Am I at Risk of Radiation Exposure?

The ongoing uncertainty of the Japanese nuclear crisis has left people around the world questioning the danger of radiation contamination in their own communities. How much is the general public really at risk of radiation? Because D-tect Systems specializes in detecting threats from radioactive and chemical sources, we offer this article to provide some information on some of the current radiation risks in context and some general guidelines on radiation safety.

The first step in qualifying contamination risks is to separate fact from fiction. The way the public views radiation has mostly been shaped by a few incidents in modern history: Chernobyl and Hiroshima/Nagasaki. These extreme cases have influenced many to assume that radiation is an exotic and deadly phenomenon. In reality, our environment is steeped in radiation that our bodies absorb without any ill effect. The most important factor in understanding the impact of radiation is quantity – how high radiation levels are and how these levels translate to risk.

To give some idea of safe radiation levels, natural background radiation – the radiation that we are exposed to every day from cosmic rays and naturally-occurring radioactive materials – is about 3 mSv (300 mrem) per year. According to the FAA, A coast-to-coast airplane trip will expose you to about 5 µSv per hour (which comes out to 43.8 mSv/yr for continuous flight), and a year of watching four hours of television of day adds up to about 20 µSv total (2 mrem). These quantities are pretty small compared to a federal occupational limit of radiation exposure set by OSHA at 50 mSv (5000 mrem) per year. Now let’s compare the situation in Japan to all this. Recent reports from the International Atomic Energy Agency stated that radiation levels at the perimeter of the Fukushima Daiichi nuclear complex have been measured at 1 – 3 mSv/hr. Although this is an elevated radiation level and prolonged exposure could be dangerous, the short-term radiation level set for Japanese workers working on the nuclear complex is 250 mSv, and would take considerable time to reach.

Although the risks of serious widespread radiation contamination in this case are low, the procedures outlined by government agencies should always be strictly adhered to. These procedures aim to limit the spread of radiation and minimize risk to exposed areas. Although the specific instructions given out for each incident vary, here are a few general guidelines that should always be followed.

First, in case of radiation contamination, get people (including yourself) out of harm’s way as quickly as possible and notify authorities. Radiation spreads easily though blowing dust and smoke, so radiation-free secure zones must be established by sealing off areas from the outside environment by closing and weather-proofing doors and windows and placing food and water in well-insulated areas such as basements.

Second, since human skin generally acts a good barrier against low-level radiation, the biggest threat is breathing in radioactive materials or somehow ingesting them. Make sure to wear a face mask in areas that may be contaminated and wash hands regularly. If you suspect someone has been exposed to radioactive dust, the best solution is usually as simple as discarding contaminated clothing and washing with soap and water, as this will rid the body of radiation before it can cause damage. As an additional precaution against significant amounts of radiation, potassium iodide tablets are sometimes given to protect the thyroid gland.

Third, preparation is vital when it comes to any kind of disaster, and we recommend everyone keep an emergency kit close at hand so that they can be personally prepared in case of any crisis. This kit should include such things as food and water for a few days, water filtration kit, emergency blanket, rain gear, batteries for radios and detectors, dust mask, extra clothing, flashlight, candles, waterproof matches, cooking utensils, necessary medications, and a first aid kit. Although we generally take these supplies for granted, shortages can occur quickly in crisis situations.

Preparation is vital when it comes to any kind of disaster, and we recommend all public safety personnel keep an emergency kit close at hand so that they can be personally prepared to serve the public. This kit should include such things as food and water for a few days, emergency blanket, rain gear, batteries for radios and detectors, dust mask, extra clothing, candles, waterproof matches, cooking utensils, necessary medications, and a first aid kit. Although we generally take these supplies for granted, shortages can occur quickly in crisis situations.

Although the current nuclear crisis continues to make headlines and is a great source of fear for many, it is important to know the real risks involved and how to cope with them. With a little knowledge of radiation safety, and material preparation for a crisis, we can minimize future risks and know better what we’re up against.

D-tect Systems is supplier of advanced radiation and chemical detection equipment sold around the world. www.dtectsystems.com.

Radiation Basics Sheet

A pdf version of this document can be found on the D-tect Systems website, here.

Background radiation: ~ 3 mSv/yr (300 mrem/yr) in North America and slightly higher in Asia. 88% of background radiation comes from natural sources (half of this from radon gas), almost all the remaining radiation comes from medical sources.

World Nuclear Organization

Safety Levels: American regulatory limit for occupational exposure: 50 mSv/yr (5 rem/yr). This limit was chosen because it is the lowest rate at which there is evidence of cancer being caused in adults. Pregnant women and children should have no more than a 10^th of this (5 mSv/yr or 500 mrem/yr). A lethal full-body dose for a man is around 4-5 Sv (400-500 rem) in a short time period.

Radiation Sickness Threshold: 1000 mSv (1 Sv or 100 rem) in a short time period. Symptoms: nausea, hair loss, weakness, skin burns

Long-term Radiation Exposure: cancer, cell mutation, birth defects.  The danger of continued overexposure to radiation is that symptoms can appear after 20 years after exposure.

Radiation Exposure vs. Distance: if you double the distance, you reduce the exposure by a factor of 4.

Ionizing Radiation Types

Alpha

Penetration: stopped by skin or paper, dangerous when ingested or breathed in.

Beta

Penetration: stopped by aluminum plate or 1 cm of human flesh, heavy clothing may be needed.

Gamma & X-rays

Penetration: easily passes through most matter, shielding requires concrete, lead or water.

Neutron

Penetration:  Just like gamma rays, shielding requires concrete or water.  Neutron radiation only comes from cosmic rays and nuclear reactions, and although it isn’t ionizing, it can cause other materials to become radioactive and is often accompanied by other radioactive materials.

Protection from Radiation

Limiting Time: For people who are exposed to radiation in addition to natural background radiation through their work, the dose is reduced by limiting exposure time.

Distance: In the same way that heat from a fire is less the further away you are, the intensity of radiation decreases with distance from its source.

Shielding: Barriers of lead, concrete or water give good protection from penetrating radiation such as gamma rays. Radioactive materials are therefore often stored or handled under water, or by remote control in rooms constructed of thick concrete or even lined with lead.

Containment: Radioactive materials are confined and kept out of the environment. Radioactive isotopes for medical use, for example, are dispensed in closed handling facilities, while nuclear reactors operate within closed systems with multiple barriers which keep the radioactive materials contained. Rooms have a reduced air pressure so that any leaks occur into the room and not out from the room.

Radiation Exposure Units of Measurement

Exposure: measure of the strength of a radiation field at some point in air.  Basic unit: “roentgen” (R).

Dose: absorbed dose is the amount of energy that ionizing radiation imparts to a given mass of matter.  Basic units: “gray” (Gy) and “radiation absorbed dose” (rad). 1 Gy = 100 rads.  In human tissue, 1 R of gamma radiation = 1 rad of absorbed dose.

Dose Equivalent: relates to the absorbed dose to the biological effects of that dose. Basic units: “sievert” (Sv) and “roentgen equivalent in man” (rem). 1 Sv = 100 rem.

Dose Rate: a measure of how fast radiation a radiation dose is being received.  Basic units: mSv/yr, mrem/yr, etc.

Half-life: The time it takes for half the nuclei in a specific isotope to undergo decay.

Radiation Examples

Air travel: measured dose during air travel is 5 µSv/hr (43.8 mSv/yr or 4380 mrem/yr) according to the FAA.  This is about 15 times background radiation.

Watching TV: 4 hours a day adds up to 2 mSv/yr (200 mrem/yr)

Allowable short-term dose for workers on the Fukushima accident: 250 mSv (25 rem)

Radiation Measurement on the perimeter of the Fukushima Nuclear Plant: 1-3 mR/h (about 10-30 µSv/h)

U.S. Environmental Protection Agency

Atomic Shorthand

Example: “Iodine-131” = ₅₃I¹³¹

Radioactive Iodine

Iodine concentrates in the thyroid. Because of this, radioactive iodine (a byproduct of nuclear reactions) contributes to thyroid cancer more than other types of cancer. For this reason, potassium iodide tablets are given to increase the amount of safe iodine in the body, as this limits the amount of radioactive iodine the body will absorb.

The most common kind of radioactive iodine (Iodine-131) has a half-life of only 8 days.

Nuclear Plants

There are over 440 commercial nuclear power plants operating in 30 countries which accounts for about 14% of the world’s power.  The US has 104 operating reactors, the most of any nation.  Japan previously had 56.

International Atomic Energy Agency

Alarm Levels for the MiniRad-D Radiation Detector

Alarm Level	µrem/hr	mrem/hr	µSv/hr	mSv/hr
1	35	0.035	0.35	0.00035
2	40	0.04	0.4	0.0004
3	55	0.055	0.55	0.00055
4	65	0.065	0.65	0.00065
5	100	0.1	1	0.001
6	200	0.2	2	0.002
7	350	0.35	3.5	0.0035
8	600	0.6	6	0.006
9	1100	1.1	11	0.011

D-tect Systems

 The radiation facts and protection information in this post were published by the World Nuclear Association and health information was published by the US Environmental Protection Agency.

Protecting the Public from a Nuclear Power Plant Radiation Leak

How can you feel safe? How much warning will you have?

The ongoing battle to control the reactors at the Fukushima Nuclear Plant is terrifying to follow, but also leads millions that live near nuclear power plants to look over their shoulder and wonder “what if”? How many of us live within 50 miles of a nuclear power plant? In the U.S. alone, there are 104 nuclear power plants, most with multiple reactors.

When a leak is detected, there are two primary tools to measure the radiation: dosimeters and radiation detectors. Both provide different critical functions.

Dosimeters are the important instruments at the radiation leak. When worn on the body, often clipped to a pocket or belt, they measure how much radiation your body has absorbed. This is critical because the human body can absorb an amazing amount of radiation without damage, but there is a limit. A dosimeter shows when it is time to get away from the radiation before health consequences can occur. Everyone working in an area of high radiation needs to have a dosimeter. Especially the workers trying to stop a radiation leak.

Radiation detectors are faster and more sensitive than dosimeters, react instantly when radiation is detected, and indicate the amount of radiation.  If dosimeters are like a doctor looking over your shoulder to continually measure your health, radiation detectors are more like guard dogs. Radiation detectors are used just like guard dogs – they can monitor a perimeter and provide instant warning if that perimeter is violated. They can also be used to inspect people and vehicles for radiation. When people leave a contaminated area they are scanned with radiation detectors to quickly determine who needs to go through decontamination and who can be waved on.  Often contamination is in the form of dust present on skin, clothes and shoes. This contamination can be washed off once detected. The people who need radiation detectors are those who establish and guard the perimeter around ground zero, control the road blocks, evacuate the local population, control hospital admittance, and check people and vehicles for contamination as they leave the danger area.

How much warning will you have if a radiation leak occurs at the local nuclear power plant? Radiation detectors inform the authorities that a leak has happened within seconds.  Then it’s up to the authorities and the local emergency management team to determine how to respond and what the public needs to know.  And if a perimeter needs to be established and  an evacuation ordered.

After the leak is stopped, how can you feel safe living next to a Nuclear Plant? How do you know radioactive dust isn’t blowing around during windy days? Those same radiation detectors keep monitoring radiation levels 24/7.  They are sensitive enough to detect very small levels of radiation and can be set to alarm at far below hazardous levels. No radiation contamination can move without detection within a network of these devices.

Radiation is invisible to us, but we have the tools to track its every move.

Mark Kaspersen is the Director of Engineering of D-tect Systems, producers of radiation detection equipment sold around the world. www.dtectsystems.com.

Radiation Exposure: What Can I Do?

Experiencing the front line of a crisis is a terrifying experience, especially in the face of uncertainty and fear of the unknown.  This point is especially well illustrated in Japan’s ongoing nuclear crisis.  For over a week now, rescue workers in Japan have dealt with floods, fires, power outages, and infrastructure damage, all compounded with the threat of an escalating nuclear crisis.  Radiation levels are at elevated levels for miles around the Fukushima Dai-ichi nuclear complex and scientists are scrambling to determine how much radiation has already been released into the environment.  In the interest of providing a little peace of mind to security personnel across the globe whose line of work brings them into contact with critical situations, we have a few basic suggestions on how to avoid radiation risks.

The way the public views radiation has been shaped by some of the most horrific incidents in modern history: Chernobyl and Hiroshima.  These extreme cases have influenced many to assume that radiation is an exotic and deadly phenomenon.  In reality, our environment is steeped in radiation that our bodies absorb without any proven ill effect.  The most important factor in understanding the impact of radiation is quantity – how high radiation levels are and how these levels translate to risk. 

Security personnel are key and assist as the first line of defense against these varying dangers of radiation.  Organization is extremely important in crisis situations, and even just a few informed individuals can drastically change the outcome of a hazardous situation.  Security personnel have to act quickly to mitigate and ascertain the amount of radiation in the environment.  Two tools that are absolutely essential to security personnel in a radiation crisis are the dosimeter and radiation detector. 

A dosimeter is a small badge worn on the body or a small handheld device used to measure how much radiation the person has been subjected to.  Security personnel are often exposed to more radiation in their line of work, and must carefully monitor their dosimeters to tell them when they are approaching risk levels and must leave the danger area.  To give some idea of safe radiation levels, natural background radiation – the radiation that we are exposed to every day from cosmic rays and naturally-occurring radioactive materials – is about 370 millirems per year in the United States.  A coast-to-coast airplane trip will expose you to about 12 millirems, and a year of watching four hours of television per day adds up to about 2 millirems.  These quantities are miniscule compared to a federal occupational limit of exposure at 5000 millirems per year. Children and pregnant women have much lower exposure levels, and very high levels of radiation can cause serious health risks in a short time. 

Radiation detectors are indispensable to security efforts because they allow personnel to find contaminated areas and people quickly.  A common detector that has been used in the past is a Geiger-Mueller detector, or a Geiger counter. A Geiger counter is a very low cost detector, typically less than $500 USD, and provides very basic detection of large levels of radiation. However, they have significant limitations in a radiation crisis including limited to no detection of lower levels of radiation that can still be dangerous, as well as slower response time. One of the best detection technologies on the market is called a scintillation detector.  These detectors, on average, are 100 times more sensitive than Geiger counter and respond more rapidly to radiation, usually within one second, and typically cost around $1,200 USD.  The much greater sensitivity of scintillation detectors is important in situations like the Japanese nuclear crisis because the heightened environmental levels of radiation in the ocean near the complex (which are 127 times normal background levels) would not even show up on a typical Geiger counter.  The information scintillation detectors gather from radiation can even be used to identify different radioactive isotopes.  Devices such as the D-tect Systems MiniRad-D (a personal handheld detector) and Rad-ID (a handheld radiation detector and identifier) and regularly used by security personnel and individuals in such situations to detect and, where necessary, identify the types of radioactive materials a person has been exposed to.

The procedures outlined by government agencies are carefully adapted to each dangerous situation and should be strictly adhered to.  These procedures aim to limit the spread of radiation and minimize risk to exposed areas.  Although the specific instructions given out for each incident vary, here are a few general guidelines that should always be followed. 

First, in case of radiation contamination, get people (including yourself) out of harm’s way as quickly as possible and notify authorities. Radiation spreads easily though blowing dust and smoke, so radiation-free secure zones must be established by sealing off areas from the outside environment by closing and weather-proofing doors and windows and placing food and water in well-insulated areas such as basements.

Second, since human skin generally acts a good barrier against low-level radiation, the biggest threat is breathing in radioactive materials or somehow ingesting them.  Make sure to wear a face mask in areas that may be contaminated and wash hands regularly.  If you suspect someone has been exposed to radioactive dust, the best solution is usually as simple as discarding contaminated clothing and washing with soap and water, as this will rid the body of radiation before it can cause damage.  As an additional guard against significant amounts of radiation, potassium iodide tablets are sometimes given to protect to the thyroid gland.

Third, preparation is vital when it comes to any kind of disaster, and we recommend everyone keep an emergency kit close at hand so that they can be personally prepared in case of any crises.  This kit should include such things as food and water for a few days, water filtration kit, emergency blanket, rain gear, batteries for radios and detectors, dust mask, extra clothing, flashlight, candles, waterproof matches, cooking utensils, necessary medications, and a first aid kit.  Although we generally take these supplies for granted, shortages can occur quickly in crisis situations.   

Although the current nuclear crisis is fraught with unanswered questions, appropriate preparation will enable you to minimize potential risks and provide you the ability to safely navigate through any crises, including potential radiation exposure.

Japan's Nuclear Crisis

Last week one of the largest earthquakes on record shook Northern Japan and triggered a devastating tsunami.  The damage is extensive: so few roads and runways are open that even humanitarian supplies have been seriously delayed.  But the greatest fear of the country isn’t the washed out roads or flattened villages.  It’s an invisible phenomenon with huge historical significance to the Japanese: the threat of nuclear radiation is rising like a ghost recalled from the past.

Nuclear power doesn’t make many headlines these days.  Until last Friday, nuclear plants have been considered in many parts of the world to be the best economical solution to growing power needs.  Japan has 55 nuclear reactors, providing approximately a quarter of the country’s power.  Advancing nuclear technologies have made power more efficient and seemed to invalidate radiation risks illustrated so horrifically by incidents at Chernobyl and Three-Mile Island.  But it is clear that innate nuclear power risks, however diminished, remain.

Japanese security personnel at the nuclear complex.  Photo credit cnn.com.

 The setting for the nuclear showdown in Japan is the Fukushima Dai-ichi nuclear complex.  Although this reactor, as well as two others, ceased operations as soon as the magnitude 9.0 earthquake hit, consequent damage to the structure has destabilized the normal cooling operation of the plant and lead to an atomic crisis.  Three hydrogen gas explosions have already rocked the plant, providing evidence that the fuel rods are at above normal temperatures.  Japanese authorities have already announced that steam from a nuclear cooling pond (used to cool the fuel rods) has been released into the atmosphere, meaning that some radiation has already leaked from the plant.  At this point, quantities of released radiation are unknown, but could rise dramatically if cooling of the reactor core is unsuccessful or a breach in the reactor wall occurs. 

But what is the real danger of nuclear radiation?  Unlike other forms of radioactive materials, such as those used commonly in hospitals and industry, nuclear materials are very heavily controlled throughout the world, and for good reason.  Nuclear materials, such as plutonium and uranium, give off neutrons at extremely high energy levels as their nuclei decay.  This kind of radiation easily passes through most matter, but can affect body tissues enough to cause serious medical problems. Short-term nuclear exposure can cause infections, hair loss, and fevers, and in extreme cases, organ failure and death.  Long-term exposure can cause cancer, tumors, and genetic damage.  Even shielded nuclear radiation sources can emit gamma radiation, which brings other health risks. 

The nature of this nuclear crisis, as well as many related scenarios, requires the use of a combination of radiation detectors all working together to minimize risks.  Our products are designed for just this.  In case of a radiation release, a perimeter could be set up using small, handheld MiniRad-D devices.  These pager-sized radiation detectors can sense radiation from tens of meters away.  The MiniRad-D could also be used to check personnel leaving the nuclear zone to determine if decontamination is needed.

The MiniRad-D is self-calibrating and uses a high-sensitivity scintillation detection system.

 The Rad-D unit is ideal for placement in unmanned locations to monitor ambient changes to radiation levels.  The system requires no maintenance and sophisticated neutron detectors can be configured into the system as well as gamma detectors. 

At the forefront of the crisis, specialized equipment designed for finding and identifying the type of radiation is needed.  The high-energy nature of nuclear radiation tends to saturate detectors and is hard to differentiate from gamma radiation.  Special neutron detector systems, such as the Helium-3 gas-filled tubes used by D-tect Systems in both the Rad-ID and Rad-D systems, sort out gamma rays and detect and identify neutron radiation.  The Rad-ID also contains a combination of detector types to find radiation over a wide range of energies, and from large amounts of radiation to sources emitting just above background radiation.

The Rad-ID can identify over 110 radioactive isotopes.

 We hope for the best in the Japan’s current nuclear crisis and that future wise decisions will mitigate the risks involved with nuclear power.

Radiation Detector Overview

“The only thing constant in life is change.” -  François de la Rochefoucauld

Although they report on thousands of different stories each day, the covers of newspapers in recent weeks have all carried a similar theme – instability.  On-going political changes in many parts of the world, as well as the rapid power transfers and challenges in the Egypt, Yemen, Libya, and many bordering countries have made it clear that political unrest is on the rise.  Recent upheavals have also made it clear that finding security in an increasingly unstable world is a difficult task. 

Adding to political turmoil, terrorist organizations have become increasingly aggressive in both their tactics and technology.   The release of diplomatic cables lays bare new plans by terrorist organizations, such as the Taliban, to construct ‘dirty bombs’ – weapons designed to spread radioactive material over large areas.  We here at D-tect Systems focus on this increasingly relevant area of that security effort: radiation detection. 

With dozens of detector types utilized of literally thousands of radiation detection products, matching the right technology to a threat is a daunting task.  To make this search a little easier, we’ve compiled a general overview of some of the main radiation detectors currently in use.

Geiger-Mueller Tubes, with low sensitivity and a wide range, are the most commonly used detectors on the market.  Available in sizes from ring-worn dosimeters to giant cargo scanners, Geiger-Mueller detectors can pick up certain types of alpha, beta, and gamma radiation.  The downside to these kind of detectors is that they are much less sensitive to radiation than other detector types and cannot differentiate between radiation types.  They are also too slow to detect moving radiation, but are cheap and durable.

Sodium Iodide (NaI(Tl)) and Cesium Iodide (CsI(Tl)) are among the most common gamma radiation detectors.  These two types of materials are commonly referred to as inorganic scintillators because of their composition and method for detecting radiation.  Unlike Geiger-Mueller Tubes, they are fast, sensitive, and can measure the actual energy of gamma rays.  D-tect Systems’ MiniRad-D and MiniRad-V devices uses CsI(Tl) detectors equipped with photo-multiplier tubes that allow the operator to detect radiation from tens of meters away.  

CsI(Tl) detectors, like those used in the MiniRad-D, can detect gamma radiation from even some shielded sources.

Plastic Scintillators (PVT) use the same detection method as NaI(Tl) and CsI(Tl) detectors but usually require much larger detector sizes the achieve the same sensitivity.  They are commonly used in high-volume portal monitors and come in a variety of shapes and sizes.

Lanthanum Bromide (LaBr3) detectors are capable of finding energy peaks more quickly (known as detector efficiency) than a corresponding NaI(Tl) detector, but LaBr3 detectors exhibit internal radioactivity that reduces its spectral resolution at energies below 100 keV.  The current cost of LaBr3 detectors is generally much higher than that of comparable NaI(Tl) detectors. 

 

High Purity Geranium (HPGe) detectors figure into the top end of radiation detection and identification.  Devices using HPGe detectors are able to identify isotopes 2-3 more quickly than NaI(Tl) partly because they need sense far less radiation to come up with an identification.  The downside to this type of detectors is that HPGe detectors must be cooled with liquid nitrogen to operate, which makes HPGe devices bulky and much more expensive than scintillator units.

Cadmium Zinc Telluride (CZT) detectors have higher resolution and stability (for gamma rays and x-rays) than NaI(Tl), but are expensive in large crystal volumes.  Many CZT systems contain arrays of multiple small CZT detectors because the detection sensitivity increases with volume and some directionality can be established this way.  The Rad-ID device by D-tect Systems is available in configurations that contain four or eight CZT crystals, as well as a large NaI(Tl) detector. The combination of multiple detector types allows the Rad-ID to quickly and accurately identify over 110 radioactive isotopes.

Detection systems for neutron radiation (extremely high-energy radiation produced by elements such as Uranium and Plutonium) are also critical for security.  This type of radiation only comes from a few highly-controlled materials. The most commonly used neutron radiation technology involves the use of He3 tubes and requires relatively large volumes.  D-tect Systems’ Rad-ID device has neutron radiation detection capabilities with an optional He3 tube.

So whatever kind of radiation detection you need, we hope this short overview allows you to make informed decisions to help ensure security in an unstable world.