Hannover 2003 – wissenschaftliches Programm

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PV: Plenarvorträge

PV XVII

PV XVII: Plenarvortrag

Freitag, 28. März 2003, 09:45–10:30, Audimax

Reducing Stockpiles and Use of Highly-Enriched Uranium — •Frank von Hippel — Program on Science and Global Security, Princeton University, USA

It would be relatively easy for terrorists to make a nuclear explosive out of highly-enriched uranium (HEU, containing more than 20% U-235) - especially out of weapon-grade uranium (WgU, > 90% U-235). Because of very low spontaneous neutron production in metallic uranium, it is possible to assemble a supercritical mass of 50-100 kg of WgU with a simple No-dqgun-typeNo-dq design with a low probability of a premature start of the fission chain reaction.

About 1000 t of WgU have become excess as a result of the down-sizing of the Russian and U.S. nuclear arsenals. The U.S. has agreed to purchase 500 t from Russia after dilution to the 4-5% U-235 mixture used in power-reactor fuel. About 200 t of excess U.S. HEU is being blended down for such use. The U.S. is putting most of its own excess WgU in storage, however, for future use in naval-reactor fuel.

While most of the world’s HEU is in nuclear weapons and associated facilities, tens of tons exist in about 100 civilian research institutes worldwide where security is typically weak. Retrieval of the spent HEU fuel at these facilities - and of the fresh HEU fuel of shut-down facilities - and conversion of still-operating facilities to low-enriched uranium (LEU) should be among the most urgent tasks for our anti-terrorist efforts.

A final focus should be on converting naval and Russian ice-breaker reactors to LEU. At least some of France’s nuclear submarines already use LEU.