More than three years after the start of the Fukushima crisis, nuclear regulators and industry still lag on implementing upgrades.

If there is one message to take from the National Academy of Sciences report, Lessons Learned From the Fukushima Nuclear Accident for Improving the Safety of U.S. Nuclear Plants, released today, it is that accidents can happen, and it is essential for nuclear plant operators, regulators and public safety responders to all have plans for what to do when one does.

The congressionally mandated report, the result of over two years of work, looked at the responses at Japanese nuclear facilities after the Great East Japan Earthquake and tsunami of 2011, and found the outcomes indicate some obvious actions going forward.

Foremost in both the lengthy report and at the press conference with its authors: Emergency managers, regulators, and most pointedly, nuclear plant operators need to pay better attention to what are called “beyond design basis events” (BDBEs).

The nuclear industry will tell you that its reactors are designed with a degree of redundancy — that there are backup systems, should primary essential safety and monitoring equipment fail. But critics ask a follow up: What if the backup systems fail or are inadequate?

This scenario was very much in evidence at Fukushima Daiichi after the March 11, 2011 earthquake. The plant had backup generators to handle the loss of station power triggered by the quake, but those generators were knocked out by the tsunami. At that point, Fukushima’s crew was left with no obvious disaster mitigation protocol.

The same could be said for emergency responders, who presented with severely damaged infrastructure, had limited access to the plant, limited tools for monitoring external contamination, and no effective plan to evacuate residents both inside and beyond a previously determined quarantine zone.

These “X+1” scenarios have long been the focus of industry watchdogs, and though the NAS will couch their recommendations in terms of better evaluating risk, the strong emphasis in their report makes clear the risk of these BDBEs has not been adequately assessed.

The report’s authors seemed to stress that there exists more and better information on the type of risks to the stability and security of nuclear power plants than is currently considered by operators and regulators. “It is not to say that risks haven’t been considered,” said one of the report’s authors, it is just that the “opportunity exists to expand the breadth and depth of the analysis.”