Sellafield Digital Twin Project Clinches Top IChemE Award

Adam Duckett reports from this year’s Awards ceremony

SELLAFIELD and the National Nuclear Laboratory were awarded IChemE’s Outstanding Achievement in Chemical and Process Engineering Award for developing a digital twin of a crucial nuclear waste processing plant which has enabled them to radically improve its performance and extend the life of the facility.

The Site Ion Exchange Effluent Plant (SIXEP) plant in Cumbria, UK, treats radioactive effluent from operations across the huge Sellafield nuclear reprocessing site. The UK Government describes SIXEP as the “kidneys” of the site, filtering waste from water and making it safe to discharge to the sea.

The challenge for engineers is that the plant was commissioned in 1986 – it was originally designed to cease operations in 2011, but needs to be kept going until a replacement comes online in 2030. The team says the plant has struggled to maintain steady operations since it was commissioned. This has been caused by variations in process operations at plants that feed waste to SIXEP, and sub-optimally configured level and flow controllers within the facility. If SIXEP were to become inoperable the UK would be forced to either emit more radioactive effluent to the sea or cease all discharges from SIXEP, which would halt remediation at one of Europe’s most hazardous nuclear facilities.

Twin it to win it

To overcome this, the team developed a model in gProms using first principles, requiring the entire facility to be replicated in terms of mass and energy balances for each unit operation, its tanks, filtration systems, pump, reactors and sand-bed columns. The model also incorporated plant operations automated through the control system and those implemented manually by operators.

Using the digital twin of the plant, the team identified five areas to improve the plant control system which allowed them to reduce flow surges through the sand beds and ion exchange beds. They have decreased cyclic loading on the plant and stress placed on aged pipework, and reduced the time that SIXEP experiences severe fluctuation from more than 20% of the time to less than 2%.

The team says the success of its model allows SIXEP to extend its operations and be more efficient. Speaking to The Chemical Engineer after the award was announced, the team said the improved maturity of modelling software enabled it to overcome the longstanding problems.

“Collaboration and buy-in was key to delivering new ways of working and implementing new solutions in a facility that has already had a long history of successfully reducing discharges,” said Felipe Basaglia, Performance Assurance Lead at Sellafield Ltd.

“This project could not have been carried out without the support of the plant to try out new approaches and the hard work and dedication from Sellafield Effluent Management Strategy (SEMS) team, operators, system engineers, technical authorities as well as the excellent collaborative working relationship with our colleagues from the National Nuclear Laboratory.”

Asked what the award means for the team, Basaglia said: “Receiving international recognition from IChemE is an incredible honour and is testimony to the vision, commitment and dedication of the team in embedding and utilising new technologies such as gPROMS to support plant operations, hopefully inspiring other organisations to do the same.”

IChemE Awards Head Judge, Keith Batchelor said: “In the midst of 14 worthy winners across different fields of engineering, this project stood out because it supports almost all UK nuclear activities which are set to become increasingly important as we grapple with current energy issues and the need to safely increase nuclear contribution as we move towards net zero. Most critically, it protects local and international populations from the significant impact of effluent discharged to sea. Well done to Sellafield and the National Nuclear Laboratory.”
The Sellafield team has formed an international community of practice with Washington River Protection Solutions (WRPS) in the US, which manages radioactive waste stored at the Hanford nuclear site, which played a leading role in the development of the atomic bomb during the Second World War.

The Sellafield team had previously scooped the Water Award and its entry was judged the best overall winner across all the non-individual categories.