‘Passive safety’ reactor designs would improve response to Japan’s nuclear events

The type of “passively safe” nuclear reactor designs that Oregon State University researchers have been testing over the last 15 years – and which are now being built overseas – have an increased ability to respond to the type of nuclear crisis being faced in Japan.

These “next generation” reactor concepts rely on natural forces such as gravity and convection to cool down a reactor when pumps or external power fail. They would address the type of problem faced in Japan, where a catastrophic earthquake and tsunami knocked out power supplies, backup pumps and the generators that provided cooling water to the affected reactors.

Some of these passively safe plants can also transition to long-term, natural circulation air cooling of the containment, rather than relying on additional water supplies.

“The whole concept of passive safety was created to avoid the sort of issues that these damaged reactors in Japan now face,” said Jose Reyes, a professor in the OSU Department of Nuclear Engineering and Radiation Health Physics. “Reactors with passive safety systems work, they are already being built, and we’re now developing small, modular systemsthat will further increase reactor safety and reliability.”

Reyes took a leave from his faculty position with OSU to work with NuScale Power, Inc., a private company developing a small modular reactor that relies on these types of passive safety systems. The NuScale design is small enough to be manufactured in a factory setting and transported on a railroad car or barge. It would be built and operated below ground level, which can further address concerns about safety, terrorist attack and even nuclear proliferation.

In the early 1990s, Reyes and other OSU experts were already helping to perfect and test passive safety systems that are now considered the future of nuclear energy, in multi-million dollar research programs at the OSU Radiation Center.

Some of the results of those efforts are finished designs now being constructed in China and proposed for the United States.

Five years ago, experts from more than a dozen nations came to OSUto confer on the latest advances in passive safety. That period was part of the renaissance of nuclear energy in the U.S., where interest in nuclear energy had been stalled for almost 30 years following the Three Mile Island nuclear incident.

Other nations, however, had moved steadily ahead with their programs. As experts pointed out at the time, nuclear power does not emit greenhouse gases, has become cost competitive with other energy sources, and could lessen the nation’s dependence on fossil fuels.

The new, small modular design now being developed in private industry, which evolved out of OSU research, also incorporates passive safety design capability. Other interesting aspects of such reactors is that they produce electricity in smaller increments, reduce upfront investment costs, and can be grouped to provide different amounts of energy suited to the needs of nearby cities and industry.

Concerns about climate change and the need for carbon-free sources of electricity are behind decisions to build dozens of new nuclear power plants in the U.S. and around the world.  China alone has some 20 plants under construction.  Four of these incorporate passive safety systems tested at OSU.

“The events at the Japan nuclear plants created by the cataclysmic earthquake and tsunami are being dealt with by remarkably dedicated workers at great personal risk,” Reyes said. “The lessons learned from these events will be sought out and understood in light of these new passively safe designs.

“We can’t afford to turn our backs on nuclear energy for another 30 years in this country,” Reyes said. “The energy and environmental issues are just too important.”


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