Claims that radiation from the wrecked Fukushima No. 1 nuclear plant is contaminating U.S. waters are "simply not correct," Nuclear Regulatory Commission Chairwoman Allison Macfarlane said on the disaster's third anniversary.

Radioactive water hasn't reached the coast and any Pacific Ocean samples with residue from the 2011 meltdowns has levels at least 100 times lower than U.S. drinking-water standards, Macfarlane said Tuesday at a commission conference near NRC headquarters in the Washington suburb of Rockville, Maryland.

"It is imperative that we as regulators find and seek out that credible information," she said.

While Macfarlane has previously ruled out contamination, the NRC continues to confront claims, often tied to Internet postings, that radiation from the March 2011 triple meltdown at Fukushima No. 1 is at dangerously high levels in the water. Macfarlane also knocked down the claims in a blog post Tuesday.

"Here the Pacific's vast volume has greatly dispersed any contamination before it can reach our West Coast," she wrote. "Scientists have not seen any Fukushima contamination that raises a concern about the U.S. food supply, water supply or public health."