MOSCOW, Russia — Pavel Vdovichenko doesn’t remember the day 25 years ago when reactor four at Chernobyl blew up. It was a day like any other.

“No one told us anything,” he said from his hometown in Russia’s Bryansk region, one of the worst affected by the nuclear disaster. “No one told us about radiation. They didn’t say radiation was dangerous so we shouldn’t go outside.”

As the crisis at Japan’s Fukushima nuclear plant unfolds in the wake of one of the worst earthquakes and tsunamis on record, the inevitable comparisons to Chernobyl — the world’s last great nuclear disaster — have begun rolling in.

What stands out most is the differences, between the types of nuclear disasters, as well as the societies afflicted. Yet the consequences — a land contaminated by radioactive isotopes, people also contaminated and psychologically scarred — might well be similar.

When Chernobyl’s reactor number four exploded during a test run on April 26, 1986, the Soviet Union showed its worst colors. A system built on secrecy and isolation clamped down even harder. The government did not announce the accident to its population — let alone the world — for days. It was forced to confront the accident only after European agencies began picking up abnormally high levels of radiation, meaning the cloud of radioactive particles that was expelled when reactor four exploded and caught on fire had begun to drift westward.

“For us, it was all closed and secret,” said Nikolai Shteynberg, the chief engineer at Chernobyl during the time of the accident. “Japan is much more prepared than we were. There’s no panic, they seem to be reacting calmly.”

“What we came up against — we didn’t understand it.”

In contrast to the Soviet Union, Japan has reacted with relative openness, thanks in part to the nature of its governance and in part to a new globalized world that has people around the world watching livestreams of events in the Pacific. The events at Fukushima — from cooling system breakdowns to fires — appear to have been reported quickly. Yet as the crisis enters its fifth day, some now worry that openness is being compromised.

Officials at Temco, the private firm that owns the Fukushima plant, have come under fire for failing to answer questions about what is actually going on — for example, what exactly caused the dangerous hydrogen explosion at reactor two on Tuesday morning? Where was the fire? Yet no one knows: Do they not want to say, or do they not know themselves?

What made the explosion at Chernobyl such an unmitigated disaster, aside from the Soviet Union’s public relations strategy, was the technology of the site. Reactor four was not encased in a container, so when fire broke out, radioactive particles were immediately thrust into the atmosphere. The plant itself is now believed to have been badly designed from the get-go.

“Uranium, fission products, everything inside the reactor spewed out. It was the worst possible accident you could have,” said David Hinde, the head of the nuclear physics department at Australian National University.

In contrast, Fukushima had a host of control systems built in, designed to withstand the harshest of shocks, including a major earthquake. Friday’s earthquake, however, coupled with the subsequent tsunami, did manage to wipe many of those controls out, and now scientists are scrambling to control the cooling and release the pressure building up inside.

“It will be rather difficult,” said Shteynberg. “Everything will depend on the situation. It’s not dictated by experts, but by events. It was the same for us.”

One thing the Soviet Union did not think about was its people, keeping them in the dark and only beginning initial evacuations some 36 hours after the reactor blew. It took many more days for the evacuation ring to be expanded, as it became clear that radiation was spreading.

“When the catastrophe happened, I was a teacher and for the first time I didn’t understand what to do,” said Vdovichenko, who in the disaster's aftermath founded an NGO to help those who suffered called Radimichi — Children of Chernobyl. “We were hostage to the situation.”

“There was one guy, a teacher with military training, who started to talk about it and went to the Party leadership in Bryansk. He got an order to shut up: ‘Don’t tell anyone that there is radiation in your town,’” he said. “This game of silence was very expensive for the population.”

Everyone was uninformed. Some of the people in Prypyat, Ukraine, the town closest to Chernobyl, were resettled in the Bryansk region, even though it also had high levels of radiation. “Everyone thought that because they came from Chernobyl they would give radiation to their neighbors, to the people sitting next to them,” Vdovichenko said. “Today it sounds crazy, but that’s how it was.”

To this day, the region’s land still suffers — its mushrooms and berries inedible, the milk from its cows undrinkable.

“The bigger issue is how does a society cope,” said David Hoffman, the author of "The Dead Hand: Reagan, Gorbachev and the Untold Story of the Cold War Arms Race." “It’s not only what crisis do you inherit, but how do you deal with it?”

“One thing that hasn’t dawned on the Japanese is they are going to have a big area that’s uninhabitable for a while and that’s where Chernobyl is a precursor — this idea of a dead zone in the middle of a modern society,” he said.

Read about the current push by the European Union and European Bank for Reconstruction and Development to raise the necessary funds to secure Chernobyl, whose aging sarcophagus is nearing the end of its lifespan.