The State Department yesterday permitted Westinghouse Electric Corp. to export the key component of a controversial $1.2 billion nuclear power plant to the Philippines.

Although the five-member Nuclear Regulatory Commission must still rule on the export, President Carter can override the NRC and permit the shipment, as he did last year in the export of seven tons of enriched uranium fuel to India.

The State Department gave its approval to the Philippine export despite reservations about safety of the plant, which is to be built at Bataan Peninsula's Nabot Point 45 miles west of Manila and within erupting distance of four volcanoes.

"The Nabot Point site has unique seismic and volcanic characteristics," the State Department said in a 60-page report to the NRC. "Seismic activity and volcanic history of the site region is not well known or understood," the department said.

However, the document says the nuclear power plant can be made safe from earthquakes and volcanoes with additional design and construction. It said the plant should be designed to go into a "safe shutdown" in the event of an earthquake and should be built to resist volcanic ash as much as 22 feet deep.

The State Department urged that the Philippines install a "volcano surveillance system" at the plant and develop an action plan "in the event of raidoactive release due to a Mt. Natib eruption."

Mt. Natib is 10 miles from the plant, one of four active volcanoes within 90 miles of the plant. The edge of a huge flow from Mt. Natib's last eruption is less than two miles from the plant site, where the foundation has begun to rise.

According to the State Department, the Philippine Atomic Energy Commission has "acknowledged the possibility of eruption of Mt. Natib" and directed its National Power Co. to evaluate "probabilities of eruption."

The State Department's action yesterday involves export of the plant component, the $118 million stainless steel reactor vessel, which protects the 60-ton uranium fuel core that will generate electricity. The export license for the reactor vessel was requested by Westinghouse more than three years ago.

The NRC has 120 days to consider the department's recommendation, at the end of which President Carter can step in and order the export. In the time it has to mull over the license, the NRC also must decide whether to grant a hearing to two groups opposing the export.

The challengers are the Center for Development Policy and the Philippine Movement for Environmental Protection, both of which claim the plant site is unsafe. They also criticize the location because the plant is 10 miles from the U.S. naval base at Subic Bay where 33,000 Americans are stationed.

Still pending at the State Department is the request for export of the uranium the Philippines must have to make electricity in the plant. Westinghouse has asked State to approve exporting more than 120 tons of enriched uranium, enough for four years' operation.

Sources said one reason the administration approved the Philippine export is the health of the U.S. atomic power industry.Only one U.S. utility has ordered a nuclear power plant in the last three years.

A new report, "The Viability of the Civil Nuclear Industry" prepared by a Swedish-British group, has concluded that General Electric and Babcock & Wilcox may be forced to quit the nuclear power business in five years and Combustion Engineering and Westinghouse in the next 10 years because of market conditions.