Economics to take back seat at summit. Nuclear accidents, East-West ties, and terrorism are expected to dominate talks. Economics will play second fiddle -- an emerging trend.

President Reagan lands in Tokyo today for an economic summit that is likely to be overshadowed by the continuing drama of the Soviet nuclear accident. Concern about the incident among summit participants and the general public only strengthens a recent trend in which political topics rather than economic issues dominate the summit meetings of the seven largest industrialized democracies.

At this year's summit, which begins Sunday, the subjects of nuclear accidents, superpower relations, and terrorism will rank higher -- at least in news media attention -- than the big economic issues on the agenda. Those financial agenda items include improving economic cooperation and coordination, battling protectionism, fostering growth, and discussing reforms of the world monetary system.

The issue of nuclear accident detection and control will ``undoubtedly'' get discussed at the summit meeting, Secretary of State George Shultz said here yesterday -- ``although we have lots of other things to discuss.'' Mr. Shultz added that the United States does not want to see the meeting ``dominated by this accident, important though the accident may be.''

Shultz criticized the Soviets for their handling of the incident. ``We don't think that they have provided as full and prompt information as they should have,'' he said. The US now knows more about the accident from its own sources than the Soviets have told the US, other countries, or the Soviet people, the secretary said, and he confirmed that Moscow has declined a US offer to provide various kinds of technical help.

Coverage of the disaster and its aftermath has pushed the first leg of President Reagan's Asia trip from newspaper front pages and network evening newscasts.

Summing up the President's talks in Bali with leaders of the Association of Southeast Asian Nations, Shultz spoke sharply in response to comments this week by Philippine Vice-President and Foreign Minister Salvador Laurel. Mr. Laurel said Wednesday that ``cobwebs of doubt'' remained about US support for the government of President Corazon Aquino. ``You will have to ask Mr. Laurel if he is satisfied. Let me remind you the President is not on trial,'' Shultz said.

Laurel complained earlier that the $150 million of new US aid proposed by the Reagan administration is inadequate. After Mr. Laurel's meeting Thursday with Mr. Reagan, Shultz said, Laurel ``gave the impression that his money needs were infinite -- and we don't have infinte capacity to provide money.'' Shultz added: ``When it comes to economic development, solutions to the problems start at home.''

Shultz said Reagan and Indonesian President Suharto had ``discussed East Timor.'' Before the trip began, 23 US senators and 125 US representatives wrote Reagan asking him to raise the issue of alleged civil rights violations in the Portuguese colony Indonesia invaded in 1975.

Beyond being a topic of summit discussion itself, the nuclear accident near Kiev is expected to increase interest in the discussion of superpower relations and arms control. Both topics were already slated to be discussed at this 12th-annual summit meeting.

Reagan is scheduled to give his assessment of the prospects for a US-Soviet summit later this year. And he will compare summit notes with Italian Prime Minister Bettino Craxi and French President Fran,cois Mitterrand, both of whom are expected to meet with Soviet leader Mikhail Gorbachev soon. Reagan will also explain and seek formal support for his decision to scrap two nuclear submarines to avoid violating limits set by the second Strategic Arms Limitation Treaty.

The US will push other nations -- especially Japan -- to open markets to US exports. Washington also seeks the early completion of preparations for the next round of multilateral trade talks under the General Agreement on Tariffs and Trade and a successful launching of the next round. Prospects appear good.

The US will also be working to head off a trade war over agricultural products with the European Community. The dispute was triggered by EC plans to put new limits on sales of US farm products.

Meanwhile, the US also wants other nations -- especially West Germany and Japan -- to speed up their economies and thus draw in more US exports. So far, the desire has met with resistance.

The dollar's rapid drop against the yen is starting to worry some financial market experts who fear the decline may go too far. The risk is that the drop could set off rapid inflation in the US. Summit leaders are likely to discuss the drop and how to reform the world monetary system to prevent extremely disruptive swings in currency values.