By Sharryn Dotson, Editor
Breeder reactors are not a new idea in the global nuclear industry, but the technology has not been widely used in the U.S. compared to other countries. The Argonne National Laboratory in Illinois is widely considered the trailblazer in developing fast reactor technology, and other nations have followed suit by using the Argonne design as a starting point in developing their own breeder reactor technologies.
Though U.S. companies tend to lean toward light and boiling water reactors to power their plants, many are starting to look for newer ways of both generating electricity and burning nuclear waste in order to avoid a future issue of spent nuclear fuel storage space.
The Electric Power Research Institute (EPRI) is a non-profit organization that performs research and development to support safe, reliable, and affordable electric power for the benefit of the public. EPRI conducts research across the electric power sector. For nuclear, this strategic focus includes assessment of advanced nuclear reactor and fuel cycle technologies. Most of these advanced reactors use different coolants, such as gases, liquid metals and molten salts, and many operate using fast neutrons (as opposed to slower “thermal” neutrons in LWRs) and/or substantially higher temperatures to provide access to new capabilities, like breeding of new fuel, and efficient generation of non-electricity products (e.g., hydrogen generation and water desalination).
|EBR-1 was the first nuclear reactor to produce useful electricity on Dec. 20, 1951. Courtesy: Argonne National Laboratory|
Many advanced reactor designs include the relatively mature sodium-cooled fast reactors and high-temperature gas-cooled reactors, whereas more novel molten salt reactors are also gaining popularity as evidenced by the emergence of multiple variants tailored for specific solutions such as the use of thorium and destruction of the current stockpile of used nuclear fuel from the existing fleet of LWRs.
An important perception to avoid is that there is a one-size-fits-all solution. The optimum future technology will likely vary from country to country, and even from region to region. For example, in the U.S., the presence of fragmented energy markets, multiple semi-independent grids, varying wind and solar resources, and diverse industries make a one-size-fits-all approach extremelt difficult.
While the new designs are termed advanced or “Generation IV,” most are direct descendants of technologies developed and demonstrated at some scale in the 1950s and 1960s. Some, like the sodium-cooled fast reactor and high-temperature gas reactor, have been operated or are operating at a commercial scale.
In many cases, the biggest hurdles are not the fundamental technologies, but rather being able to operate these designs reliably. Poor performance has historically inhibited commercialization of many non-LWR designs. However, supporting technologies such as material science have advanced significantly over the intervening decades, perhaps to the point where some new reactor concepts are now ripe for commercialization.
A major concern for developers of advanced reactors in the U.S. is regulatory uncertainty. They do not know how long it will take or how much it will cost for a new reactor design to be certified and licensed for construction, even if all technical challenges are overcome.
In response, the U.S. Department of Energy (DOE) has an advanced licensing initiative to develop general design criteria for advanced design reactors beyond Generation III reactors, which are all light water-based.
“The NRC (Nuclear Regulatory Commission) is trying to accommodate and come up to speed, but one must recognize that NRC’s resources are limited,” said Andrew Sowder, senior technical leader for EPRI.
The stakeholders have many reactor designs to choose from that include choices in coolant, fuel type, speed or energy of the neutrons. “The billion-dollar question is do you pick one design or do you pick three as part of a medium- to long-term research, development and demonstration program?” Sowder said. “If you pick one, you’re picking a winner.” Many believe it is better to focus on providing the R&D infrastructure to support multiple developers and their designs and let the market select the best concept(s) based on demonstrated performance and value.
“The perspective of a national utility in France will likely be very different from that of a smaller utility in the U.S,” Sowder said. “In addition, the UK has a sizeable inventory of separated plutonium left over from operation of the Magnox reactor fleet, so burning of plutonium in LWRs or fast reactors will represent a more compelling mission than for another country that does not have separated plutonium to manage.” These are examples of how different priorities and perspectives can drive differing technology choices.
|The KAERI-designed fast breeder nuclear reactor is a joint project between the nuclear developer and the Argonne National Laboratory. Courtesy: KAERI|
However, picking an appropriate reactor design and overcoming the technology hurdles are just the first steps toward successful implementation,” Sowder said. “In addition, there are several key infrastructure considerations (regulatory framework, supply chain and fuel cycle facilities) and institutions (such as financial markets to provide capital) that must be in place to support commercialization of a new design as well.”
If the goal is to move to a closed fuel cycle, the capacity to reprocess and fabricate the fuel is necessary. “Those facilities can cost tens of billions of dollars and take years to build,” Sowder said. This implies the need for long-term planning and investment.
Sowder said U.S.-based companies may have a lot to learn from international companies due to their continued use of fast reactors. France’s EDF operated the Super-Phenix sodium-cooled reactor from 1986 to 1996. The Super-Phenix reactor uses technology similar to the one used in the Argonne National Laboratory in Illinois.
Argonne National Laboratory begins fast reactor development
The Argonne National Laboratory has partnered with the Korea Atomic Energy Research Institute (KAERI) to develop a 150-MW prototype Generation IV sodium-cooled fast reactor (PGSFR). The Argonne Lab is widely considered to be where nuclear energy was born, according to Yoon Chang, Distinguished Fellow and PGSFR Project Manager with the lab.
The PGSFR will use metal fuel, a fuel type that was first developed in tandem with the reactor technology by Argonne scientists. Metal fuel was first used in the two experimental reactors at the lab from the 1940s through the 1970s, Chang said. The Fermi 1 reactor in Michigan and the Dounreay nuclear plant in the UK also used metal fuel. Early on, GE proposed using oxide fuel and it was successfully used in commercial fast reactors around the world. It achieved a low burn up rate of 1 percent, but after further development, that rate was increased to 20 percent, Chang said.
In 1977, President Carter announced a nuclear policy that abandoned component recycling, effectively ending fast reactor programs in the U.S., including the breeder reactor demo project at Argonne, Chang said. The President signed the bill into law in 1980. That decision was mostly based on several concerns.
“One of those concerns was safety, with TMI (Three Mile Island) happening in 1979, so we had to come out with a safer reactor concept, new fuel cycle technology to respond to proliferation concerns, waste management, etcetera,” Chang said. “The option we came out with was the integral fast reactor.”
The IFR was developed from 1984-1994, and scientists demonstrated what is new in the concept compared to conventional fast reactor technologies, Chang said.
“The technology was proven to be quite unique, in terms of ensuring the passive safety and most important characteristics of the technology,” he said. “It provides a solution to spent fuel management by removing transuranic elements, reducing the effective lifetime of nuclear waste from 300,000 years to 300 years.”
South Korea announced in that the country could run out of spent nuclear fuel storage capacity by 2016. The PGSFR could help maintain the amount of spent fuel, but the design approval isn’t scheduled to go before Korea’s licensing authority until 2020, and potentially have the reactor commissioned by the end of 2028.
“In near term, this reactor will not be commercial, so they will have to adopt interim storage anyway, but they have longer-term vision and longer-term solutions,” Chang said.
Korea decided the best way to handle their spent fuel issue was to adapt the Argonne Lab technology in their own fast reactor technology.
“When they decided to build a prototype, since it is based on our technology, they came to us to work together on this reactor,” Chang said. “This is a Korean project for now, we are just providing technology support for this.”
With the Argonne Lab and EPRI both performing research on fast reactor technology, it shows that scientists can create new and improved reactor designs from old technologies.
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