Deep Isolation’s disposal concept leverages directional drilling expertise to isolate spent nuclear fuel and high-level radioactive waste in horizontal drillholes located deep underground in suitable rock formations.
SPENT NUCLEAR FUEL
Nuclear waste is composed of dense, compact pellets made of uranium dioxide and stored in a fuel assembly made of zirconium alloy that can hold 22,000 to 92,000 pellets.
When the fission energy in these pellets is spent, the assemblies along with their pellets are removed from the reactor and placed in cooling pools. After several years the radioactivity has decayed to the point where “dry” storage is possible; about one third of the current nuclear waste is stored in dry casks above ground at the nuclear reactor sites. This is considered to be “interim storage”; there is not yet any licensed location where the waste can be sent for long-term disposal.
DIRECTIONAL DRILLHOLE CONFIGURATION
Rather than creating large tunnels, Deep Isolation will place nuclear waste in narrow 18-inch horizontal drillholes in rock that has been stable for millions of years. No humans need go underground.
The Deep Isolation repository begins with a vertical access drillhole extending thousands of feet deep and will then gently turn horizontal. Canisters containing nuclear waste would be stored in the deep horizontal section.
Benefits of this patented design:
- One drillhole can store 5 years of waste from a Boiling Water Reactor (BWR) and 11 years of waste from a Pressurized Water Reactor (PWR).
- Tilted horizontal drillhole offers excellent isolation from surface.
- The drilling, placement, and retrieving techniques are standard and reliable.
- Sites can be at or near power plants to minimize transportation.
A deep horizontal drillhole repository takes advantage of the exceptional isolation properties of geologic formations whose stability has endured for a million years or more.
Deep disposal would also be far below aquifers, in a region in which water has had no contact with the surface for a million years or more.
Deep, stable rock formations thousands of feet underground provide:
- A billion tons of rock between the waste and the surface.
- Extremely long time for waste to diffuse to the surface, even if it penetrates the engineered barriers, allows most radioisotopes time to decay naturally.
SAFETY IS PARAMOUNT
Experience with oil and gas drilling shows that the drilling itself does not trigger earthquakes; the observed earthquakes from oil and gas fracking come from the high-pressure injection of liquid underground. There is no fracking performed with any of our technology. Compare the risks of fracking with the safety of the Deep Isolation solution.
The geology of the deep horizontal repository also offers natural protection against human intrusion and terrorist attempts.
Disposal of High-Level Nuclear Waste in Deep Horizontal Drillholes
Dr. Richard Muller introduces our method and issues pertaining to safety requirements.
Thermal Evolution near Heat-Generating Nuclear Waste Canisters Disposed in Horizontal Drillholes
This paper examines the impact that design parameters and host-rock thermal properties have on temperatures in and around the drillhole.
Numerical Simulations in Support of a Generic Post-Closure Safety Analysis for a Horizontal Drillhole Repository
Preliminary safety calculations for the disposal of spent nuclear fuel in a generic deep horizontal drillhole repository published in the peer-reviewed journal, Energies, by MDPI. May 2020