Fukushima: Long Term Impact

The gripping drama that unfolded during this month last year filled headlines and news hours all across the world.  On March 11th last year, a huge earthquake and tsunami left more than 20,000 people dead or missing in eastern Japan.  Amidst widespread destruction, the tsunami slammed into the Fukushima Daiichi Nuclear Power Station, disabling cooling systems and leading to fuel meltdowns in three of the six nuclear units.  As invariably occurs, after a few months the media coverage moved on, even though countless problems remain unresolved.  

So why hasn’t the radiation washed away or faded into neutrality?  This same query has plagued eastern Europeans for over 25 years as they continue to deal with heightened radiation levels stemming from the Chernobyl disaster. The answer is that radioactive materials released into the environment in both of these catastrophes are extremely finely dispersed and will last for decades.  In fact, just controlling the spread of radiation has become higher priority than cleaning up the mess in many cases.

In a nutshell, radioactive elements are unstable atoms. They seek stability by giving off particles and energy—ionizing radiation—until the radioisotope becomes stable. This process occurs within the nucleus of the radioisotope, and the shedding of these particles and energy is commonly referred to as ‘‘nuclear disintegration.’’  During their disintegration, most radioactive elements morph into yet other radioactive elements on their journey to becoming lighter, stable atoms. Some of the morphed-into elements are much more dangerous than the original radioisotope, and the decay chain can take a very long time¹. This is the reason that radioactive contamination has a variable lifespan, depending on the composition of the radioactive material. For more information on this topic, see this post on radioactive lifespans.

The most common contamination radionuclides in the Japanese crisis are cesium-134 (with a half-life of 2 years) and cesium-137 (with a half-life of 30 years).  Radiological risk assessment expert John Till, president of the U.S.-based Risk Assessment Corporation, says the fallout will probably be gone from the surface of plants within a few years, but attach strongly, through ion exchange, to soil — in particular to the clay soils common throughout Fukushima². From there, the rate and risk level at which cesium will move into plants is still unclear.  And the oceans are a different matter: sediment levels and changing currents make radioactive duration almost impossible to estimate.

Japanese soldiers collect contaminated leaves near the Fukushima nuclear power plant in December. source

 

All of this information adds up to the need for sustained radiation observation.  In particular, on-going dose rate measurements are essential to avoid overexposure to people, animals, and crops.  Since much of the radiation is mobile, weather changes can cause radiation levels to rapidly fluctuate.  This is a common occurrence in Japan, where after a rain storm brings down radioactive particles, the sun and wind can produce radioactive dust clouds that travel in unpredictable ways.  The mobility of these radioactive particles requires constant monitoring to warn people and keep them indoors on increased risk days.

Not only do these detectors need to consistently and accurately make measurements, they also need to efficiently relay information to analysis locations.  A self-healing mesh network is ideal for this kind of seamless measurement and communication.  This kind of network routes around disabled detectors and can incorporate new detectors at any location in the network.  The Rad-DX, D-tect’s newest addition, operates on the D-tect SensorNet – a mesh network with these capabilities.  To learn more about the SensorNet, visit this page. 

Although the cleanup in Japan may take decades, conditions are steadily improving.  With careful and constant radiation monitoring and improvements to safety standards, future risks may be mitigated.

1: http://www.oecd-nea.org/press/press-kits/fukushima-faq.html

2: http://www.energybulletin.net/stories/2012-01-09/fukushima-cleanup-begins-long-term-impacts-are-weighed

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

My Trip to Japan

While in Japan, I was paired with a group that was sent to check on the structural integrity of several church buildings in several cities. My role was to show them how to use the equipment and gauge the levels of radiation at each site. To check on these levels I went armed with two different radiation detectors: the MiniRad-D (a small, pager-sized detector) and the Rad-ID (a portable radiation identifier).

In my visits to cities from Tokyo to Iwaki I checked radiation levels and talked with the local church officials about what those levels meant. Radiation levels in downtown Tokyo were near natural background levels but the closer I got to Fukushima, the higher the radiation levels rose. The cities I visited showed readings of anywhere from 0.35 µSv/hr to 2 µSv/hr above background radiation, which are elevated levels, but definitely not dangerous. Using the Rad-ID, I found out that most of the radiation came from the radioactive isotopes Co-60, I-131, I-132, and Cs-137, which are commonly given off in nuclear processes.


An interesting observation that I made was that storm drains in the areas I visited showed higher levels of radiation than the surrounding areas. I surmised that rainfall had carried down and collected some of the radioactive dust in the air and deposited the contamination as it flowed down these drains.


Although the Japanese have shown amazing resilience and are working as hard as they can to solve these enormous problems, there is still much uncertainty about health risks and what the future will bring. We’ll be back soon to check on the radiation levels again. If you’d like to brush up on your radiation basics, you can check out this sheet we’ve complied. It has basic conversions, safety levels, and doses to put radiation exposure in perspective. An interesting chart on radiation dose rates can be found here.

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.

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.