Dominion (NYSE: D) has told the Nuclear Regulatory Commission (NRC) that although several dry cask storage canisters at the North Anna plant in Virginia shifted slightly after a 2011 earthquake, there's no evidence of actual damage.
Dominion and NRC officials discussed the issue in a Jan. 28 meeting at NRC headquarters in Rockville, Md. A March 9 memo summarizing that meeting was recently posted on the NRC document website.
On Aug. 23, 2011, a 5.8 magnitude earthquake, one of the largest to occur in the eastern United States for many decades, was recorded. The epicenter of the quake was in Louisa County, Va., just a few miles from the North Anna station.
Twenty-five of the 27 casks on Pad No. 1 of the Independent Spent Fuel Storage Installation (ISFSI) “showed indication of slight movement from pre-earthquake positions,” according to the memo.
“Following the earthquake that occurred on August 23, 2011, the center to center spacing of the DSCs [dry shielded canisters]varies from 15 feet 2 ¼ inches to 16 feet 11 ¼ inches,” according to the report.
According to the technical specifications, the canisters “will be spaced a nominal 16 feet apart center to center,” according to the memo. “Although the casks moved slightly, they show no other indications of adverse effects (including no detection of local radiation leakage or streaming), and no damage.”
Dominion has proposed to leave the canisters in their current positions, saying there is significant safety margin already for the spent fuel storage pad. The canisters could withstand “another earthquake of the August 2011 type,” according to the memo.
Dominion also said it has done a “thermal analysis” and detected no problems with the cask temperatures, the memo stated. Dominion expects to file a formal amendment for the dry cask storage facility soon. The memo was drafted by B. Jennifer Davis, Senior Project Manager for NRC's Licensing Branch in the Division of Spent Fuel Storage and Transportation.
In addition to Dominion and NRC, representatives of vendors AREVA and Transnuclear were also on hand, as was one member of the public.
Dominion's North Anna nuclear station is home to two pressurized water reactors (PWRs) each with listed with an operating capacity of more than 900 MW. Dominion also has a new plant license application in the pipeline with NRC for a third unit at North Anna.
Dominion has not made a decision to actually build a third unit there, however.
This article was republished with permission from GenerationHub.