1.1 What is Radiographic Testing (RT)
Radiographic Testing is a non-destructive testing method that uses X-rays or gamma rays to detect internal defects in materials without cutting or damaging them. It produces an image of the internal structure on film or digital detectors.
1.2 Purpose of Radiography
The main purpose is to find hidden defects such as cracks, voids, porosity, lack of fusion, and corrosion inside welds, pipes, vessels, and structures. It ensures equipment integrity and prevents failures.
1.3 Applications in Industry
Used for inspection of pipelines, pressure vessels, storage tanks, heat exchangers, reactors, columns, and critical weld joints during fabrication, installation, shutdown, and maintenance.
1.4 Types of Radiography (Gamma, X-ray)
Gamma Radiography: Uses radioactive sources like Ir-192 or Co-60. Portable and suitable for field work.
X-ray Radiography: Uses X-ray machines. Better image control, mainly used in workshops and controlled areas.
1.5 Why Radiography is High Risk
Radiography uses ionizing radiation which can damage human cells. Exposure can cause burns, radiation sickness, cancer, and genetic damage. It is invisible, odorless, and painless, making uncontrolled exposure very dangerous. Hence strict controls, permits, and monitoring are required.
2. Basics of Radiation
2.1 What is Radiation
Radiation is energy that travels in the form of waves or particles. In radiography, it is used to pass through materials and create images of internal defects.
2.2 Types of Ionizing Radiation
Ionizing radiation has enough energy to remove electrons from atoms, which can damage human cells. This type of radiation is used in industrial radiography.
2.3 Alpha, Beta, Gamma, X-rays
Alpha: Heavy particles, very low penetration, stopped by paper or skin. Not used in RT.
Beta: Medium penetration, stopped by plastic or thin metal. Rare in RT.
Gamma: High penetration, emitted from radioactive sources like Ir-192 and Co-60. Common in field radiography.
X-rays: High penetration, produced by X-ray machines. Common in controlled environments.
2.4 Radiation Properties
Radiation is invisible, cannot be felt, has no smell, and can pass through solid objects. It spreads in all directions and weakens with distance.
2.5 Penetration Power
Penetration depends on radiation type and energy level. Gamma rays and X-rays have high penetration, allowing them to pass through thick metals, making them suitable for pipe and vessel inspection.
3. Radiation Sources Used in NDT
3.1 Gamma Ray Sources (Ir-192, Co-60, Se-75)
These are radioactive isotopes used in portable radiography.
Ir-192: Common for pipeline and vessel weld inspection; medium penetration.
Co-60: High penetration; used for thick materials.
Se-75: Lower energy; gives better image quality for thin sections.
3.2 X-ray Machines
X-ray machines generate radiation using electricity. They allow better control of exposure time and intensity. Mainly used in workshops, labs, and fixed locations due to power requirement.
3.3 Source Strength and Activity
Source strength indicates how much radiation a source emits. It is measured in Becquerel (Bq) or Curie (Ci). Higher activity means higher radiation intensity and higher risk.
3.4 Half-Life Concept
Half-life is the time taken for a radioactive source to lose half of its activity. Shorter half-life means faster decay and frequent source replacement.
3.5 Source Containers
Radiation sources are kept inside heavy, shielded containers called exposure devices or cameras. These prevent radiation leakage and protect workers when the source is not in use.
4. Health Hazards of Radiation
4.1 Acute Radiation Effects
These occur immediately or within hours/days of high exposure. Symptoms include skin burns, redness, nausea, vomiting, fatigue, dizziness, and hair loss. Very high doses can be fatal.
4.2 Chronic Radiation Effects
These develop slowly over months or years due to repeated low-level exposure. Effects include organ damage, weakened immunity, cataracts, and long-term health deterioration.
4.3 Genetic Damage
Radiation can damage DNA. This damage may be passed to future generations, causing birth defects, developmental issues, and genetic disorders.
4.4 Cancer Risk
Long-term exposure increases the risk of cancers such as leukemia, thyroid cancer, lung cancer, and skin cancer. Risk depends on dose, duration, and frequency of exposure.
4.5 Radiation Sickness
Occurs when the body receives a large dose in a short time. Symptoms include severe nausea, diarrhea, internal bleeding, infections, and bone marrow failure. It is a medical emergency.
5. Radiation Exposure & Dose Limits
5.1 Radiation Dose Units (Sv, mSv, Gy)
Gray (Gy): Measures the amount of radiation energy absorbed by the body.
Sievert (Sv): Measures the biological effect of radiation on the body.
MilliSievert (mSv): One-thousandth of a Sievert, commonly used for occupational dose monitoring.
5.2 Occupational Exposure Limits
These are maximum safe limits for radiation workers. They are set to reduce long-term health risks. Workers must not exceed the annual prescribed dose limits defined by regulatory authorities.
5.3 Public Exposure Limits
Lower limits apply to the public because they are not trained or monitored like radiation workers. These limits protect people outside controlled radiation areas.
5.4 Whole Body Dose
This is the radiation dose received by the entire body. It is important because whole-body exposure increases the risk of cancer and organ damage.
5.5 Organ Dose
This is the dose received by specific organs like eyes, skin, hands, or thyroid. Some organs are more sensitive to radiation and have separate safety limits.
6. Radiation Protection Principles
6.1 ALARA Principle
ALARA means As Low As Reasonably Achievable. Radiation exposure must be minimized as much as possible by proper planning, control measures, and safe work practices.
6.2 Time Control
Less time near a radiation source means less exposure. Workers should complete tasks quickly and efficiently to reduce radiation dose.
6.3 Distance Control
Increasing distance from the radiation source greatly reduces exposure. Even a small increase in distance can significantly lower dose.
6.4 Shielding
Using barriers like lead, concrete, or steel between the source and workers reduces radiation intensity. Proper shielding is essential for safety.
6.5 Inverse Square Law
Radiation intensity decreases rapidly as distance increases. If the distance from the source is doubled, the exposure becomes one-fourth. This principle is key for safe positioning.
7. Radiography Permit to Work System
7.1 What is a Radiography Permit
A Radiography Permit is a formal written authorization that allows radiographic testing using radiation sources under controlled and safe conditions. It ensures all safety checks, barricading, monitoring, and approvals are completed before exposure starts.
7.2 Why Special Permit is Required
Radiography involves ionizing radiation which is invisible and highly dangerous. Uncontrolled exposure can cause serious health damage to workers and the public. A special permit ensures strict control of access, area safety, radiation monitoring, and emergency readiness.
7.3 Permit Validity
The permit is valid only for a specific job, location, and time period. It must be revalidated if the shift changes, job scope changes, or conditions become unsafe.
7.4 Permit Display Requirements
The approved permit must be displayed clearly at the job site. It should show radiation warning, job details, validity time, and authorized signatures for easy verification.
7.5 Area Clearance Rules
Before exposure, the area must be cleared of all unauthorized persons. Barricades, warning signs, and radiation boundaries must be established. Re-entry is allowed only after final radiation survey confirms the area is safe.
8. Roles & Responsibilities
8.1 Radiographer
Performs radiography safely, operates equipment, handles the source correctly, follows permit conditions, conducts surveys, and ensures the source is fully retracted after exposure.
8.2 Radiation Safety Officer (RSO)
Ensures compliance with radiation safety rules, approves safety arrangements, verifies monitoring systems, investigates incidents, and controls radiation protection measures.
8.3 Permit Issuer
Reviews job details, verifies safety controls, confirms barricading and clearance, and authorizes radiography only when all conditions are safe.
8.4 Area Owner
Ensures the area is handed over safely, stops nearby activities, coordinates with operations, and prevents unauthorized entry.
8.5 Supervisor
Manages the job execution, ensures team follows procedures, maintains communication, and stops work if unsafe conditions arise.
8.6 Helpers
Assist radiographer, maintain barricades, control access, wear dosimeters, and immediately report unsafe conditions.
9. Regulatory Requirements
9.1 National Radiation Safety Rules
National laws define how radiation sources must be used, stored, transported, and monitored. These rules aim to protect workers, the public, and the environment from radiation exposure.
9.2 AERB / Regulatory Authority Guidelines
Regulatory bodies issue detailed safety guidelines for radiography operations, area control, dose limits, emergency response, training, and equipment standards. Compliance is mandatory.
9.3 License Requirements
Radiography work can only be performed by licensed organizations and certified personnel. Separate licenses are required for source possession, use, storage, and transport.
9.4 Source Storage Rules
Radiation sources must be stored in approved shielded rooms or containers with proper locking, warning signs, access control, and radiation monitoring.
9.5 Transport Regulations
Sources must be transported in certified containers, properly labeled, with valid documents and trained personnel. Unauthorized access and public exposure must be prevented at all times.
10. Radiography Equipment
10.1 Gamma Camera
A heavily shielded container that holds the radioactive source safely when not in use. It prevents radiation leakage and allows controlled source movement.
10.2 Guide Tubes
Flexible or rigid tubes used to guide the radioactive source from the camera to the exposure point. They help maintain distance and control.
10.3 Exposure Devices
Mechanisms that move the source from the safe position to the exposure position and back. They ensure smooth, controlled source handling.
10.4 Collimators
Shielding devices fitted at the exposure point to focus radiation in one direction. They reduce scatter radiation and protect surrounding areas.
10.5 Source Projectors
Devices that push and retract the source through the guide tube. They allow remote operation to reduce worker exposure.
10.6 X-ray Machines
Electrical machines that generate X-rays on demand. They allow control over intensity and exposure time and do not involve radioactive material storage risks.
11. Area Classification & Control
11.1 Controlled Area
An area where radiation levels can exceed safe public limits. Entry is restricted to authorized and trained persons only. Barricading, warning signs, and continuous monitoring are mandatory.
11.2 Supervised Area
An area adjacent to the controlled area where radiation levels are low but still monitored. Access is limited, and routine checks are done to ensure safety.
11.3 Radiation Zone
The immediate area around the radiation source where exposure is highest. No unauthorized person is allowed inside this zone during exposure.
11.4 Public Area
Any area accessible to non-radiation workers. Radiation levels here must always remain within public dose limits.
11.5 Safe Distance Calculation
The minimum distance required to reduce radiation to safe levels. It is calculated based on source strength, exposure time, and shielding, using the inverse square law.
12. Barricading & Signage
12.1 Barricade Types
Physical barriers used to restrict entry into radiation areas. These include rigid barricades, chains, cones, ropes, and caution tapes. They must be stable, visible, and clearly define the radiation boundary.
12.2 Radiation Warning Signs
Standard radiation symbols with clear messages such as “Radiation Area,” “Do Not Enter,” and “Radiography in Progress.” These warn people about invisible radiation hazards.
12.3 Night Radiography Precautions
Extra lighting, reflective barricades, flashing lamps, and illuminated signs are required to maintain visibility and prevent accidental entry in low-light conditions.
12.4 Reflective Tapes
Used on barricades, ropes, and poles to improve visibility in dark or poorly lit areas. Helps prevent accidental crossing of radiation boundaries.
12.5 Multilingual Sign Boards
Signs must be displayed in local language and English to ensure clear understanding by all workers and visitors.
13. Pre-Radiography Planning
13.1 Job Scope Definition
Clearly define what joint, weld, or component will be tested, the method to be used, location, timing, and expected duration. This avoids confusion and unsafe exposure.
13.2 Drawing Review
Study drawings and layouts to understand job position, nearby equipment, access routes, and possible public or worker movement around the exposure area.
13.3 Exposure Time Calculation
Calculate correct exposure time based on material thickness, source strength, and film/detector sensitivity. Wrong timing can cause overexposure or poor image quality.
13.4 Source Strength Check
Verify the activity of the radiation source. Higher activity means higher radiation intensity and larger controlled area requirement.
13.5 Weather Condition Check
Check wind, rain, and visibility. Strong winds can move barricades and signs, while rain can affect equipment stability and area control.
14. Radiation Survey & Monitoring
14.1 Radiation Survey Meters
Portable instruments used to measure radiation levels around the source and work area. They help identify safe and unsafe zones.
14.2 Area Monitoring
Regular or continuous checking of radiation levels inside controlled and supervised areas to ensure exposure remains within limits.
14.3 Boundary Dose Measurement
Radiation is measured at the barricade boundary to confirm that people outside are not exposed above permissible levels.
14.4 Leak Testing
Checks are performed on source containers, guide tubes, and equipment to ensure no unintended radiation leakage when the source is in the safe position.
14.5 Background Radiation
Natural radiation present in the environment. This value is recorded to compare with work-related radiation and confirm actual exposure.
15. Personal Monitoring Devices
15.1 TLD Badge
Thermo Luminescent Dosimeter records cumulative radiation dose over a fixed period. It is used for official dose tracking and regulatory reporting.
15.2 Pocket Dosimeter
A small, direct-reading device that shows real-time exposure. It helps workers immediately know if they are receiving abnormal dose.
15.3 Electronic Dosimeter
Digital device that provides continuous dose reading, alarms at preset limits, and data logging. It improves real-time safety control.
15.4 Badge Wearing Rules
Dosimeters must be worn on the chest level, outside protective clothing, during all radiography work. Sharing, forgetting, or improper wearing is strictly prohibited.
15.5 Dose Record Maintenance
All dose readings must be recorded, reviewed regularly, and stored safely. Abnormal exposure must be investigated and reported immediately.
16. PPE for Radiography Work
16.1 Lead Aprons
Worn to reduce radiation exposure to the torso and vital organs. Used mainly in controlled or close-proximity work.
16.2 Lead Gloves
Protect hands from scattered radiation when working near exposure devices or during equipment handling.
16.3 Thyroid Shields
Protect the thyroid gland, which is highly sensitive to radiation and prone to long-term damage.
16.4 Safety Helmet
Protects from head injuries due to falling objects, low structures, or movement in plant areas.
16.5 Reflective Jackets
Improve worker visibility, especially during night radiography or low-light conditions, preventing accidental entry into radiation zones.
17. Radiography Execution Procedure
17.1 Equipment Inspection
Before starting, inspect gamma camera, guide tubes, source projector, survey meters, and dosimeters. Ensure there is no damage, blockage, or malfunction that can cause source jamming or leakage.
17.2 Source Transfer Procedure
The radioactive source is remotely moved from the shielded camera to the exposure point using guide tubes. This must be done slowly and smoothly to avoid source damage or stuck conditions.
17.3 Exposure Process
Once the source is at the exposure position, the area must be fully cleared and barricaded. Exposure is maintained only for the calculated time to get proper image quality.
17.4 Source Retraction
After exposure, the source must be fully returned to the shielded position inside the camera. Position indicators and radiation surveys must confirm safe storage.
17.5 Final Radiation Survey
A full radiation scan of the area is done to confirm that no radiation is present outside the safe limit. Barricades are removed only after clearance.
18. Communication & Coordination
18.1 Control Room Intimation
Before starting radiography, the control room must be informed about the job location, time, and duration. This prevents accidental equipment operation and helps in emergency response.
18.2 Shift Handover
If the job continues across shifts, clear handover must be done. It should include source status, barricade condition, exposure status, and any pending actions.
18.3 Public Warning
Nearby workers and contractors must be informed about radiography activity. Verbal warnings, signboards, and announcements help prevent accidental entry.
18.4 Emergency Contact List
A visible list of emergency contacts such as RSO, supervisor, medical team, fire team, and security must be available at site for quick action.
19. Emergency Scenarios
19.1 Source Stuck
Occurs when the radioactive source fails to return to the shielded position. This creates continuous radiation hazard. Immediate area evacuation, barricading, and RSO notification are required.
19.2 Source Lost
Happens when the source becomes detached, misplaced, or unaccounted for. This is a critical emergency due to uncontrolled radiation risk. Area must be isolated and regulatory authority informed.
19.3 Overexposure
Occurs when a person receives radiation dose beyond permissible limits. Immediate medical evaluation, dose assessment, and incident reporting are mandatory.
19.4 Equipment Failure
Includes guide tube damage, projector malfunction, or camera defects. This can cause radiation leakage or stuck source conditions. Work must stop immediately.
19.5 Unauthorized Entry
When a person enters the radiation zone during exposure. This can cause unintentional radiation exposure. Exposure must be stopped and the person assessed.
20. Emergency Response Procedure
20.1 Area Evacuation
Immediately stop radiography and evacuate all persons from the affected area. Move people to a safe distance up to the defined radiation boundary.
20.2 Emergency Barricading
Install temporary barricades, warning tapes, and radiation signs to prevent any unauthorized entry into the hazardous zone.
20.3 RSO Intimation
Inform the Radiation Safety Officer immediately. No corrective action should be taken without RSO guidance.
20.4 Medical Response
If exposure is suspected, shift the affected person for medical evaluation. Dose assessment and health monitoring must be done without delay.
20.5 Source Recovery
Source recovery must be performed only by trained and authorized personnel using approved procedures and tools under RSO supervision.
21. Transport & Storage of Radiation Sources
21.1 Approved Containers
Radiation sources must be kept and moved only in certified, shielded containers designed to prevent radiation leakage and physical damage.
21.2 Labeling Requirements
Containers must have standard radiation warning symbols, source details, emergency contact numbers, and handling instructions clearly displayed.
21.3 Vehicle Safety
Vehicles used for transport must be authorized, secured, and clearly marked. Sources must be fixed properly to prevent movement, shock, or tampering during transit.
21.4 Storage Room Design
Storage rooms must be shielded, ventilated, fire-resistant, and located away from public access. Radiation warning signs and monitoring systems are mandatory.
21.5 Access Control
Only authorized and trained personnel are allowed to enter storage areas. Entry must be logged, and keys or access systems must be strictly controlled.
22. Incident Reporting & Investigation
22.1 What is a Radiation Incident
Any event that results in or could result in unsafe radiation exposure, loss of source control, equipment failure, or breach of safety barriers. This includes overexposure, source mishandling, or unauthorized entry.
22.2 Near Miss Reporting
A near miss is an unsafe event that did not cause harm but had the potential to do so. Reporting near misses helps identify gaps in safety before a serious accident occurs.
22.3 Root Cause Analysis
A systematic method to find the real cause of an incident, not just the visible problem. It may include human error, procedure gaps, training issues, or equipment failure.
22.4 Corrective Actions
Steps taken to eliminate the root cause and prevent recurrence. This may include procedure updates, retraining, equipment repair, or stricter controls.
22.5 Regulatory Reporting
Serious radiation incidents must be reported to the regulatory authority within the defined time frame. This ensures legal compliance and external safety review.
23. Documentation & Records
23.1 Radiography Permit Format
A standard permit that records job location, source details, exposure time, area classification, barricading, monitoring arrangements, and approvals. It ensures legal and safety compliance.
23.2 Source Log Book
Maintains daily records of source usage, movement, storage time, transfer details, and person in charge. Helps in traceability and control.
23.3 Dose Records
Personal radiation dose data from TLDs and dosimeters. Used to track cumulative exposure and ensure dose limits are not exceeded.
23.4 Survey Reports
Documents radiation readings taken before, during, and after exposure. Confirms area safety and boundary control.
23.5 Equipment Calibration Records
Shows that survey meters, dosimeters, and radiography equipment are tested and calibrated regularly for accurate readings and safe operation.
24. Training & Competency
24.1 Radiographer Qualification
Radiographers must be formally trained in radiation safety, equipment handling, exposure procedures, emergency response, and regulatory rules. Only certified personnel are allowed to perform radiography.
24.2 RSO Certification
Radiation Safety Officers must hold valid certification from the regulatory authority. They are responsible for radiation protection, compliance, audits, and incident control.
24.3 Refresher Training
Periodic training is required to update knowledge on safety rules, new equipment, incident learnings, and procedural changes. It prevents skill decay.
24.4 Mock Drills
Practical emergency simulations such as source stuck, unauthorized entry, or overexposure scenarios. These drills improve response time and coordination.
24.5 Authorization Process
Workers are authorized only after training completion, competency assessment, medical fitness, and regulatory approval. Authorization must be renewed periodically.
25. Common Violations & Unsafe Practices
25.1 No Barricading
Failure to install proper barricades allows unauthorized persons to enter radiation zones, leading to accidental exposure.
25.2 No Survey
Skipping radiation survey before, during, or after exposure can result in undetected radiation leakage and unsafe boundary control.
25.3 Improper Storage
Storing sources in non-approved locations, without shielding or locks, can expose workers and the public to radiation.
25.4 Unauthorized Access
Allowing untrained or non-authorized persons into controlled areas increases the risk of radiation exposure and legal violations.
25.5 Permit Violations
Starting work without a valid permit, extending work beyond permit time, or ignoring permit conditions can lead to serious safety and regulatory breaches.
26. Accident Case Studies
26.1 Source Loss Incidents
These occur when a radioactive source is misplaced, dropped, or left unattended. Such incidents create uncontrolled radiation hazards and can expose workers or the public unknowingly.
26.2 Overexposure Cases
Happen when workers stay too close to the source, work longer than planned, or fail to use monitoring devices. This can cause serious health damage and long-term illness.
26.3 Public Exposure Cases
Occur when barricading is poor, warning signs are missing, or radiography is done near public areas. Untrained people may enter the radiation zone without knowing the risk.
26.4 Equipment Failure Accidents
Include source stuck, guide tube damage, projector malfunction, or camera defects. These can lead to continuous radiation emission and emergency situations.
26.5 Lessons Learned
Always maintain strict area control
Never skip radiation survey and monitoring
Use only certified and maintained equipment
Follow permit conditions strictly
Ensure proper training and supervision
27. Course Assessment
27.1 Written Test
Used to evaluate understanding of radiation basics, hazards, safety rules, permit system, emergency actions, and regulatory requirements.
27.2 Practical Demonstration
Trainees must show correct use of equipment, barricading, survey meter handling, dosimeter use, and safe source handling procedures.
27.3 Scenario-Based Questions
Real-life situations like source stuck, unauthorized entry, or overexposure are given to test decision-making, response actions, and safety judgment.
27.4 Permit Filling Practice
Trainees practice filling radiography permits correctly, including area control, time limits, approvals, and safety checks to ensure procedural compliance.
28. Final Authorization & Certification
28.1 Competency Evaluation
Candidates are evaluated through written tests, practical demonstrations, and scenario handling to confirm knowledge of radiation safety, procedures, and emergency response.
28.2 Authorization Criteria
Authorization is granted only to those who meet training requirements, pass assessments, are medically fit, and comply with regulatory standards.
28.3 Certificate Issue
After successful evaluation, an official certificate is issued confirming the person is competent to perform radiography work safely.
28.4 Validity Period
Certification is valid for a defined period. Renewal requires refresher training, reassessment, and proof of continued competency.