Nuclear Waste Disposal

[Cambridge Nuclear Energy Center]:

"The safe disposal of waste is a critical issue for the current generation of nuclear power stations and will continue to be one for future designs. Deep geological disposal is the most practical and accepted solution, but research and development is required to give greater certainty about long-term containment and to reduce costs. The Departments of Engineering, Earth Sciences and Materials collaborate in this area. In Engineering, our geotechnical engineers are working on these issues bringing their expertise in soil mechanics, tunnelling, earthquakes, soil liquefaction and soil remediation, together with structural design, to find practical approaches to identifying the best sites for disposal, designing the best disposal method, monitoring its performance and planning for intervention in the event of failure (Professor Robert Mair, Professor Malcolm Bolton, Dr Gopal Madabhushi and Dr Abir Al Tabbaa).

The Department of Earth Sciences has strengths in understanding the subsurface geophysics of repository site, as well as near field geochemistry in high level containment areas. It combines quantum mechanical and classical atomistic modelling with fundamental experimental methods to elucidate the behaviour of solids and fluids in repository settings. For example, the Department has used experiment, simulation and ab-initio computational studies to quantify the number of atoms displaced by the alpha-decay of pollutants e.g. plutonium, uranium and thorium in minerals and provided a detailed understanding of the related damage and the dissolution of the minerals. This work is critical for safe storage of nuclear waste. Research includes: mineralogical models for long term behaviour of high level nuclear waste, ceramic waste forms, geophysical stability of repository site, clay mineral barriers and radionuclides in the environment. (Posted: August, 2013)"

[IEEE Spectrum]:

"Finland may be the first to build a long-term nuclear waste repository.

Finland’s government issued a construction license to nuclear disposal consortium Posiva last week, Reuters reported. The license gives the group approval to build a storage facility on Olkiluoto Island, Finland, designed to last 100,000 years.

The facility would be the first of its kind in the world. Since the beginning of the nuclear power age, energy firms have paid to store nuclear waste in temporary holding ponds unlikely to last more than a couple of centuries.  The Posiva facility, decades in the planning, may pioneer a more sustainable era of disposal. (See “Finland’s Nuclear Waste Solution,” IEEE Spectrum, December 2009.)

Nuclear waste consists of metal rods composed mostly of uranium with a molecular weight of 238. Over time, the depleted uranium atoms release radioactive particles—a process called decay—that converts the uranium into lighter elements. Over billions of years, those atoms decay, too. By the end, all that is left is lead.

In the (long) meantime, however, the radioactive material can contaminate its surroundings, and therefore requires costly management. The United States and other nuclear-powered countries have thus far proven unable to agree on where to store their half-century’s worth of accumulated nuclear waste. An earthquake, volcanic activity, or even a slow leak of water could disrupt the temporary facilities in which the waste now sits.

To provide safer and more permanent storage, Posiva proposes to bury electrically-welded iron-and-copper capsules 400 meters underground. The capsules would be surrounded by clay barriers and capped with rubble and cement. The facility, which would have a 6,500 metric ton capacity, could likely hold Finland and Sweden's projected future nuclear waste. But that capacity doesn’t come close to the volume required by larger nations such as the United States, which has over 70,000 metric tons of waste piled up, and produces an additional 2,200 tons a year.

Though tunneling has been going on for over a decade, Posiva had to wait for the Finnish government to approve its 2012 construction permit application before it could begin the trickier task of loading radioactive waste into its metal coffins. That task may begin as soon as 2023, continue for up to a century, and end when operators fill in the access tunnels with rubble and cap them off with cement. Posiva estimates that installation and operating costs for the first century will be around €3 billion (US $3.21 billion). (Posted: 11/17/15)"

[Monument Valley, Arizona - Civil Engineering Discoveries]

[Posiva]: 

"Posiva Oy is an expert organisation responsible for the final disposal of spent nuclear fuel of the owners. Posiva has been established in 1995.

The final disposal of spent nuclear fuel is based on the use of multiple release barriers, which ensure that the nuclear waste cannot be released into organic nature or become accessible to humans. A deficiency of a single barrier or a predictable geological or other change will not endanger the performance of the insulation. The release barriers include the physical state of the fuel, the disposal canister, the bentonite buffer, the backfilling of the tunnels and the surrounding rock.."

[Sogin]:

"Sogin is an Italian state-owned Company. It is responsible for the environmental decontamination of Italy's nuclear sites and for the management of radioactive waste generated by research, nuclear medicine and industrial activities. As a result, the safety of the Italian citizens, the safeguard of the environment and the protection of future generations will be ensured."

[More to come ...]