Economics has been a main driver of nuclear power, not just financially, but also literally. Since nuclear power generation was born in the 1950s, reactor size has grown from 60MWe to more than 1600MWe.
But with changing market conditions, smaller-scale reactors are gaining interest due to their lower upfront capital investments and ability to provide power to remote areas off the main grid system. In addition to being reliable, affordable, low cost power, small modular reactors (SMRs) offer enhanced safety, nonproliferation and water purification features, and high flexibility as their key selling points. SMRs are anticipated to come online as early as 2024.
SMRs are not a new concept. Rather, these reactors have been in use for more than 60 years. Hundreds of SMRs have been successfully operating around the world in nuclear submarines, warships, merchant ships, icebreakers and as research and medical isotope reactors at universities.
SMRs were first designed and tested in the 1950s by the United States Atomic Energy Commission (AEC), and the Army and Navy research programs. The Army Nuclear Power Program (ANPP) focused on developing a reactor to provide power for remote areas, which could be transported entirely by truck. The Navy’s nuclear program focused on creating a reactor that could operate on a ship. Admiral Hyman Rickover led the development of the first Pressurized Water Reactor (PWR) for use in submarines. The PWR used enriched uranium fuel and was moderated and cooled by light water because sodium coolants have adverse reactions with sea water. The first nuclear-powered submarine — the USS Nautilus — was launched in 1954.
Admiral Rickover’s success spurred advances in light water reactor development in the Army program and the AEC’s Power Reactor Development Program. The Army developed a pressurized water reactor, the single-loop Mobile High Power Nuclear Plant (MH-1A), which operated on a barge. From 1968 to 1976 it successfully powered the entire Panama Canal Zone.
The AEC’s Power Reactor Development Program funded the design and operation of a few small PWR commercial reactors. Despite the Army program’s success in providing safe remote power generation, the program was discontinued due to high logistical costs. In the years that followed, the Army’s involvement in nuclear power R&D waned and eventually ended. The AEC’s reactors were also shut down once their engineering lifetimes expired, but they did successfully demonstrate that small-scale reactors could be constructed and put into commercial operation in a relatively short timeframe (less than 4 years in most cases).
The Navy’s initial success with PWR reactors in submarines propelled the light water design into the commercial spotlight, but even during the earliest years of nuclear power plant development there were arguments that small, fast-breeder and molten salt reactors may be better suited for commercial production than the large-scale light water reactors which are commonly used today. In 1951, the EBR I (Experimental Breeder Reactor Number One) was the first reactor to generate electricity. The fast breeder reactor operated for 10 years before it was replaced by a slightly larger version, the 62.5 Mwt EBR II.
Work on the EBR II was interrupted when politics shifted the laboratory’s research in favor of developing a large fast breeder reactor. The breeder reactor project eventually failed. Research on the EBR II continued on a small budget allocation, and in 1984 the Argonne National Laboratory started development of an IFR (Integral Fast Reactor) based on the EBR II design. The IFR uses a new process that recycles its fuel and produces less waste with shorter radiological lifetime. After 10 years of promising developments, the IFR project was shut down by President Clinton in 1994, who described all advanced reactor development as “unnecessary.”
Following this decisive political interruption, SMRs were largely ignored and the large light water reactor projects absorbed the international spotlight. Following the lead of the United States, the majority of countries around the world have since chosen light-water reactor designs, so that today about 81 percent of world capacity is through light water reactors.
However, huge upfront capital costs and long construction times have turned the attention back toward the simple structure and reduced cost and construction time of SMRs. Growing safety concerns following the Fukushima large reactor disaster have also shifted the spotlight back toward SMRs and their inherent passive safety features and significantly smaller radioactive waste burden. Lastly, the projected worldwide demand increase for emission-free electricity has stirred interest in SMRs, particularly in developing countries because of their remote-siting and desalinization capabilities. These factors have combined to revive the global prospects for nuclear power and naturally coincide with the available benefits of a new generation of SMRs.
The Brief SMR History of Japan-U.S.
In the late 1980s, Japanese researchers and heads of industry visited the IFR program at the Argonne Laboratory and signed agreements for a joint IFR program with the U.S. Department of Energy. In these agreements, the Japanese planned to contribute more than $100 million to the program. The agreements were terminated when the IFR program was shut down by President Clinton in 1994. The leader of the IFR program, Dr. Charles Till, wrote that “The few years we collaborated with the Japanese utilities were among the highlights of my career. Given the situation with nuclear energy in the U.S. I truly believed that the IFR with pyroprocessing might be first commercialized in Japan.”
Following the atomic bomb and the Fukushima accident, safety and non-proliferation questions are critical determinants for the future of nuclear power plants. It is unlikely that a direct extension of Japan’s existing large-scale, light water nuclear power plants will be accepted socially, providing a unique opportunity for the revival the historical collaboration to promote the development of SMRs.