A MILESTONE has been marked at the former nuclear research site at Winfrith with the removal of a hazardous material.

Winfrith was a major centre for groundbreaking reactor development from the late 1950s to the 1990s.

The site is now managed by Research Sites Restoration Limited (RSRL) which is responsible for the closure programme at Winfrith.

In another step towards closure, work to recover, repackage and dispose of a substantial non-nuclear hazard has now been completed.

For more than 30 years, 25 tonnes of sodium metal was stored at the site in a variety of containers, the result of past research projects at Winfrith, Dounreay and Hun-erston in Scotland, and Cadarache in France.

Funding became available two years ago to enable RSRL to launch a project to dispose of this ‘legacy sodium’.

It involved retrieving the sodium from existing containers, some of which contained up to five tonnes of sodium, before packing it into 10kg units for incineration at the Tradebe facility at Fawley, near Southampton, and later the Veolia facility at Ellesmere Port, Cheshire.

RSRL’s project manager Andy Philps said: “Sodium in its elemental form is particularly dangerous in contact with water, as it reacts violently, generating a hazardous cocktail of inflammable hydrogen, heat and caustic sodium hydroxide.”

Very careful handling was clearly required – a purpose-built tented processing facility, designed by RSRL’s parent body organisation, Babcock, was constructed, equipped with dehumidification and ventilation equipment, and fitted with extra safety measures, including gas detection equipment and sodium fire extinguishers.

Mr Philps said: “A specialist sodium contractor, NDSL, undertook the processing. The steel vessels were cut open in a dry nitrogen atmosphere, the sodium removed in the tented enclosure, packed in dry nitrogen-filled bags in sealed kegs and, finally, the kegs were over-packed in steel transport drums, blanketed with dry nitrogen.”

Despite the hazards encountered, Winfrith’s sodium processing project was completed, with the final packages sent to the incinerator at the end of February.

Mr Philps added: “Behind the success of this project has been an effective working collaboration between the NDA, RSRL, contractors, the parent body organisation and the regulator, culminating in the successful removal of a substantial hazard from the site.”