WIREDGOV

Magnox has successfully emptied more than 120 tonnes of hazardous material from the first of Hunterston A’s five solid waste bunkers.

Retrieval of the highly radioactive graphite and metallic waste has posed a technical challenge for many years and the recent success is a major milestone for the site.

Hunterston’s two reactors were, unusually, constructed in an elevated position at a height of more than 10 metres, which enabled access from underneath. Gravity assisted the removal of used fuel, while refuelling could be carried out without the need for lifting machinery above the active core.

Similarly, the fuel elements were also unique to the plant, incorporating a graphite sleeve which was stripped from the irradiated uranium during discharge from the reactors, along with associated metallic components.

This Intermediate Level Waste (ILW) was transported via underground tunnels into one of the five above-ground bunkers made of reinforced concrete.

The Solid Active Waste Bunker Recovery (SAWBR) project will recover all contents from the bunkers, and process it into a passively safe state for storage in the site’s ILW Store.

Following removal of the 62 packages from Bunker 5, work will start on breaking through into the next bunker, No 4, with a scheduled completion date for late in 2016. Magnox expect that emptying the solid waste from all bunkers will fill more than 1,200 packages and take a further three to four years.

The NDA’s Brian Burnett, Head of Programme Delivery for Magnox and RSRL, said:

“This has been an extremely challenging programme with many technical problems to overcome. The journey to this achievement has been long and difficult, but is a major step in reducing hazards at the site.”

Martin Grafton, Site Director, added:

“This is a key milestone for the site and work is already under way to access Bunker 4 using remote equipment. The team have worked hard to improve productivity rates in the waste retrieval process and a number of lessons learned and successes achieved during the Bunker 5 clearance will now be applied to the recovery of waste from the four remaining bunkers.”

Specially engineered stainless steel packages containing the waste have been transferred to the ILW store.

Eventually, the contents will be encapsulated in grout and then returned to the store for the decades-long Care and Maintenance phase before the site is fully cleared.