Exposure To Radiation; Time; Distance; Shielding - Thermo Scientific XL2 User Manual

2
Using Your Analyzer
Safely and Effectively Using Your Analyzer

Exposure to Radiation

4 Niton XL2 Analyzer User's Guide

Time

The longer you are exposed to a source of radiation the longer the radiation is able to interact
in your body and the greater the dose you receive. Dose increases in direct proportion to
length of exposure.

Distance

The closer you are to a source of radiation, the more radiation strikes you. Based
on geometry alone, dose increases and decreases with an inverse-squared relation
to your distance from the source of radiation (additional dose rate reduction comes
from air attenuation). For example, the radiation dose one foot from a source is
nine times greater than the dose three feet from the source. Remember to keep your
hands and all body parts away from the front end of the analyzer when the shutter
is open to minimize your exposure.

Shielding

Shielding is any material that is placed between you and the radiation source. The more
material between you and the source, or the denser the material, the less you will be exposed
to that radiation. Supplied or optional test stands are an additional source of shielding for
analysis. A backscatter shield accessory is also available and may be appropriate in some
applications.
Human dose to radiation is typically measured in rem, or in one-thousandths of a rem, called
millirem (mrem), 1 rem = 1000 mrem. Another unit of dose is the Sievert (Sv), 1 Sv = 100
rem. The allowable limit for occupational exposure in the U.S (and many other countries) is
5,000 mrem/year (50 mSv/year) for deep (penetrating) dose and 50,000 mrem/year (500
mSv/year) for shallow (i.e., skin) dose or dose to extremities. Deep, shallow, and extremity
exposure from a properly used Niton XL2 analyzer should be less than 200 mrem per year,
(2.0 mSv per year) even if the analyzer is used as much as 2,000 hours per year, with the
shutter open continuously. The only anticipated exceptions to the 200 mrem maximum
annual dose are: 1) routine and frequent analysis of plastic samples without use of a test stand,
backscatter shield, or similar additional protective measures, or 2) improper use where a part
of the body is in the primary beam path.
Note NEVER OPERATE THE DEVICE WITH A PART OF YOUR BODY IN THE
PRIMARY BEAM PATH OR WITH THE PRIMARY BEAM PATH DIRECTED AT
ANYONE ELSE.
Also, consider the use of protective accessories such as a shielded test stand or backscatter
shield (or equivalent) when performing routine and/or frequent analysis of any of the
following:
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