Crude Nukes on the Loose?
By Morten Bremer Mærli
This PhD thesis assesses the threat of nuclear terrorism and identifies strategies for diminishing the risk of such incidents. Never before have the material, the technology, the know-how, and, perhaps, the motivations needed to perform acts of nuclear terrorism been more exploitable.
Building on eight research papers, the thesis sets out to answer three principal questions:
Can terrorists possibly perform acts of terror by means of crude nuclear explosive devices based on highly enriched uranium? What are the main barriers to the production of crude nuclear explosives?
Is there an optimum way of protecting fissile material from falling into terrorist hands? What role – if any – do transparency and non-intrusive verification play in this regard?
Within legitimate security constraints, what kind of measures could be put in place to enhance the transparency and non-intrusive verification of stocks of sensitive fissile material?
Answers to these questions may be summarized as follows:
To would-be nuclear terrorists, access to fissile material is the most formidable obstacle to their nuclear ambitions. If non-state actors have sufficient quantities of unirradiated, or “fresh”, highly enriched uranium (HEU), the production of crude nuclear explosives could be within their reach. Terrorists will have far less stringent requirements to their nuclear explosives in terms of reliability, safety, security and delivery, than states do.
Once the needed quantities of fissile material have been obtained, it is easier to construct a nuclear explosive device using highly enriched uranium than using plutonium. Technical barriers to the construction of crude nuclear explosives based on HEU should not be regarded sufficient to avoid nuclear terrorism, because:
HEU allows for the easy and reliable manufacture of crude nuclear explosives;
perpetrators with access to sufficient quantities of HEU of high enough quality will have good chances of achieving an explosion in the lower kiloton-range, i.e. with a yield comparable to that of the Hiroshima bomb;
HEU exists in large quantities, in part under unsatisfactory levels of protection, control and accounting;
HEU detection, e.g. at bordercrossings and checkpoints, is demanding due to the low levels of radiation that are emitted;
radiation levels from unirradiated uranium are low and the handling of HEU involves limited health hazards.
Several implications for countermeasures against nuclear terrorism and protection and control of highly enriched uranium follow from these findings.
There is scant protection against the pressure, heat, and radiation that would ensue from the detonation of even a crudely assembled nuclear device. There would be very few possibilities for meaningful mitigation after a nuclear terrorist attack. Reducing vulnerability by shielding particular or possible targets is neither prudent nor desirable. Accordingly, efforts to thwart nuclear terrorism should aim entirely at prevention .
Detecting illicit fissile material at borders or in a busy urban environment, however, is challenging. The production of crude nuclear explosive devices could go undetected. To stem nuclear terrorism, comprehensive stockpile inventories and stringent norms should be developed to ensure that all stocks of highly enriched uranium are secure and rendered unuseable as nuclear explosives. Denying terrorists access to fissile material through satisfactory security at possible sources of supply could be the beall and end-all of nuclear terrorism countermeasures.
Hence, a key issue for nuclear terrorism prevention becomes how to ensure optimum nuclear husbandry. The past decade has shown some remarkable achievements in the field of practical, cooperative nuclear arms control. Scientists and others whom very few had believed would ever collaborate have worked jointly to secure the excessive stocks of fissile material that were produced during the Cold War arms race. But despite unprecedented efforts, the majority of the security challenges remain. Less than half of the estimated hundreds of tons of proliferation-attractive fissile material in Russia have been secured with international assistance.
The highly enriched uranium, enough for tens of thousands of crude nuclear explosive devices, is managed with very little of the transparency necessary to build confidence that it is safe and secure, or to provide the foundation for deep, transparent and irreversible reductions. Optimal countermeasures against nuclear terrorism thus require significantly more openness on existing holdings of fissile material in the nuclear weapon states. Appropriate schemes for nonintrusive verification of sensitive stocks of HEU are available and ready for implementation.
Keeping a massive shroud of secrecy on stocks of highly enriched uranium can only maintain and exacerbate current uncertainties in fissile material stockpiles and levels of protection and control. This could increase the risk of diversion and, accordingly, elevate the threat of nuclear terrorism. It is not beneficial to the security of any state.
For the complete PDF file, trail lectures, etc.
see www.nupi.no/IPS/?module=Articles;action=Article.publicShow;ID=1437.
