New technology maps plutonium at Sellafield

Monday, 20 August 2018

Cavendish Nuclear's standard DISPIM (Decommissioning In-Situ Plutonium Invention Monitor) is currently used at the Sellafield site for mapping alpha contamination. This uses a significant number of neutron detectors which are placed in close proximity with the location under investigation, such as a glove box. Neutron counts and multiplicity counts are taken and the results processed to obtain information about the level and distribution of neutron sources within the location. That system is heavily shielded and weighs half a tonne.

A smaller version of this monitor - known as the ARKTIS S670e - was subsequently developed which is much more mobile and weighs just 6 kg.

However, Cavendish - a subsidiary of Babcock International Group - said it is "taking advantage of a breakthrough in fast neutron detection technology to develop a lightweight system that combines simple 'plug-and-play' electronics with algorithms developed by Cavendish Nuclear".

It says the resulting PHUMS (for Plutonium Hold Up Management System) is a lightweight and highly manoeuvrable system that combines the slimline ARKTIS detector head with a simple "plug-and-play" laptop housed in a carry-case. It can be used for rapid and highly-accurate modelling of plutonium deposits inside gloveboxes, pipes and valves used to process nuclear materials.

Cavendish has been working with Sellafield Ltd for the past 12 months on trials of PHUMS at the Sellafield site.

"The results have been impressive, delivering rapid and accurate models of facilities for the presence of plutonium," Cavendish said.

Janet Fletcher, head of products and services at Cavendish Nuclear, said: "Innovation in the use of technology is transforming the ease with which redundant plant can be mapped for the build-up of plutonium on the insides of pipes, valves, gloveboxes and other kit that is reaching the end of its operational life." She added, "Sellafield Ltd is an important customer of Cavendish Nuclear and we share a strong desire to innovate to deliver nuclear clean-up safer, faster, at lower cost."

Paul Little, head of post-operational clean-out of special nuclear materials at Sellafield Ltd, said: "We are always keen on making the most of innovation and new techniques to transform the way we work and support us in our mission of safe and cost effective risk retirement."

He noted, "Both the standard DISPIM Imaging device and the new PHUMS system have been used in special nuclear material facilities with comparable results; however, the major advantage of the PHUMS technique is its ability to be deployed in areas where the DISPIM technique cannot due to its size and weight advantage."