Israel has proposed to Egypt joint operation in the Sinai of the two nuclear power plants promised separately to the two Middle East nations by President Nixon in June, 1974.

Yitzchak Modai, Israeli Minister of Energy and Resources, said Friday that he would try the idea out on Secretary of Energy James Schlesinger. However, a spokesman for Schlesinger said that Modai had not brought the topic up in a meeting with the secretary later that day.

Modai told reporters that he had already broached a plan for joint Israeli-Egyptian operation of the nuclear power plants to Egyptian officials during President Anwar Sadat's visit to Jerusalem December 17.

At that time, Modai said, the Egyptians were enthusiastic. But since the suspension of diplomatic talks, no further progress has been made on this or other Israeli initiatives for economic development of the region.

The proposal to supply Israel and Egypt wtih atomic energy plants, based on low-enriched uranium fuel, has been stalled since mid-1976, when both countries initialled identical agreements for the purchase of the plants -- 1,280 megawatts capacity for Egypt, and 1,970 megawatts for Israel.

The agreements were accompanied by stringent safeguard arrangements to bar against possible use of nuclear by products for the manufacture of nuclear weapons. A delegation of 12 Senators, after visits on the site in December, 1976 approved the program, and said licenses could go forward without inspection of Israel's existing atomic energy installations at Dimona, which reportedly give Israel a nuclear weapons capacity.

But the Carter Administration, intent on taking a fresh look at the whole picture, has not approved the Egyptian and Israeli requests. "They're definitely on the back, burner," said a Congressional source.

Modai said that if there is a peace settlement in the region, joint operation of the Israeli and Egyptian nuclear plants totally more than 3,000 megawatts of capacity would be more efficient than two facilities operated separately.

Moreover, he said that a common location in the Sinai would be ideal for supplying the power needs of both nations, and that Israel could contribute not only management expertise, but link the operation with its know-how on water desalinization

The Israeli Minister -- a member of the Likud party, in charge of a brand new cabinet department -- saw other potential areas of Israeli-Egyptian cooperation on energy. With peace, he said. Egypt could supply all of Israel's needs for crude oil.

He estimated Egypt's current production of petroleum at 20 million tons annually, of which it uses about half, and exports the rest Israel's annual consumption is now about 7.5 million tons a year, he said, most of which has been supplied by Iran since Israel returned the Abu Rodeis fields to Egypt.

Modai said that Egypt has made great strides in the last few years in development of new oil fields, and within another 5 years could become a major exporter of oil.

Another Israeli plan for a co-operative effort in the Sinai would be to make it a center for blending Egyptian and other oil because the Sinai is "a strategic crossroads." The operation, as he visualized it, would be similar to American refining and trans-shipment operations in the Caribbean.

In addition to the economic benefits that could accrue to both nations through joint ventures in the Sinai, the Israelis clearly hope that co-operative projects will give both sides a heavy financial stake in assuring continued peace and stability in the region.