Stephen Mash | July 14, 2022
Radiation is one of those words that can strike fear into the heart, but the vast majority of radiation sources found in the industrial environment are harmless. Sources of radiation are all around us, sunlight, radio and television signals, mobile phones, igneous rocks such as granite, and even bananas. But, to understand the risks, we first need to understand what forms of radiation are benign and which are potentially harmful. So, we’ll start by looking at what radiation is and what forms it can take.
Radiation is energy emitted from a source that travels across a medium, such as air, before its absorption by someone or something. We classify radiation into ionizing and non-ionizing, determined by whether or not the radiation can alter matter at the atomic level by causing ionization-stripping electrons from atoms to create ions. So, the first step is to look at the different ionizing and non-ionizing radiation forms.
Ionizing radiation is the more complex and potentially more harmful form of radiation thanks to the potential to alter matter at the atomic level. It can occur as particles such as alpha and beta or as electromagnetic waves such as gamma rays.
Alpha particles are composed of protons and neutrons created by radioactive decay processes. While highly dangerous if ingested or inhaled, a single sheet of paper can contain them. Alpha particle sources are present in industrial and domestic products, including smoke detectors and static electricity eliminators.
The containment of sources of alpha particles within protective enclosures to prevent their release into the environment forms the basis of risk management. Hazards occur when sources become uncontained, such as incorrectly recycling an end-of-life smoke alarm and exposing the radioactive Americium-241 alpha source.
Beta particles are electrons or positrons created by radioactive decay processes. They have higher energies than alpha particles, but a sheet of aluminum foil can stop them. The medical sector commonly uses beta particle sources for imaging, tracers and cancer treatment, while the manufacturing industry uses these to measure material thickness.
As for alpha sources, the containment of sources of beta particles within protective enclosures prevents their release into the environment. However, hazards can occur with the accidental exposure of a source, such as the incorrect maintenance or disposal of equipment allowing the release of the radioactive Strontium-90 beta source.
There are two main types of electromagnetic wave-based ionizing radiation. Radioactive decay processes can create X-rays that originate in the electrons of the decaying atom. Accelerating electrons through an electric field will also generate X-rays. The medical sector commonly uses X-rays for imaging, diagnostic and cancer treatment purposes. In addition, X-rays have common uses in engineering processes for materials inspection and imaging purposes.
The radioactive decay processes originating in the nucleus of the atoms can create gamma rays. This is the process employed by nuclear power stations to produce energy. The risk of exposure to this form of radiation is dependent on the energy density and exposure times. For example, we are all exposed to low levels of gamma radiation from the sun, other stars, and the Earth’s core over our lifetimes. However, exposure to substantial doses over a short duration can be fatal.
We don’t just find harmful levels of ionizing radiation in nuclear power stations. The health sector typically uses high-energy sources of ionizing radiation for medical treatments. Still, they have applications across the manufacturing, construction and engineering sectors, including non-destructive testing. The food and beverage processing sectors also commonly use gamma rays for sterilization processes, while the health sector uses these for medical diagnosis and treatment procedures. They are also common in education and research establishments.
The containment of sources of x-rays and gamma rays is far more complex, requiring dense materials such as lead or concrete to reduce potentially harmful levels down to a safe level. Hazards occur when personnel without appropriate protection enter an area with harmful levels of radiation or unsafe practices that produce dangerous levels outside of protected areas.
Harmful levels of ionizing radiation can also naturally occur where a facility allows radioactive materials such as radon gas seeping from the ground to accumulate undetected in occupied spaces such as basements and other underground areas. Radon occurs in locations where the underlying rocks and soil contain radioactive uranium and thorium, which naturally decay to form radium and subsequently Radon. The belief is that Radon is the second biggest cause of lung cancer after smoking.
Non-ionizing radiation is more straightforward, and is caused by electromagnetic waves. Although it is potentially less harmful than ionizing radiation, its effects come by providing energy to excite matter at the atomic level. However, at high energy levels, it can have catastrophic consequences.
Harmful levels of non-ionizing electromagnetic radiation are typically present across industrial sectors, including communications, engineering, broadcasting, transport, and energy distribution. Radio communications, radar, and television broadcasts generate harmful radiation levels at the point of transmission.
In addition, we commonly find harmful levels of non-ionizing radiation in the infrared and ultraviolet frequencies in high-power lasers. The engineering, scientific research, and food and beverage processing sectors use this technology for cutting, shaping and engraving purposes.
Different types of electromagnetic wave-based non-ionizing radiation are characterized by their frequency, with ultraviolet light at one end of the spectrum, and extremely low frequency (ELF) signals at the other. Other categories ordered by frequency include visible light, infrared light, microwaves, ultra-high frequency (UHF), very high frequency (VHF) radio waves, and very low frequency (VLF) signals.
A general guide for electromagnetic wave-based radiation is that waves with frequencies greater than ultraviolet light are ionizing. In contrast, those with frequencies at ultraviolet light and below are non-ionizing.
Controlling non-ionizing radiation sources primarily rely on shielding and physical separation to prevent exposure to harmful levels. Hazards occur when personnel get too close to the source of non-ionizing radiation, such as a radio transmitter aerial, or as a consequence of removing shielding from an active source during maintenance.
Ionizing radiation hazards
Millions of personnel routinely experience exposure to radiation sources across a range of industry sectors and academic and scientific research establishments. These persons must be protected to ensure their exposure is not just within safe limits but as low as reasonably achievable as the effects of radiation exposure are accumulative.
This protection requires organizations to recognize and understand the radiation-related risks for their personnel. These are not just the obvious risks, such as using radioactive sources to produce gamma radiation for testing purposes. Any assessment needs to include less obvious risks such as handling of equipment containing alpha or beta particle sources or the accumulation of naturally occurring radon gas in unventilated spaces. TLD and film badges are a means to monitor the radiation dosages of individuals working in zones with ionizing radiation
In terms of the impact of radiation on humans, unsafe levels of ionizing radiation can damage the body at the molecular level, damaging proteins, RNA and DNA, leading to long-term health impacts. At higher levels, acute health effects, including burns, sickness, and organ failure, can be more immediate. By contrast, the damage caused by non-ionizing radiation will be more limited to thermal effects, though by no means less severe consequences.
Non-ionizing radiation hazards
Three primary hazards are associated with exposure when working with non-ionizing electromagnetic radiation sources such as high-power transmitters.
The hazards of electromagnetic radiation to personnel (HERP) encompass risks that result in injuries to anyone in the vicinity of the radiation emissions.
These can be direct effects such as heating effects on body tissues seen around the microwave frequencies, indirect effects such as generating heat or electrical potentials on surfaces that the person may come into contact with, resulting in burns or electrocution risks. Radiation can also interfere with medical equipment, resulting in loss of function and consequential effects such as disrupting a person’s heart pacemaker or wearable insulin pump.
The health effects will depend on the frequency of the radiation. Lower frequency radiation typically used for communications causes sensory effects, including nausea, vertigo, and nerve and muscle stimulation. Higher frequency radiation seen in microwaves, infrared and ultraviolet lighting can cause heating effects in tissues and organs, burns, and organ damage.
For most industrial sectors, exposure to sufficiently high radiation levels to cause health effects is extremely rare. However, exposure to high radiation levels can cause acute health effects, including burns, tissue and organ damage, blood diseases such as leukemia, and long-term effects, including various cancers.
The hazards of electromagnetic radiation to fuels (HERF) encompass risks that explosive vapors may ignite if radiation-induced arcing occurs during fuel handling activities such as refueling a vehicle near a source of radiation emissions. The hazard primarily requires the presence of explosive vapors in an oxygen-rich environment combined with a surface on which field-generated potential differences can create discharge arcs. Filling a car with gasoline at a gas pump is the most common scenario for materializing this hazard.
The hazards of electromagnetic radiation to ordnance (HERO) encompass the risks that a source of radiation emissions may accidentally trigger electrically initiated devices (EID) or electro-exploding devices (EED). We tend only to see such risks in mining, construction and defense industries.
Controlling the risks
Controlling radiation risks involves containing the emitted energy and their physical separation from vulnerable personnel and equipment. The type and power of the radiation source will determine the mitigating controls required. These controls include protective clothing, exposure monitoring, shielding and exclusion zones.
One of the most significant risk sources is portable radiation sources such as those typically used for non-destructive testing. Such radiation-based testing effectively ensures the physical integrity of structures and equipment, particularly castings, joints and welds. This testing is vital to ensure equipment is safe to operate, mainly where high pressures and temperatures exist or contain harmful materials. However, introducing radiation sources into an industrial location for a short-term task typically relies on working practices to ensure the operators keep radiation exposures of personnel in the industrial facility as low as reasonably practicable.
Safe use requires careful planning, local source shielding, and robust work practices to minimize radiation exposure levels within safe levels. These practices can be challenging when testing in difficult working conditions such as confined spaces or extreme environments.
Exposure to radiation sources is a risk faced by personnel across various industry sectors. Where the radiation is at harmful levels, these workers must be protected to minimize exposure to an as low as reasonably achievable and safe level.
Specific risks will depend on the type of radiation, determined by the source’s nature and the operating procedures and protective measures to manage the source.
Identifying, understanding, controlling, and managing radiation risks is an essential part of industrial safety processes, necessary to protect personnel from harm. In addition, the potential reach of radiation hazards over long distances can extend the risks beyond the boundaries of industrial facilities that hold the radiation source.
About the author
Stephen Mash is a freelance editor from the U.K. He has over 30 years of practical experience in IT, aerospace, defense and communications sectors. He develops and assesses safety-critical and business-critical systems, providing risk management and cybersecurity consultancy. He has a bachelor’s degree in electrical and electronic engineering, and has been a Member of the Institute of Engineering and Technology (MIET) for over 20 years.