United States Nuclear Regulatory Commission - Protecting People and the Environment

Origins of Accident Tolerant Fuel

This page includes links to files in non-HTML format. See Plugins, Viewers, and Other Tools for more information.

On this page:


On March 11, 2011, a 9.0-magnitude earthquake struck Japan about 231 miles (372 kilometers) northeast of Tokyo off the Honshu Island coast. Eleven reactors at four sites (Fukushima Daiichi, Fukushima Daini, Onagawa, and Tokai) along the northeast coast automatically shut down after the quake. Fukushima Dai-ichi lost all power from the electric grid, with diesel generators providing power for about 40 minutes. At that point, an estimated 45-foot-high (14 meter) tsunami hit the site, damaging many of the generators. Four of six Fukushima Dai-ichi reactors lost all power from the generators. The tsunami also damaged some of the site's battery backup systems.

Units 1, 2 and 3 at Fukushima Dai-ichi were operating when the earthquake hit. Units 4, 5 and 6 were shut down for routine refueling and maintenance. One of Unit 6's diesel generators continued working, providing power to keep both Units 5 and 6 safely shut down. Steam-driven and battery-powered safety systems at Units 1, 2 and 3 worked for several hours (and more than a day in some cases). Those systems eventually failed and all three reactors overheated, melting their cores to some degree. The conditions in the reactors generated extreme pressure, causing leaks of radioactive gas as well as hydrogen. The hydrogen exploded inside the reactor buildings of Units 1, 3 and 4, damaging the buildings and releasing more radioactive material from Units 1 and 3. Radioactive contamination spread over a large area of Japan, requiring the relocation of tens of thousands of people. The Japanese government has reopened limited areas for residents to return to, but many communities remain off-limits. Japanese authorities eventually stabilized the damaged reactors with alternate water sources. Work continues to isolate the damaged reactors and radioactive contamination from the environment.

The following links are for additional information regarding the Fukushima nuclear accident:

After the Fukushima accident, the NRC quickly developed a lessons-learned report, "Recommendations for Enhancing Reactor Safety in the 21st Century" that resulted in many safety enhancements to the U.S. nuclear fleet, but the report did not document any shortcomings in the nuclear fuel designs. However, the associated economic, social, and environmental impacts of the accident renewed the worldwide drive to improve nuclear fuel technology that should only enhance the safety of the reactor and the public.

Consolidated Appropriations Act, 2012

After the 2011 Japanese tsunami and resultant nuclear accident at Fukushima Daiichi, the U.S. Congress directed the pursuit of advanced fuel technologies that would enhance the safety of nuclear power reactors in the United States. In the Consolidated Appropriations Act, 2012, Congress provided $59 million to the U.S. Department of Energy, Office of Nuclear Energy, and, in the accompanying Conference Report–H.R. Conference Report 112-331–ordered the Office to prioritize the increase in funding on, "efforts to develop and qualify meltdown-resistant, accident-tolerant nuclear fuels that would enhance the safety of light water reactors."

The Senate Energy and Water Appropriations bill and Senate Report 112-75 preceded the Consolidated Appropriations Act. In that report, the U.S. Department of Energy, Office of Nuclear Energy, was:

  • Directed "to give priority [with the increased funding] to developing enhanced fuels and cladding for light water reactors to improve safety in the event of accidents in the reactor or spent fuel pools,"
  • Urged "that special technical emphasis and funding priority be given to activities aimed at the development and near-term qualification of meltdown-resistant, accident-tolerant nuclear fuels that would enhance the safety of present and future generations of Light Water Reactors."


On January 14, 2019, the President signed the Nuclear Energy Innovation and Modernization Act (NEIMA). Specifically, NEIMA, Section 107, "Commission Report On Accident Tolerant Fuel," states the following:

  1. Definition of Accident Tolerant Fuel – In this section, the term "accident tolerant fuel" means a new technology that –
    1. makes an existing commercial nuclear reactor more resistant to a nuclear incident (as defined in section 11 of the Atomic Energy Act of 1954 (42 U.S.C. 2014)); and
    2. lowers the cost of electricity over the licensed lifetime of an existing commercial nuclear reactor.
  2. Report to Congress – Not later than 1 year after the date of enactment of this Act, the Commission shall submit to Congress a report describing the status of the licensing process of the Commission for accident tolerant fuel.

The requested report was sent to Congress on January 9, 2020.

To top of page

Page Last Reviewed/Updated Monday, August 03, 2020