In the tense days after a powerful earthquake and tsunami crippled the Fukushima Daiichi power plant in Japan on March 11, 2011, staff at the U.S. Nuclear Regulatory Commission made a concerted effort to play down the risk of earthquakes and tsunamis to America’s aging nuclear plants, according to thousands of internal emails reviewed by NBC News.

The emails, obtained via the Freedom of Information Act, show that the campaign to reassure the public about America’s nuclear industry came as the agency’s own experts were questioning U.S. safety standards and scrambling to determine whether new rules were needed to ensure that the meltdown occurring at the Japanese plant could not occur here.

At the end of that long first weekend of the crisis three years ago, NRC Public Affairs Director Eliot Brenner thanked his staff for sticking to the talking points that the team had been distributing to senior officials and the public.

“While we know more than these say,” Brenner wrote, “we’re sticking to this story for now.”

There are numerous examples in the emails of apparent misdirection or concealment in the initial weeks after the Japanese plant was devastated by a 9.0 earthquake and 50-foot tsunami that knocked out power and cooling systems at the six-reactor plant, eventually causing releases of radioactive material:

•Trying to distance the U.S. agency from the Japanese crisis, an NRC manager told staff to hide from reporters the presence of Japanese engineers in the NRC’s operations center in Maryland.

•If asked whether the Diablo Canyon Power Plant on the California coast could withstand the same size tsunami that had hit Japan, spokespeople were told not to reveal that NRC scientists were still studying that question. As for whether Diablo could survive an earthquake of the same magnitude, “We’re not so sure about, but again we are not talking about that,” said one email.

•When skeptical news articles appeared, the NRC dissuaded news organizations from using the NRC’s own data on earthquake risks at U.S. nuclear plants, including the Indian Point Energy Center near New York City.

•And when asked to help reporters explain what would happen during the worst-case scenario – a nuclear meltdown – the agency declined to address the questions.

As the third anniversary of Fukushima on Tuesday approaches, the emails pull back the curtain on the agency’s efforts to protect the industry it is supposed to regulate. The NRC officials didn’t lie, but they didn’t always tell the whole truth either. When someone asked about a topic that might reflect negatively on the industry, they changed the subject.

NBC News requested in late March 2011 all of the emails sent and received by certain NRC staffers during the first week of the crisis. Other news organizations and watchdogs filed similar requests. The NRC has now been posting thousands of emails in its public reading room over the past two years.

The NRC declined to discuss specific emails or communications. But Brenner provided an emailed statement: “The NRC Office of Public Affairs strives to be as open and transparent as possible, providing the public accurate information in the proper context. We take our communication mission seriously. We did then and we do now. The frustration displayed in the chosen e-mails reflects more on the extreme stress our team was under at the time to assure accuracy in a context in which information from Japan was scarce to nonexistent. These e-mails fall well short of an accurate picture of our communications with the American public immediately after the event and during the past three years.”

Dating back to the Three Mile Island nuclear crisis in 1979, many nuclear watchdogs and critics have said that the NRC acts first to protect the industry, and its own reputation. One critic said these emails solidify that perception.

“The NRC knew a lot more about what was going on than it wanted to tell the American people,” said Edwin Lyman, senior scientist at the nuclear watchdog group Union of Concerned Scientists and co-author of the new book “Fukushima: The Story of a Nuclear Disaster,” which relied on some of the same emails. “They immediately put out information that implied that U.S. reactors were in a better position to withstand Fukushima type events than Fukushima reactors were, but it was clear that the what the NRC knew internally was not nearly as positive.”

‘We all need to say a prayer’

From the earliest hours of the crisis, the emails among NRC staff show deep concern about the developing crisis in Japan, particularly among the technical experts.

The first word that the powerful earthquake and tsunami waves had devastated the Fukushima plant came early morning (Eastern time) on March 11, 2011. Throughout the day, staff at NRC headquarters in Rockville, Md., struggled to learn what was going on in Japan. The chief of the NRC Component Integrity Branch, senior engineer David Rudland, was asked by a colleague if he had any new information.