When you are performing an electronic inspection
of a room, remember the "Inch Worm Rule" that we
follow when sweeping someone for radiological contamiation..
If goes something like thing, take your probe
(Near Field Probe, Magnetic Probe, RF Probe,
etc), place it on the wall, and move it from lft
to right at a speed that does not exceed one
linear inch of wall space per second, then change
position up of down by 30% the width of the probe (or less) and repeat.
If we take a room that has nothing it in, no
furniture, no pictures, no lamps, just naked
office with nothing it in we can work out some
rough numbers. Ok, let's say the room is 20 foot
by 20 foot, which is an average to small
executive office in these parts, and let's say
the false ceiling is set at 9.5 feet, and the
sheet rock wall extend two feet above the false
ceiling, so that the true wall height is almost 12 feet.
Alright, let us assume that we have a total of 80
linear feet of 12 foot high wall. If we use a 20
inch active probe, we will be able to swaths of
the wall that are around 6 inches wide, so it
will take 24 passes of the probe to cover all four walls with 30% overlap.
Eighty linear feet of wall is 960 inches, and 24
swaths is 23,040 seconds of "sweeping", or 384 minutes, or 6.4 hours.
Since you should check vertically, then
horizontally, and then diagonally this works out
to be a 20x20 room requiring 19.2 hours of
sweeping using basic equipment. You can cut this
down somewhat by using multiple probes spaced 3-6
inches apart, but is it still going to take all day to do a single room.
This assumes that you have already pulled all
their ceiling tiles down, and your partner is checking those out.
When someone has been exposed to a minor amount
of radioactive contamination the national
standard is for the head of the Geiger counter to
be moved over thier (hopefully still alive) body
at a rate that does not exceed one square inch of
skin surface, per second. Modern science tell us
that an average human's skin surface can be
calculated by the formula of 0.1321 + 0.00003433
ยท weight[g], or basically an average human has
2880 square inches of skin, so a radiological
surface scan will take at least 2880 seconds (or
48 minutes), not including the probing rinsing of
orifices, folds, and so forth. Students who are
taught how to properly decontaminate a patient
are taught to perform "gross" wash down to get
as much as possible off the patient (this only
takes a few minutes), and then to meticulously
examine and decontaminate every square inch, and
that it will take at least 90 minutes if
performed by a single person, but with a team of
6 medical people performing the examination it
will take about 20 minutes as you have to roll
and turn the patient (unless the patient is able to stand).
I was in a class recently where the instructor
hid a pin sized dot of radioactive paint on a
wall just below the paper of the sheet rock, and
then had the wall repainted so that you could not
see where the paint had been applied, or where
the seams in the sheet rock were, etc. The
extremely weak radioactive source was visible to
a radiation sensor but you had to line up the
probe just right and you had to use a very slow,
and very careful inspection method to correctly
find the source, AND you had to make sure that
you caught all of the dot he planted in the room,
under the paint and sheet rock compound. Note: A
student failed the course unless they correctly
located all sources in the room the were inspecting (I passed with no problem).
When you spend 4 hours sweeping an entire suite
of offices you're not doing your customer any
favors... slow down, do the job tight, take your
time. If the client is not going to let you take
three days to sweep a single office, then work
with the amount of time you have, and tell them
up front about the rule of inspecting one inch
per second... and tell them that THEY are not letting you do your job right.
Real sweeps take time, never forget it.
-jma
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World Class, Professional, Ethical, and Competent Bug Sweeps, and
Wiretap Detection using Sophisticated Laboratory Grade Test Equipment.
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James M. Atkinson Phone: (978) 546-3803
Granite Island Group Fax: (978) 546-9467
127 Eastern Avenue #291 Web:
http://www.tscm.com/
Gloucester, MA 01931-8008 E-mail: mailto:jm..._at_tscm.com
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We perform bug sweeps like it's a full contact sport, we take no prisoners,
and we give no quarter. Our goal is to simply, and completely stop the spy.
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Received on Sat Mar 02 2024 - 00:57:20 CST