No need for US to resume nuclear testing, experts say

The US is in a better position today than at any time since the dawn of the nuclear era to ensure the reliability and safety of its nuclear weapons without the need for underground testing, a National Academies committee concluded. The US also is well-equipped to detect clandestine efforts by other nations to test nuclear weapons. To accomplish that the US can either use its own military and intelligence capabilities or a separate international monitoring system that is about 80% complete.

Although US surveillance systems for detecting a nuclear detonation—collectively called national technical means—are superior to those of the international system, the committee advised continued US support for the latter system, in part so that the US won’t have to reveal classified capabilities to denounce the tester. Seismic, hydroacoustic, radioisotopic?, and satellite technologies for detecting nuclear detonations have improved markedly in the 10 years since the National Academies last advised on the possibility of tests going undetected. In particular, seismometers can detect underground explosions below 1 kiloton in yield.

“Provided that sufficient resources and a national commitment to stockpile stewardship

are in place, the committee judges that the United States has the technical capabilities to

maintain a safe, secure, and reliable stockpile of nuclear weapons into the foreseeable future without nuclear-explosion testing,” the report stated. The committee, chaired by Ellen Williams, chief scientist at BP, acknowledged that nations might develop a rudimentary nuclear weapon that doesn’t need to be tested—whether a gun-type device such as the Hiroshima bomb or a copy of an existing weapon design. But the US wouldn’t need to resume its testing in response to such a development, the report said. The US has observed a moratorium on testing since 1992. The Senate, however, rejected ratification of the Comprehensive Nuclear-Test-Ban Treaty in 1999. The Obama administration has indicated that it will put the CTBT before the Senate again.

The treaty would enter into force after ratification by the 44 countries that either already possessed nuclear weapons or had nuclear reactors in 1996. To date, 36 nations have done so, including Russia, the UK, and France. In the event that the US determines that a new weapon needs to be designed and tested, it could invoke the CTBT’s “supreme national interest clause” and withdraw from the pact.

The committee said that the Department of Energy’s stockpile stewardship program has made sufficient technical progress since 2002 to consider reusing and replacing components to help extend the lifetimes of aging nuclear weapons. Until now, life extensions have been accomplished solely by refurbishing the original components.

The report cautioned that satellite nuclear detonation capabilities be maintained as a priority. “Sustainment of the U.S. satellite monitoring capability to detect any nuclear explosion in the atmosphere or space, whatever its origin, will continue to be in the interest of the United States and its allies, regardless of whether the CTBT enters into force,” it said.

The panel urged the government to attract and sustain a highly qualified scientific and engineering workforce to maintain the stockpile and to recapitalize the aging nuclear weapons infrastructure.

The committee judged that, to clandestinely test a nuclear device, a country located in the Northern Hemisphere would have to limit the explosive yield to below 1 kiloton in order to have a 90% probability of the test going undetected. That holds true even were the evasive tester to succeed at fully decoupling the explosion—that is, detonating the device in a large subterranean chamber created in a previous test or one specifically created for the test.