Small/modular reactors and near-term expectations

There is considerable activity right now in the United States aimed at the addition of new nuclear generating capacity. Tens of millions of dollars are being spent, and hundreds of skilled professionals have been put to work. For the purposes of this post, I'll call this activity nuclear expansion, although it actually involves two separate activities with very little overlap: the licensing of new, large, light-water reactors (LWR), and the development of small/modular reactors (SMR). While the latter activity might help return the United States nuclear industry to a leadership position worldwide, I believe it would be unwise to expect SMRs to be deployed on a large scale in the near term.

Aside: Apart from the rather smirky title of "Renaissance Watch," a recurring feature in Nuclear News, I generally don't use the term "nuclear renaissance," in part because it suggests that what went before must have been "nuclear dark ages." While there had been more than two decades without new-reactor activity in the U.S. before 2003, the people operating the reactors that were in service made those reactors far more productive and reliable than they were ever expected to be. Why is this not seen as a "renaissance?" End Aside.

While the push for new reactor construction, based on LWRs, does not have as many participants now as it did three years ago, there has been enough progress in licensing reviews to suggest that as many as four reactors could be under full-scale construction by this time next year, and that at least six more will be pursued despite some delays. This would re-establish the United States as a growing market--but not as the industry leader, because all of the reactor vendors have foreign ownership ranging from 50 percent (GE Hitachi Nuclear Energy) to 100 percent (Areva, Mitsubishi).

Could the U.S. dominate the SMR market?

Given the globalization of so many different enterprises, it might be unrealistic to expect that a revived American nuclear industry could ever again dominate the world LWR market the way it did in the 1960s and 1970s. An opportunity may exist, however, on the other side of the U.S. nuclear expansion: SMR development. By my rough count, half or more of the companies developing SMR concepts are American-owned.

Why this matters has nothing to do with nationalistic pride, and not all that much to do with the pursuit of a competitive edge in the global economy. In my view, the sprouting of designs from so many different sources attests to the creativity and innovation possible in this country's nuclear energy community. The atmosphere of ingenuity and opportunity could attract more top-level talent to nuclear fields. This should generate cycles of product improvement that can make U.S.-developed SMRs the most desired fission-based energy production devices for decades to come (based on my perception that U.S. designs already appear to be more developed than those in other countries). All of the usual economic benefits should follow from that--abundant high-paying jobs, improved trade balance, and so forth.

Long overdue in this post is an explanation of what counts as an SMR. In essence, an SMR is a relatively small reactor (300 MWe is usually defined as the upper limit), designed so that the entire energy-producing unit is a module that takes up relatively little space, and several modules can be built together in a single facility.

If one looks back far enough in time, one can observe that small power reactors existed long before large reactors were developed. Since then, there have arisen design aspects, construction techniques, and innovations in fuels, materials, and coolants that can (according to the designers) overcome the historic economies of scale that spurred the move to larger reactor designs, starting about 40 years ago. Ideally, modular construction would allow a reactor to be put into service quickly, with most of the work done at the factory and only a few tasks (final assembly, testing, etc.) at the plant site.

That word "ideally" must be applied to all SMR attributes, especially those that, in the designers' view, should allow them to receive lighter treatment from regulators than large LWRs get. The Nuclear Regulatory Commission, as far as I can see, has been receptive to the notion of SMRs (going back several years to discussions of "technology-neutral" licensing), and has begun pre-application reviews of designs for what are classed as "integral pressurized water reactors," the SMRs that most closely resemble power reactors that have operating experience. The NRC's job, however, is (and should be) to uphold public health and safety. If the agency eventually modifies some regulations for the sake of SMRs, it would only be once the claims made for these designs (such as inherent safety, insignificant radiation dose at the site boundary under any circumstances, and so forth) have been backed up by verifiable testing.

The closest thing yet to a demonstration project for an SMR is the Tennessee Valley Authority's proposal to seek licenses for two or more of The Babcock & Wilcox Company's mPower reactors at the Clinch River site in Tennessee. The effort would also entail certification of the reactor design by the NRC. Even if TVA pursues this (the project has not yet been approved by the TVA Board of Directors) and the NRC's estimated schedule can be maintained, certification would be complete in mid-2018 and the first modules would enter service perhaps at the end of 2019. So, for what may be the most advanced SMR project, power operation is more than eight years away.

Two of the less conventional designs-GE Hitachi's PRISM, and Hyperion Power's HPM-are in a feasibility study stage for possible use at the Department of Energy's Savannah River Site in South Carolina, to consume "legacy" materials left over from the site's mission in nuclear weapons development. These designs, based on fast-neutron spectra and liquid metal coolants, depart substantially from the NRC's experience base in reactor licensing. The site operator, Savannah River Nuclear Solutions, has encouraged the developers of other SMRs with actinide-burning capability to propose similar studies. It has been suggested that prototype versions of these SMRs could be built with limited licensing requirements, allowing the reactors to establish experience and prove principles while assisting in site cleanup--but even if the NRC is receptive to this approach, working out and using such a system would take years.

Could SMRs be developed more rapidly overseas?

Could SMR developers get their reactors built sooner by selling them overseas? My own view is that operating something in another country before it has passed muster in its own country smacks of imperialism. Besides, for some SMR models operation isn't the only licensable aspect. If the reactor is shipped with fuel sealed in the vessel, with the entire reactor to be returned to the manufacturer after a long duty cycle, the manufacturer's home base would be producing and managing what are just short of critical assemblies before shipments leave and after they return. Some SMRs also depend on closed fuel cycles, and thus reprocessing, for which there is no licensing system (or legal authority) now in place. Moving every aspect of a sealed-reactor SMR business offshore, to avoid the NRC at every turn, would not only increase the imperialism, it would export the jobs that SMR work would provide.

As with the other side of nuclear expansion-licensing of new large LWRS-the SMR effort will probably require vast reserves of patience. An untried licensing system under 10 CFR Part 52, and a demanding qualification process for DOE loan guarantees, have drained the enthusiasm of some large-LWR license applicants. The aftermath of the Fukushima Daiichi accident could further darken the prospects. Other applicants, however-including those for Vogtle-3 and -4 in Georgia, and Summer-2 and -3 in South Carolina-have thus far stayed the course and may be in full-scale construction by this time next year. For SMRs, opportunities like those offered by TVA and Savannah River may start the process of bringing the designs to reality, but there is every indication that it will be a long process, with usable energy not available for many years.

Blake

E. Michael Blake is a senior editor of the American Nuclear Society's Nuclear News magazine. The views expressed in this article are the author's, and do not represent the editorial position of Nuclear News magazine or the policy of the American Nuclear Society.