Understanding Personal Radiation Detectors – A Primer
For anybody working in a field with risks of exposure to radiation, it’s supremely important to understand the basics of choosing appropriate devices for measurements. Getting an idea of the intensity of radiations is the first step of planning on safe operations. However, the world of radiation measurement devices is expanding at breakneck speed, which often leaves people confused as to which instrument they should use, for which application. You’re likely to have heard about personal radiation detectors (PRDs) as portable and highly useful instruments for people working in departments such as Customs and Border control (especially at the borders of countries such as Thailand, Vietnam, Malaysia, Hong Kong), Law enforcement agencies, Fire Fighters, emergency medical services, radioactive waste storage & isotopes research, medical radiology, etc. In this guide, we will help you understand PRDs better.
What’s The Need for Personal Radiation Detectors?
Before PRDs became well known and highly preferred among personnel employed in areas with potential radiation exposure and contamination risks, dosimeters and survey meters were the most commonly used devices for radiation detection. These instruments are ideal for applications wherein the user remains in a physical space where radiation is expected, and where a handheld device is convenient for unobstructed use.
However, there are several situations where people require a more portable, lightweight, and above all, more sensitive device that can quickly report radiological threats. This led to the increasing popularity of personal radiation detectors.
More About PRDs
A personal radiation detector is a very small device, much like a pager, which can be easily carried around in the wearer’s pockets. The main purpose of the PRD is to alert the wearer of the presence of radiation sources very quickly. PRDs are known to have very fast response rates and can display measurements of the radiation dosage as well. From very basic PRDs that only beep to indicate the presence of a radiation source to more advanced versions that help in identification of radionuclide (SPRD) in the vicinity of the wearer, there are all kinds of PRDs available. Among the other functionalities and features you might be interested in are:
- The ability of the PRD to work in environments such as water bodies, areas with high dust concentration, etc.
- The temperature range in which the PRD can operate without any noticeable impact on its measurement accuracy
- The intrinsic safety certifications acquired by the PRD version
- Availability of LED backlit displays for easy visualization of measured radiation values in darkness
- Resistance to RFI (radio frequency interference) and EMI (electromagnetic interference)
- Extra strong casing
How do PRDs Work?
To be able to find and purchase the ideal PRDs for your applications, you need to understand the basics of how these devices operate. Here are some key points to remember.
- Most of radiation detection devices can detect gamma radiation, but PRD can easily detect neutron radiation as well as gamma; gamma radiation is most abundant, easiest to detect, and lethal even in small doses.
- Most of PRDs (gamma & neutron radiation measurement devices)use scintillation crystals which produce light flashes when contacted by neutrons, alpha, beta, and gamma rays.
- The light photons emitted from these crystals are coupled with a PMT tume (photomultiplier), for signal amplification, which facilitates easier detection.
- Scintillation crystals are made from materials such as sodium iodide, lithium iodide, and cesium iodide.
- Some PRDs also use cadmium-zinc-telluride (CZT) based semiconductor sensors.
- The size of the detector is a good determiner of the sensitivity of the instrument.
- Also, the pulse strength depends on the radiation type and the source of radiation; this lends some PRDs the ability to also identify the radiation source based on the intensity of the pulse of light produced by the detector crystals.
Applications of PRDs
Because of its small size and high sensitivity, a personal radiation detector excels in a range of situations where radiation exposure detection and prevention are imperative. The device can mostly be used on its own, and sometimes as a part of a larger radiation safety plan. Here are some of the most important applications of PRDs.
First Responders
A PRD, attached to the uniform of a fire respondent or hazmat team member, can be invaluable for him/her to identify the presence of radiations, and to communicate the information to the second wave of respondents. This helps the response team to come prepared with the necessary radiation shielding equipment. This, firefighters, EMS personnel, and hazmat respondents must be equipped with PRDs to quickly identify radiation presence, and avoid contamination of the respondents.
Border Protection Forces
A key application of PRDs is in the hands of a border protection agent, who depends on the device to actively look for the presence of radiations in baggage entering a country, and persons crossing the immigration checkpoints. Should a person or object trigger the PRD, the agent then takes the person or baggage to a secondary checking station, where another officer with more sophisticated radioactive detection devices, can subject the suspicious object to a more thorough check.
Transportation Security
Personal Radiation Detectors prove invaluable in areas such as subways, airports, and railway stations, as these inconspicuous devices allow security officers to do a preliminary scan of objects and people without raising or causing alarm. A PRD worn on a frisker’s belt, for instance, is all that’s needed to subject every passing object to a quick scan for radiation presence. No wonders, then, that transportation security departments, as well as logistics companies are keenly interested in personal radiation detectors.
PRDs as Parts of Larger Radiation Security Implementations
In large-scale events such as soccer games, public events, and international conferences, personal radiation detectors work well as parts of a larger integrated system of nuclear security. PRDs work well in conjugation with the stationary walk by monitors, helping security personnel quickly identify potentially suspicious people and objects, and subjecting them to further search and investigation.
Concluding Remarks
The world we live in presents unimaginably hazardous situations; nuclear radiation risks are no more a part of sci-fi movies. Every day, hazmat respondents, firefighters, and EMS personnel deal with dangerous radiation. Personal radiation detectors help them quickly identify potential radiation risks, which in turns enables them to prevent smuggling, save lives, and remain safe themselves.