Limerick Nuclear Plant Ordered to Upgrade Ventilation System

In light of the hydrogen explosion at Japan’s Fukushima nuclear plant in March of 2011, Limerick Generating Station has been given an updated order to upgrade ventilation systems in both of its nuclear reactors as part of the Nuclear Regulatory Commission (NRC)'s “Japan Lessons-Learned Project.”

This order supersedes a 2012 order that required changes to ensure “maintaining containment integrity and limiting the release of radioactive materials if the venting systems were used during severe accident conditions,” according to a letter from Eric J. Leeds, director of the Office of Nuclear Reactor Regulation.

The new order provides more specifics regarding requirements for the new systems.

“The NRC staff has determined that continued operation does not pose an imminent risk to public health and safety; however the additional requirements in Order EA-13-109 are necessary in light of insights gained from the events at Fukushima Dai-ichi,” said Leeds.

After the earthquake and tsunami in March of 2011 near the Fukushima Dai-ichi nuclear power plant, operators were “unable to successfully operate the containment venting system” due to the extreme conditions, which caused inadequate cooling of the core, leading to core damage and over-pressure and over-temperature conditions, which eventually destroyed the secondary containments of three units on the property and released radioactive materials, according to the order.

 “The events at Fukushima reinforced the importance of reliable operation of hardened containment vents during emergency conditions, particularly for small containments such as the Mark 1 and Mark II [boiling water reactor] designs,” according Order EA-13-109.  Limerick has a Mark II design.

The NRC staff is currently scheduling a series of public meetings to “begin following the issuance of this order to engage stakeholders on developing guidance for implementation of this order,” according to Leed’s letter.