WASHINGTON — President Donald Trump signed four executive orders Friday aimed at accelerating the construction of nuclear power plants in the United States, including a new generation of small, advanced reactors that offer the promise of faster deployment but have yet to be proven.

One order directs the Nuclear Regulatory Commission, the nation’s independent safety regulator, to streamline its rules and to take no more than 18 months to approve applications for new reactors.

Another order directs the Energy and Defense departments to explore siting reactors on federal lands and military bases, possibly alongside new data centers. That could allow the departments to bypass the NRC and develop their own, faster processes for approving reactors.

“This is a huge day for the nuclear industry,” said Doug Burgum, the interior secretary, as he stood behind Trump at a signing ceremony in the Oval Office. “Mark this day on your calendar. This is going to turn the clock back on over 50 years of overregulation.”

In one of his first acts in office, Trump declared a “national energy emergency,” saying the country did not have enough electricity to meet its growing needs, particularly for data centers that run artificial intelligence.

While most of Trump’s actions have focused on boosting coal, oil and natural gas, administration officials have supported nuclear power, too.

Nuclear power enjoys bipartisan backing in Congress. While some Democrats remain opposed because of concerns about safety and disposal of nuclear waste.