RADIATION CONTAMINATION SURVEYING
RADIATION EXPOSURE SURVEYING
To locate radioactive material in unwanted locations.
To locate and measure sources of radiation.
CPM (counts per minute)
Micro R/hr (µR/hr), Milli R/hr (mR/hr), R/hr
Pancake probe (Model 44-9)
Tubular probe (Model 44-2)
Locating contamination on personnel & equipment.
Determining effectiveness of decontamination.
Verifying contamination control boundaries.
Determining extent and magnitude of a contaminated area
Establishing control zone boundaries
Controlling personnel exposure
Assessing package integrity
Locating sources of radiation
1. Determine background radiation levels by observing the
meter readings in the Cold Zone.
2. Verify instrument is ON, the audio can be heard, and there is
a visual response.
3. Probe/detector should be held within 1 inch of the surface
being surveyed.
4. Move probe slowly, approximately 1-2 inches per second.
5. If count rate increases while surveying, pause for 5-10
seconds over the area to provide adequate time for
instrument response.
1. Determine background radiation levels by observing the
meter readings in the Cold Zone
2. Verify instrument is ON, the audio can be heard, and there is
a visual response.
3. Survey with detector extended in front of you with probe’s
beta shield OPEN.
4. Periodically monitor in 360 degree circle.
5. Hold detector at waist level. Periodically check above and
below this level.
6. When source located, survey as necessary to determine its
approximate location.
ALPHA RADIATION
Use: Pancake probe
All shielding material must be removed
from the suspected source.
Ensure instrument F/S switch is in [F]
position.
When surveying, place window of detector
within 3/4 inch of surface to be surveyed.
Move detector slowly over area being
measured (typically one to two inches per
second). Response time varies from 2-50
seconds.
Keep in mind that moisture or dirt may
block alpha particles, making them
impossible to be measured.
BETA RADIATION
Use: Pancake probe
Move slowly over area being measured.
Response time varies from 2-50 seconds.
Shielding may be utilized to determine type
of source (alpha/beta).
Take a measurement with no shielding in
place, then another with a piece of paper or
other thin material placed over the
suspected source. Compare the first
reading with the second to determine the
amount of alpha and beta contribution.
(This will be a very rough number.)
GAMMA RADIATION & X-ray
Use: Tubular probe.
Detector 50x more sensitive than pancake
probe.
This detector is able to detect low-level
gamma and X-rays in the range of 60 keV-
1.25 MeV.
Detector may be used for measurements up
to 50 mR/hr.
Hold detector in hand, move slowly from
side to side.
Very end of detector, opposite cable
connection, is most sensitive. Point in
direction of source being measured.
DECONTAMINATION/MAINTENANCE
Instrument may be externally cleaned with a damp cloth, using only
water as the wetting agent.
Do not immerse the instrument in any liquid.
Observe the following precautions when cleaning:
o Turn instrument OFF and remove the batteries.
o Allow the instrument to sit for one minute before
performing any external cleaning or accessing internal
components for maintenance.
An operational check should be performed prior to each use and
monthly by exposing the detector to the supplied check source,
confirming the proper reading on each scale. See “Ratemeter
Operational Check”.
Recalibration should be accomplished after any maintenance or
adjustment of any kind has been performed on the instrument.
Remove batteries from compartment during storage.
Ludlum 2241
Survey Meter
Manual
DELRAY BEACH FIRE-RESCUE DEPARTMENT
QUICK USER GUIDE
LUDLUM (2241) SURVEY METER
Fast/Slow
Response Switch
Off/Ratemeter/
Scaler Switch
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