A year after the meltdown of the Fukushima reactor, Ukraine’s nuclear-safety experts are busy consulting their Japanese colleagues on how to deal with the long-term fallout of the world’s second-worst nuclear accident. “Our leaks stopped over 20 years ago, but in Fukushima the radiation is still spreading,” says Viktor Krasnov of the Institute of Nuclear Power Station Security at Chernobyl, Ukraine, who just got back from a trip to Fukushima. “Their catastrophe is still ongoing. The 40-kilometer alienation zone in Chernobyl will stay dangerous for thousands of years. The same could happen in Japan if they do not clean up radioactive contamination on the surface before spring [rains]. That was the advice we gave them: hurry!”

Luckily for the Japanese, the casing of the reactor core was not breached to the atmosphere, as it was in Chernobyl—and the environmental impact has been much less devastating. “It took us two years to fully estimate the full damage after the Chernobyl explosion,” says Natalia Manzurova, an engineer who participated in the post-Chernobyl cleanup and has since had her thyroid gland removed as well as experienced other health problems. “But we had the graphite [reactor core] exposed to the air for four days—land for 30 kilometers around was contaminated.” In Fukushima, she says, the main risk is to the sea life exposed to radioactive seawater used to cool the core. And unlike Chernobyl, where 157 people died of radiation poisoning and thousands more continue to suffer from cancers, nobody has died as a direct result of the Fukushima catastrophe.

In part, that’s thanks to lessons learned from Chernobyl. Its not the scale of a nuclear accident itself that makes a human disaster—it’s the response. Both Chernobyl and Fukushima were classed “Level 7 events” by the International Atomic Energy Agency. But Japan did better than the Soviet Union at stopping a catastrophe from killing hundreds of people. The Japanese authorities “acted quickly and effectively to communicate with the local residents,” nuclear engineer Ilgiz Iskhatov, who was decorated for his role in containing the fallout of the Chernobyl blast, told Newsweek soon after the disaster. “They didn’t treat their population like idiots like ours did.” Fukushima residents not only were evacuated quickly but also given medicine to prevent absorption of atmospheric radiation. Officials continue to monitor food and tap water and embargo food products from the area.

“Chernobyl was really a very different story, in part because of the horrible way that the Soviet Union kept it secret and mismanaged the crisis,” says Matthew Bunn, an associate professor at Harvard’s Belfer Center for Science and International Affairs. “They didn’t evacuate people in a timely way. They denied that the accident was occurring and that radiation was being released. And they didn’t tell children not to drink contaminated milk or eat contaminated food.” The local population is still paying the price for that secrecy: an estimated 6,000 cases of childhood thyroid cancer have been caused by radiation entering the food chain.

Quick as the Japanese emergency response was, though, other key Chernobyl lessons were not learned. According to a detailed Soviet report released to the public after the fall of communism, the Chernobyl blast was caused by a sudden, catastrophic spike in temperature at the reactor that caused cooling graphite rods to shatter, which in turn allowed a runaway nuclear reaction that within three seconds produced more than a hundred times the unit’s usual heat output. The coolant from burst pipes flashed into steam, blowing a 2,000-ton steel and concrete lid off the reactor core and spreading radiation across the Soviet Union and Europe.

In order to prevent a repeat of such a catastrophe, subsequent Russian reactors were designed with “fail-safe” control rods that dropped down by gravity from the top of the reactor to shut down the nuclear reaction in the event of a power failure. At Fukushima, though, “they had an old-fashioned security system, where the control rods came up from underneath the reactor core,” says Sergei Novikov, spokesman for the Russian nuclear agency RosAtom. “They had to be activated by a human, unlike in all our stations, where they automatically drop down with no human command in a power-loss situation.” A giant tsunami knocked out main power as well as two backup generators at Fukushima, paralyzing the cooling systems and preventing personnel from activating the control rods. Russia also has a law forbidding the construction of nuclear reactors in seismically active zones—unlike Japan.

“In our case the cause was human error, in theirs the catastrophe was the result of a natural disaster—but the consequences were similar,” says Krasnov. Some of the post-disaster photographs from Chernobyl and Fukushima are even eerily similar, because in both accidents the roof of the reactor halls blew off, scattering debris across the compound. Nonetheless, Krasnov, whose institute is inside the 40-kilometer Chernobyl exclusion zone and cannot work in his office for more than 15 days a month for safety reasons, still believes in the future of nuclear power. “Nothing so awful happened to make mankind decide to say goodbye to nuclear energy. They will learn to live with Fukushima just like we learned to live with Chernobyl.”