is Good Plutonium"
Printed October 1996
Sandia National Laboratory: J.P. Hinton, G.A. Harms, R.W. Barnard, L.W. Kruse, D.E. Bennett, J.A. Milloy, R.W. Crocker, W.A. Swansiger, M.J. Davis, K.J. Ystesund. Savannah River Site: H.J. Groh Los Alamos National Laboratory: E.A. Hakkila, W.L. Hawkins Lawrence Livermore National Laboratory: E.E. Hill
Introduction: Security Risks
Stealing Plutonium for Bombs
How Difficult Would It Be?
Proliferation vulnerabilities are features of lower proliferation resistance that provide the greatest opportunities for illicit removal and recovery of plutonium for use in nuclear weapons, thereby reducing the effectiveness of the disposition process.
The objective of the Proliferation Vulnerability Red Team (PVRT) assessment was to identify such features of greatest significance. This report summarizes the assessments and findings....
The single summary statement about the utility of plutonium from the disposition program and its potential for use in nuclear explosive devices is: "All plutonium is good plutonium; some is better than other."
The weapons grade materials, and materials with isotopic composition not much different from weapons grade, are clearly directly weapons-usable once processed into the right chemical and physical forms. [ This includes any fresh MOX fuel made from weapons-grade plutonium. ]
The remaining question involves "reactor-grade" plutonium. The isotopic composition of these materials can range from 8 to 10 percent plutonium-240 up to more than 40 percent plutonium-240, 241, et cetera. [ This includes any irradiated MOX fuel. ]
The Department of Energy has issued a press release acknowledging that the United States has successfully tested a nuclear device using reactor grade plutonium, and that the device produced a yield of less than 20 kilotons....
In response to a question of why weapons-grade plutonium is better than reactor-grade plutonium, the release states: "Reactor-grade plutonium is significantly more radioactive, which complicates its use in nuclear weapons."
The principal complications arising from plutonium isotopes other than plutonium-239 are
These two weapon design issues affect utility depending on the scenario under consideration....
Therefore, the physics design issues could have greatly different impacts, depending on the "proliferant" and their desired goals....
A significant point is that a simple fission design would not require testing to prove that it would work. The only debate would be about the yield.
As the development program advances, there would be increased sophistication of the device, transition to a militarily useful weapon, and higher assurances of achieving design yield, even with reactor grade plutonium.
In a way, the starting point for a non-nuclear-weapon state could be considered to be the end point for a sub-national group -- a simple, unsophisticated nuclear explosive device based in large part on information publicly available, and on the expertise of a few competent scientists and engineers.
Most of the technology required for the recovery process is available in the unclassified technical literature....
Weapons grade plutonium is preferable for the development and fabrication of both nuclear weapons and nuclear explosive devices for terrorist/subnational groups, non-nuclear-weapons states, and host nation rearmament.
However, reactor grade material can also be used in any of these scenarios. Thus, weapons-usable plutonium can be recovered from any of the forms in the disposition program.
The two major discriminators in ranking the relative difficulty of recovering plutonium metal from the various intermediate and end-forms are the presence of a radiation barrier and the complexity of the mechanical and chemical processing steps....
The preparation lead-time varied from six months for a facility requiring shielding and remote operations to about three months for a facility requiring only containment.
The time to process 1 SQ [one significant quantity of plutonium, enough for a nuclear weapon] varied from eight weeks for materials with a radiation barrier to four weeks....
Thus, although chemical processing and a radiation field are discriminators, they are not sufficient barriers to prevent recovery should sufficient material be removed from within a disposition process.
Dilution complicates the recovery by requiring larger batches or more batches of material to recover a bomb's worth of plutonium, but with adequate planning and equipment, recovery would still be feasible.
All plutonium from all stages of all alternatives can be made weapons usable, should sufficient material be successfully removed. For the host nation it is no problem at all.
Although weapons-grade plutonium is preferable for the development and fabrication of nuclear weapons and nuclear explosive devices, reactor grade plutonium can be used.
The technology for recovering plutonium from spent fuel is in the open literature and can be adapted for the materials forms within the alternatives.
The resources required for the recovery of a significant quantity of plutonium are estimated to be relatively modest.
The presence of a radiation barrier sufficient to require shielding and the complexity of the mechanical and chemical processing steps during recovery provide the greatest discrimination among the material forms.
However, a small, well-prepared group could recover sufficient plutonium for a device within perhaps two months. Thus the utility barrier is not sufficient.
Keeping plutonium inaccessible is the key to proliferation resistance.
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