Nuclear Test Talks Resume Today : U.S., Soviets Seek to Ratify 2 Accords, Discuss Total Ban

The longest-running U.S.-Soviet arms negotiations--on limiting nuclear testing--resume today in Geneva in an effort to get two decade-old agreements ratified and then to move toward a total test ban.

The testing negotiations are separate from the strategic arms reduction talks, which resumed in Geneva last Monday.

Verification disagreements continue to hold up progress on the testing issue, however, with the United States appearing to drag its feet more than the Soviet Union.

The U.S. government, for example, has refused to make public the results of a joint U.S.-Soviet experiment in Nevada last September. On its face, the experiment proved that the intrusive on-site inspection system favored by the United States is less accurate than the off-site method favored by the Soviets.

“The information (on the experiment) was made available to the Soviets,” an Energy Department spokesman said last week, “but it remains classified.” Test ban supporters in Congress and elsewhere see this as additional proof that the Pentagon wants to keep the public uninformed to avoid pressure to change its position.

Behind this posture is the Pentagon’s conviction that--as long as the nation relies on nuclear weapons to deter war--some nuclear testing always will be required to insure reliability of the nuclear arsenal, to develop new warheads as weapons change and to maintain U.S. technological expertise.

The Defense Department is even unhappy with the Reagan Administration’s commitment at last year’s U.S.-Soviet summit in Moscow to negotiate, once the old treaties are ratified, “further intermediate limitations on nuclear testing leading to the ultimate objective of the complete cessation of nuclear testing. . . .”

In a review in preparation for resumption of the testing talks, the Pentagon sought to get the Bush Administration to back away from talks on “further intermediate limitations,” according to sources. No decision has been made on the U.S. negotiating position, but a senior Administration official said he doubts that any significant change will be made within the next few months.

Further limits of the type opposed by the Pentagon could include a cap on the annual number of underground tests, which are now unlimited, and reduction in the maximum size of such tests, now set at 150 kilotons, or equal to 150,000 tons of TNT.

But pressure on the Administration is coming from both international and domestic groups.

Key nations that are capable of producing nuclear devices, led by India, are threatening to withdraw from the 1968 Nuclear Non-Proliferation Treaty unless the superpowers make serious progress toward a total test ban. Under that treaty, to which more than 135 nations subscribe, nations with limited or no nuclear capabilities pledge not to make weapons in exchange for help on peaceful nuclear programs.

Major Bush Issues

President Bush has made nonproliferation of ballistic missiles as well as nuclear and chemical weapons one of the major foreign policy issues of his Administration. The have-not nations apparently hope to hold the non-proliferation treaty hostage to progress toward further limits on weapons tests, an Administration official said.

Domestic opponents of testing contend that, if testing is stopped, the United States will need less new highly enriched uranium and plutonium for weapons and could save some of the $5 billion needed to rebuild reactors and other facilities that produce those materials.

Some Administration officials fear that congressional supporters of a total test ban may hold up funding for those facilities unless the Administration is more forthcoming in the negotiations, which are resuming after a seven-month break.

The first superpower testing agreement, signed in 1963, banned tests in the air, sea and space. Only underground tests are permitted under the two treaties now pending. These are the Threshold Test Ban Treaty of 1974, which covers weapons tests, and the Peaceful Nuclear Explosions Treaty of 1976, which deals with nuclear devices used for such purposes as excavating canals and creating underground gas and oil reservoirs.

The Carter Administration did not submit the two treaties for ratification in the hope that a total test ban might be achieved. The Soviet invasion of Afghanistan ended that effort. And the Reagan Administration declared that it did not want a total ban and would not ask for congressional ratification of the two treaties until improved verification measures were worked out.

This position produced a standoff for several years, with the Soviets promising to devise better monitoring measures only after the two treaties were ratified and insisting that any new negotiations aim at a total ban.

But with the warming of relations under Soviet President Mikhail S. Gorbachev, the two nations resumed discussions on the testing issue and eased their stands enough to produce the Moscow summit communique.

Beyond compromising on the final goal of test ban talks, the summit reached agreement on two joint verification experiments, in which nuclear devices would be set off at each nation’s test sites in the presence of inspectors from the other nation.

The purpose was to resolve disagreement over the most accurate method of verifying the size of a test, to insure that it did not exceed the 150-kiloton limit.

Of three ways to conduct such monitoring, the most accurate method--radiochemical analysis of the soil near the explosion--was rejected by both sides because it discloses too much secret information about how the weapon was constructed. The argument has been over the other two methods:

--Seismic, in which the earthquake-like waves from a blast travel through the Earth to sensitive instruments that estimate its force. The Soviets favor this method, in large part because it can be done away from the test site, thus requiring little on-site inspection.

--Hydrodynamic, in which an instrumented cable is lowered into the shaft containing the weapon (or into a parallel shaft). The rate at which the cable is crushed by the blast is a measure of the explosive power of the device. This method, called CORRTEX, is favored by the United States.

The U.S. proposal calls for using CORRTEX to monitor all weapons tests above 50 kilotons in size and all peaceful blasts above 35 kilotons. About 30 on-site inspectors would be needed to scrutinize details of the preparations, including the material used to fill in the shaft. The purpose would be to guard against “tamping,” or masking, the shock waves from the explosion, which provides a measure of its true size.