Information
Welcome to The ASR PRE SHIPMENT INSPECTION AGENCY
What is Radiation?
Radiation refers to the emission and transmission of energy in the form of waves or particles through space or a material medium. In industrial and inspection environments, radiation is commonly associated with testing, safety monitoring, and quality assurance processes—especially within Non-Destructive Testing (NDT) and metal inspection activities.
Radiation is broadly classified into ionizing and non-ionizing radiation, based on how it interacts with matter.
Ionizing Radiation
Ionizing radiation has sufficient energy to remove electrons from atoms, which can result in material changes or biological effects. In inspection applications, ionizing radiation is carefully controlled and used in techniques such as Radiographic Testing (RT) to detect internal defects in welds, castings, and structural components.
Non-Ionizing Radiation
Non-ionizing radiation does not carry enough energy to ionize atoms but can still transfer energy in the form of heat or light. Examples include radio waves, visible light, infrared, and most ultraviolet radiation. These forms are commonly used in visual inspections, monitoring, and industrial applications.
Radiation & Safety in Inspection
While radiation can be hazardous if improperly managed, professional inspection agencies follow strict safety protocols and international standards to ensure safe application. At ASR Inspection Agency, radiation-based inspection methods are performed by trained and certified professionals using approved equipment and safety procedures.
Proper control and monitoring of radiation help ensure accurate inspection results while protecting personnel, assets, and the environment.
What Radiation Levels Are Considered Safe?
Radiation exposure is a part of everyday life and comes from both natural and man-made sources. Understanding typical radiation levels helps place exposure in proper context and supports safe application in industrial and inspection environments.
The first step in radiation safety is estimating your annual radiation dose. Most exposure received by individuals comes from natural background sources rather than industrial activities.
Natural Sources of Radiation
Cosmic Radiation
Cosmic radiation originates from the sun and distant stars. Earth’s atmosphere provides natural shielding, meaning radiation levels increase with altitude.
- Sea level: ~25 millirem (mrem) per year
- 1 mile altitude: ~50 mrem per year
- 2 miles altitude: ~100 mrem per year
- Commercial air travel: ~0.5 mrem per hour of flight
Terrestrial Radiation
This radiation comes from naturally occurring radioactive materials such as uranium and thorium found in soil and rocks.
- Average exposure: ~30 mrem per year
- Coastal regions: Approximately half the average level
- Inhaled radon gas: ~200 mrem per year (largest natural source)
Other Common Radiation Sources
- Nuclear weapons fallout: Less than 1 mrem per year
- Television viewing: ~1 mrem per year
- Dental materials (crowns, porcelain): ~0.1 mrem per year
- Living near coal-fired power plants: ~0.01 mrem per year
Although nuclear power plants receive attention, coal-fired plants often release more naturally occurring radioactive material due to trace uranium in coal.
Radiation Safety & Occupational Limits
Regulatory authorities establish strict limits to protect radiation workers and the public. Current international guidelines set occupational exposure limits at:
- 20 mSv per year for radiation workers
- Controlled area safety threshold: 7.5 µSv per hour
- Levels above 3 µSv per hour are treated as potentially hazardous
At ASR Inspection Agency, radiation-based inspection activities are conducted strictly within permitted limits, using approved shielding, monitoring systems, and certified personnel.
Radiation in Food & the Human Body
Naturally occurring radioactive elements such as Potassium-40 and Carbon-14 are present in food and the human body.
- Radiation from food: ~20 mrem per year
- Natural radiation from the human body: ~40 mrem per year
Medical Radiation Exposure (Typical Values)
- Dental X-ray: ~1 mrem
- Chest X-ray: ~6 mrem
- Neck / Skull X-ray: ~20 mrem
- CT Scan: ~110 mrem
- Barium studies: Up to ~400 mrem
Most individuals receive an average total radiation dose of approximately 300–360 mrem per year, primarily from natural sources.
Understanding Radiation Risk
Scientific studies indicate that health risks from low-level radiation exposure are minimal. Severe health effects occur only at extremely high doses, far beyond everyday or industrial exposure levels.
A single acute dose of approximately 450,000 mrem is associated with serious health outcomes, emphasizing the importance of strict control and monitoring—practices followed rigorously by ASR Inspection Agency.
Radioactive Decay (Nuclear Decay)
Radioactive decay, also referred to as nuclear decay or radioactivity, is a natural process by which an unstable atomic nucleus releases excess energy in the form of ionizing radiation. Any material that emits this radiation spontaneously is classified as radioactive.
During this process, an unstable nucleus known as the parent radionuclide transforms into a more stable form, producing a daughter nuclide. In many cases, this transformation results in the formation of a completely new chemical element due to changes in the number of protons and neutrons within the nucleus.
Types of Radioactive Decay
Alpha decay occurs when the nucleus emits an alpha particle, consisting of two protons and two neutrons (equivalent to a helium nucleus). This process reduces the atomic number by 2 and the mass number by 4, and is most commonly observed in heavy radioactive elements.
Beta decay occurs when a nucleus emits an electron (β⁻) or a positron (β⁺). This happens when a neutron converts into a proton or vice versa. The process is accompanied by the release of a neutrino and results in a change in the atomic number without altering the mass number.
In electron capture, the nucleus absorbs one of its own orbital electrons, converting a proton into a neutron. This process often leads to the emission of X-rays or gamma radiation and results in a nuclear transformation.
Gamma decay occurs when an excited nucleus releases excess energy in the form of gamma rays. Unlike alpha and beta decay, gamma emission does not change the atomic number or mass number but reduces the energy level of the nucleus.
Ionizing Radiation
Ionizing radiation is radiation with sufficient energy to remove electrons from atoms, creating ions. The primary forms of ionizing radiation produced during radioactive decay include:
- Alpha particles
- Beta particles
- Gamma rays
Each type of radiation differs in penetration capability and biological impact. While low-level exposure occurs naturally in everyday life, prolonged or high-level exposure can pose health risks and therefore must be controlled through proper radiation safety measures.
This is a list of radioactive elements. While all elements have radioactive isotopes, the elements listed here do not have any stable isotopes. Each element is accompanied by its most stable known isotope and its corresponding half-life.
How Is Radioactivity Measured?
Radioactivity and radiation exposure are measured using four interrelated units. These are commonly remembered by the mnemonic R-E-A-D, representing Radioactivity, Exposure, Absorbed Dose, and Dose Equivalent. Both traditional (British) and international (metric) units are widely used.
1. Radioactivity
Radioactivity refers to the amount of ionizing radiation released by a radioactive material. This includes emissions such as alpha particles, beta particles, gamma rays, X-rays, or neutrons. It represents how many atoms decay within a given time period.
Units: Curie (Ci) and Becquerel (Bq)
2. Exposure
Exposure measures the amount of radiation traveling through the air. Many radiation monitoring instruments are designed to measure exposure levels directly.
Units: Roentgen (R) and Coulomb per kilogram (C/kg)
3. Absorbed Dose
Absorbed dose describes the amount of radiation energy absorbed by a material or the human body as radiation passes through it.
Units: Rad and Gray (Gy)
4. Dose Equivalent (Effective Dose)
Dose equivalent combines the absorbed dose with the biological effect of the type of radiation. While beta and gamma radiation have similar absorbed and effective doses, alpha and neutron radiation are more harmful and therefore result in a higher dose equivalent.
Units: Roentgen Equivalent Man (rem) and Sievert (Sv)
Note: Biological dose equivalents are commonly measured in millirem (mrem), where 1 rem = 1000 mrem.
1 R (Exposure) ≈ 1 rad (Absorbed Dose) ≈ 1 rem = 1000 mrem (Dose Equivalent)
Radiation Exposure Limits
On average, people are exposed to approximately 2 mSv per year from natural background radiation. However, exposure levels can vary significantly depending on location and lifestyle.
The annual occupational exposure limit for radiation workers is 50 mSv.
Measurement During Scrap & Shipment Inspections
For monitoring radioactivity in scrap materials and bulk shipments, ASR Inspection Agency uses advanced radiation detection instruments such as:
- Geiger Counters
- Radiation Survey Meters
- Radiation Spectrometers
Radiation readings are measured and recorded in Microsieverts per hour (µSv/hr) and are used for issuing Pre-Shipment Inspection Certificates, ensuring safety and regulatory compliance.