The Nuclear Regulatory Commission is proposing modified nuclear export rules that critics charge would undermine efforts to persuade nations to permit international inspection of all their nuclear facilities.

The changes also could facilitate sale of atomic reactor components to China by Westinghouse Electric Corp.

The amendments to the NRC's export control regulations were approved by the three new commissioners appointed by President Reagan and opposed by the two holdovers. They are to be published in the Federal Register for comment within the next two weeks.

Under existing regulations, certain equipment can be exported only to countries that have signed the Nuclear Nonproliferation Treaty or have agreed to permit the International Atomic Energy Agency to inspect all their nuclear facilities. One of the proposed amendments would remove two major atomic reactor components--primary coolant pumps and reactor control rods--from that list.

Westinghouse late last year applied for an export license to sell two primary coolant pumps for a small nuclear power station that China plans to build near Shanghai. But the license has not been approved because China is not a signatory of the treaty and has shown no inclination to accept international inspection of all its facilities.

"This change goes a long way towards nullifying congressional intent in enacting the Atomic Energy Act's full-scope safeguards requirement," Victor Gilinsky, a member of the NRC, said. "Instead of reducing the number of types of equipment which trigger this requirement, the commission should be considering whether additional types of equipment should be added."

NRC sources conceded yesterday that the amendment could make the Westinghouse sale possible, but they emphasized that the transaction faces an uphill struggle for a variety of reasons.

A second proposed amendment would create a new, privileged category of countries that could obtain nuclear reactor components under a "general license" without having each export approved on a case-by-case basis.

In this group are 15 countries that have signed the NPT and have atomic cooperation agreements with the United States. They include four developing countries that at times have seemed interested in nuclear weapons: South Korea, Taiwan, the Philippines and Indonesia. The other 11 are Britain, Belgium, Canada, France, Denmark, Italy, Japan, the Netherlands, Sweden, Switzerland and West Germany.

"In essence, this provision would permit a manufacturer to export virtually an entire nuclear reactor without having to give notice to, or obtain the approval of, the United States government," Gilinsky said.

"In light of our recent experience with the illegal export of sensitive items through the use of bogus destinations and invoices, it is reasonable to expect that any such general license will be abused."

Gilinsky's comments were made in a letter to Rep. Richard L. Ottinger (D-N.Y.), whose House Energy subcommittee held hearings on NRC issues yesterday.

Commissioner John F. Ahearne joined Gilinsky in opposing the new amendments, according to NRC sources. Chairman Nunzio J. Palladino, Thomas M. Roberts and James K. Asselstine--all Reagan appointees--supported the changes.