Dry Cask Storage has been in use at various nuclear facilities in the United States since the mid 1980s. In fact, more than half of the nuclear power plants in US are either using Dry Cask Storage now or are in the process of implementing the storage capability. (View map)
Dry Cask Storage is an efficient and safe way of adding fuel storage capacity at Fermi 2 until the national storage facility is in operation.
A Dry Cask Storage installation seals used nuclear fuel inside massive steel and concrete cylinders. The concentric cylinders create a simple, yet extremely safe and reliable system that provides both structural strength and radiation shielding.
The casks are placed upright on a concrete pad. They are capable of withstanding natural disasters and terrorist attacks. Each cask is about 20 feet in height and 11 feet in diameter. The outer wall of a cask is over two feet thick. Each loaded cask system weighs about 360,000 pounds. The inner canisters and outer casks have no operating equipment requiring regular maintenance.
Dry Cask Storage systems are also referred to as Independent Spent Fuel Storage Installations (ISFSI).
Fermi 2 plans to be ready to load the first casks and transport them to the ISFSI pad in spring 2010. Pad construction began in spring 2009. In preparation for the installation, an ISFSI support equipment storage building is currently under construction. Fermi's reactor building overhead crane capacity has been upgraded and tested to 125 tons to allow it to lift and manipulate the fully loaded storage canisters. A rail line through the reactor building air lock is being re-installed to allow the movement of ISFSI casks and other support equipment in and out of the reactor building.
The concrete storage pad being built will be approximately two feet thick and 141 feet by 141 feet. More than 1472 cubic yards of concrete will be purchased from local suppliers. Pad design and construction take into consideration the issues of earthquakes, drainage, cask transport equipment, lighting and security. The NRC must inspect both the design and the physical preparation of the pad form work and reinforcing bars before the concrete gets poured, and has the option to monitor the actual concrete pour to ensure compliance with regulations.
The general license granted to Fermi 2 by the NRC allows us to operate an Independent Spent Fuel Storage Installation (ISFSI). Fermi 2 can use this license after it has successfully demonstrated to the NRC that it has complied with all requirements and is proficient in the use of equipment and the steps needed to perform loading of casks. Local and state construction and use permits are also required, as with any structure built at the site.
Construction of this ISFSI specifically addresses concerns about such issues as :
Due to the low dose rate associated with the ISFSI casks, public heath will be unaffected. Radiation detectors will be mounted in the immediate ISFSI area. These detectors will be routinely analyzed to determine the amount of radiation present. In addition, radiation protection personnel will perform periodic surveys using hand-held instruments to determine the radiation amounts present over time. Typical dose rates for workers at the ISFSI site are expected to be < 5 millirem/hour at contact and < 1 millirem/hour at 2 meters. These values are well within the limits imposed by federal regulations. Learn more about radiation.
Environmental impacts resulting from the ISFSI are minimal both for construction and the use of the facility. There is no radiologically-contaminated storm water runoff since the canisters holding the fuel are seal-welded shut. The NRC has performed a generic environmental impact study for ISFSIs. It states that spent fuel can be stored safely and without significant environmental impacts for at least 30 years beyond the licensed reactor life. In addition, the NRC completed an environmental impact assessment on the Transportation of Radioactive Material by Air and Other Modes in 1977.
Storm Water Control
The Fermi ISFSI has been designed to satisfy storm water drainage and pollution prevention requirements mandated by local and state law. ISFSI construction complies with the requirements of the plant's Discharge Permit issued by the State of Michigan.
The ISFSI is designed to withstand earthquakes without a release of radiation. Its design satisfies federally mandated requirements for structural characteristics and resistance to seismic events.
The ISFSI will be located inside the plant's Protected Area, where it will be continuously monitored. The storage casks are massive, with over two feet of concrete surrounding a stainless steel canister. The free-standing casks dissipate heat using a passive cooling system which does not rely on any power source. Another advantage of the design is that the casks remain in full view at all times.
Roads and Transportation
Only the cask metal shells, which weigh considerably less than after they have been filled with concrete, will be transported by truck over local roads. No modification will be needed to local roads nor will transport of shells or concrete exceed road weight restrictions. Within the plant's property some road improvements will be made to protect underground utility installations and facilitate transportation to the new ISFSI building and pad.