© Tokyo Electric Power Co. The crippled Fukushima Daiichi Nuclear Power plant is seen in Fukushima Prefecture in this undated handout photo.
- Japanese authorities continue to struggle to control the damaged Fukushima Daiichi nuclear plant, the chairman of the U.S. nuclear regulator told lawmakers on Wednesday.

"The NRC continues to characterize the status of the Fukushima site as static -- meaning that while we have not seen or predicted any new significant challenges to safety at the site, we have only seen incremental improvements toward stabilizing the reactors and spent fuel pools," said Gregory Jaczko, chairman of the Nuclear Regulatory Commission, in prepared testimony.