International Medcom Radalert 100X User manual

Operating Manual
Nuclear Radiation Monitor
X

© 1996, 2005, 2013 International Medcom, Inc.
All rights reserved.

Contents
1 Introduction ..........................................................................1
How the Radalert 100XDetects Radiation..............................1
Precautions............................................................................2
2 Features ................................................................................3
The Display............................................................................4
The Switches .........................................................................5
The Detector .........................................................................6
The Input/Output Ports ..........................................................6
3 Operation..............................................................................7
Units of Measurement ...........................................................7
Starting the Radalert 100X.....................................................7
Operating in the Dose and Count Rate Modes.......................7
Operating in Total/Timer Mode ..............................................8
Operating Ranges and Response Times................................10
Using the Alert ....................................................................11
The Utility Menu..................................................................12
Interfacing to an External Device..........................................13
4 Common Procedures ...........................................................14
Establishing the Background Count .....................................14
Environmental Area Monitoring ...........................................15
Checking an Object .............................................................15
5 Maintenance .......................................................................16
Calibration ..........................................................................16
Troubleshooting and Service ................................................19
6 Basics of Radiation and Its Measurement .............................21
Ionizing Radiation................................................................21
Measuring Radiation............................................................23
Radiation Measurement Units..............................................24
Higher Than Normal Readings .............................................24
Appendix: Technical Specifications ...........................................26
Limited Warranty .....................................................................28

Radalert 100X1
1 Introduction
The Radalert 100Xis a health and safety instrument that measures
alpha, beta, gamma, and X-ray radiation. Its applications include:
• Monitoring possible radiation exposure while working with
radionuclides
• Ensuring compliance with regulatory standards
• Checking for leakage from X-ray machines and other sources
• Alerting you with an audible alarm if the radiation goes above an alert
level that you set
• Screening for environmental contamination or environmental sources
of radioactivity
• Connecting to a computer or data logger to record and tabulate your
data
How the Radalert 100XDetects Radiation
The Radalert 100Xuses a Geiger-Mueller tube to detect radiation.
The Geiger tube generates a pulse of electrical current each time
radiation passes through the tube and causes ionization. Each pulse
is electron- ically detected and registers as a count. The Radalert
100Xdisplays the counts in the mode you choose: microsieverts
per hour (µSv/hr), either counts per minute (CPM) or counts per
second (CPS), or total counts. In conventional units, milliroentgens
per hour (mR/hr) and CPM are used.
The number of counts detected by the Radalert 100Xvaries from
read- ing to reading due to the random nature of radioactivity. A
reading is expressed more accurately as an average over time, and
the average is more accurate over a longer time period. For more
information, see “Operating in Total/Timer Mode” in Chapter 3.

2Radalert 100X
Precautions
To keep the Radalert 100X ingood condition, handle itwith care
and observe the following precautions:
• Do not contaminate the Radalert 100X by touching it to radioactive
surfaces or materials.
• Do not leave the Radalert 100X in temperatures over 122° F (50° C) or
in direct sunlight for extended periods of time.
• Do not get the Radalert 100X wet. Water can damage the circuitry and
the coating of the mica surface of the Geiger tube.
• Do not put the Radalert 100X in a microwave oven. It cannot measure
microwaves, and you may damage it or the oven.
• If you expect to not use the Radalert 100X for longer than one month,
remove the battery to avoid damage from battery corrosion.
• Change the battery promptly when the battery indicator appears on
the display.

Radalert 100X 3
2 Features
The Radalert 100X measures alpha, beta, gamma, and X-ray radiation.
This chapter briefly describes the Radalert 100X’s functions. For more
information on how to use the Radalert 100X, see Chapter 3,
“Operation.”
The Radalert 100X counts ionizing events and displays the results on
the liquid crystal display (LCD) (4). You control which unit of
measurement is shown by using the mode switch.
Whenever the Radalert 100X is operating, the red count light (1)
flashes each time a count (an ionizing event) is detected.
1Count
Light
2Calibration
Input Port
3Output Port
4LCD
5Mode
Switch
6On/Off/
Audio
Switch
End Panel
7+, –, and
Set Buttons
8Alpha
Window
ETotal Mode
DTimer
CAlert Mode
Indicator
BLow Battery
Indicator
ANumeric
Display
ITimer, Alert,
or Calibration
Set Mode
JUnits of
Measurement
KMenu
LRange Full
FX1000
Mode
HCalibration
Mode
GAverage

4Radalert 100X
The Display
Several indicators on the LCD show information about the mode setting,
the current function, and the battery condition.
• e numeric display (A) shows the current radiation level in the unit
specied by the mode switch setting.
• A small battery (B) appears to the le of the numeric display to indicate
low battery voltage.
• A radiation symbol (C) appears when the Alert feature is on.
• An hourglass (D) appears during a timed count.
•TOTAL (E) appears when the Radalert 100X is in Total/Timer mode.
•X1000 (F) appears when the radiation level is displayed in X1000
mode.
• AVG (G) appears when the Radalert 100X is showing the average reading
for a timed count.
•CAL (H) appears while you are calibrating the Radalert 100X.
•SET (I) appears when you are setting the Timer, the Alert level, or the
calibration factor, or working in the Utility Menu (the numeric display
shows the setting being adjusted instead of the current radiation level).
• e current unit of measurement (J)—CPM, CPS, mR/hr, or µSv/hr—is
displayed to the right of the numeric display.
•MENU (K) appears when you are in the Utility Menu.
•RANGE:Full (L) appears when the radiation level goes beyond the
range that can be displayed.
1Count
Light
2Calibration
Input Port
3Output Port
4LCD
5Mode
Switch
6On/Off/
Audio
Switch
End Panel
7+, –, and
Set Buttons
8Alpha
Window
ETotal Mode
DTimer
CAlert Mode
Indicator
BLow Battery
Indicator
ANumeric
Display
ITimer, Alert,
or Calibration
Set Mode
JUnits of
Measurement
KMenu
LRange Full
FX1000
Mode
HCalibration
Mode
GAverage

Radalert 100X 5
The Switches
The Radalert 100X has two switches on the front and three buttons on
the end panel. Each switch has three settings, which are described
below.
Mode Switch (5)
Dose Rate. e numeric display shows the current radiation level
in the selected unit of measurement. In SI units it shows the current
radiation level in microsieverts per hour, from .000 to 1100. In con-
ventional units, it shows milliroentgens per hour from .000 to 110.
Count Rate. e display shows the current radiation level in counts
per minute from 0 to 350,000 or in counts per second from 0 to
3500. When X1000 is shown, multiply the numeric reading by 1,000
to get the complete reading.
Total/Timer. e display shows the accumulated total of counts
starting when the switch is turned to this position, from 0 to
9,999,000. When X1000 is shown, multiply the numeric reading
by 1,000 to get the complete reading.
On/Off/Audio Switch (6)
Audio. The Radalert 100X is on, and it makes a clicking sound
for each radiation event detected.
On. The Radalert 100X is operating, but audio is off.
Off. The Radalert 100X is not operating.
+, –, and SET Buttons (7)
ese buttons are used for setting the alert level and the timer. ey
are also used for calibration and for using the Utility Menu. For
more information, see “Taking a Timed Count,” “Using the Alert,”
and “e Utility Menu” in Chapter 3 and “Calibration” in Chapter 5.

6Radalert 100X
The Detector
The Radalert 100X uses a Geiger tube to detect radiation. Alpha
radiation does not penetrate most solid materials, so this Geiger tube has
a thin disk of mica, which alpha radiation can penetrate, on its end.
The screened opening at the top of the Radalert 100X is called the
alpha window (8). It allows alpha and low-energy beta and gamma
radiation to penetrate the mica end of the tube.
CAUTION:The mica end surface of the Geiger tube is fragile. Be
careful not to let anything penetrate the screen.
The Input/Output Ports
There are two ports on the left side of the Radalert 100X.
e calibration input port (2) is used for calibrating electronically using
a pulse generator. For more information, see “Calibrating Electronically”
in Chapter 5.
The output port (3) below the calibration input port allows you
to interface the Radalert 100X to a computer, data logger,
earphones, or other device using a 3.5 mm stereo plug. For more
information, see “Interfacing to an External Device” in Chapter 3.

Radalert 100X 7
3 Operation
The guidelines in this chapter describe how to use the Radalert 100X.
Units of Measurement
The Radalert 100X is designed both for users of SI units
(microsieverts per hour and counts per second or counts per minute)
and for users of conventional units (milliroentgens per hour and
counts per minute). The default is microsieverts per hour and counts
per minute. To switch between units of measurement, use the Utility
Menu. See “The Utility Menu” in this chapter.
Be sure that a standard 9-volt alkaline battery is installed in the
battery compartment in the lower rear of the Radalert 100X.
Note: When installing the battery, place the battery wires along the side
of the battery and not under it.
To start the Radalert 100X, set the top switch to the mode you want,
and set the bottom switch to On or Audio. The Radalert 100X then
does a brief system check, displaying all the indicators and numbers.
After the system check, the radiation level is displayed in the
selected mode. Ninety seconds after you start the Radalert 100X, a
short beep indicates that enough information has been collected to
ensure statis- tical validity.
When using the Radalert 100X,always be sure there is no obstruction
be- tween the detector window and the source you are surveying or
monitoring.
Operating in the Dose and Count Rate Modes
When the mode switch is set to Dose Rate or Count Rate, the numeric
display is updated every three seconds. At low count rates, signicant
changes in the radiation level displayed can take up to 90 seconds to
stabilize. See “Operating Ranges and Response Times” in this chapter
for more information.
Count Rate (CPM or CPS) and timed total counts are the most direct
methods of measurement; Dose Rate (µSv/hr or mR/hr) measurements
Starting the Radalert 100X

8Radalert 100X
are calculated using a conversion factor optimized for Cesium-137, so this
mode is less accurate for other radionuclides unless you have calibrated
the instrument for a specic radionuclide using an appropriate source.
It is more appropriate to measure alpha and beta activity using Count
Rate than using Dose Rate. Conversion for alpha and beta emitters
is calculated differently, and the Radalert 100X’sDose Rate reading
may not be accurate.
e most immediate indicators of the radiation level are the count light,
the audio beep, and the alert. It takes three seconds before an increase
is shown on the numeric display in Dose Rate mode.
Operating in Total/Timer Mode
When the mode switch is set to Total/Timer, the Radalert 100X
starts totaling the counts it registers, and the numeric display is
updated every second.
Taking a Timed Count
A timed total count is useful for determining the average counts per
minute over a period of time. The number of counts detected by the
Radalert 100X varies from minute to minute due to the random nature
of radioactivity. When a count is taken over a longer period, the average
count per minute is more accurate, and any small increase is more
significant.
Taking an average allows you to detect low-level contamination or dif-
ferences in background radiation due to altitude or soil mineral content,
and can be useful for educational purposes. For example, if one 10-minute
average is one count higher than another 10-minute average, the increase
may be due to normal variation. But over 12 hours, a one count increase
over the 12-hour background average is statistically signicant.
The Radalert 100X can give you a total count for a timed period of
from one minute to 40 hours. Follow these steps:
1.
With the Radalert 100X operating, set the Mode switch to Total/
Timer. The display shows TOTAL.
2. Press the Set button twice in quick succession. e display shows SET,
the hourglass, and the most recent timing period used. e rst time
you use the timer, the setting is 24:00, which means 24 hours.

Radalert 100X 9
3. Use the + and – buttons to set the timing period. e timed period can be
for 1 to 10 minutes in one-minute increments, for 10 minutes to 2 hours
in ten-minute increments, or for 2 to 40 hours in one-hour increments.
4.
Press the Set button again to start the timed count. The Radalert
100X beeps three times and starts counting. The hourglass indicator
flashes during the timed period.
During the counting period, if you want to see how much time re-
mains, press and hold down the Set button. e display counts down
in hours and minutes to zero. For example, if the display says 00:21,
21 minutes remain.
5. At the end of the timed period, the Radalert 100X beeps three
times and repeats the beeping several times. The number
displayed is the total count.
6. To display the average count and dose rates for the timed period, press
and hold the Set button. e display alternates between the average
count rate and the average dose rate every 3 seconds, and shows AVG
above the numeric display.
7. Press the Set button twice to return to normal operation.
Aer you start a timed count, the timer mode is active in the background
even when the Mode switch is set to Dose Rate or Count Rate. For
example, during and aer the timed period, you can switch back and
forth between Total/Timer and Dose Rate; when the timed period is
over, the total is displayed whenever you switch back to Total/Timer.
e hourglass indicator is shown on the display in any mode setting; it
is blinking while the timer is totaling counts.
Taking a Total Count
e timer can take timed counts of up to 40 hours. In certain situations,
you may want to take a total count without the timer; for example, taking
a count for longer than 40 hours. Follow these steps:
1. Place the Radalert 100X in the location where you plan to take the count.
2. Note the time.
3. Immediately when you note the time, set the mode switch to Total/
Timer.

10 Radalert 100X
4. At the end of the time period, note the time and the total on the
numeric display.
5. Subtract the starting time from the ending time to determine the
exact number of minutes in the timing period.
6. To get the average count, divide the total reading by the number of
minutes in the timing period.
Operating Ranges and Response Times
In some modes, when radiation levels increase over certain preset levels,
the Radalert 100X uses autoranging, automatically changing to the X1000
scale. Whenever X1000 is shown above the numeric display, multiply the
displayed reading by 1000 to determine the radiation level. The following
table shows the radiation levels the Radalert 100X measures in each mode
and how they are displayed.
Mode Regular Range x1000 Range
μSv/hr .000–1100 N/A
mR/hr .000–110 N/A
CPM 0–9999 10,000–350,000
(displayed as 10.00–350 with x1000 indicator)
CPS 0–3500 N/A
Total/Timer 0–9999 10,000–9,999,000
(displayed as 10.00–9999 with x1000 indicator)
Maximum Level
When the maximum level for the current mode is reached, the Radalert
100X beeps for three seconds, pauses for three seconds, and repeats that
pattern. The display shows RANGE:Full. The beeping pattern and the
Range Full icon continue until the level decreases or the Radalert 100X is
turned off.
Display Update and Response Time
In Total/Timer mode, the numeric display is updated each second. In the dose
and count rate modes, the numeric display is updated every three seconds.
When the radiation level is less than 1,000 CPM, the reading in the dose
and count rate modes is based on the radiation detected in the immediately
previous 90 seconds. In order to give a quicker response to changes, when

Radalert 100X 11
the radiation level exceeds 1,000 CPM in any 90-second period, the reading
is based on the previous 6 seconds, and when it exceeds 6,000 CPM, the
reading is based on the previous 3 seconds, as shown in the following table.
is automatic change in response time is called auto averaging.
Radiation Level Basis for Reading
(after first 90 seconds)
<1000 CPM or <8.3 μSv/hr or <.83 mR/hr
(<17 CPS) 90 seconds
1000–6000 CPM or 8.3–50 μSv/hr or .83–5 mR/hr
(17–100 CPS) 6 seconds
>6000 CPM or >50 μSv/hr or >5 mR/hr
(>100 CPS) 3 seconds
Note: You can set the response time to 3 seconds at all radiation levels
using the Utility Menu; see “e Utility Menu” in this chapter.
Using the Alert
The Radalert 100X can sound an audible alert whenever the radiation
reading reaches a certain level. The +, –, and Set buttons on the end of the
Radalert 100X allow you to turn Alert mode on and off and to set the
alert
levels. You can set the alert level when the Mode switch is set to Dose
Rate or Count Rate. Follow these steps:
1. Press the Set button on the end panel twice in quick succession. e
display shows the current alert level in µSv/hr, mR/hr, CPM, or CPS,
depending on the current setting. e radiation symbol and SET icon
are also displayed.
2. To change the displayed alert level, use the + and – buttons to adjust
the level up or down.
3. When the desired alert level is displayed, press the Set button once
to save the new level and to continue in Alert mode. The radiation
symbol is displayed to show that the Radalert 100X is in Alert mode.
4. To reset the alert level while you are in Alert mode, press the Set
button four times (twice for O, and twice more for Set), then repeat
steps 2 and 3.
5. To turn o Alert mode, press the Set button twice.

12 Radalert 100X
When Alert mode is started, the Radalert 100X restarts counting,
and beeps after 90 seconds to show that the reading is statistically valid.
When you first start the Radalert 100X, the alert levels are preset at 1 µSv/ hr
and the equivalent values in the other units: .1 mR/hr, 120 CPM, and 2
CPS. If you set the alert level in one mode, the settings for the other
modes are automatically updated to the equivalent values (the conver-
sion may not be exact due to rounding). When you change the units of
measurement, the alert level is reset to the defaults.
e best alert level is one that rarely gives a false alarm, yet warns you
when the radiation is higher than normal.
The Utility Menu
The Utility Menu allows you to change the default settings for several
operating parameters. When a setting is changed, it remains in effect
after the Radalert 100X is turned off and until you change it again.
• To activate the Utility Menu, hold down the +button on the end panel
while you turn on the Radalert 100X. The word MENU appears at the
bottom right of the numeric display, and the display shows 1for menu
option 1.
• To scroll through the menu, push the plus (+) and minus (–) buttons.
• To select an option, push the Set button.
• Once an option is selected, use the + and – buttons to scroll among
the settings.
• Aer you choose the setting you want, select option 0 to exit the Utility
Menu.
e options are:
0Resume normal operation.
1Auto Averaging. on (the default) selects Auto averaging; oFF selects
3-second (fast response) averaging at all radiation levels.
2Units of measurement. CPM µSv/hr (the default) selects counts per
minute and microsieverts per hour; CPM mR/hr selects counts
per minute and milliroentgens per hour; CPS µSv/hr selects counts per
second and microsieverts per hour.

Radalert 100X 13
3Cal 100 Reset. Automatically resets the calibration factor to 100.
4, 5, 6 Reserved for future options.
7Cal Factor Adjust. Displays the current calibration factor, which
you can then adjust to the new factor you want. See “Calibration” in
Chapter 5.
8Factory Default Reset. Automatically resets items 1, 2, and 3 to Auto
averaging, CPM and µSv/hr, and 100, and resets the Alert level to
1.000 µSv/hr.
9Revision #. Displays the soware version number.
Interfacing to an External Device
The lower output jack on the left side of the Radalert 100X is a dual min-
iature jack that provides a data output that can be used to drive external
devices. You can use it to record the counts on a computer, data logger, or
accumulating counter. Use a 3.5 mm stereo plug to access this port.
e outputs provide a positive pulse (9 volt peak, 1 kOhm impedance)
each time the Geiger tube detects a count. At the ring of the plug, the
pulse is approximately 1 millisecond wide and is well suited for chart re-
corders and audio input. e tip signal is approximately 80 microseconds
wide and is suitable for high-speed counting and RS-232 interfacing.
Computer cables for USB or serial ports and accompanying soware for
Windows are available from International Medcom, Inc.
For 4.5V logic compatible output, externally connect a 1 kOhm resistor
from the output to ground. A standard stereo or mono headphone can
be plugged directly into the jack. For some types of headphones, external
volume control may be needed.

14 Radalert 100X
4 Common Procedures
e following sections give guidelines for several commonly-used pro -
cedures. With any procedure, the user must determine the suitability
of the instrument or procedure for that application.
Establishing the Background Count
Normal background radiation levels vary at different locations, according
to altitude and other factors, such as types of minerals in the ground.
Levels vary at different distances from the ground, and may differ even in
different areas of the same room. To accurately interpret the readings you
get on the Radalert 100X, it is a good idea to establish the normal back-
ground radiation level for each area you plan to monitor. You can do this
with a timed count. Use the following steps to get a ten-minute average.
1.
With the Radalert 100X operating, set the Mode switch to Total/Timer.
2. Press the Set button twice in quick succession.
3. e display shows the current timer period and SET. Unless you have
previously changed it, the display reads 24:00, which means 24 hours.
Use the + and – buttons to change the timer period to ten minutes.
4. Press the Set button on the end panel. The Radalert 100X beeps
three times and starts counting.
During the timed count, if you want to see how much of the ten
minutes remains, hold down the Set button. e display counts down
from ten minutes to zero. For example, if the display says 00:03, seven
minutes have elapsed and three minutes remain.
5. At the end of the ten minutes, the Radalert 100X beeps three times,
and repeats the beeping several times. Note the total reading.
6. To nd the average count and dose rates, hold down the Set button.
A ten-minute average is moderately accurate. You can repeat it several
times to nd how close the averages are. To establish a more accurate
average, take a one-hour timed count. In some locations, you may want
to take a longer count (for example, 12 hours). If you need to determine
whether there is prior contamination, take averages in several locations
and compare the averages.

Radalert 100X 15
For more information on using the timer, see “Taking a Timed Count”
in Chapter 3.
Environmental Area Monitoring
You can keep the Radalert 100X in Dose Rate or Count Rate mode when-
ever you want to monitor the ambient radiation, and look at it from time to
time to check for elevated readings. You can also use Alert mode to warn
you if the radiation increases above the alert level.
If you suspect an increase in ambient radiation, use the timer to take a
ten-minute count, and compare the average to your average background
count. If you suspect an increase that is too small to detect with a short
timed reading, you can take a longer count (for example 6, 12, or 24 hours).
Checking an Object
To check an object, place the Radalert 100X
next to it with the end window facing and
near the object; otherwise you may miss alpha
and low- level beta radiation. To determine if
an object is slightly radioactive, place the
Radalert 100X next to it and take a timed
count over an ap- propriate period of time.
When not using the end window, hold the
Radalert 100X so that the side wall of the tube
is as close as possible to the object. The best
position is with the top right corner of the
back of the Radalert 100X closest to the object
To measure as much as possible of the radioactivity of an object, place
the
Radalert 100X as close as you can without touching the object. The
radiation level for gamma radiation from a localized source decreases
according to the inverse square law. If you move to twice the distance
from the object, the radiation drops by a factor of four.
Alpha
Window
Position of Geiger Tube
Geiger
Tube
CAUTION: Never touch the Radalert 100X to an object that may be
contaminated. You may contaminate the instrument. A contaminated
instrument will not be accepted for repair or servicing.

16 Radalert 100X
5 Maintenance
The Radalert 100X should be handled with care and can be calibrated as
necessary to comply with regulations. Use the following guidelines to
maintain the Radalert 100X properly.
Calibration
The Radalert 100X’s readings typically remain stable for many years of
use. Specific industries, such as diagnostic laboratories, radiography, and
public safety, operate under standards or regulations that require routine
calibrations. In most regulated environments, an annual calibration meets
these standards. Some standards require more frequent calibrations, and
some also require the occasional use of a check source to make sure the
instrument is working properly. For a list of recommended laboratories for
instrument calibration, see the International Medcom, Inc. website at
medcom.com. Check sources are available from various licensed
sources. Any radioactive source should be handled with caution and
shielded properly during storage.
e standard radionuclide for calibration is Cesium-137. To calibrate to
another radionuclide, use a calibrated source for that radionuclide or deter-
mine the appropriate conversion factor referenced to Cs-137. A certied test
range should be used. Depending on the facility, calibrations are typically
done at about two-thirds of the maximum reading, or 660 μSv/hr (66 mR/
hr). Some labs can do a three-point calibration check at, for example, 250,
500, and 660 μSv/hr (25, 50, and 66 mR/hr). Calibration should not be
done at levels below 10 μSv/hr (1mR/hr) or above 900 μSv/hr (90 mR/hr).
If no source is available, and the Geiger tube is functioning normally,
an electronic calibration can be performed using a calibrated pulse
generator. is conrms that the instrument is counting accurately, but
does not conrm the Geiger tube sensitivity.
Calibrating Using a Source
Most certified calibration laboratories utilize robotics to minimize or
eliminate radiation exposure to the calibration personnel. The Radalert
100X’s calibration procedure is designed to further minimize exposure.