It's also interesting that the security guards are tripping the monitors. I
would hazard a guess that they wear uniforms primarilly made of synthetic
fibers. I can't prove it, but there seemed to be a correlation between
clothing type and false alarms when I was at the Ferry. Whenever the VPs
(suits) came through the plant we would have the same problem. As a group,
our security guards also seemed to have more trouble clearing the monitors -
uniforms again. I think the radon daughters glom onto certain fabrics that
develop a static charge. Cotton seemed to be the least likely to cause a
problem, I think becaue cotton readily absorbs moisture, which keeps it from
developing a static charge.
We saw this because we used "whole body" contamination monitors. It may
not be a factor if you are just doing hand and hoof monitors.
Keith Welch
Thomas Jefferson National Accelerator Facility
Newport News VA
welch@cebaf.gov
Ph: (757)269-7212
FAX:(757)269-5048