Perform the following steps depending on the type of direct reading dosimeter used.
Direct reading electronic dosimeter
3.1. Insert fresh battery and switch on. If instructed pre-set the audible alarm to the predetermined operational dose limit.
3.2. Place dosimeter in chest pocket inside your protective clothing.
3.3. Note the audible chirp or beep rate. Be aware if this beep rate increases as this indicates that the ambient dose rate in your vicinity has increased. Take a dose rate measurement to relate significance of change.
immediately and report your status and the circumstances to base.
3.5. Periodically (to a previously agreed schedule) check your dosimeter reading and record details in your personal dosimetry record form (Worksheet A5).
Quartz fibre electrometer (QFE)
3.1. Zero your QFE with the QFE zero adjust charger. If you do not have a zero adjust charger, record the QFE initial reading in your personal dosimetry record form (Worksheet A5).
3.2. Place dosimeter in chest pocket inside your protective clothing.
3.3. Periodically (to a previously agreed schedule) check your dosimeter reading and record details in your personal dosimetry record form (Worksheet A5).
3.4. Report any significant readings (greater than a pre-determined level) immediately to base.
Dose rate meter -with dose integrating capability
3.1. Switch on the dose rate meter prior to entering affected area and leave it on for the duration of time you are in the accident area.
3.2. Routinely record integrated dose readings at predetermined intervals in your personal dose record form (Worksheet A5).
3.3. Report any significant readings (greater than a pre-determined level) immediately to base.
Dose rate meter
3.1. Switch your dose rate meter on prior to entering an affected area.
3.2. Routinely record the ambient dose rates in your vicinity and the time intervals spent in areas of elevated dose rate (Worksheet A5).
3.3. From the dose rate and time spent in the area, routinely estimate your accumulated dose in your personal dose record form (Worksheet A5).
3.4. Report any significant readings (greater than a pre-determined level) immediately to base.
Personal dosimetry — external Procedure A8a, Pg. 3 of 3
Step 4
Follow the directions of your field controller/supervisor.
StepS
On completing your shift, sign off your personal dosimetry record form (Worksheet A5) and return it to the designated officer.
Iodine taken in by inhalation or ingestion is concentrated in the thyroid gland where it is required as an essential part of its function. Radioiodines taken into the body therefore concentrate in the thyroid and can give rise to thyroid cancer. If stable (non-radioactive) iodine is administered to the person prior to exposure or within the first few hours of exposure, it has the effect of blocking the thyroid (prophylaxis), reducing the uptake of radioiodine, which is then rapidly excreted from the body. A full description of iodine prophylaxis is given in [11].
Equipment/Supplies
> Nal(Tl) probe contamination monitor
> Common equipment to all response teams (Checklist AO)
> Personal Monitoring and Decontamination Team equipment (Checklist A2)
Step 1
Do QC instrument check (Procedure AO) on Nal probe contamination monitor.
Step 2
Position the Nal(Tl) probe next to the neck and monitor between the Adams apple and the cricoid process (hard cartilage in the vicinity of the voice box at the front of the neck — see Figure A4). For reasons of fixed and repeatable geometry touch the neck with the probe. Use plastic sheet and trash paper tissue to avoid detector contamination.
Step 3
Record observed count rate of the meter on the Worksheet A6. If the observed count rate during the thyroid survey is greater than the "normal" background count rate, the thyroid should be considered to have possibly taken up radioiodine i.e. if the observed count rate minus the background count rate is positive within statistical significance. The person should
Thyroid monitoring Procedure A8b, Pg. 2 of 2
then be given a stable iodine tablet and transported to an appropriate medical facility for further evaluation. If the thyroid survey is negative the person may be released.
FIGURE A4
SCANNING THYROID FOR RADIOIODINE UPTAKE
Emergency personnel entering an accident area where a spill or airbourne release has occurred need to be checked on leaving the contaminated area for personal skin and protective clothing contamination. Their equipment and vehicles should also be checked (Procedure A5).
Also, persons working or living in the affected area may become contaminated and where this is suspected, they need to be monitored for skin and clothing contamination. This can be done in-situ or at designated contamination control or assembly points or on arrival at evacuation centres where whole body surface contamination monitors are advantageous for rapid and sensitive personal contamination monitoring.
Equipment/Supplies
> Common equipment to all response teams (Checklist AO)
> Personal Monitoring and Decontamination Team equipment (Checklist A2)
Stepl
Perform QC checks on contamination monitor using Procedure AO.
Step 2
Turn contamination monitor audio on and place probe in a light-weight plastic bag or cover to prevent it from being contaminated. Do not cover the probe window.
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Personal contamination monitoring Procedure A8c, Pg. 2 of 4
Step 3
Determine and record the background radiation level periodically at the location where the monitoring is to take place (Worksheet A6).
Step 4
Place the probe about 1 cm from the person's body being careful not to touch him/her.
Starting at the top of the head, move the probe downward on one side of the neck, collar, shoulder, arm, wrist, hand, underarm, armpit, side, leg, cuff, and shoe. Monitor the insides of the legs and the other side of the body in the sequence indicated in Figure A5. Monitor the front and back of the body. Pay particular attention to the feet, seat, elbows, hands and face.
The probe should be moved at a speed of approximately 5 cm per second. Any contamination will be detected primarily using the audio response. If in a noisy environment earphones may be appropriate to listen to the instrument audio response.
FIGURE A5 FRISKING TECHNIQUE