|Dry Casks at Vermont Yankee|
Photo courtesy of Entergy
Among the challenges Entergy will face is spent fuel storage.
According to the U.S. Government Accountability Office, commercial nuclear power production in the U.S. has generated over 70,000 metric tons of spent nuclear fuel—fuel that has been irradiated and removed from nuclear reactors—and the inventory is increasing by about 2,200 metric tons per year. This high-level waste is extremely radioactive and needs to be isolated and shielded to protect human health and the environment. In 1982, Congress passed the Nuclear Waste Policy Act, assigning the federal government’s long-standing responsibility for disposal of spent nuclear fuel to the U.S. Department of Energy. Although the DOE was to begin accepting spent fuel by January 31, 1998, the nation remains without a repository for disposal after spending decades and billions of dollars to research potential sites for permanent disposal, including Yucca Mountain in Nevada. Instead, it is currently being stored primarily at the sites where it was generated.
In the absence of a national repository and as spent nuclear fuel continues to accumulate at individual reactor sites, Entergy and other power plant owners have been forced to contend with the continued on-site storage of spent nuclear fuel in spent fuel pools and dry cask storage when the pools’ storage capacity is reached. Spent nuclear fuel usually cools for at least several years in a pool before it is transferred into either a vertical or horizontal dry storage system. The cooled fuel is then loaded into canisters, which are then filled with helium, sealed and tested to confirm that the canister is leak tight in accordance with ASME pressure vessel standards. A loaded canister is transferred from the transfer container into a storage overpack or cask (large steel cylindrical structures) that contains high-density concrete for radiation shielding and ventilation openings for cooling of the canister. The casks are placed on a concrete storage pad that is part of an independent spent fuel storage installation, or ISFSI. The casks are monitored to confirm that the vents at the top and bottom of the outer cask are not blocked so that air can circulate and therefore remove the heat generated by the fuel.
At the Vermont Yankee plant, for example, the spent fuel pool began nearing maximum storage capacity in the mid-2000s, and Entergy needed to construct a dry storage facility in order to continue plant operations. Under Vermont state law, the Vermont Public Service Board has the authority to review proposals for the construction of any new spent nuclear fuel storage facilities in the state. This required plant owner Entergy Nuclear Vermont Yankee (ENVY) to apply to the Public Service Board for a Certificate of Public Good (CPG) to construct a dry fuel storage facility at Vermont Yankee.
In 2006, after a litigated administrative proceeding, the Vermont Public Service Board issued an order approving ENVY’s petition to construct a dry fuel storage facility at Vermont Yankee. A concrete pad, 76 feet by 132 feet, was subsequently constructed that could accommodate 36 dry casks supplied by Holtec International. Dry loading campaigns occurred in 2008, 2011 and 2012 in which 13 dry casks were placed on the pad.
On August 27, 2013, Entergy announced that it would permanently cease operations at Vermont Yankee by the end of 2014. The reactor shutdown occurred on December 29, 2014. By mid-January of 2015, all nuclear fuel was removed from the reactor and placed in the spent fuel pool.
In June, 2014, ENVY filed another petition before the Vermont PSB to construct a second ISFSI storage pad to store the spent nuclear fuel that remained in the VY spent fuel pool. The need for the second pad continues due to the absence of Department of Energy performance in transferring the fuel from VY to a federal repository. Entergy expects to complete transferring fuel from the spent fuel pool to the ISFSI in 2020. Once the final loading campaign has been completed, ENVY expects to reduce the protected area to the area surrounding the two ISFSI pads to reduce the security costs that will be funded from the nuclear decommissioning trust. The proposed second ISFSI storage pad would be 76 feet by 93 feet and built 30 feet immediately to the west of the existing ISFSI storage pad and would continue to use the same system that was previously approved by the PSB for dry cask storage of spent fuel on site.
ENVY has asked that the approval of the Certificate of Public Good be granted in May 2016. If this occurs, then construction of the second ISFSI can be completed in 2017 at the same time casks are being loaded on the first ISFSI pad. This will ensure complete transfer of all spent fuel to dry casks by the end of 2020.
ENVY is funding the costs for the construction of the second ISFSI pad, procurement of dry storage systems and transfer of the fuel from the spent fuel pool to the ISFSI through two revolving credit facilities totaling approximately $145 million. ENVY plans to repay borrowings on these credit facilities with funds recovered in litigation from the DOE for breach of its contract to remove spent nuclear fuel from the VY Station.
Franklin Orr, Under Secretary for Science and Energy, recently wrote, "According to consensus in the scientific community, geological repositories--which would store nuclear material deep within the earth’s surface in safe, scientifically proven locations—represent the safest and most cost-effective method for permanently disposing of spent nuclear fuel and high-level radioactive waste. The first step for commercial spent fuel begins with developing a pilot interim storage facility that will mainly accept used nuclear fuel from reactors that have already been shut down. The purpose of a pilot facility is to begin the process of accepting spent fuel from utilities, while also developing and perfecting protocols and procedures for transportation and storage of nuclear waste. It is our goal that throughout the process of developing a pilot interim facility that the Department of Energy builds trust with all of the local communities involved."
Full decommissioning and site restoration of the VY and other shutdown plant sites cannot take place until the used fuel is removed by the DOE. The DOE has collected over $10 billion from nuclear plant owners to construct and operate a spent fuel repository without taking any spent fuel. In 1987, Congress designated Yucca Mountain in Nevada as a national disposal site. Over twenty years later, however, President Obama abandoned the project. It is imperative that Congress acts to find a solution for the used fuel issue because a reactor licensee cannot fully decommission a licensed reactor site until the spent fuel has been removed from the site. In the meantime, Entergy and other plant owners must continue to store the spent fuel on-site in a safe, cost effective manner.
This guest post is by Martin Cohn, Senior Communications Specialist at Vermont Yankee. This post first appeared as an article in Nuclear Power International Magazine, January-February 2016. It also appears in Power Engineering Magazine, February 16, 2016