Influential Nuclear Weapons Experts Detail Key Security Measures in Talk at AAAS

Robert Gallucci

In a wide-ranging discussion on how to control the spread of nuclear weapons, two leading specialists agreed at a 20 October AAAS discussion that the most important measure is control of the production of fissile materials—plutonium—and highly enriched uranium—from the very outset.

"Fissile material is the key," said Robert Gallucci, dean of the Georgetown University School of Foreign Service and the lead U.S. negotiator on a 1994 agreement with North Korea regarding its nascent nuclear program.

While efforts to rein in North Korea's nuclear ambitions continue, the bottom line is clear, Gallucci said. "We do not want them producing fissile material. That's it." The concern, he said, is not so much that they might mount an attack on Los Angeles. It is the possibility that North Korea or other rogue states might try to peddle fissile materials on the black market to terror groups for use in "dirty" bombs or crude nuclear devices.

Illicit trafficking in nuclear materials will be difficult to detect and stop, even with ambitious plans to use radiation monitors at ports and border crossings, Gallucci said. "I think it is great to have port monitors," he said, but called them "largely a CYA exercise." If such surveillance should catch a bomb at a port of entry, he said, "you're already in a bad place."

Richard Wagner

Richard Wagner, a senior scientist at Los Alamos National Laboratory, said that radiation monitors can raise the bar and make it more difficult for terrorists to succeed in smuggling nuclear materials. He said that control of nuclear smuggling is not as impossible as it might seem, particularly if the radiation monitors are used as part of a multi-level defense that includes other types of surveillance and intelligence-gathering operations overseas.

Wagner and Gallucci spoke at one in series of salon-style discussions on "Science and Society: Global Challenges." The discussions are sponsored by the AAAS Center for Science, Technology and Security Policy. David Kestenbaum, a science correspondent for National Public Radio, was moderator for the session on nuclear weapons.

Wagner has been concerned about the possibility of a terrorist nuclear threat since the late 1960s when he was in charge of the design of single-stage nuclear weapons and fission primaries for thermonuclear weapons at the Lawrence Livermore National Laboratory. A few years earlier, physicist Theodore Taylor had published a paper arguing that a few clever graduate students could design a nuclear weapon using publicly available information. An FBI agent brought Wagner a drawing the bureau had received from a letter writer claiming to have designed a homemade nuclear weapon. While the drawing was a hoax, Wagner and others were concerned enough to help organize the Nuclear Emergency Search Team, a group of experts who can use technology to help law enforcement agencies find and identify illicit nuclear materials.

While serving on the Defense Science Board in 2003, in the aftermath of the 9/11 terrorist attacks, Wagner helped draft a plan calling for the use of very large numbers of radiation detectors at key locations to help find any fissile materials being smuggled into the country. Development and fielding of radiation monitors at ports and borders has now become a growth industry.

Still, critics say the detectors can be defeated by using lead or other shielding materials to surround the fissile material in a shipping container. Gallucci said that enforcement agencies can look for clues to such shielding efforts, including an unusual amount of mass in a container. "None of this is easy," Wagner acknowledged. "It will always be possible for someone to smuggle through" a quantity of fissile material. But he the risk can be significantly reduced through a combination of greatly improved detectors, which are feasible, and global operations to discover and prevent attacks.

While the possibility of nuclear terrorism will remain a real and unpredictable concern, Kestenbaum also asked Gallucci and Wagner about the status of existing arsenals of warheads in nuclear weapons states and the prospects for further reducing their numbers. "How many nukes should we have and is zero an option?" he asked.

Gallucci said it may be possible to get the U.S. and Russian arsenals down to low numbers. "I think a low number is 1000," he said. The U.S. now has about 5700 warheads, according to a recent estimate by the nonprofit Center for Defense Information. The Center gave an estimate of 7200 for Russia. The United States has decided to reduce the number of its deployed warheads to between 1700 and 2200 by 2012.

But to get down to much few fewer than 1000 warheads and still be able to call them survivable in event of a preemptive attack "becomes much more problematical," Gallucci said. Wagner said international relations would have to be much more benign than they are now in order to permit one nation to unreservedly verify that another nation does, indeed, have zero nuclear weapons.

Experts in deterrence long have been concerned that dozens of states might try to develop their own nuclear weapons capability. That hasn't happened so far, but there are nine states now with nuclear weapons or, in the case of North Korea, a presumed weapons capability. North Korea tested a nuclear device in 2006 but the yield was small and there remains debate on how many nuclear weapons, if any, the country may possess.

Wagner said it remains possible that the world may someday have many more nuclear weapons states. "It's conceivable to me that there could be a nuclear tipping point at some time in the future, 10 years or 30 years, when 30 or 40 nations have the capability to develop nuclear weapons," he said. If some event or geopolitical development triggers it, he added, nuclear breakout could happen quickly.

Designing a workable nuclear weapon is no longer considered as challenging an obstacle, Wagner said. "I think the cat is out of the bag on design," he said. With articles in the public literature and some declassified documents from the early days of the U.S. weapons program, he said, nuclear wannabes "don't need information from us, they can do it themselves."

The key factor, again, is controlling access to the fissile materials needed for a weapon.

Gallucci noted the renewed interest in building civilian nuclear power reactors in the United States and abroad. Conventional light-water reactors create weapons-suitable plutonium as a byproduct of burning low-enriched uranium fuel. The plutonium can be chemically separated from the spent reactor fuel and recycled for use as fuel in power reactors. But such fuel reprocessing also raises the risk that plutonium from the civilian nuclear industry could be diverted for nefarious purposes.

Gallucci called for a once-through use of nuclear fuel in power reactors, with the spent fuel going into long-term secure storage. The United States currently does not do reprocessing of spent fuel from civilian power reactors, a policy adopted in the 1970s over concerns about nuclear proliferation.

But the Bush administration has spearheaded a controversial effort called the Global Nuclear Energy Partnership (GNEP), an international agreement that has been signed by 21 nations including the United States, the United Kingdom, Russia, China, and France.

Under GNEP, the United States and other nations with advanced civilian nuclear energy production facilities would be responsible for safely reprocessing spent nuclear fuel and then would export it to be reused for other nations' energy programs. The administration argues this approach would reduce the number of nuclear enrichment and reprocessing sites around the world.

On the military side, the Bush administration has pushed for a new generation of reliable replacement warheads (RRWs) that would be more easily manufactured and maintained than existing nuclear weapons and with enhanced performance margins. A study group convened by AAAS's Center for Science, Technology and Security Policy concluded last year that the anticipated benefits of such replacement warheads would only occur in the long term, subsequent to a costly modernization of the weapons production complex. After funding the RRW program for three years, Congress halted any new financing for the program until a blue-ribbon study on nuclear weapons policy is completed in December.

Gallucci said he remains skeptical about the RRW program, which would depend on data from past underground tests, current understanding and computer simulations of the physics of nuclear detonations, and new non-nuclear experiments in order to certify that the new warheads would work as intended. There would be no underground testing. Gallucci called it "counter-intuitive" to consider replacing weapons that have been extensively tested with warheads that have never been tested. "I am very skittish about this," Gallucci said.

But Wagner, who acknowledged that he had been very skeptical of the RRW program at first, said he has changed his mind. The proposed replacement warhead, he said, is a design that is "easily traceable to tested designs... I'm pretty convinced that the RRW will be more reliable without testing than the old weapons as they degrade."

Asked by one member of the audience to discuss chemical and biological weapons under the umbrella term "weapons of mass destruction," Gallucci demurred and said he dislikes the common practice of lumping chemical and biological weapons into a category along with nuclear weapons. He said it is hard to get hundreds of thousands of deaths, even with an advanced chemical or biological weapon.

"A nuclear weapon has a certainty to it," Gallucci said, lending a touch of ominous reality to what had been an otherwise rather academic discussion.

Earl Lane

29 October 2008