Hardened Vents and Filtration
(for Boiling Water Reactors with Mark I and Mark II containment designs)
The Fukushima accident disabled the plants' ability to cool their reactor cores, causing heat and pressure to build within the concrete containment buildings that surround the reactors. This buildup eventually damaged the buildings and made it easier for radioactive material to reach the environment. The NRC issued an Order on March 12, 2012, requiring all U.S. nuclear power plants with the Fukushima-style containment design to install a reliable, hardened vent that can remove heat and pressure before potential damage to a reactor core occurs. This not only helps preserve the integrity of the containment building, but can also help delay reactor core damage or melting. After issuing the order, additional NRC evaluations examined the benefits of venting after reactor core damage occurs. In June 2013, the NRC modified the Order to ensure those vents will remain functional in the conditions following reactor core damage. The NRC is also considering revising its regulations through the rulemaking process to include strategies for filtering or otherwise confining radioactive material that gets released as a reactor core is damaged. These strategies would be in addition to the protections already in place.
- Original NRC Order on Reliable Hardened Vents (EA-12-050) (March 12, 2012)
- Modified NRC Order for Containment Venting Systems (EA-13-109) – supersedes original Order (June 6, 2013)
- NRC-issued guidance for original Reliable Hardened Vents Order (JLD-ISG-2012-02) (August 29, 2012)
- Consideration Of Additional Requirements For Containment Venting Systems (SECY-12-0157) (November 26, 2012)
- Commission Decision on Additional Requirements for Containment Venting Systems (SRM-SECY-12-0157) (March 19, 2013)
- All documents related to the Filtering Strategies rulemaking are available in Docket NRC-2013-0075 on Regulations.gov
For plant-specific documents, visit our Plant Implementation Status page.