Fukushima sees only incremental improvement-NRC

May 4 (Reuters) - 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 towards stabilizing the reactors and spent fuel pools," said Gregory Jaczko, chairman of the Nuclear Regulatory Commission, in prepared testimony. (Reporting by Roberta Rampton and Ayesha Rascoe)