At the close of business today, more than 90 percent of the staff of the Nuclear Regulatory Commission will go home on furlough as a result of the government shutdown. The Commission had been operating on carryover funds since last Monday, when the shutdown began, but those funds run out today, reducing the staff to a skeleton crew of 300 "essential" personnel who will be responsible for monitoring the nation's 63 nuclear sites until the government reopens.

Those 300 employees do include resident inspectors who work on-site at the various plants, as well as a skeleton crew of managers in the central headquarters. More employees can be recalled in case of an emergency, but the furlough will inevitably delay the agency's response. "Yes, I am worried," Ed Lyman of the Union of Concerned Scientists told CNN. "You can only hope for the best that a situation doesn't occur during this time."