Nuclear power plants have traditionally stored spent fuel in secure water pools at the reactor site. In the early 1980s, as space in the pools at the reactor sites ran out, the nuclear power industry began to explore alternative storage methods. Another option is to store the spent fuel in an independent spent fuel storage installation, which can be stored at the site or elsewhere. This option is referred to as dry cask storage. Indian Point implemented dry cask storage for the first time in 2007.
Dry casks cutaway view.
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Dry cask storage is a remarkably simple, yet extremely safe and reliable system that seals used nuclear fuel in massive steel and concrete canisters that provide both structural strength and radiation shielding. The system of concentric cylindrical containers provides above ground, long-term storage of spent nuclear fuel. Casks are placed upright on a concrete pad and are hardened structures capable of withstanding natural disasters and terrorist attacks. The vertical system is referred to as dry because the fuel is surrounded by helium gas rather than water. The canister/cask system is very robust, about 20 feet in height and 11 feet in diameter, with a cask wall that is over 2 feet thick and a total loaded weight of about 360,000 pounds. The inner canisters and outer casks have no operating equipment requiring regular maintenance. The fuel is cooled by passive means, with its heat dissipating via cooling channels in the outer cask that allow air to circulate naturally on the outside of the inner canister.
The NRC reviews and approves the designs for spent fuel dry storage systems as well as periodically inspects the design, fabrication and use of dry casks to ensure continued compliance with radiation safety and security requirements.
Dry Cask Storage is safe and environmentally sound, with four decades of exemplary safe performance worldwide. Since 1986, more than a dozen U.S. plants have successfully used dry storage facilities including Entergy. Strict federal regulations pertaining to environmental protection, radiation control, and occupational safety govern the process. The containers used in the dry storage systems are designed to resist floods, tornadoes, projectiles, temperature extremes, and other unusual scenarios. Over the last 20 years, there have been no radiation releases which have affected the public, no radioactive contamination, and no known or suspected attempts to sabotage spent fuel containers.
The environmental and public health risks associated with irradiated fuel and placed in casks produced by Indian Point are well below federally mandated minimum requirements. These requirements are found in 10 CFR 72 and in the cask system vendor’s Final Safety Analysis Report. The systems, structures and components that ensure these requirements are continually met, are maintained through a stringent program of continuous inspections, in-service and post-maintenance tests, preventive maintenance, and regulatory oversight.