WASHINGTON — Calling the Japan nuclear disaster “unacceptable,” an expert task force convened by the Nuclear Regulatory Commission has concluded that nuclear power plants in the U.S. need better protections for rare, catastrophic events.

The series of recommendations, included in portions of a 90-page report obtained Tuesday by The Associated Press, will reset the level of protection at the nation’s 104 nuclear reactors after the worst nuclear disaster since Chernobyl by making them better prepared for incidents that they were not initially designed to handle.

The panel will tell the commission that nuclear plants should be ordered to re-evaluate their earthquake and flood risk, add equipment to address damage to multiple reactors, and make sure there is electrical power and instruments in place to monitor and cool spent fuel pools after a disaster.

In a news release issued late Tuesday, the NRC said that the 12 steps recommended in the report would “increase safety and redefine what level of protection to public health is regarded as adequate.” The full report will be released today.

The three-month investigation was triggered by the March 11 earthquake and tsunami that cut off all electrical power to the Fukushima Dai-ichi nuclear power plant in Japan, resulting in core damage at multiple reactors, the loss of cooling at spent fuel pools, hydrogen explosions and radioactive releases.