Smaller reactors may still have a big nuclear waste problem

Lindsay Krall wanted to study nuclear waste. It takes a blend of particle physics, careful geology and engineering to figure out how to bury radioactive atoms. Time is the most difficult of all ingredients. It will take thousands of years to make nuclear waste safer. Any solution that requires too much stewardship can't be done. It needs to work and keep working. The company that designed the reactor won't exist by that time. Who doesn't know? It is possible that the United States won't exist.

The US doesn't have a plan like that right now. After regulators pulled the plug on a decades-long effort to store waste underneath a mountain in Nevada, stranding $44 billion in federal funds, that has been the case since 2011. Congress has shown little interest in working out a solution for future generations because the nuclear industry has done a great job of storing its waste on a temporary basis. Long-term thinking isn't their strength. It has been a failure in the US.

But there’s a new type of nuclear on the block: the small modular reactor (SMR). For a long time, the US nuclear industry has been stagnating, in large part because of the tremendous costs of building massive new plants. SMRs, by contrast, are small enough to be built in a factory and then hauled elsewhere to produce power. Advocates hope this will make them more cost-effective than the big reactors of today, offering an affordable, always-on complement to less-predictable renewables like wind and solar. According to some, they should also produce less radioactive waste than their predecessors. A Department of Energy-sponsored report estimated in 2014 that the US nuclear industry would produce 94 percent less fuel waste if big, old reactors were replaced with new smaller ones. Advertisement

Krall was not sure about that final part. She says that smrs are being marketed as a solution that doesn't require a geological repository for them. She and two prominent nuclear experts began digging through the patents, research papers, and license applications of two dozen proposed reactor designs, none of which have been built so far. Krall, who is now a scientist with Sweden's nuclear waste company, got an answer after thousands of pages of redacted documents, a few public records requests, and a huge appendix full of calculations. The research was published in the national academy of sciences

While the US works out permanent disposal of waste, some startup companies want to build SMR designs. The Nuclear Energy Institute, the industry's trade association, says that five times a small number is still a very small number.

The authors think that the back-end of the fuel cycle should be a bigger factor in determining the economics of the new reactor. Allison Macfarlane is a former chair of the US Nuclear Regulatory Commission. We don't know how much it will cost until we comprehend what we're dealing with.

Smaller reactor designs can make them easier to build, but they can also cause a problem. The energy produced by the reactor is caused by the split of the atom. A chain reaction ensues when this sends out more neutrons. Some of these particles miss. They fly out of the core and hit the other parts of the reactor. More of the neutrons leak because there is less space for them inside. There is no way to deal with the issue. The laws of physics are being dealt with. You have to figure it out.