Correction: An earlier version of this article incorrectly described Bechtel’s offer to provide pumping equipment to Japan. The article said that Bechtel attributed original estimates of the cost to the U.S. Agency for International Development, but the company says it knows of no estimate. (NRC e-mails described in the article refer to an “original price,” but Bechtel says it is not clear what that refers to.) The article also said that Bechtel’s $9.6 million price covered equipment, design and delivery costs, but the company says it charged only for the equipment. The Royal Australian Air Force delivered the system. This version has been corrected.

In the confusion following the earthquake and tsunami that damaged Japan’s Fukushima nuclear complex last March, the Nuclear Regulatory Commission said it was standing by to help.

But a trove of e-mails posted on the NRC’s Web site shows an agency struggling to figure out how to respond and how to deal with the American public while cutting through what one official called “the fog of information” coming out of Japan.

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“THIS IS NOT A DRILL,” said an e-mail from the NRC operations center early on March 11, hours after the quake. “This may get really ugly in the next few days,” said one NRC official later in the day after a report that Tokyo Electric Power Co. was venting gas from a containment building.

Three days later, another official said, “It’s frustrating, but we have very little factual info as an agency.”

Now, as the first anniversary of the Fukushima catastrophe approaches, the initial response by regulators still holds lessons for the nuclear industry and policymakers.

The NRC e-mails reveal disagreement about how to advise the Japanese. The NRC staff chafed at some un­or­tho­dox advice coming from an ad hoc group of scientists assembled by Energy Secretary Steven Chu. Famed physicist Richard Garwin, one of Chu’s group, proposed setting off a controlled “shaped” explosion to break through the concrete shield around the primary steel containment structure to allow cooling water to be applied from the outside. One NRC scientist called the idea “madness.”

Another idea from the Chu group was to attempt a “junk shot” — a variation on what some engineers proposed to stop the oil spill in the Gulf of Mexico — to plug leaks of radioactive water from Fukushima’s nuclear reactors into the sea. When using a mixture of sawdust, newspapers and other junk failed, Japan’s Tepco ultimately used a compound known as liquid glass.

“The e-mails provide a candid picture of the level of uncertainty and confusion within the U.S. government and indicates that even U.S. experts had major divisions about what was going on and how to best mitigate the crisis,” said Edwin Lyman, a senior scientist and nuclear expert at the Union of Concerned Scientists.

One of the e-mails said that during the first week after the earthquake, a major U.S. company, Bechtel, offered to provide desperately needed equipment to pump sea water to cool the Fukushima reactors, but the price of $9.6 million came in at more than a dozen times what the e-mail called the “original price.” Bechtel says that it did not provide an initial estimate, nor did it make a profit, and that the price included the cost of equipment only, not time spent on design or delivery. The Energy Department stepped in to provide “a couple of million,” the e-mail said, and instead of three or four sets of pumps and hoses, only one was delivered.

While assuring Americans publicly that there was no danger, the NRC did not disclose one worst-case scenario, which did not rule out the possibility of radiation exceeding safe levels for thyroid doses in Alaska, the e-mails show. “Because things were uncertain, we considered it but the data that was available . . . did not support that very pessimistic scenario so no, it was not discussed publicly at that point,” NRC spokesman Scott Burnell said. In the end, Alaska was not affected.

As if the NRC didn’t have enough on its plate, the office of Jordan’s Queen Noor called the agency’s operations center asking that NRC Chairman Gregory B. Jaczko brief the queen, according to a March 14 e-mail written by the NRC international relations officer Mugeh Afshar-Tous, seeking guidance from the State Department.

The NRC also found itself in a sensitive spot on the state of pools for spent nuclear reactor fuel. The pools were located either above or next to the Fukushima reactors. NRC officials were concerned during the first week about making sure those pools did not leak or dry up, which would lead to more radiation releases.

Yet the NRC did not want to share all its background — much of it classified — on this subject. Lyman said that after the Sept. 11, 2001, terrorist attacks on the Pentagon and World Trade Center towers, the agency was worried about potential attacks on reactors. He said that in 2003 Sandia National Laboratory built a pool just to observe what might happen if a pool went dry or caught fire in the event of an airplane crash at a reactor.

The e-mails say that experts from France, Germany and Japan — all worried about their own reactors — sought access to the information on March 17, six days after the Fukushima quake. But the NRC was reluctant to share studies even when asked by a science adviser to the Domestic Nuclear Detection Office and an adviser to the French government’s institute for radiation protection and nuclear safety.

“There is a whole base of information about spent fuel fires and pools that the NRC is not sharing with the public,” said Lyman. “We understand that when you’re concerned about terrorist attacks that you want to conceal information, but I don’t think there’s any reason to maintain such a broad blackout over this type of information.”

The e-mails have been publicly available for weeks on the NRC Web site, but the voluminous files have attracted little attention.

Many of the e-mails show that the NRC shared much of the same confusion — and anxiety — as everyone else. A March 25 e-mail written by Mitchell T. Farmer, a nuclear engineer at Argonne National Laboratory near Chicago, raised questions about the detection of noble gases outside the Fukushima plant and the low water pressure in unit 1.

“These are some questions, none of them good,” he wrote.

Many of the scientists were worried about water issues and the level of water in spent fuel pools. On March 29, Giulia Bisconti, a senior adviser at the Energy Department, said “Need to establish the water level of the pools — want to get water above the rods, maybe 3-4 feet above.” Per F. Peterson, chairman of the department of nuclear engineering at the University of California at Berkeley, wrote with urgency that Japanese workers had to get a hose into the pool, even if just an unmanned fire hose.

Not everyone relished the frequent calls with outside nuclear experts and physicists. Richard Lee, a veteran NRC staffer, on March 28 wrote to Dana Powers, a senior NRC scientist: “No call today. I know you going to cry!” Powers replied with apparent sarcasm, “Cry!?! No, I will need immediate therapy by overpriced psychologists of international reputation.”

Powers took a dim view of some of the ideas proposed by Chu’s group, such as Garwin’s explosion idea. Garwin was worried that pouring water into the reactor vessel and containment vessel wouldn’t be enough to cool the overheated fuel rods.

“Now we are seriously discussing using shaped charges in the vicinity of the head — madness,” Powers wrote.

“The rarefaction off the backside of the concrete is the way we kill people inside bunkers,” Powers wrote on April 5.

“Let’s send some of the DOE Sci. Council advisers to have this done. I have at least 2 suggestions!” Lee responded.

The Chu group also worried about metal fatigue and corrosion from the injection of salt water to cool the Fukushima plants, though the NRC scientists were less alarmed about that.

“I was glad to be able to help,”Garwin says. “Exactly what of what I was proposing and observing reached the Japanese government is not clear, but I did my best.”

“I brought together an informal group of top engineers, scientists and nuclear experts . . . to help better inform the U.S. response and to offer whatever independent help we could to TEPCO and the Japanese Government,” Chu said in a recent statement. “Our job was not only to brainstorm about possible solutions but also to think through the ‘what-ifs’ and help anticipate next steps . . . as well as new challenges that might be lurking around the corner.”

The NRC was also worried about appearances. By coincidence, the NRC staff had told the commissioners on March 11, the day of the Japanese earthquake, that they intended to issue a license extension to the Vermont Yankee nuclear reactor on March 16.

But the Vermont Yankee reactor was built to the same design as unit 1 at Fukushima Daiichi; in the wake of the tsunami, the NRC communications experts realized, that would invite questions about the safety of the Vermont facility.

So on March 15, an e-mail was sent to the commissioners saying: “In light of recent international events, the staff has decided to delay the issuance of the VYNPS renewed license so that it can better prepare needed communication messages for internal and external stakeholders.”

NRC Commissioner Kristine Svinicki fired off a note: “I am very confused on what the regulatory nexus is here,” she said on March 15. “Are you withholding the issuance to perform some additional analysis? If so, what is the regulatory basis?”

Eric J. Leeds, director of the NRC’s Office of Nuclear Reactor Regulation, wrote to another colleague that “I assured her we are not doing any additional technical reviews or analysis and we are simply ensuring that our communications plans are prepared for the stakeholder responses which are sure to come. I reminded her that [Vermont Yankee] was . . . similar in design to the Japanese plants.”

The NRC publicly approved the 20-year extension of Vermont Yankee’s license on March 21.