"I think the vast majority of people coming to the site were able to get on and do what they had to do," Health and Human Services Secretary Sylvia Mathews Burwell said on NBC's "Meet the Press." (Chip Somodevilla/Getty Images)

Secretary of Health and Human Services Sylvia Mathews Burwell said 100,000 people submitted applications for coverage under the Affordable Care Act on Saturday, the first day of the law's second enrollment period.

Speaking Sunday on NBC's "Meet the Press," Burwell said that more than 500,000 people were able to log on to the government's Web site, healthcare.gov, and that more than 1 million people have been "window-shopping" for insurance options.

"I think the vast majority of people coming to the site were able to get on and do what they had to do," she said.

The numbers and apparent smoothness of the process are a stark contrast to last year's rollout of the site, which was hobbled by technical difficulties.

Burwell also addressed comments by Jonathan Gruber, a former health-care consultant to the Obama administration. A video emerged last week of Gruber, an architect of the Affordable Care Act, saying that the law passed through Congress because of the "stupidity of the American voter" and a "lack of transparency" over how it is funded.

"I have to start with how fundamentally I disagree with his comments about the bill and about the American people," Burwell said, adding that she has "focused on transparency" since being nominated as secretary. "The law is based on the issues of transparency and belief in the American people and choices in the marketplace."