The Nuclear Regulatory Commission has ordered some modifications made to plants that are similar in design to those in Fukushima that melted down in Japan two years ago.

The NRC wants 31 plants that are similar in design to the Japanese model to make some modifications to their venting systems.  According to the Associated Press:

The order requires U.S. operators to upgrade vents to ensure they remain operable even during severe accidents, such as the March 2011 incident at Japan's Fukushima Dai-ichi nuclear plant. The order stops short of requiring plants to install filtered vents, as some safety advocates and NRC's staff had urged. The filters are required in Japan and much of Europe, but U.S. utilities say they are unnecessary and expensive.

The commission said the order will improve safety and help prevent radioactive particles from escaping into the atmosphere after a Japan-style meltdown. The commission said it will study requiring filters."

Reports did not indicate if the Columbia Generating Station at Hanford would be required to make these modifications. While the CGS uses similar technology to Fukushima, it's only reactor is a General Electric Type 5, which is considerably newer than the ones in Japan.  It has also had numerous other upgrades over the last two decades.