Thermo Scientific NITON XL3t 500, User Manual

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Radiation and General Safety
Safe Handling of Samples
Thermo Scientific NITON XL3 Analyzer User’s Guide 3-9
Extremity is defined by the NRC as the hand, elbow, arm below the elbow, foot, knee, or leg below
the knee. Whole Body is defined by the NRC as the head, trunk (including male gonads), arms
above the elbow, or legs above the knee.
Safe Handling of
Samples
As mentioned many times in this chapter, never place any part of your body
in the path of the x-ray beam. There is always a safe way to handle samples
whether they are small, irregularly shaped, or of low density. Never look into
the path of the primary beam.
Small Samples
A small sample would be any sample that is smaller than the measurement
window. Small samples present a unique risk because they don’t block the
entire beam path. The difficulty with placing small samples down on a work
surface to analyze them is that you may get readings from the work surface
that interfere with analytical results. A test stand is an effective way of
analyzing small samples accurately and safely. Never hold samples during
analysis or look into the path of the primary beam.
Irregularly Shaped Samples
Irregularly shaped samples may not allow the proximity button to be
depressed, or they may not entirely cover the primary beam and cause
additional scattering. A back scatter shield is a safe way of reducing your
radiation exposure while effectively analyzing an irregularly shaped sample.
Low Density Materials (such as
plastics)
X-rays are attenuated more through denser materials and less through low
density materials such as plastic. This causes higher dose rates in the
scattered radiation. If you are frequently handling low density samples, you
should consider the use of test stands, backscatter shields, or the equivalent.
Table 3-3. Potential Exposure Limit Times
Location of Dose Limit Time to Reach Limit
Deep Dose / Whole
Body 5 rem (50 mSv) 2.1 minutes
Shallow Dose /
Extremities 50 rem (500 mSv) 0.95 minutes
Member of Public
(i.e. untrained
operator) 0.1 to 5 rem (1 to 50 mSv) 2.5 to 9.5 seconds