Radiological Safety Traning for Uranium Facilities
Module 104 - Internal Dose Control
When performing personnel monitoring it is very important to keep the
detector (i.e., the probe) close to the surface being monitored and to
move the detector slowly. If the detector is not held close to the surface
being monitored, the alpha particles may not reach the detector. If the
detector is moved too quickly across the surface, the electronics in the
instrument will not have time to respond to indicate the amount of
radioactive contamination present.
The general method for personnel scanning for alpha contamination is to
scan at appro ximately 2 inche s/ sec at a dis tance of appr oximately ¼
inch. For personnel scanning for beta contamination, it is recommended
to scan at 2 inches/ sec at a distance of ½ inch. However, the surface
being surveyed (i.e., soil, building surfaces, equipment, personnel), the
scanning speed, and the instrument response time will determine the
level of contamination that can be detected.
Failing to survey properly can have the same results as not surveying at
all. Contamination may go undetected and may be tracked out of the
may be transferred from surface to surface. This transfer of
contamination could result in uranium ending up inside your body, the
body of a co-worker, or even the bodies of your family members and
friends. The potential for spreading undetected contamination should
always be kept in mind when perfor ming self-monitori ng.
Interference from Radon
One of the problems encountered when monitoring for contamination is
interference from radon and its decay products.