40. Radiography

Radiographic Testing (RT) – This method of weld testing makes use of X-rays, produced by an X-ray tube, or gamma rays, produced by a radioactive isotope. The basic principle of radiographic inspection of welds is the same as that for medical radiography.

X-Radiation:

The radiography testing techniques shall demonstrate that the required radiography sensitivity has been obtained. Maximum x-ray voltage is 300 KV.

Gamma radiation:

The recommended minimum thickness for which Radio-active isotopes may be used as follow:

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The maximum thickness for the use of radioactive isotopes is primarily dictated by exposure time, therefore; upper limits are not shown. The minimum Recommended thickness limitation may be reduced when the radiography techniques are used to demonstrate that the required radiographic testing sensitivity have been obtained, by purchaser approval.

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Hazard Category

Hazards

Controls

Collapse of Trench Walls

1. Radiation can not be detected by any human sense.

2. Radiation is harmful to living tissue

3. Radiation is differentially absorbed by materials and can be reflected and refracted

1. Calibrated radiation survey meters shall be used at all times.

2. No radiation worker shall be exposed to a dose rate exceeding 20uSr/h

3. All exposures of individuals shall be as low as reasonalbly practical and in any event will not exceed 7.5 USV/HR forunclassified personnel. This limitation shall be achieved by use of shieldings, distance from the exposure point and limitation of exposure duration.

Exposure to Unshielded Source of Radiation

1. Isotopes may become unshielded due to poorly maintained equipment.

2. Persons may enter areas where unshielded isotopes are used.

3. Equipment may be damaged and left in an unsafe condition.

4. Access to high dose rate areas must be restricted.

1. All equipment shall be properly maintained and checked before use.

2. “Controlled” areas shall be clearly defined and evacuated.

3. Emergency tools, shielding, ifotope container shall be abailable.

4. Local rules shall define controlled areas, barriers shall be erected with warning signs and dose-rates checked and recorded.

Radioactive Isotope may be Operated by Authorized Person

1. Equipment may be left in situ ready to use.

2. Unathorized person may find equipment

3. Equipment by be stolen or damaged by malicious person.

1. Equipment shall never be left unattended when ready to use, even in an emergency, It shall be at least locked and the key removed.

2. Equipment shall be locked in store and accounted for when not in use.

3. Mislaid equipment shall be thoroughly checked and recovered – before use

Radioactive Isotope may be Stolen or Lost

1. Equipment may be operated or interfered with by untrained person.

2. Isotope may present hazard if containment shielding deteriorates.

1.All isotopes shall be locked in a store when not in use.

2. Record of daily check of store, daily location in use shall be kept against details of isotope identification, nuclide, container identification.

3. Isotope details and container details and description plus last known location and activity of source shall be available.

4. If suurce is lost, barrier last known location, report to senior person on site and instigate immediately search using instruments where possible.

Radiographers May Work Unsafely

1. Radiographers may not obey or be aware of legislation.

2. Radiographers may not maintain equipment properly.

3. Radiographers may not control radiation areas properly or use correct shielding.

4. Radiographers may not follow procedures or permit to work conditions.

1. Only trained, qualfied, authorized rediographers shall carry out radiography,

2. Local rules and safety procedures shall be obeyed at all times.

3. All necessary safety equipment shall be proved.

4. Radiation protection supervisors shall be appointed to supervise work and ensure compliance with all requirements.

Persons are not aware of work

1. Persons working in the vicinity may not be aware that radiography is taking place.

2. Radiography may interfere with safety systems