Finnish spent nuclear fuel disposal firm Posiva has selected New Zealand firm Aranz Geo’s advanced software for use in the construction of a final disposal facility.

Posiva has licensed Aranz Geo’s Leapfrog 3D geological modelling software, which will be helpful in geological understanding, modelling and management of geological risk for the construction of a final disposal facility for spent nuclear fuel.

The software will allow geologists to model geology at the nuclear repository site, including fractures and faults that could become possible pathways for waste or contaminant migration.

Finland has granted permission to construct final disposal facility at its island of Olkiluoto.

The repository will need 100 years of geological management and construction, and then it will be sealed. The long-term safety of the storage will be evaluated up to a time period of 1,000,000 years.

Initially, Posiva has to create deep burial disposal caverns for spent nuclear fuel from nuclear power plants Teollisuuden Voima and Fortum Power and Heat, which co-own the company.

Finland’s nuclear regulatory authority STUK will evaluate each stage of the project.

Spent nuclear fuel will be packed in around 5m long copper canisters and planted in crystalline Olkiluoto bedrock, which is away from faults and fractures and locations of high groundwater flow, at a depth between 400m and 450m.

Eventually, around 35km of bedrock tunnels will include over 3000 canisters each holding two tonnes of spent fuel.

Aranz Geo CEO Shaun Maloney said: “We’re actively involved in understanding and managing some of the biggest environmental challenges facing humanity and the planet.

“This world first project for deep geological nuclear disposal over almost unfathomable timescales requires total confidence in the geological understanding – which is critical for both effective management and regulation of radioactive waste.”

Posiva research manager and structural geologist Dr Jussi Mattila said: “Leapfrog allows our geology team to handle numerous inputs of disparate data types, and comprehend the impact in dynamic 3D models to gain an accurate picture of the geology.”

Image Aerial image of Posiva Oy’s spent nuclear fuel disposal facility which is under construction on the Finnish Island of Olkiluoto. Photo: courtesy of Posiva Oy.