After a three-and-a-half-year hiatus, South Korea’s nuclear research reactor has restarted operations and experiments there will resume this month. Material scientists and students are eager to make up for lost time after the facility was closed to address safety concerns after the Fukushima nuclear disaster.
“Students have been thirsty for neutrons,” says Sung-Min Choi, a materials scientist and neutron-scattering expert at the Korea Advanced Institute of Science and Technology in Daejeon. “Now they are very excited, planning and preparing experiments.”
After the High-Flux Advanced Neutron Application Reactor (HANARO) in Daejeon was shut down for minor repairs in July 2014, the South Korean nuclear regulator ordered the facility to address whether it could resist seismic activity before it could restart. Following the March 2011 earthquake off the coast of Japan, which triggered a tsunami that swamped the Fukushima Daiichi nuclear power station, many governments, including that of South Korea, insisted that reactors be able to withstand major earthquakes or other disasters.
Another neutron source in the region, Japan’s JRR-3 facility in Tokai, was also closed in March 2011. Some buildings sustained superficial damage during the 2011 quake. But even with the repairs complete, its future remains in limbo after more than six years offline, say scientists.
Researchers who use these facilities to study the inner workings of various materials say that the closures have left them struggling to continue their projects. For research communities in Japan and Korea, the drought of neutron sources has been devastating, says Sungil Park, a condensed-matter physicist at the Korea Atomic Energy Research Institute in Daejeon.
HANARO completed alterations to improve its resistance to seismic activity, including reinforcing its walls, in April 2017. But the agreement that was reached with local government required that a citizens’ watchdog group be permitted to verify the safety of the site, which took until September. Scientists say that it was prudent to disaster-proof the reactor, but it has been a “long and agonizing" three-and-half years waiting for the facility to reopen, says Park.
The shutdown has not just interrupted scientists’ projects — it has reshaped or even ended their research careers, says Park. When HANARO shut down, he was putting the finishing touches to an instrument he had built to study magnetic systems that show exotic behaviour, which have applications in computing. But after the shutdown ended his experiments and he started to lose funding, Park decided to take a management position as director of the Neutron Science Division of the Korea Atomic Energy Research Institute. “I don't think I can go back to science at this point,” says Park, who passed his work on to another scientist.
The burden of HANARO’s closure has been particularly heavy on early-career scientists, who are usually expected to produce a paper within three years, and graduate students, many of whom finished their degrees without sufficient training or moved on to other fields. “We lost a generation of neutron scatterers,” says Park.
Some researchers have salvaged their careers by working at other neutron facilities. The South Korean government set up a US$100,000 programme to help scientists travel overseas to do experiments. “Neutron-scattering experiments are relatively short and frequent, thereby making life excruciating unless you have a local source,” says Park. Researchers have also had difficulty tailoring the foreign instruments to their own needs.
Japan also created a fund to send scientists abroad, but only a small proportion (13%) of the 1,381 experiments slated to run at the JRR-3 facility between 2011 and 2017 have been done overseas.
The Japan Atomic Energy Agency announced in June 2016 that it would restart JRR-3 by March 2018, but the process is behind schedule and there is no longer an estimate of when it will be able to restart, according to a spokesperson for the agency.
Japanese scientists are making do. Mitsuhiro Shibayama, a condensed-matter physicist at the University of Tokyo, shifted his research projects from neutron scattering to X-ray and light scattering so that his students could progress. “The number of experts on neutron scattering is dramatically decreasing,” he says. “Many graduate students left without any experience on neutron-beam experiments and many professors have had to change their research topics and expertise.”
In South Korea, researchers are starting to rebuild their community as HANARO undergoes final tweaks before experiments can start. “It will be a hectic but happy week for all of us working at HANARO,” says Park.
Nature 552, 302 (2017)