Electronic Dosimeter

Canberra Mini-Radiac

ED Advantages

• Advantages

– Alarms alert user

– Can be read by user at scene

– Can be set to alarm on dose or dose rate

– Can measure both dose and dose rate

– Gamma and x-ray doses (some available for beta and neutron)

– Able to measure a wide range of doses

ED Disadvantages

• Disadvantages

– Not as accurate as TLDs

– Most have to be programmed

– More expensive than TLDs or DRDs

– Require batteries

– Some are not rugged (but some are)

High Dose Rates

For emergency life rescue operations, without a high rate survey meter, you can use an electronic dosimeter as a substitute if the dosimeter can read high rates (200 R/hr or higher)

Do not hold your dosimeter up to sources because that can make your dose reading higher than what your body actually received

Canberra Mini-Radiac Dosimeter • Max Rate: 500 R/hr • Max Dose: 999 R• Rugged & Water Resistant • Large Display & Large Buttons• Designed to be operated while

wearing gloves and PPE• Two Levels each for Dose & Rate Alarms

– Low: Caution, Near Radioactive Material– High: Danger, Snatch & Grab Rescue

Canberra Mini-Radiac

Rate Button

Dose Button

On/Off Button

Units

Mini-Radiac: AAA Batteries

Low Dose Rate = 1 mR/hr

Near something radioactive

CAUTION

High Dose Rate = 100 R/hr

DANGER Turn Back

Snatch & Grab Rescue

4 Types of Mini-Radiac Alarms

GREEN

RED

Low Dose = 1 R

Approaching EPA 5-Rem

Limit for Emergency Activities

High Dose = 20 R

Approaching EPA 25-Rem

Limit for Life-Saving

4 Types of Mini-Radiac Alarms (continued)

GREEN

RED

Low Dose Rate Alarm

Visible DoseRate Alarm(Green)

Alarm Indicators

High Dose Rate Alarm

Visible DoseRate Alarm(Red)

Low Dose Alarm

Visible Dose Alarm (Green)

High Dose Alarm

DOSE

Visible Dose Alarm (Red)

Signals

Display (LCD)

Vibrate

AudioSignal

Clearing Low Alarms

Display(LCD)

ClearLow Alarm

Doesn’t Stop:

Display

Stops:

X Audio

X Vibrate

PressClear/TestButton

Clearing High Alarms

Display(LCD)

PressClear/TestButton

AudioSignal

ClearHigh Alarm

Doesn’t Stop:

Display

Audio

Stops:

X Vibrate

Light Button

Light Button

Normal Background on Dosimeter

• 5 – 30 µR/hr for Dose Rate

• 5 – 30 µR of Dose for every hour since dosimeter was cleared

• About 0.25 – 0.5 mR (250 – 500 µR) of Dose per day if dosimeter is left on

Training Value CorrelationReal World Values

Actions

Low Dose Alarm

1 R Serious radiological event

•Administrative controls•Rotate teams to stay under 5 R

High Dose Alarm

20 R Limit for life saving activities

•Leave immediately•Another team takes over•OR volunteer/aware risks/ w/permission

Low Dose Rate Alarm

1 mR/hr Three times background

•Proceed with caution•Continue to measure dose rate

High Dose Rate Alarm

100 R/hr Time to get out •Rapid Egress

• If available, every responder at radiological/nuclear incident should be issued a dosimeter

• Wear dosimeter between the neck and waist

Wearing Dosimeters

TLD and Another Dosimeter

Direct Reading Dosimeter

TLD Dosimeter