NRC Hearing on Filtered Containment Vents

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Dave Lochbaum was one of nine experts testifying on emergency pressure-relief vents at an NRC hearing last Wednesday, December 9.

These vents can relieve the buildup of pressure inside the primary containment—the steel and concrete housing surrounding the reactor vessel—during an accident. The focus of the hearing was containment vents at General Electric Mark I and Mark II boiling water reactors. Five of the six reactors at Fukushima were Mark I reactors; the remaining one was a Mark II design. During the March 2011 accident in Japan, radioactive releases through the vents, which did not have filters, caused widespread contamination around the plant.

There are 23 Mark I and eight Mark II reactors in the United States. Following the recommendations of its staff following the Fukushima accident, the NRC last March issued an order requiring all of these reactors to have reliable hardened vents to allow such venting. Wednesday’s hearing was to discuss a subsequent NRC staff recommendation that those vents should be required to have filters that would reduce the amount of radioactive material released into the environment if those vents were used. The staff recommendation said:

“Based on its regulatory analyses, the staff concludes that installation of engineered filtered venting systems for Mark I and Mark II containments is the option that would provide the most regulatory certainty and the timeliest implementation. The vast majority of Mark I and Mark II severe accident sequences would benefit from a containment vent, (whether the vent includes an engineered filter or not) and the addition of an engineered filter reduces the release of radioactive materials should a severe accident occur.

“A comparison of only the quantifiable costs and benefits of the proposed modifications, if considered safety enhancements, would not, by themselves, demonstrate that the benefits exceed the associated costs. However, when qualitative factors such as the importance of containment systems within the NRC’s defense-in-depth philosophy are considered, as is consistent with Commission direction, a decision to require the installation of engineered filtered vent systems is justified.”

Dave’s slides with the comments he used for his presentation to the NRC are available here. The slides themselves are here. The NRC website includes the agenda of the hearing, with the list of speakers; the full set of slides from the presenters, and a video of the webcast.


Posted in: Nuclear Power Safety Tags: , ,

About the author: Dr. Wright received his PhD in physics from Cornell University in 1983, and worked for five years as a research physicist. He was an SSRC-MacArthur Foundation Fellow in International Peace and Security in the Center for Science and International Affairs in the Kennedy School of Government at Harvard, and a Senior Analyst at the Federation of American Scientists. He is a Fellow of the American Physics Society (APS) and a recipient of APS Joseph A. Burton Forum Award in 2001. He has been at UCS since 1992. Areas of expertise: Space weapons and security, ballistic missile proliferation, ballistic missile defense, U.S. nuclear weapons and nuclear weapons policy

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One Response

  1. Idir says:

    It’s good that Progress Energy has requested a liencse application for the operation of two more units. It will create much needed jobs. Its a big step for what Progress Energy is doing, considering the America was left in the dust when is comes to nuclear as a means of creating power (just look at the rest of the world). We need to build more units to phase out the steam plants of oil and coal and turn back to nuclear and hydroelectric, after all the climate is not getting any cooler and going to nuclear power is a safe and exceedingly more efficient way to product power. Now about the whole waste disposal what do you want them to do? Companies that own nuclear plants have been giving money to our government to build a facility to put that waste in and to no surprise that has not happen. Poor little Yucca mountain will never see the day that it becomes much more than a hill of dirt. I don’t know about that fifty mile radius around the plant. It seems to me that no matter how many units are at a nuclear plant that does not increase the unit: “Mile Impact Zone ratio. Take a look at where other reactors are there is one in the center of Raleigh at North Carolina State University.