Particle size distribution of dust collected from Alcator C-MOD

There are important safety issues associated with tokamak dust, accumulated primarily from sputtering and disruptions. The dust may contain tritium, i t may be activated, chemically toxic, and chemically reactive. The purpose of this paper is to present results from analyses of particulate collected from the Alcator C-MOD tokamak located at Massachusetts Institute of Techno logy (MIT) in Cambridge, Massachusetts following the run period ending in s pring of 1997. The sample obtained from C-MOD was not originally intended f or examination outside of MIT. The sample was collected with the intent of performing only a composition analysis. However, MIT provided the INEEL wit h this sample for particle analysis. The sample was collected by vacuuming a section of the machine (covering approximately 1/3 of the machine surface ) with a coarse fiber filter as the collection surface. The sample was then analyzed using an optical microscope, SEM microscope, Microtrac FRA partic le size analyzer. The data fit a log-normal distribution. The count median diameter (CMD) of the samples ranged from 0.3 mu m to 1.1 mu m with geometr ic standard deviations (GSD) ranging from 2.8 to 5.2 and a mass median diam eter (MMD) ranging from 7.22 to 176 mu m.