Suzanne L. Jones, Frank N. von Hippel, "Transparency measures for subcritical experiments under the CTBT," Science & Global Security, 6, no. 3, (1997): 291-310.
This paper outlines transparency measures that could be taken to build international confidence that subcritical experiments conducted underground by the U.S. or any other country do not violate the Comprehensive Test Ban Treaty. Our calculations suggest that on-site measurement of the integrated radiation output from these experiments should be adequate to verify that nuclear yields greater than grams of TNT equivalent had not occurred, even allowing for the possibility of substantial shielding. However, our calculations also indicate that a pure fission experiment that remained strictly subcritical for its entire duration should have a yield no greater than 0.1 microgram TNT equivalent, even given irradiation by an external deuterium-tritium neutron source. Experiments involving chemical-implosion-induced deuterium-tritium fusion could have yields above this limit, and may require fission product measurements in addition to prompt radiation measurements to rule out a supercritical test.
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Article access: Taylor & Francis Online | Free PDF