SELLAFIELD’S CUTTING EDGE

The sharpness of the shearing machine blade used to strip the spent nuclear fuel rods in readiness for reprocessing needs to be continuously monitored, so that it can be replaced in good time, reducing plant downtime and boosting productivity. Measurement of sharpness poses problems, since the blade is permanently sealed from the outside world by […]

The sharpness of the shearing machine blade used to strip the spent nuclear fuel rods in readiness for reprocessing needs to be continuously monitored, so that it can be replaced in good time, reducing plant downtime and boosting productivity.

Measurement of sharpness poses problems, since the blade is permanently sealed from the outside world by a biological shield. The solution is a system of real-time graphical analysis using a high speed Fluke data acquisition tool. The cutting tool consists of one fixed and one moveable blade, whose position is adjusted by a ram to cut the fuel rods into lengths of 100mm.

The Fluke NetDAQ data acquisition tool is linked to a pressure transducer in the hydraulic circuit of the ram operating the cutting tool. A second channel reading linked to an LVDT (linear variable displacement transducer) mounted on the shaft of the ram provides an accurate indication of the position of the blade.

Using the standard Fluke support software, NetDAQ Logger for Windows, it is a straightforward task to record a continuous string of pressure and displacement readings.

Fluke’s Developers Toolbox PC software provides two dynamic link libraries (DLLs) and allows application programs that can access the logged readings in real-time in a Windows environment.

Each fuel assembly is allocated a unique file and serial number. These serial numbers are provided by a SCADA system connected to the same network as the NetDAQ data logging equipment.

Measurements of pressure and displacement are taken at up to 500 readings per second providing graphical representation of force against distance.

By integrating the force/displacement readings, a direct measure of the energy expended at all stages of the cutting process is obtained, which can provide an automatic signal to tell technicians when the cutting edge needs replacing.

{{Fluke,Tel: 01293 240511; Fax: 225067.350 on enquiry card}}