Life Time Monitoring in Nuclear Power Stations

This is a safety critical application from the nuclear power industry.

Here Zr is used to clad the fuel rods used in power stations.  It is important that the lifetime and potential failure mechanisms of the Zr are understood and monitored, in order to maintain safety in the system.

Zr is used in this application because it is highly resistant to heat and chemical corrosion. However, it can be prone to hydrogen embrittlement which can cause cracking, and therefore be a source of failure.

In order to monitor and prevent this, recognising the presence and distribution of ZrH in the cladding material is important.  This will enable modelling of the ‘in service’ performance of the Zr.

This application uses EBSD to identify ZrH, within the Zr cladding material. In this application EBSD is essential as EDS alone will not separate Zr and ZrH.

By identifying the amount and location of any ZrH the performance of Zr overtime can be monitored.

Typically ZrH developing at grain boundaries are unfavourable as they have more potential to cause cracking and failure.

The inclusions in the Al matrix are visible in the secondary electron image. Combined EBSD and EDS is applied to identify the nature of these precipitates, which are then mapped to determine the location and spatial frequency in the can material.