Mini-reactors join renewable energy race

Global interest has begun for recent development in the renewable energy race with an unlikely contender – miniaturized nuclear reactors.

This relatively new nuclear reactor design, known as a small modular reactor, or SMR, is based off already well-established nuclear technology principles, providing a new direction for companies seeking to create smaller, more strategically located mini-reactors in an increasingly competitive market.

The appeal of these small and medium sized modular reactors has been growing due to their ability to meet the need for flexible power generation for a wider range of users and applications and to replace aging fossil fuel power plants.

The smaller size and modular design of SMRs allow them to be manufactured at a plant and brought to a site for assembly.

Several SMR designs have been put forward, ranging from scaled down versions of existing nuclear reactors, to entirely new fourth generation designs. Both thermal-neutron reactors and fast-neutron reactors have been proposed, as well as molten salt and gas cooled models.

Due to the unique properties of this reactor type, distinct safeguards and security are available such as an increase in containment efficiency and advantages in nonproliferation.

Since there are several different ideas for SMRs, there are many different safety features that can be involved. Coolant systems can use natural circulation – convection – so there are no pumps or any moving parts that could break down, and they continuously remove decay heat after the reactor shuts down, so that the core does not overheat and melt.

Negative temperature coefficients in the moderators and the fuels keep the fission reactions under control, causing the fission reactions to slow down as temperature increases.

While passive control is a key selling point, a functioning reactor may also need an active cooling system as backup in the event of passive system failure. This addition is expected to increase the cost of implementation but not so much as to reduce demand.

Some SMR designs also have underground placement of their reactors and spent-fuel storage pools, which provides more security.

As these smaller reactors are also easier to upgrade quickly, they would still require a permanent workforce, yet would have better passive quality controls.

According to SMR designer estimates, full factory assembly of units will allow large savings in the costs of manufacturing, as most SMR designs require the construction of five to seven plants to get the most out of a supply chain establishment.

In addition, in absolute terms, a single SMR is much cheaper than an advanced light water reactor (ALWR), a type of thermal-neutron reactor that uses normal water. As it is expected to be easier to finance for incremental deployment of the smaller modules, this makes SMRs more affordable for many utilities.

Plants with several SMR units would also offer better flexibility for utilities as they offer options for remote regions with less developed infrastructures and the possibility for synergetic hybrid energy systems that combine nuclear and alternate energy sources, including other renewables.

The transmission infrastructure requirements would also be smaller for SMRs because of lower electric output. This, then, would make them suitable for deployment in a larger number of locations.

Many countries are now focusing on the development of SMRs, which are defined by a benchmark of electricity production of up to 300 megawatts electrical per module.

These reactors also have advanced engineered features, as they are deployable either as a single or multi-module plant.

Currently there are about 50 SMR designs and concepts globally, with most being in the development stage and some even claiming as being near-term deployable.

There are four SMRs at present in the advanced stages of construction in Argentina, China, and Russia, with several existing and newcomer nuclear energy countries conducting their own SMR research and development.

The primary hinderance to commercial deployment of SMRs at the moment is licensing, since current regulatory regimes are adapted to conventional nuclear power plants, new regulations need to be put in place for current SMR technology.

Many organizations in the United States and around the world are making efforts to expand this technology, including the Office of Nuclear Energy, the Nuclear Regulatory Commission and International Atomic Energy Agency.

The U.S. Office of Nuclear Energy said, "they have long recognized the transformational value that advanced SMRs can provide to the nation's economic, energy security, and environmental outlook."

Currently, the licensing review by the NRC is being conducted so deployment is likely to happen within the next 10 to 15 years.

With the seemingly strong efforts to develop this safe, clean and affordable power option, the fuel used in these reactors should also see new demand. With the thermal-neutron and fast-neutron reactors consuming the elements of uranium and plutonium, market prices for these should see similar increase to that new demand.

The advanced SMRs currently under development in the U.S. represent a variety of sizes, technology options, and deployment scenarios. These advanced reactors, envisioned to vary in size from a couple megawatts up to hundreds of megawatts, can be used for power generation, process heat, desalination, or other industrial uses.

With waystations of nuclear power being constructed in safe, strategic locations, and at an affordable cost for utilities as well as governments, the future of clean, reliable and cheap energy may not be so far off yet.