When I contemplate China’s plan to build as many as 135 nuclear reactors, I’m transported back to that harrowing March 2011 week when Fukushima No. 1 was melting down.

At 2:46 p.m. on March 11, a magnitude-9 earthquake struck 278 km northeast of Tokyo. Within hours, rumors of radiation-leakage began spreading. Word was that the Fukushima No. 1 nuclear power plant had been hit hard by the trembler and resulting tsunami. Around 8:15 that evening, the government confirmed our worst fears, declaring an emergency 217 km north of the capital. Two hours later we learned the plant’s cooling system had failed; authorities admitting they, too, were “bracing for the worst.” The word “Chernobyl” quickly began trending in Japanese cyberspace.

And then, the spin machine kicked into action. Aside from the odd press report — and admission by Tokyo Electric Power Co. that radioactive substances “may” have leaked out — Japanese officialdom and its compliant media agreed on a script: our nuclear facilities are state-of-the-art and safe, and the public needn’t worry. NHK put on a parade of academics, armed with charts and scientific jargon, to say all’s well. Even though explosions at Fukushima No. 1 were aired live on television, the media message was don’t panic.

It was a stunningly disorienting moment. Even as Pentagon officials told reporters about radiation traces on reconnaissance planes returning to U.S. aircraft carriers, the local media stressed calm. The foreign media was often a different story. Gaijin TV celebrities standing in the rubble near Fukushima hyperventilating about impending apocalypse smacked more of disaster porn than journalism.

For us local scribes trying to keep up, it was a crash course in nuclear science. We sought out neighbors who owned Geiger counters, Googled words like “becquerel” and “sievert” and tracked wind-pattern websites. I was regretting not paying more attention in Mr. Payne’s high school physics class, while my family in New York called me daily demanding that I rush to the airport. Many fellow expats did, with Japan’s media deriding the fleeing crowd as “fly-jin” and “bye-jin.”

The truth, of course, was somewhere in between. But only in the months that followed did we learn how close the world actually came to losing Tokyo. Tepco was preparing to abandon the wrecked facility. Leaving the reactors to melt down unencumbered would have meant the immediate evacuation of 13 million-plus people. On March 15, then-Prime Minister Naoto Kan literally stormed Tepco headquarters and demanded its technicians contain the crisis. Thanks to the government’s collusion with the media, it’s taken years for we in Tokyo to realize we probably owe Kan our lives.

I retrace Japan’s March 2011 because it is as clear and cautionary a tale as Beijing will find as it goes nuclear in a hurry. The number 100, China’s ranking on Transparency International’s corruption perceptions index, tells the story. If a developed, tech-savvy, safety-obsessed nation like Japan — corruption ranking 15 — can avoid a nuclear disaster only by the skin of its teeth, what hope for a Communist China notorious for lax safety procedures, weak oversight and rampant graft? It’s a question officials meeting in Paris this week for the United Nations’ COP21 climate talks should ask early and often.

China operates 30 nuclear power plants, from which it derives about 2.5 percent of its electricity. Only by bringing at least six to eight new ones online per year, it’s widely thought, can President Xi Jinping make good on pledges to cap carbon emissions by 2030. Many new reactors will be constructed inland, away from coastal areas. China’s limited water supplies should be sufficient reason for concern. Beijing’s abysmal safety record is even more problematic.

Mega-projects are the hallmark of the Communist Party’s can-do reputation. But hyper-fast growth has its risks in a nation plagued by endemic corruption, rash planning, shoddy construction, murky regulations and opaque supervision. Time after time, this pattern plays out in the most-populous nation — just as it will again.

An August explosion 145 km from Beijing was just the latest reminder China isn’t ready for nuclear prime time. On the evening of Aug. 12, a series of thunderous blasts killed at least 173 people and made the port city of Tianjin global news. Two more explosions at hazardous-chemical plants close to residential areas followed over the next two months. Just as with deadly earthquakes, train crashes and ferry accidents in recent years, the world was shut out, government officials obfuscated, and Beijing learned nothing.

Here’s how Murong Xuecun, author of “Dancing Through Red Dust,” put it in a recent New York Times op-ed: “The only government competence on show is with information control: hiding facts, forbidding media reporting and rapidly closing social media accounts suspected of spreading rumors.”

Now apply this crisis-control playbook to a nuclear disaster, perhaps one near the Yangtze River, China’s biggest. The environmental fallout would be immense and exacerbated by Beijing’s efforts to — Fukushima-style — downplay the risks to avoid instability. Hundreds of millions of people eating contaminated fish and using irradiated water would make Chernobyl seem insignificant.

Not surprisingly, He Zuoxiu, a leading Chinese physicist, has called China’s plans for a bubble in nuclear reactors “insane.” As He told the Guardian in May: “Japan has better technology and better management, and yet it couldn’t avoid an accident despite the fact that it tried very hard to learn from the U.S. and U.S.S.R.”

China’s nuclear ambitions have the tacit approval of many COP21 participants amid calls for the biggest polluter to forsake coal. But this should be a moment of caution for global nuclear authorities who should be urging China to increase safety standards and emphasize more benign energy sources. Ditto for investors sensing a no-brainer profit opportunity. One reason China considers the nuclear option cheaper than solar, windmill and water sources, He says, is that staffing is sparser than in other nations and cost-cutting is de rigor. Just something for David Cameron to consider as the U.K. prime minister gloats over hosting a Chinese-designed reactor.

The sound science behind nuclear power is no match for the human factor. Japan had a mini reactor crisis in 1999, 13 years after Chernobyl, when technicians at the Tokai nuclear facility in Ibaraki Prefecture literally mixed radioactive materials in buckets.

Twelve years after that, the Einsteins at Tepco had all of Fukushima’s backup generators in the same place — a basement that was flooded by a tsunami (in the nation that coined the word). They also had 10,000-plus spent fuel rods sitting nearby. Four-plus years after March 2011, radiation is still leaking at Fukushima and the government has done little to punish Tepco’s negligence or raise its nuclear-safety game.

Nuclear power, industry cheerleaders claim, is cheap, safe and clean. In theory, perhaps, but ask the 100,000-plus Japanese in the Tohoku region who can’t return home. Or the Fukushima farmers and fishermen who can’t sell their wares. Just some food for thought for officials in Paris this week figuring a comparable scenario near the Yangtze is unthinkable. Think again.

William Pesek, executive editor of Barron’s Asia, is based in Tokyo and writes on Asian economics, markets and politics. www.barronsasia.com

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