The Nuclear Regulatory Commission issued the first of many far-reaching safety orders for U.S. nuclear power plants in response to Japan's nuclear crisis that erupted a year ago.

Plant operators must now shore up enough emergency backup equipment by 2016 to protect reactors from earthquakes, floods and other natural disasters. Wet pools that store hot, spent nuclear fuel must also be equipped with instrumentation for operators to gauge temperature and water levels during an emergency, according to the order.

A separate order requires boiling water reactors to ensure vents can release heat and steam to prevent explosions.

NRC Chairman Gregory Jaczko said in a statement that the orders represent a significant step in the agency's efforts to upgrade nuclear safety after the March 11, 2011, nuclear crisis in Japan. A magnitude-9 earthquake and tsunami struck the Fukushima Daiichi plant along Japan's northeastern coast, triggering explosions, radioactive leaks and evacuations.

But Jaczko warned that "there's still a great deal of work ahead of us."

The nuclear power industry has already purchased or ordered more than 300 fire trucks, ventilation units, batteries and generators in anticipation of today's orders. But the $100 million plan has drawn the ire of anti-nuclear and environmental groups who say the industry is trying to save money by sharing the equipment in regional warehouses that may not meet federal safety standards.

The NRC addressed that issue today and ordered staff to weigh in on what equipment is appropriate. "Reliable, commercial grade equipment could be an appropriate solution, so long as the expectations for 'reliable' are clearly outlined in the guidance documents," the commission said.

Southern Co. and other utilities building the first new reactor in decades in Georgia will be required to buy backup power equipment and spent fuel pool instrumentation, the NRC said.

A second utility hoping to build two new reactors in South Carolina has also indicated it will include language in its license -- should one be approved -- that would bind the company to making post-Fukushima safety upgrades, said NRC spokesman Scott Burnell. Scana Corp. has applied for a license to build two 1,117-megawatt nuclear units at its V.C. Summer plant near Jenkinsville, S.C.

The commission also ordered staff to collect information on each plant relating to seismic and flooding risks, the ability to withstand the loss of power, and whether each facility has adequate staffing.

Despite today's action, Jaczko and his fellow commissioners still disagree on whether the agency is moving quickly enough to roll out Fukushima-related orders.

Jaczko told House lawmakers earlier this week that the agency is not on pace to make all changes within five years. But Democratic Commissioner Bill Magwood feels that the commission may actually be ahead of schedule and that there's been no delay in reacting to the disaster, according to his office.

Jaczko has also called on the agency to impose a tighter deadline on plant operators to re-analyze their seismic risks, and said that time frames proposed by staff -- that would give operators until 2019 to identify seismic risks -- are too long and unreasonable.

Magwood countered that argument in his written vote and said operators need flexibility and may have other risks like flooding, tornadoes or hurricanes to concentrate on.

The panel is expected to testify on the orders, as well as dozens of other safety upgrades related to the Japanese disaster, at a Senate Environment and Public Works hearing next week. Notably, Sen. Barbara Boxer (D-Calif.), the committee's chairwoman, has criticized the agency for not moving fast enough.