year ago. The design was finished by a team of material and fuel experts, nuclear engineers and technicians, and constructed and assembled in the Petten workshop.

‘Small material samples can be irradiated under very well controlled conditions, but measuring expansion and deformation of a significant number of these small samples during irradiation and at high temperatures was not possible until now. The data we can now generate provides input and validation information for the new generation of material and fuel performance models. The nuclear community has been waiting for this, as these new models will provide better knowledge and insight, and will allow efficient development of better and safer materials and fuels for current and new nuclear power plants.’

‘The data generated is at a the mesoscopic level, which is the bridge between microscopic and nanoscopic material behavior (the world of atoms) and macroscopic material behavior (the world of components and systems)’

The facility will be irradiated in an even higher flux position in December, where temperatures beyond 1200 degree can be achieved.

Multiple projects are currently planned for execution in 2017, in which the focus will be on new nuclear fuel behavior characterization, as a basis for safer fuels.

This project is part of the research program funded by the Dutch Ministry of Economic Affairs. On behalf of the Dutch government, NRG carries out a nuclear research program allowing to constantly update and improve the nuclear knowledge.

Image courtesy: NRG