In my seemingly endless desire to dive headfirst into controversy, let me return to the issue of nuclear waste storage -- something I last wrote about in this column five years ago, in January 2009. This is a relevant issue today because of the pending closure of Vermont’s only nuclear power plant.

Entergy has announced that Vermont Yankee will close around the end of this year -- largely a victim of low-cost natural gas. The big question now is how long it will be until the plant can be decommissioned and what to do with the large quantities of radioactive waste that are being stored onsite.

Terrorism risks with
nuclear power

My concern with nuclear power has always been more about terrorism than accidents during operation or storage. I continue to worry that terrorists could gain entry to nuclear plant operations and sabotage plants from the inside -- disabling cooling systems and causing a meltdown.

There is also a remote risk of unanticipated natural disasters causing meltdowns or radiation release, as we saw so vividly with the Fukushima Power Plant catastrophe in Japan in March 2011.

But it’s radioactive waste storage I’ll cover here.

Rethinking long-term storage of high-level radioactive waste

For more than 30 years the nuclear industry in the U.S. and nuclear regulators have been going down the wrong path with waste storage -- seeking a repository where waste could be buried deep in a mountain. Nevada’s Yucca Mountain was the place of choice until ... it wasn’t.

Any time we choose to put highly dangerous waste in someone’s backyard, it’s bound to cause a lot of controversy, even in a sparsely populated, pro-resource-extraction place like Nevada. NIMBY opposition can be boosted by people in powerful places, and in the case of Yucca Mountain, Nevada senator Harry Reid has played such a role (he has been the Senate Majority Leader since 2006 and served prior to that as the Minority Leader and Democratic Whip).

Aside from NIMBYism, the problem with burying nuclear waste in a mountain (like Yucca Mountain) or salt caverns (like New Mexico’s Carlsbad Caverns -- an earlier option that was pursued for a while in the 1970s) is that the maximum safety is provided at day one, and the margin of safety drops continually from there. The safety of such storage sites could be compromised over time, due to seismic activity (Nevada ranks fourth among the most seismically active states), volcanism (the Yucca Mountain ridge is comprised mostly of volcanic tuff, emitted from past volcanic activity), erosion, migrating aquifers, and other natural geologic actions.

A better storage option

I believe a much better solution for long-term storage of high-level radioactive waste is to bury it deep under the seabed in a region free of seismic activity where sediment is being deposited and the seafloor getting thicker. In such a site, the level of protection would increase, rather than decrease, over time.

In some areas of seabed, more than a centimeter of sediment is being deposited annually. Compacted over time, such sediment deposition could be several feet in a hundred years, and in the geologic time span over which radioactive waste is hazardous, hundreds to thousands of feet of protective sedimentary rock would be formed.

The oil and gas industry -- for better or worse -- knows a lot about drilling deep holes beneath a mile or two of ocean. I suspect that the deep-sea drilling industry would love such a growth opportunity to move into seabed waste storage, and I believe the Nuclear Regulatory Commission and/or other agencies could do a good job regulating such work.

The waste could be placed in wells extending thousands of feet below the seabed in sedimentary rock in geologically stable regions. Lets say a 3,000-foot well is drilled beneath the seabed two miles beneath the surface of the ocean. Waste could be inserted into that well to a depth of 1,000 feet, and the rest of the well capped with 2,000 feet of concrete or some other material. Hundreds of these deep-storage wells could be filled, capped, and such a sub-seabed storage field designated as forever off-limits.

To address the very real risks of shipping radioactive waste out to sea for sub-seabed storage, perhaps the radioactive waste could be vitrified (incorporated into molten glass-like material) to reduce leaching potential into seawater should an accident occur at sea, and that waste could be tagged with radio-frequency emitters so that any lost containers could be recovered with robotic submarines in the event of such accidents.

While I’m not an expert in any of this, I’ve looked at how much money taxpayers and industry have already poured into Yucca Mountain -- about $15 billion by the time the Obama Administration terminated federal funding for it in 2010, according to Bloomberg News -- and the estimates for how much more it would take to get a working waste storage facility of that sort operational had risen to about $96 billion by 2008, according to the U.S. Department of Energy at the time. I believe that sub-seabed storage would be far less expensive.

Should nuclear power be part of our energy future?

I used to be a firm opponent to nuclear power, and I am still opposed to the form of nuclear power we have today. But my position is softening. Should nuclear power plants be developed that have failsafe, passive cooling systems that would prevent a meltdown even if sabotaged from the inside (I don’t know if that would be possible), if the economics of such plants could work, and if we can shift to safer long-term storage, I could get behind a rebirth of the nuclear power industry.

Those are big "ifs" and I have doubts that they will be satisfied, but I recognize that nuclear power is largely free of carbon emissions -- unlike natural gas, oil, and, especially, coal. We need to dramatically reduce carbon emissions if we are to prevent catastrophic global warming, according to leading scientists.

A starting point for the nuclear industry in building new support for nuclear power should be reexamining sub-seabed waste storage, which could be far safer and far less expensive than other approaches being focused on most actively today.

Alex Wilson is the founder of BuildingGreen, Inc. and the Resilient Design Institute (www.resilientdesign.org), both based in Brattleboro. Send comments or suggestions for future columns to alex@buildinggreen.com.