Lining Up New Protections with New Flood Info

Lauren K. Gibson
Project Manager
Japan Lessons Learned Division

Walkdowns (3)The NRC is moving forward on connecting two important lessons we learned from the Fukushima nuclear accident in Japan: protecting key safety functions and reevaluating flood hazards. The agency’s ongoing work would require U.S. nuclear power plants to ensure their protection strategies account for updated flood levels.

The Commission has approved the staff’s plan for completing the reevaluated flooding hazards review. The staff’s plan also covers how U.S. plants must account for the new hazards in their mitigation strategies for beyond-design-basis events. The plan requires U.S. plants to determine which flood hazard data could affect their strategies. We believe this approach is the quickest way to provide the most significant flood protection improvements.

The NRC assesses plants’ re-evaluated flood hazards to see whether the re-evaluated hazards were properly calculated. Plants need these assessments to evaluate their strategies against the re-evaluated hazard. We’re still reviewing some plants’ work; we’re issuing interim letters so those plants know how to follow the rest of the staff’s plan.

The plants examine whether their strategies work under the new hazard conditions and make any appropriate adjustments. For example, a strategy might require a pump in a location submerged by the new possible flood level. The plant would then consider options such as relocating the pump. These assessments and adjustments would be substantially complete by 2016.

The second part of completing the flooding hazard work involves either a focused evaluation or a broader integrated assessment of the plant’s protection capabilities. The specific work depends on:

  1. Which hazards, if any, cause flood levels higher than the plant’s original level.
  2. Whether the plant’s flood protections have available physical margin. (For example, if the new flood hazard level is six feet and a plant’s existing wall is seven feet tall, the wall has available physical margin to handle the new flood level.)
  3. Whether the higher flooding levels disable the plant’s ability to cool the reactor core or spent fuel pool, or protect containment.

If the local intense precipitation hazard is the only cause of a higher level, then the plant performs a focused evaluation. If other flooding hazards are involved, but the plant has available physical margin and can maintain safety functions, then the plant only needs a focused evaluation. The focused evaluation would identify any physical or procedure changes needed to address the new flood level. We would review and inspect these changes to ensure they resolve the issue.

The remaining plants would perform an integrated assessment, looking at all flooding hazards and identifying any changes needed to protect the plant from the new hazard. We’ll review these assessments and decide if voluntary plant actions would be effective or if the NRC must order plant changes.

You can find out more information about Recommendation 2.1—Flooding on the Japan Lessons Learned portion of the NRC website.

UPDATE: Reducing Proliferation Risks AND Treating the Sick

Steve Lynch
Project Manager
Research and Test Reactor Licensing Branch

The United States does not produce a medical isotope used domestically in millions of diagnostic procedures each year. We’re talking about technicium-99m, or Tc‑99m — which has been called the world’s most important medical isotope.

Tc-99m is created from another radioisotope, molybdenum-99 (Mo-99), which, in some cases, is produced  using highly enriched uranium. A supply shortage that delayed patient treatments several years ago, coupled with the desire to reduce proliferation risks, prompted the world community to find better ways of securing the future supply of this isotope.

In 2012, Congress passed the American Medical Isotope Production Act to support private U.S. efforts to develop non-HEU methods for medical isotope production and begin phasing out the export of HEU. The National Nuclear Security Administration has been promoting domestic Mo‑99 production using different technologies through formal cooperative agreements with commercial partners.

These partners and several other companies have said they are interested in producing Mo‑99 in the U.S. They have proposed using several different technologies, ranging from non-power reactors to accelerator-driven, subcritical solution tanks. To support the transition to new technologies, the NRC is prepared to receive and review applications for construction permits, operating licenses, and materials licenses for new facilities, as well as license amendments for existing non-power reactors.

In fact, we are now reviewing two construction permit applications and a license amendment request. We licensed a small-scale technology demonstration project earlier this year.

Companies, facilities, and technicians involved in producing and administering Tc-99m to patients may also need to be licensed by either the NRC or an Agreement State. (There are 37 Agreement States, which have formal agreements with the NRC allowing them to regulate certain nuclear materials, including medical isotopes.)

For more information on the role of the NRC and other agencies in regulating the use and production of medical isotopes and other nuclear materials, visit the NRC webpage.

Kara Mattioli also contributed to this post.

This is an update to the original blog post, which originally ran in October 2013