1. International Medcom 707-823-0336
How to Use the Radalert 50
March 2005
International Medcom

2. International Medcom 707-823-0336
This presentation is intended to give the user a brief overview of how to operate the Radalert 50. For a complete understanding of this instrument please refer to the operating manual.
March 2005
International Medcom

3. International Medcom 707-823-0336
What the Radalert 50 Does
The Radalert 50 measures the rate of the following types of nuclear radiation
Alpha
Beta
Gamma
X-radiation
The Radalert 50 measures the amount of radiation in
Counts per minute (CPM) or
MilliRoentgens per hour (mR/hr).
The Radalert 50 can audibly alert the user when a pre-determined level of nuclear radiation occurs.
March 2005
International Medcom

4. International Medcom 707-823-0336
How to Turn On Radalert 50
Turn the Radalert 50 on by moving the lower switch from Off to On or Audio.
On--The Radalert 50 is measuring radiation but there is no audio.
Audio--The Radalert 50 is measuring radiation, and beeping with each count of radiation that is detected.
When the Radalert 50 is first turned on it does a 3 second system check, displaying all the indicators and numbers.
After the system check is finished the Radalert 50 shows the current radiation level.
March 2005
International Medcom

5. How to Select the Operating Mode
Move the upper switch to
Total
CPM (counts per minute)
mR/hr (milliRoentgen per hour)
In Total mode the Radalert 50 starts totaling the counts it registers, and updates the numeric display each time it registers a count.
In the CPM and mR/hr modes the numeric display is updated every minute.
The CPM mode is the easiest to understand for the layperson.
March 2005
International Medcom

6. What is Background Count?
The background count is the normal level of nuclear radiation that is occurring at a given time and place.
Some sources of background radiation are:
The sun
Minerals in the earth
Residual radiation from nuclear testing and other man made sources
Nuclear radiation is a naturally occurring phenomenon. When the Radalert 50 is on it is normally measuring the background count.
A user should determine the normal background count to be able to set the appropriate alarm level in the case of abnormal levels of nuclear radiation.
The mesh screen covers the end window of the Geiger-Mueller sensor.
March 2005
International Medcom

7. How to Determine the Average Background Count
Turn the Radalert 50 on, and put it in CPM mode.
Wait one minute until the hourglass icon on the left side of the screen disappears. After this icon disappears the Radalert 50 updates once per minute.
Take 30 consecutive minute readings and record each of the readings.
Add together each of the readings and divide this number by 30.
This number is the average background count.
March 2005
International Medcom

8. Considerations Involved in Finding the Best Level to Set the Alert
The ideal alert setting provides enough sensitivity to detect any increase in the radiation level above naturally occurring background levels without false alarms caused by normal random variations in the background radiation level.
A good setting for one location may cause alerts in another location since background radiation levels can vary due to
altitude
geography
radon gas
radioactive materials in buildings
mineral content in soil and rocks
Each user should balance the need for sensitivity against false alarms occurring from local geography and conditions.
A good alert level can be developed experimentally or through the formula found on the next slide.
Use this number and adjust it as necessary for local conditions.
March 2005
International Medcom

9. One Way to Determine Where to Set the Alert
Use the Radalert 50 in CPM mode to measure counts for 30 consecutive minutes.
Record each reading.
Add the readings and divide the sum by 30.
Find the difference between each reading and the average.
Square each of these differences (multiply it by itself).
Total the squares of the differences and divide the sum by 29.
Find the square root of this sum. This number is the standard deviation.
Multiply the standard deviation by 4 and add this number to the average from step 3 above. Set the alert level to this number.
March 2005
International Medcom

10. International Medcom 707-823-0336
How to Set the Alert
Put the Radalert 50 in CPM mode.
Press the Set button on the end panel.
Use the + or - buttons to set the alert level to the desired setting.
Press the Set button again. There will be a short beep, and a nuclear radiation icon will appear on the left side of the screen. This icon means that the alert is set.
Each time you turn the Radalert 50 on you will have to turn on the alert, but the setting will remain the same.
March 2005
International Medcom

11. How to Change the Battery
Turn the Radalert 50 over.
Remove the battery cover.
Detach the 9 volt battery from the wire connector and replace.
The battery life for the Radalert 50 is approximately 2,000 hours.
March 2005
International Medcom