Exelon Goes ‘Dry’ for Fuel Storage

Friday, October 28, 2011 @ 02:10 PM gHale

Exelon’s Braidwood Station nuclear plant will store spent fuel in a whole new way.

The nuclear power facility rolled out its first dry cask storage blocks today, beginning a new era of spent fuel storage at the facility.

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Currently, spent fuel, the radioactive byproduct of nuclear power plant operations, is stored on site in a concrete steel-lined fuel containment pool. The Nuclear Waste Policy Act of 1982 required the federal government’s Department of Energy to construct a national repository for disposing of spent fuel. However, political red tape has kept construction of that repository from becoming a reality. With the containment pool expected to reach storage capacity by 2013, Exelon found another way to store that fuel.

In 2009, the provider began working on dry cask storage as a solution. Dry cask storage already sees use at several of Exelon’s facilities, including Dresden, LaSalle and Byron.

The new process works by placing the spent fuel inside multiple, sturdy, cylindrical containers for storing liquids, known as “casks.” The casks go together like nesting dolls, where one fits inside another, and so on.

The first cask collects the spent fuel inside the containment pool, and then they seal it while under water. They then purge the water from the cask (making a “dry cask”) and removed into another cask. From there, the fuel seals inside a huge cask made of rugged steel or steel-reinforced concrete, with concrete walls of up to 35 inches thick.

That final, large cask will transport via a special, slow moving vehicle to a concrete storage pad on site at the facility. That storage area remains gated and sealed within the secure compound of Braidwood Station, and can hold the weight of multiple dry casks.

“It’s actually safer than the pool,” said Gary Dudek, Braidwood Station’s training director. Dudek also noted dry cask storage is more efficient in that it does not require water or electricity to maintain the safety of the storage.

Site Vice President Dan Enright said dry casks are capable of storing spent fuel for up to 100 years. He expects advancements to be available for disposal at that point, and that it’s possible they may never have to worry about reaching the 100 year mark.

“It could be a long-term solution, but I don’t expect that it is,” Enright said.

Enright also spoke to the safety aspects of dry cask storage versus the containment pool.

“You can walk right up and touch these containers. They’re very safe, they’re not hot, they’re cool, no radiation,” Enright said.

The dry cask storage will not replace the containment pool altogether. The original industry plans called for power plants to take fuel from the reactor to the containment pool, then to the national repository, which was to be the Yucca Mountain in Nevada. However, that plan ended in 2009, and funding terminated this year. That means nuclear power facilities have had no choice but to find interim storage. The current industry plan is to have spent fuel from the reactor taken first to the containment pool, then into dry cask storage, and then to as yet determined national repository.

Dry cask storage gained approval from the Nuclear Regulatory Commission (NRC), which oversaw test runs of the entire dry cask storage procedure last week at Braidwood Station. According to the NRC, dry cask storage is a reliable, safe and secure way to store spent nuclear fuel.

Braidwood Station went operational in 1988. At that time, each reactor earned an operating license. The license for Unit 1 expires in 2026, and the license for Unit 2 expires in 2027. Exelon is currently in the process of renewing those licenses with the NRC. If renewed, the licenses for Unit 1 and Unit 2 would extend until 2046 and 2047, respectively. Enright said the renewal process takes about three years.

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