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Why should safeguards by design be a global effort?
Jeremy Whitlock
I can’t think of a more exciting time to be working in nuclear, with the diversity of advanced reactor development and increasing global support for nuclear in sustainable energy planning. But we can’t lose sight of the need to plan for efficient international safeguards at the same time.
Global nuclear deployment has been underpinned since 1970 by the Treaty on the Non-Proliferation of Nuclear Weapons (NPT), making it a key customer requirement for governments to demonstrate unequivocally that the technology is not being misused for weapons development.
The International Atomic Energy Agency (IAEA) has helped verify this commitment for more than 50 years, but it has never safeguarded many of the advanced reactors (and related fuel cycle processes) being developed today.
A. A. Haasz, J. W. Davis
Fusion Science and Technology | Volume 50 | Number 1 | July 2006 | Pages 58-67
Technical Paper | doi.org/10.13182/FST06-A1220
Articles are hosted by Taylor and Francis Online.
Both physical sputtering and chemical erosion take place in tokamaks. Physical sputtering occurs for all elements for incident particle energies greater than an energy threshold. For carbon targets the threshold difference for the three hydrogen isotopes is relatively small. In the energy range of 100 to 3000 eV, the physical sputtering yields are similar for D and T, and the H yields are lower by about a factor of 2 to 3. Chemical erosion studies of graphite due to H+ and D+ impact also show evidence of some isotopic effect - with the deuterium yield being larger. The isotopic yield ratios (D-yield/H-yield) observed in almost all of the chemical erosion measurements, including ion beams, laboratory plasma devices, and tokamaks, lie between 1 and 2. The recently measured chemical erosion yields due to tritium ions also fall in this range. (The notable exceptions are the mass-loss studies at the Max-Planck Institut für Plasmaphysik in Garching, Germany, where for energies <100 eV, the isotopic yield ratio was seen to increase from 4 to 7 with decreasing energy.) A nominal value of 1.5 ± 0.5 is suggested as the most appropriate value for the D/H yield ratio. This is fully consistent with the square root of mass dependence proposed for the modeling of chemical erosion.