The materials, produced by Dr Claire Corkhill and her team from the university’s Department of Materials Science and Engineering, in collaboration with scientists in Ukraine, can simulate the Lava-like Fuel Containing Materials (LFCMs) that are obstructing decommissioning efforts at the nuclear disaster sites.

LFCMs are a mixture of highly reactive molten nuclear fuel and building materials that fuse together during a nuclear meltdown.

Published in the journal Nature Materials Degradation, the team at the university said the development is the first time a close approximation of a real LFCM has ever been achieved.

During the Chernobyl and Fukushima nuclear accidents, radioactive materials mixed with fuel cladding and other building materials in the reactors and have proved difficult and dangerous to remove from the sites. If left untreated, the LFCMs pose an ongoing radiological safety risk to the local environment.

In the case of Chernobyl, the mixture of molten fuel, cladding, steel, concrete and sand formed nearly 100 tonnes (100,000kg) of highly radioactive glass-like lava, which flowed through the nuclear power plant and has solidified into large masses.

These masses pose a highly dangerous risk to personnel and the environment in the surrounding area and could remain a hazard for decades unless something can be done to stabilise and remove them.

However, the team said that very few samples of these meltdown materials are available to study and the masses are often too hazardous for people, or even robots, to get close to in order to better understand the behaviour of the materials.

“Understanding the mechanical, thermal and chemical properties of the materials created in a nuclear meltdown is critical to help retrieve them, for example, if we don’t know how hard they are, how can we create the radiation-resistant robots required to cut them out?” said Dr Corkhill.

In the new research published, the engineers at the NucleUS Immobilisation Science Laboratory (ISL) reported their development of small batches of low-radioactivity materials that can be used to simulate LFCMs. These simulated materials have been used to analyse the thermal characteristics and corrosion kinetics of LFCMs, which produced results that are very close to those of real LFCM samples reported by previous studies.

According to the researchers, the study of the corrosion behaviour is vital to support ongoing decommissioning efforts – both at Chernobyl and the Fukushima Daiichi Nuclear Power Plant – where LFCM-type materials are thought to have formed and remain submerged in water used to cool the melted core.

Using the new simulant materials developed, Dr Corkhill and her team are collaborating with researchers at the University of Tokyo and the Japan Atomic Energy Agency to investigate the process of highly radioactive dust formation that occurs at the surface of LFCM when water is removed.

“The major difficulty in understanding the real materials is that they are too hazardous to handle and, although the Chernobyl accident happened over 33 years ago, we still know very little about these truly unique nuclear materials,” said Corkhill.

“Thanks to this research, we now have a much lower radioactivity simulant meltdown material to investigate, which is safe for our collaborators in Ukraine and Japan to research without the need for radiation shielding. Ultimately this will help advance the decommissioning operations at Chernobyl and also at Fukushima too.”

The team declared that the investigation into the corrosion behaviour needs a lot more work, but having established a starting point, they hope to advance this work rapidly. Dr Corkhill noted: “Since the clean-up of Chernobyl is anticipated to take around 100 years, and Fukushima at least 50 years, anything we can do to speed up the process will be beneficial to Ukraine and Japan, in both financial and safety terms.”

The research paper – ‘Synthesis, characterisation and corrosion behaviour of simulant Chernobyl nuclear meltdown materials’ – is published in Nature Materials Degradation.

E&T recently spoke to experts at the Radioactive Waste Management (RWM) about different solutions in preserving radioactive waste – ensuring its containment is safe for thousands of years to come.

In November 2019, researchers suggested a new type of safety barrier for nuclear reactors, which could have prevented the disasters at Chernobyl and Fukushima, could reduce the probability of core melt to that of a large meteorite hitting the site.

Also back in September 2019, the Japanese government called on its nuclear plants to plan ahead in order to lower costs and reduce safety risks. Later that month, Tokyo Electric Power (Tepco) said that it may have to start dumping radioactive water from the Fukushima nuclear plant into the Pacific Ocean from 2022.

The materials, produced by Dr Claire Corkhill and her team from the university’s Department of Materials Science and Engineering, in collaboration with scientists in Ukraine, can simulate the Lava-like Fuel Containing Materials (LFCMs) that are obstructing decommissioning efforts at the nuclear disaster sites.

LFCMs are a mixture of highly reactive molten nuclear fuel and building materials that fuse together during a nuclear meltdown.

Published in the journal Nature Materials Degradation, the team at the university said the development is the first time a close approximation of a real LFCM has ever been achieved.

During the Chernobyl and Fukushima nuclear accidents, radioactive materials mixed with fuel cladding and other building materials in the reactors and have proved difficult and dangerous to remove from the sites. If left untreated, the LFCMs pose an ongoing radiological safety risk to the local environment.

In the case of Chernobyl, the mixture of molten fuel, cladding, steel, concrete and sand formed nearly 100 tonnes (100,000kg) of highly radioactive glass-like lava, which flowed through the nuclear power plant and has solidified into large masses.

These masses pose a highly dangerous risk to personnel and the environment in the surrounding area and could remain a hazard for decades unless something can be done to stabilise and remove them.

However, the team said that very few samples of these meltdown materials are available to study and the masses are often too hazardous for people, or even robots, to get close to in order to better understand the behaviour of the materials.

“Understanding the mechanical, thermal and chemical properties of the materials created in a nuclear meltdown is critical to help retrieve them, for example, if we don’t know how hard they are, how can we create the radiation-resistant robots required to cut them out?” said Dr Corkhill.

In the new research published, the engineers at the NucleUS Immobilisation Science Laboratory (ISL) reported their development of small batches of low-radioactivity materials that can be used to simulate LFCMs. These simulated materials have been used to analyse the thermal characteristics and corrosion kinetics of LFCMs, which produced results that are very close to those of real LFCM samples reported by previous studies.

According to the researchers, the study of the corrosion behaviour is vital to support ongoing decommissioning efforts – both at Chernobyl and the Fukushima Daiichi Nuclear Power Plant – where LFCM-type materials are thought to have formed and remain submerged in water used to cool the melted core.

Using the new simulant materials developed, Dr Corkhill and her team are collaborating with researchers at the University of Tokyo and the Japan Atomic Energy Agency to investigate the process of highly radioactive dust formation that occurs at the surface of LFCM when water is removed.

“The major difficulty in understanding the real materials is that they are too hazardous to handle and, although the Chernobyl accident happened over 33 years ago, we still know very little about these truly unique nuclear materials,” said Corkhill.

“Thanks to this research, we now have a much lower radioactivity simulant meltdown material to investigate, which is safe for our collaborators in Ukraine and Japan to research without the need for radiation shielding. Ultimately this will help advance the decommissioning operations at Chernobyl and also at Fukushima too.”

The team declared that the investigation into the corrosion behaviour needs a lot more work, but having established a starting point, they hope to advance this work rapidly. Dr Corkhill noted: “Since the clean-up of Chernobyl is anticipated to take around 100 years, and Fukushima at least 50 years, anything we can do to speed up the process will be beneficial to Ukraine and Japan, in both financial and safety terms.”

The research paper – ‘Synthesis, characterisation and corrosion behaviour of simulant Chernobyl nuclear meltdown materials’ – is published in Nature Materials Degradation.

E&T recently spoke to experts at the Radioactive Waste Management (RWM) about different solutions in preserving radioactive waste – ensuring its containment is safe for thousands of years to come.

In November 2019, researchers suggested a new type of safety barrier for nuclear reactors, which could have prevented the disasters at Chernobyl and Fukushima, could reduce the probability of core melt to that of a large meteorite hitting the site.

Also back in September 2019, the Japanese government called on its nuclear plants to plan ahead in order to lower costs and reduce safety risks. Later that month, Tokyo Electric Power (Tepco) said that it may have to start dumping radioactive water from the Fukushima nuclear plant into the Pacific Ocean from 2022.