InstroTek
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the license. Unless stated so, the gauge cannot be used to do
things like helping your child do a science projects.
Leak Testing
Portable moisture density gauges use radioactive material that
is double encapsulated in stainless steel identified as special
form. The probability of such a sealed source leaking is very
remote. To verify that the sealed source is not leaking the
gauge must be tested periodically.
A gauge should be checked upon its receipt to see that its leak
test is current and should not be used unless it is current. A new
test must be taken within twelve (12) month period. A leak test
kit has a swab or patch which is moistened, wiped around the
source area, placed in a plastic bag and then mailed to a lab
for analysis. A source is considered leaking if more than 0.005
microcurie of removable contamination is found. A copy of the
leak test certificate should be kept with the gauge and a
second copy in the RSO’s files available for inspection by the
regulatory agency. If the user has several gauges it is more
convenient if they are all tested at the same time, e.g. the first
working day of January and July.
Personal Monitoring
Dosimetry (measurement of the dose to an individual) is
required if the expected dose is 10% or more of the allowed
occupational dose of 5,000 mRem in a year. Most licensing
agencies require personal monitoring for their operators. Proper
use of a moisture/density gauge will result in a dose less than 1%
of the allowed dose, but most regulatory agencies take the
position that it may be exceeded if improperly used and thus
require dosimetry. Dosimetry is also used for long-term legal
protection to the licensee.
