Storing Nuclear Waste in Casks - An Issue of Concern for Wyoming

by Wyoming Liberty Group

Recently, state lawmakers said no to the idea of storing other states' nuclear waste in Wyoming. But if history has taught us anything, it's that just because a bill dies in committee doesn't mean the issue is dead. The idea of Wyoming as a repository for spent nuclear fuel has resurfaced repeatedly for decades. With nuclear energy gaining traction nationwide and current projects underway in Wyoming, the issue is sure to come up again in the Cowboy State.

As a result, it's crucial for us, as laypeople, to understand the dimensions of this ongoing and critical issue, which could have a far-reaching impact on our way of life. One essential aspect is how spent nuclear fuel is stored in casks. Dry storage casks have been used at power plants in the United States for decades. According to experts, there are over 3,000 casks at more than 70 storage sites across the country, holding over 90,000 metric tons of spent nuclear fuel.

However, cask thickness is an important factor when storing toxic nuclear waste. Perhaps most surprising is that in the United States, casks tend to be thinner than those used in other countries. Domestically, most casks are only 0.5 inches thick, while casks in other countries range from 10 to 20 inches thick. When we spoke with Dr. Gordon Edwards from Canada, he noted that Canadian thick-walled casks can weigh 60 tons when empty and hold only 10 tons of material.

The risk, then, is that thinner-walled canisters suffer from a variety of issues.

But let's back up a sec.

A Bit of Background on Thick-Walled Casks

Thick-walled casks, with steel walls between 10 and 20 inches thick, provide built-in radiation shielding. They are used to store nuclear waste above ground, typically sitting on concrete pads at power plants. Advocates argue that thick-walled casks are safer because they are designed to withstand transportation, natural disasters such as earthquakes and tornadoes, and potential radioactive leakage that could threaten human life and the environment.

But—there's always a "but", isn't there?—the thin-walled canisters used in the United States can corrode or crack, especially in marine or humid environments. The thin stainless-steel walls are also insufficient to fully stop gamma rays. Because thin-walled canisters do not completely block gamma rays, they must be placed inside concrete overpacks. However, gaps and seams in the shielding design can allow gamma radiation to "stream" through bolt holes, weld seams, or other structural weaknesses.

Making matters worse, there is no approved method for repairing these thin-walled canisters once cracks develop.

Expert Warnings on Thin-Walled Casks

Donna Gilmore, founder of San Onofre Safety and an expert on spent nuclear fuel storage, has made a series of recommendations to improve safety.

For one, she argues that the U.S. should require thicker-walled casks.

"Thick-wall casks are less expensive when considering maintainability, life span, and reduced risks of nuclear disasters that could lead to evacuations, radioactive contamination, and economic and security instability," she said.

She also recommends that thicker-walled casks be stored in more secure, air-cooled facilities. Perhaps most importantly, she insists:

"Unsafe thin-wall nuclear waste canisters must be replaced."

A major concern, she points out, is that current casks are not designed to last more than 20 years and may begin to crack in as little as 17 years. Factors such as moist salt air can accelerate stress corrosion cracking in these thin-walled canisters.

She also warns:

"Current unsafe, uninspectable welded thin-wall canisters are vulnerable to short-term cracking and do not meet safety codes."

And she adds:

"This is a now problem. We cannot keep kicking these 'Chernobyl cans' down the road. The consequences are too high.

The Bigger Picture: Temporary Storage vs. Permanent Solutions

Yet, the broader issue is that dry cask storage was never meant to be a permanent solution. According to U.S. policy, the plan has always been to find a permanent disposal site for spent nuclear fuel in a deep underground geological repository—which is a fancy way of saying a big hole in the ground.

However, no community—including those in Wyoming—has been eager to host such a site, whether for "temporary" or permanent storage.

It's essential for everyone to recognize that no industry is without its problems, and the nuclear industry is no exception. As time progresses, it is vital that the people of Wyoming fully understand the state's nuclear ambitions, current projects, and what they all entail.