Nuclear Waste could be Recycled for Ultra-Long-Lasting Diamond Batteries
Work has begun at Berkeley power station in Gloucestershire in the U.K. to remove radioactive waste products from the site as part of its decommissioning program. To try and reduce the time and cost of this operation, a team of physicists and chemists from the University of Bristol hope to recycle material from the irradiated graphite to generate ultra-long-lasting power sources.
Berkeley power station was decommissioned in 1989 and it has only just become safe to start removing radioactive waste products from the plant. These are currently stored in concrete vaults eight meters underground and require specialized equipment to retrieve and process securely.
The second nuclear station on the bank of the River Severn is Oldbury, which stopped producing electricity in 2012. This site completed defueling in 2016 is now in the early decommissioning phase.
These two sites, as well as the reactors at Hinkley Point in Somerset and other decommissioned sites across the UK, hold vast amounts of irradiated graphite that hold the Carbon-14 isotope that could be recycled to generate power.
Diamond batteries to use waste for power
The University of Bristol researchers have grown a man-made diamond that, when placed in a radioactive field, is able to generate a small electrical current. By using Carbon-14 which has a half-life of 5730 years, the batteries could potentially provide power on a near-infinite basis.
Previously, the team demonstrated a prototype ‘diamond battery’ using Nickel-63 as the radiation source. However, they are now working to significantly improve efficiency by utilizing carbon-14, a radioactive version of carbon, which is generated in graphite blocks used to moderate the reaction in nuclear power plants. Research by academics at Bristol has shown that the radioactive carbon-14 is concentrated at the surface of these blocks, making it possible to process it to remove the majority of the radioactive material. The extracted carbon-14 is then incorporated into a diamond to produce a nuclear-powered battery.
Dr. Neil Fox from the School of Chemistry explained: “Carbon-14 was chosen as a source material because it emits a short-range radiation, which is quickly absorbed by any solid material. This would make it dangerous to ingest or touch with your naked skin, but safely held within diamond, no short-range radiation can escape. In fact, diamond is the hardest substance known to man, there is literally nothing we could use that could offer more protection.”
Despite their low-power, relative to current battery technologies, the life-time of these diamond batteries could revolutionize the powering of devices over long timescales. The actual amount of carbon-14 in each battery has yet to be decided but one battery, containing 1g of carbon-14, would deliver 15 Joules per day. This is less than an AA battery.
Standard alkaline AA batteries are designed for short timeframe discharge: one battery weighing about 20g has an energy storage rating of 700J/g. If operated continuously, this would run out in 24 hours. Using carbon-14 the battery would take 5,730 years to reach 50 per cent power, which is about as long as human civilization has existed.
The ultimate aim is to have a factory based at one of the former power stations in the South West that takes Carbon-14 isotopes directly from the graphite blocks for use in diamond batteries. This would significantly reduce the radioactivity of the remaining material, making it easier and safer to manage.