Catalyst Summer 2013

The Growing Threat of Nuclear Waste


by Seth Shulman

Earlier this spring, workers at Reactor Unit 3 of the Indian Point nuclear power plant, 40 miles north of New York City, undertook a routine procedure vital to the operation of any such plant in the United States: they replaced the reactor’s “spent” nuclear fuel rod assemblies with fresh ones, transferring the older assemblies to a cooling pool adjacent to the reactor core.

Back in 1976, when Unit 3 was first licensed, the Nuclear Regulatory Commission (NRC) authorized its cooling pool to hold a maximum of 264 spent fuel assemblies. Now, however, 1,218 assemblies are packed into the pool like giant radioactive sardines in a large underwater tin.

This is not only more than four times the number of spent fuel assemblies for which the pool was initially designed, but also close to the maximum 1,345 permitted by the NRC¾a reality that no doubt presents a headache for Indian Point’s corporate owner, Entergy. After all, as Entergy spokesperson Jerry Nappi notes, “A reactor cannot continue to operate unless there is room in its cooling pool for its spent fuel.”

Of course crowded cooling pools represent more than an inconvenience for the nuclear industry. As UCS Nuclear Safety Project Director Dave Lochbaum explains, “Densely packed cooling pools represent an undue risk to the public because they are unacceptably vulnerable to accidents, natural disasters, or terrorist attack.”

Running Out of Room

Sadly, the situation at Indian Point is the norm in the United States rather than the exception: more than 50,000 tons of spent fuel now sit in cooling pools that were never intended for long-term storage. Companies like Entergy, Nappi rightly notes, had expected the U.S. government to take title to this waste and bring it to a permanent repository. But Congress has stood at an impasse over the siting of such a repository since 1998.

In the interim, the NRC has authorized U.S. plants to follow the easiest and cheapest storage path available: namely, to pack their pools ever tighter and add boric acid to the water in order to absorb neutrons and limit the likelihood of a nuclear reaction caused by the increased proximity of fuel assemblies. Even with these so-called re-racking authorizations, the NRC says that all the nation’s nuclear power plants will run out of space in their pools by 2015.

The danger inherent in overcrowded storage pools lies in their nature as an “active” storage system; that is, plant operators must ensure a constant supply of water is pumped into the pool and circulated around the fuel assemblies in order to keep them cool.  If the water supply is interrupted, the assemblies are hot enough to begin boiling away the water in the pool; the more fuel a pool contains, the faster its water will boil away. Once the fuel is exposed to air, it can burn, melt, and possibly release massive amounts of radiation—which could be cataclysmic at a plant like Indian Point that is so close to a metropolitan area. This was one of the main concerns during the 2011 nuclear disaster in Fukushima, Japan, when cooling systems lost power. (Thankfully, none of the storage pools lost all their water, and the plant operators were able to dump and spray seawater into the pools and restore cooling before the fuel could overheat.)

The Simpler, Safer Choice
Why nuclear waste should be moved to dry casks.

After five years in a cooling pool, spent fuel assemblies are cool enough to be moved into dry casks: concrete and metal containers that are filled with inert gas, then placed on concrete pads or in large concrete silos at the reactor site. Unlike cooling pools that require mechanically driven water circulation, dry casks employ “passive” cooling: air enters an opening at the bottom of the cask, absorbs heat from the spent fuel, then rises and exits through an opening at the top, creating a “chimney effect” that pulls more air into the bottom of the cask.

Passive cooling makes dry casks less likely to lose their cooling capacity than “active” systems like cooling pools, which are vulnerable to mechanical failure, technical or human error, terrorist attack, and natural disaster. In addition, maintaining safety is simpler with dry casks, involving such mundane tasks as ensuring that birds have not built nests that block the chimney’s air flow.

It is worth noting that some of the spent fuel from Japan’s Fukushima Daiichi plant had already been stored in dry casks prior to the 2011 earthquake and tsunami. The safety of this radioactive waste was never a concern during the subsequent crisis.

 

And while a nuclear reactor is surrounded by six to nine inches of steel and sits within a concrete containment dome some three to four feet thick, the spent fuel pool is located outside the containment dome, in a traditional industrial building often composed of “sheet metal siding like that in a Sears storage shed,” according to Lochbaum. These structures are not better reinforced because neither the industry nor its regulators intended to store spent fuel in pools for as long as they have.

Industry, Congress Delay the Inevitable

Fortunately, there is an established and sensible solution to the problem of overcrowded cooling pools: storing waste in dry casks on site (see the sidebar). Most analysts agree that dry casks provide a safer and more secure way to store spent fuel at nuclear power plants while it is waiting to be moved offsite to long-term storage—a process that will require the transfer of spent fuel to dry casks anyway. So as David Wright, co-director of the UCS Global Security Program, puts it, “If the industry is going to have to do this eventually and we know it is safer, why not do it now?” Because of what’s at stake for public safety, UCS and its team of technical specialists, legislative experts, and activists have made dry cask storage a top priority.

Rob Cowin, our senior Washington representative on nuclear waste issues, has been working with the offices of four U.S. senators to make sure overcrowded cooling pools are addressed in comprehensive nuclear waste management legislation. When draft legislation released in late April focused primarily on long-term waste repositories and failed to outline short-term storage strategies at power plants, UCS mobilized its activists to call for the inclusion of dry cask storage guidelines. We have been publicizing both the benefits of dry cask storage and the favorable experience many nuclear operators have had with dry casks; in addition, the BlueGreen Alliance (made up of 14 of the nation’s largest environmental and labor organizations, including UCS) sent a letter to the four senators in May explaining how dry cask storage could also create a substantial number of skilled American jobs and improve worker safety.

As Catalyst went to press, policy makers were reviewing these and other public comments and preparing a final draft bill that will likely be debated by the Senate Energy and Natural Resources Committee later this summer. See the sidebar to learn how you can get involved during the next round of debate.

Even if dry cask storage is included in the final bill, Cowin emphasizes that many logistical hurdles remain, such as determining how quickly the industry should be required to transfer waste to dry casks, and whether funds the government has collected from the industry for creating long-term storage solutions might be used for the task. The industry has wanted to delay fuel transfers until its pools are filled to capacity, but Cowin says this strategy “leaves the risks to the public unacceptably high.”

UCS is committed to reducing these risks. With your help we can push the nuclear industry to develop long-term solutions for nuclear waste storage that put public safety first.

Seth Shulman is a senior staff writer at UCS.

 

 

Learn more about our efforts to improve U.S. nuclear power plant safety.