This method of statement describes the specific performance requirement for safe conduct of industrial gamma ray radiography at a project site.
The method shall be implemented as per the local regulations concerning Radiation Protection in using sealed Radioactive isotopes in Industrial Radiography.
This page gives just general information for basic understanding and should not be considered as specific guide.
Radiation Protection Officer (RPO) shall be responsible for the implementation of this procedure on a project site.
RPO shall be approved and Licensed by MOE (Ministry of Environment).
RPO is responsible for the mentoring of Radiography works, check the equipment, Safe Barrier distances etc.
He shall make sure that all the permits from higher authorities are in place prior to start the job.
RPO shall hold copies of the following documents
a. Safety Manual
b. Emergency procedure
c. Isotope Decay Chart
d. Local Routes
e. Survey Meter Calibration Certificates
Industrial Radiographer shall perform the on site works, he shall hold the qualification of ASNT Level II in Radiography and License from local agencies / MOE.
The safe distance is the distance where the radiation level not exceeds 7.5 iSv (0.75m R/hr).
Safe distance for 15.00
Ci = 96.41 Meters (Without Collimator)
Ci = 24.85 Meters (With Collimator)
The Radio active source shall be Iridium 192 (Ir-192) and active dimension 2.0mm x 2.0mm.
Following equipment is mandatory to carry with Radioactive Material
1. Emergency Tong
2. Lead Shot Bags
3. Lead Apron
4. Emergency source container
5. Lead Gloves
6. Bolt Cutter
7. Warning Signs
8. Flash Lights
9. Barrier Tapes
10. Lead shield
11. Radiation Survey Meter
Personnel Monitoring TLD and Dosimeter
Approved TLD shall be worn by all classified workers engaged on work involving the use of ionizing radiation TLD shall be issued on a monthly basis.
At the end of the monthly period TLD shall be returned to the supervisor together with the personnel dosimeter records.
The TLD results shall be entered on personnel dose record and kept in the personnel file.
Personnel dosimeter shall be worn at all times during working hours by all workers engaged on work involving the use of ionizing radiation.
Personal dosimeter shall have a measuring range of 0 to 200mR.
Personal dosimeter shall be zeroed and recharged at the beginning of each working day.
A personal dosimeter rate record shall be maintained.
Bleeper (or) Radiation Alarm:
Radiation workers wears the good working condition bleeper or radiation alarm at all times during the working hours.
The equipment shall be transported to and from site locations in the appropriately marked transportation container along with the necessary Emergency Equipment.
Source mobilization shall be informed to MOE in writing prior to the mobilization.
Radiation warning placard, black and yellow color shall be displayed on each side and rear of the vehicle.
The number 7 on the placard is the UN Class number for radioactive material.
Placard size should not be less than 100 mm X 100 mm.
The driver shall observe all the regulation that effects the carriage of isotopes by road.
Safety Warning Signs in Work Site
All accessories required for the safe use of the radiographic source shall be taken along with the projector.
Warning signs, barriers and the flashing lights shall be placed around the restricted area of the exposure.
During the exposure barriers shall be monitored, particularly for any change in location or orientation of the source.
Cordon-off the radiation area using a survey meter and move the barrier and warning signs to the new restricted area where the radiation level less than 7.5pSv/hr.
Operation of the Radiography
Radiation source shall only be operated by the classified workers.
The radiography personnel shall always position himself as far away from the source as possible during exposure.
All the exposure shall be planned in advance and executed in the minimum possible time.
During operations the radiation survey meter duly calibrated shall be used for monitoring the radiation level.
Collimators shall be used with an isotope since a shielded source is less hazardous, also the primary beam of the collimated exposure shall be directed away from areas of occupancy.
After completion of the radiography work, the projector and the source shall be securely locked away to avoid accidental exposure due to opening of the shutter and also to avoid the source dropping out of the projector.
Radiation workers ensure the Non-classified personnel shall be away from the controlled area before starting the radiography works.
Non-classified personnel in the supervised area shall be informed of the radiation activity
Emergency Response in Case of Radiation Incident
When the source becomes stick outside the projector, the following procedure shall be followed.
Stop all operations and inform the Radiation Protection Officer (RPO) regarding the accident.
Cordon – off the radiation area using a survey meter and move the barrier and warning signs to the new restricted area where the radiation level less than 7.5micro Sv/hr.
Try to retract the source or provide radiation shielding such as lead or steel sheets around the source where possible.
The Radiation Protection Officer (RPO) will assess the nature of the incident and plan for further action taking in to consideration the source strength, shielding, dose rates, location and the other related factors.
Written accident reports shall be prepared that includes:
– a description of the accidents
– methods used to render the source of the radiation safe
– assessment of exposures (to all involved)
– the case of the accident
– corrective actions
All the personnel exposed in excess of their dose limits shall be sent for medical examination.
TLD of the affected personnel shall be sent for dose record.
RPO shall investigate and submit the report to the management.
Any incident involving ionizing radiation where a dose rate in excess of that permitted is suspected shall be reported immediately.
Any source accident involved at site shall be informed to RPO and relevant authorities / MOE ( Ministry of Environment).