"Would You Like to Place a Nuclear Power Plant in Your Backyard?" [Reading Science]

Small Modular Reactors (SMR), Hearing the Pros and Cons Debate

[Asia Economy Reporter Kim Bong-su] "Dream energy." On the 10th, at a seminar hosted by the Nuclear Nonproliferation Education and Research Center (NEREC) of the Korea Advanced Institute of Science and Technology (KAIST), listening to the confident "boasts" of nuclear scholars and industry officials about Small Modular Reactor (SMR) technology naturally brought this thought to mind. Recently, there has been a growing view that nuclear power, including SMRs, is an alternative to supply energy in the decarbonization era. It is claimed that SMRs have overcome all the weaknesses of large nuclear power plants by balancing safety, economy, flexibility, and acceptability. However, voices dismissing this as "nonsense" still persist on the opposing side. At best, SMR technology is still "under research," and since decarbonization must be achieved by 2050, SMRs, which require at least 10 to 20 more years of research and experimentation, cannot be considered a viable alternative.

◇ What exactly is SMR? ... Growing Interest

In short, SMRs refer to small nuclear power plants with an output of 300MW or less. Facilities such as the reactor, steam generator, coolant pump, and pressurizer are integrated into a single unit. Additionally, modularization means that parts are standardized and produced in factories for assembly. After the Fukushima nuclear accident in Japan, many countries that were skeptical have recently started to pay attention to SMRs while redesigning energy policies aiming for a "2050 decarbonized society." This is because nuclear power itself does not emit carbon when generating electricity, unlike fossil fuels. Some countries, such as Germany, which experienced significant electricity price hikes and hardships after phasing out nuclear power and shifting to renewable energy like solar and wind, have begun considering SMRs as an alternative. The reason is that affordable and stable power supply is paramount.

French President Emmanuel Macron's announcement on the 9th to resume new reactor construction is a representative example. South Korea recently selected the "Innovative Small Modular Reactor (i-SMR) Development Project" as a preliminary feasibility study (PFS) target project, albeit with the premise of "for export." South Korea has been developing small reactors since the 1980s and even signed an export contract with Saudi Arabia, but it was not realized due to the U.S. nonproliferation policy, as the facility requires uranium reprocessing. Recently, the "pyroprocessing" technology, which is currently under review after joint research between South Korea and the U.S., is key to reprocessing used uranium fuel for use in small reactors. Last week, former UN Secretary-General Ban Ki-moon sparked attention by citing SMRs as an energy alternative in the decarbonization era. In South Korea, there are also claims that nuclear power should complement renewable energy due to the low total generation capacity of renewables. In the U.S., NuScale's 77MW NPM-20 integral pressurized water reactor is under development, with government investment. Bill Gates' TerraPower is also developing a sodium-cooled fast reactor.

[Image source=AP Yonhap News]

◇ Is it safe?

Concerns about nuclear power remain after accidents like Chernobyl and Fukushima. However, SMR researchers are confident about safety. Professor Kim Yong-hee of KAIST's Department of Nuclear and Quantum Engineering asserted at the seminar, "The probability of a 4th generation reactor (including SMRs) causing an explosion accident is the same as the probability of a 5km diameter asteroid colliding with Earth." A nuclear accident involves overheating that melts the core and releases radiation, but since SMRs are originally small in scale, the heat to be cooled is also small, and they secure passive safety by design, allowing heat to dissipate naturally, so accidents are virtually impossible.

However, Professor Kim's confident claims have not been "verified." In the case of sodium-cooled reactors being developed by Bill Gates and the Korea Atomic Energy Research Institute, many major countries worldwide have attempted similar technologies but paid huge costs due to fire and explosions. Sodium-cooled fast breeder reactors such as the UK's Dounreay, France's Ph?nix, Russia's BN-600 and BN-800, Germany's SNR-300, and Japan's Monju were all prematurely shut down due to accidents.

◇ Is it economical?

SMRs have lower construction costs per unit compared to large nuclear power plants. Also, because of their small size, multiple units can be installed at each site, and if hundreds or more are installed simultaneously, construction costs can be significantly reduced through factory production and assembly. Lee Tae-ho, head of the SMART development team at the Korea Atomic Energy Research Institute, emphasized at the seminar, "Compared to large nuclear power plants, SMRs have smaller initial investment costs, shorter construction periods, and reduced maintenance costs through modularization and simplification of systems and equipment." However, the opposing side is negative. Because the power output per unit is too small to secure economic feasibility, there have been cases of small reactors that failed when trying to increase capacity. Also, the economies of scale of modularization can only be realized if hundreds of units are built simultaneously, which is practically impossible in any country. Energy Transition Forum expert Seok Gwang-hoon pointed out, "Westinghouse also researched the 600MW AP600 but changed the design to AP1000 due to economic issues, yet eventually went bankrupt due to construction delays and cost overruns. NuScale, which was considered the most advanced, is also on a similar path, repeatedly increasing capacity and changing designs due to economic problems."

It is also questionable whether it truly achieves zero carbon emissions and whether the generation cost will be cheap. Nuclear power emits significant carbon during uranium mining, refining, transportation, plant operation, and waste management and disposal. Thermal discharge harms marine ecosystems, and frequent malfunctions and shutdowns occur. Generation costs are also problematic. According to the 2021 World Nuclear Industry Status Report, the cost to produce 1MW/h of renewable energy last year was $37, while nuclear power was $163, more than four times higher, with long construction periods, accident risks, and social costs for waste management also considerable.

◇ Is it flexible?

Flexibility is one of the most important characteristics SMRs must have. Although renewable energy is becoming mainstream, the problem is "intermittency," meaning power generation fluctuates depending on weather conditions like sunlight and wind. For stable power supply to society as a whole, the key is "flexibility," producing a lot when needed and minimal when weather is good. Professor Kim said, "In the case of the sodium reactor being developed by Bill Gates with TerraPower, a thermal storage system is combined, enabling very flexible load-following operation," adding, "Wyoming in the U.S. is pushing to build it to replace coal power plants."

However, molten salt is very expensive, raising generation costs. SMR load-following operation technology is still "under research," and it is unknown when it will be completed. Currently, most countries legally prohibit rapid power output reductions in nuclear plants due to accident risks. Expert Seok pointed out, "The cost of concentrated solar power (CSP) using molten salt is four times higher ($126~156/MWh) than photovoltaic power ($31~42/MWh). The only commercial example of a high-temperature gas-cooled reactor is the U.S. Fort St. Vrain (330MW, 1979?1989), which was closed early due to cooling system corrosion, transformer damage, frequent unplanned shutdowns, and safety issues."

◇ A nuclear power plant in your backyard?

Public acceptability is also an issue. Anxiety about nuclear power remains, and SMR safety verification is incomplete. For SMRs to become an energy alternative in the decarbonization era, at least one 100~200MW unit must be built in each small to medium-sized city. South Korea already has the highest density of nuclear power plants worldwide; how will the public react? Few people would readily vote in favor of the question, "Would you allow a nuclear power plant in your backyard?"

The nuclear industry also recognizes this as a challenge. Lee said, "Since SMRs will be installed near residential areas, it is necessary to dispel safety concerns and solve the spent nuclear fuel disposal problem."