Lees_Garage
03-18-2011, 02:24 AM
Came across this article. It is a quite lengthy article, but is very informative and I thought it might be helpful. This was written by Brett Edward LaVigne
Nuclear info for people tired of the ignorant Media
by Brett Edward LaVigne on Thursday, March 17, 2011 at 7:05pm
For those who don't know me, or don't know what I do for a living. I am an ANSI qualified Radiation Protection Technician. I have worked in the nuclear field for more than 21 years, mostly commercial nuclear plants. I would like to share some information from a nuclear professional standpoint.
With all of the chaos in Japan, and all of the poor reporting on CNN, FOX or pretty much any other news outlet concerning the nuclear part of the disaster, I feel compelled to help. Help those of my friends that do not work in the nuclear industry understand what to be worried about and not. I want to write about the worst accident there has ever been in our industry and how it impacted the surrounding communities immediately after the accident and years after, Chernobyl. There are a few facts throughout the following that are important to note as a comparison between our plants and their plants, I'll point them out. Also I would like to briefly talk about the accident that happened in Pennsylvania, where we had similar type events happen as the one in Japan (ie. Loss of coolant, melted fuel, hydrogen explosion).
First, I would like to clarify some terms and what they mean. The media has done an incredible job of completely confusing everyone by their blatant ignorance on nuclear power and radiological terms. Believe me when I say, they don’t have the first idea of what this really is. I don’t want to say that there is no good information coming from them, there is melted fuel, there have been several hydrogen explosions, and the situation is quite dire…that much I will give them. However, their reporting on the potential and current impacts, and comparisons to the Chernobyl accident are completely directed at causing wide spread panic and are completely misguided. I must assume that due to the fact that they only give significant interview time to so-called “experts” that do not speak intelligently about these issues. They don’t use terms correctly and exaggerate the possible outcomes. If someone can not differentiate between Radiation, Radioactivity, Contamination and use them in the correct way, how can they know anything beyond that? These terms and their usage are one of the most basic things that nuclear workers know, and these “experts” can’t even get them right!
A few terms and definitions, some that are commonly confused by the media and some that are helpful in understanding radiological hazards:
Ionizing: This is the term that refers to a given radiations ability to strip an electron from an atom creating an ion pair (the free electron along with the original atom minus an electron is called an Ion Pair). Things like radio waves, visible light and infrared are all examples of Non-Ionizing radiation that does not have the energy to remove electrons. Gamma/X-Ray, Beta, Alpha and Neutron radiations are examples of Ionizing Radiation that DO have the energy required to strip an electron.
Ionizing Radiation: This is the energy that is released in the form of photons(very energetic light waves with energy above infrared, basically in the X-Ray energy range) and/or highly charged atomic particles. This happens when an atom is unstable (having a different number of electrons vs. protons = radioactive). The atom will emit energy (Ionizing radiation) until it reaches a stable state (equal electrons to protons).
Half Life: The amount of time it takes for a Radioactive Isotope to decay to one half of its original activity. Typically, radioactivity is reduced to negligible levels after about 7 to 8 half lives. For example, one curie of I-131 decays to 0.5 curies in 8 days. After approx. 55 – 60 days, it is effectively gone.
Contamination: This is nothing more than radioactive materials in an area you don’t want them. This can be anything from corrosion products like Cobalt-60 (basically rust within the plant system that encounters neutron bombardment within the core of the operating reactor causing it’s atoms to become unstable) to Americium-241 (an unstable isotope created within the fuel it self that is undergoing fission). There are many more than that, but this example should do.
Radioactivity: Refers to the capacity of a radioactive material to emit radiation.
For an example: The media continualy refers to radiation “leaking” from the plant, or a radiation cloud or plume. They have even refered to it as “Explosive Radiation leaking from the damaged reactor"
Radiation does not “leak” out of anything. Radioactive Material can leak out or be released. There is no such thing as a plume of radiation, there IS such a thing as a plume of radioactive material which in turn emits Radiation. And that radiation is NOT explosive!
Radiation Exposure, US Federal Limits, Threshold limits and associated damage to human beings
Radiation Exposure: Radiation exposure is basically a measurement of energy that was deposited within your body as a result of exposure to Ionizing Radiation. This exposure is denoted in the unit REM (Radiation Equivalent Man). Because of the variying types of radiation and how they affect our cells in a different manor from each other, we must use a quality factor (damage potential factor) that can be related to a single term that refers to the damage in the human body. RAD(Radiation Absorbed Dose) is a general term that relates the effects to any type of material, REM is a conversion from RAD that specifically speaks to the damage (potential) to human cells.
A persons exposure to radiation can not be measured by a hand-held instrument. If you receive a radiation exposure or “dose”, there is nothing left behind (inside you or on you) to measure. The way a persons radiation exposure is measured is by wearing a TLD (Thermo-luminescent Dosimeter or film badge), Whole body gamma counts (very sensitive, stationary counter) to measure how much radioactive material your body has taken in, Bioassay sample (fecal, urine or other that is gamma counted to quantify the type and amount of radioactive material inside the body), and dose estimates based on how long a person was in a certain area compared to the known radiological conditions in that area. A persons total exposure is a combination of exposure to outside sources of penetrating radiation (Gamma, Neutron, and Beta which generally only gives dose to the skin and lens of the eyes when exposed externally, but can effectively equate to deep dose in higher energy ranges similar to Gamma) and internal exposure from radioactive materials that have been taken into the body (Alpha, Beta and there is usually Gamma as well
What are the limits for expoure to ionizing radiation, and what are dangerous levels that can actually do harm? In the United States, trained and monitored nuclear workers are held to a several limits. The different organs of the human body have different tollerances for exposure to radiation. There is a whole body limit that refers to external dose plus internal organ dose (where the different organs are assigned a “weighting factor” based on their individual radio-sensitivity). That Whole Body Anual Limit is 5000 millirem. The most radiosensitive areas of the body are blood-forming organs like the large bones, liver etc. and the sex organs. Some of the lesser radiosensitive areas are extrmities like the arm below the elbow to the fingers, the legs below the knee to the toes, skin, and believe it or not, one of the least radiosensitive areas...the brain and nervous system. Below I will list the federal limits for us and then the thresholds for noticable damage to the body up to death from Acute Radiation Sickness
Annual Federal Limits for trained/monitored Radiation Workers in the US:
Whole Body (Internal plus External dose): 5,000 Millirem or 5 Rem
Extrmities (below the elbows, below the knees) and skin: 50,000 Millirem or 50 Rem
Lens of the eyes : 15,000 millirem or 15 Rem
Any internal organ: 50,000 millirem or 50 Rem
Fetus of a monitored worker: 500 millirem or .5 Rem total gestation period.
Unmonitored members of the public: 100 millirem from licensed facilities.
Note: all of the above are annual besides the fetus limit
For conversion to international units that are being reported: 1 milliSevert equals 0.1 Rem or
100 milliRem
Threshold limits where damage to human cells can be observed up to Death from Acute Radiation Sickness
There are two different definitions when it comes to radiation exposure and how it can potentially cause damage.
Chronic exposure: Relatively small doses of exposure over longer periods of time.
Acute Exposure: Large doses of exposure over short periods of time.
Acute exposures are the ones that cause immediate damage to the extent you can observe evidence of damage to the body. So that is the exposure I want to outline. Acute exposure is what people are exposed to in an accident like Chernobyl or the one in Japan and is of the highest concern. Chronic exposure from contamination left over after the accident may or may not relate to health problems years down the road. If interested, search the net for Hiroshima/Nagasaki radiation exposure studies that detail the long term effects of chronic exposure.
These are numbers that are ballpark. Remember that 1000 milliRem is equal to 1 Rem. For the sake of saving zeros, I will use Rem. Also remember that the average American receives around 350 milliRem/yearly from natural sources and medical procedures such as dental x-rays. Nuclear workers like myself recieve an average of around 500 – 1000 MilliRem/yearly additional dose from chronic, occupational exposure
Acute Exposure Thresholds
50 Rem: Noticeable blood changes, will most likely have no other short term effects
100 Rem: Vomiting along with the blood changes. Still a very good chance of long term survival assuming medical care
150 Rem: Mortality threshold. Still a majority chance of long term survival assuming medical care.
320 – 360 Rem: This is the known 50/60 threshold where it is expected that 50% of the exposed people will die within 60 days of the initial exposure. This is assuming limited or no medical care.
480 – 540 Rem: This is the known 50/60 threshold where it is expected that 50% of the exposed people will die within 60 days of the initial exposure. This assumes advanced medical care.
800 Rem: This is the 100% fatality threshold where all exposed are expected to die from Acute Radiation Sickness.
Can taking potassium iodide really help?
The answer is yes. One of the most immediately damaging isotopes released in an accident is I-131(RadioIodine). This isotope really likes the thyroid gland and tends to settle there. This was the most impactfull thing to the public right after the Chernobyl accident. Particularly the youngest people. Taking Potassium Iodide prior to exposure to I-131 will saturate the thyroid gland and help prevent the thyroid from taking in I-131, allowing the body to eliminate it and not retain significant amounts that can lead to Thyroid cancer.
RadioIodine or I-131 is a radioactive isotope that is extremely abundant during fission. It has an 8 day half life and is really only a hazard for a few weeks after a release. During an accident like Chernobyl, it is one of the most abundant isotopes released.
So how does Radiation hurt the body?
There are a few things that could possibly result from radiation exposure at all levels, but of course the potential increases along with the dose recieved. The radiation could pass through your body and never interact with any of your cells.
The radiation could damage a cell/cells and then the cell/cells could repair themselves. This is the most common scenario for chronic exposure within the federal limits.
The radiation could damage the cell and kill it.
The radiaiton could damage the cell and then the cell mutates (cancer basically)
How ionizing radiation damages our cells is through depositing energy to the atoms of the cell and ionizing them by removing electrons. As many of you already know, we are mostly made up of water (H2O). When ionization occurs within your cells, it can create a variety of combinations. Most of the time you will have a ion pair combination of H2 and O which will most likely recombine to H2O and effectively be repaired, no harm no foul. One of the combinations that could occur is Hydrogen Peroxide, which is a poison to our cells and will make it die. Free radicals can also be formed which can promote cancer and can damage DNA.
There are two different types of effects to humans from damage after exposure to Ionizing radiation.
Somatic effects: A term used to describe the effects on the person that was actually exposed to the radiation.
*Genetic Effects: A term used to describe the passed down, genetic effects to the off-spring of the person that was actually exposed.
*Note: Genetic effects are purely theroretical. There has never been a proven case of genetic mutations in the offspring of a human that was exposed acutely or chronicly to Ionizing Radiation. The children of Chernobyl who had deformities or thyroid/other cancers related to the exposure from the accident were still Somatic effects. Their health issues stem from being directly exposed to the radiation while in the womb. Same goes for the Hiroshima/Nagasaki bombs.
Ok, now that you have a little information about Ionizing Radiation and its effects, lets talk about the accidents.
Chernobyl:
On April 26, 1986 the worst nuclear accident in history occurred in the Ukraine Republic of the Soviet Union. The plant was operating at the time, there were safety systems that were bypassed and a lot of human error involved in the accident, really not important for this. What is important to know are the differences between US (and Japan) nuclear plants and the Chernobyl nuclear plant? The biggest difference is the total lack of a containment building. Our US plants (and Japan) ALL have a primary containment building that is typically a web of re-bar surrounded by concrete, 4+ feet thick. Inside of this circular building are all of the most vital parts of the plant including the reactor pressure vessel which of course contains the nuclear fuel that is undergoing fission. This is also a very formidable chuck of metal several inches thick that is capable of slowing the progression of melted fuel. This is the same type of containment that contained the hydrogen blast, fuel melting and ultimately prevented a massive disaster at Three Mile Island in Harrisburg Pennsylvania. We'll get to that later.
Chernobyl was basically built in a pole barn. So when the accident happened, the reactor went super-critical, blew the HUGE reactor head into the air and released Millions of Curies of assorted radioactive isotopes into the atmosphere. One of the most immediately damaging isotopes released was Radioactive iodine-131. This isotope has an affinity for the thyroid gland. It only has an 8 day half life so the threat is right after the release and up to a couple of months, after which time it will have effectively decayed off to negligible levels. The ones most impacted were children, infants and fetus. Due to the fast rate of cell division in younger people, the chance for cell mutation is much higher than in adults. Their government did very little to help these communities in the short term after the accident. Had people been evacuated in a more timely manor, given potassium iodide, and prevented from coming back for a time, it would have saved many from Thyroid cancer. There are lots of other things that get released as well. Transuranics (isotopes with a higher atomic number than Uranium), generally produced in a nuclear reaction. These are typically Alpha emitters and pose significant health risks internally. Americium and Plutonium are a couple you may recognize.
The total radioactive release of the Chernobyl accident was hundreds of times more than the atomic bombs dropped on Hiroshima or Nagasaki, however, they are really different animals and hard to compare. Atomic bombs generally have shorter lived isotopes released making the affected land area inhabitable in a shorter period of time. The explosion associated with a bomb is what causes most of the damage and loss of life which is exponentially more than a reactor accident of any magnitude. Most all of the impacted areas from the Chernobyl accident are now inhabitable and have had residents since the accident.
So how many people actually died from the worst nuclear accident in history? It’s hard to put a firm number on that. We know that in the initial accident and response, <span>237 people suffered from acute radiation sickness, 31 of the diagnosed actually died within the first three months. Most of these were fire and rescue workers trying to bring the accident under control. There were no further deaths identified, in the general population affected by the disaster, as being caused by ARS (acute radiation sickness). It is also thought that there may be as many as 4000 total deaths from cancer related to the accident of the 600,000 people considered to be the highest exposures due to the accident. Not to downplay the impact of this accident, but consider that this represents a .6% increase in Thyroid cancer over the course of about 20 years. This increase is due to the acute, short term exposures to I-131 right after the accident and mostly in the youngest of the population. This also outlines the importance of government response to an accident like this. Getting people out of the immediate affected areas and distributing Sodium Iodide to reduce the impact of Radioiodine on the Thyroid gland. While even one person lost is one too many, I think when looked at in terms of percentages, the overall impact on human life in this “worst-case” accident demonstrates how over-blown the media makes it sound. Again, it is horrible either way and I don’t want to take away from that fact, it just needs to be put in context.
For comparison, just in the United States, nearly 500,000 people die each year from illnesses related to smoking. The percentages of people who died related to the nuclear accident vs the population exposed to the radiation is far less than the expected mortality rate for people who smoke. Still doesn't make me feel any better about the people who died because of the Chernobyl accident, just wanted to draw that comparison.
Three Mile Island
In a nutshell, because there is simply not much to talk about in terms of impact on human life or health.
In 1979, one of the units at Three Mile Island in Harrisburg, PA underwent a Loss of Coolant Accident. Much like the issues in Japan right now, the core of the operating reactor was unable to be cooled due to a relief valve that was stuck open. This allowed much of the primary coolant to escape resulting in a partially melted core, hydrogen buildup and explosion and release of up to 13 million curies of I-131. The plant was brought under control pretty quickly which prevented a full blown meltdown. The impact to the surounding public was exactally...zero. No one died, no one got sick. With the exception of the one unit that had the accident, Three Mile Island is safely generating power to this day.
The events that are unfolding in Japan are very significant, but even if all of the units undergo a complete meltdown, it will pale in comparison to the Chernobyl accident. Chernobyl literally exploded due to super-criticality, sending millions and millions of curies into the atmosphere unchallenged by any containment structures. Unlike the plants in Japan and the US, Chernobyl was a Graphite moderated reactor (we use water). The Graphite ignited during the accident and blazed for 10 days, this was a significant contributer to the total radioactive release of the accident. Because of containment structures that are in place (Japan), and the fact that all fission automatically stopped when the earthquake happend (auto scram), there was no super-critcal explosions. Even if there would have been, it would not have had the same outcome as Chernobyl. Once fuel starts to melt, it looses its very important geometry and can no longer sustain a chain reaction (fission). This means that there is no way that these (Japan) plants can release quantities of radioactive isotopes that Chernobyl did, not even a significant fraction. Most of the activity that will be released from this accident will be short lived gases. There will be a release of some of the heavier isotopes, but not anything like Chernobyl because there was no super-critcal explosion sending the actual core into the atmosphere. People in the United states should not have a single worry about what the impact will be in our country. By the time any I-131 could reach us, it will have gone through at least a few half-lifes along with being diluted by the massive volume of our atmosphere. There is no reason to take Potassium Iodide or take any other action to protect yourself from radioactive fallout. We will see environmental increases in radioactivity, but they will be so miniscule that they are not worth mentioning in terms of human health in our country.
I hope that this helped.
Brett LaVigne
Nuclear info for people tired of the ignorant Media
by Brett Edward LaVigne on Thursday, March 17, 2011 at 7:05pm
For those who don't know me, or don't know what I do for a living. I am an ANSI qualified Radiation Protection Technician. I have worked in the nuclear field for more than 21 years, mostly commercial nuclear plants. I would like to share some information from a nuclear professional standpoint.
With all of the chaos in Japan, and all of the poor reporting on CNN, FOX or pretty much any other news outlet concerning the nuclear part of the disaster, I feel compelled to help. Help those of my friends that do not work in the nuclear industry understand what to be worried about and not. I want to write about the worst accident there has ever been in our industry and how it impacted the surrounding communities immediately after the accident and years after, Chernobyl. There are a few facts throughout the following that are important to note as a comparison between our plants and their plants, I'll point them out. Also I would like to briefly talk about the accident that happened in Pennsylvania, where we had similar type events happen as the one in Japan (ie. Loss of coolant, melted fuel, hydrogen explosion).
First, I would like to clarify some terms and what they mean. The media has done an incredible job of completely confusing everyone by their blatant ignorance on nuclear power and radiological terms. Believe me when I say, they don’t have the first idea of what this really is. I don’t want to say that there is no good information coming from them, there is melted fuel, there have been several hydrogen explosions, and the situation is quite dire…that much I will give them. However, their reporting on the potential and current impacts, and comparisons to the Chernobyl accident are completely directed at causing wide spread panic and are completely misguided. I must assume that due to the fact that they only give significant interview time to so-called “experts” that do not speak intelligently about these issues. They don’t use terms correctly and exaggerate the possible outcomes. If someone can not differentiate between Radiation, Radioactivity, Contamination and use them in the correct way, how can they know anything beyond that? These terms and their usage are one of the most basic things that nuclear workers know, and these “experts” can’t even get them right!
A few terms and definitions, some that are commonly confused by the media and some that are helpful in understanding radiological hazards:
Ionizing: This is the term that refers to a given radiations ability to strip an electron from an atom creating an ion pair (the free electron along with the original atom minus an electron is called an Ion Pair). Things like radio waves, visible light and infrared are all examples of Non-Ionizing radiation that does not have the energy to remove electrons. Gamma/X-Ray, Beta, Alpha and Neutron radiations are examples of Ionizing Radiation that DO have the energy required to strip an electron.
Ionizing Radiation: This is the energy that is released in the form of photons(very energetic light waves with energy above infrared, basically in the X-Ray energy range) and/or highly charged atomic particles. This happens when an atom is unstable (having a different number of electrons vs. protons = radioactive). The atom will emit energy (Ionizing radiation) until it reaches a stable state (equal electrons to protons).
Half Life: The amount of time it takes for a Radioactive Isotope to decay to one half of its original activity. Typically, radioactivity is reduced to negligible levels after about 7 to 8 half lives. For example, one curie of I-131 decays to 0.5 curies in 8 days. After approx. 55 – 60 days, it is effectively gone.
Contamination: This is nothing more than radioactive materials in an area you don’t want them. This can be anything from corrosion products like Cobalt-60 (basically rust within the plant system that encounters neutron bombardment within the core of the operating reactor causing it’s atoms to become unstable) to Americium-241 (an unstable isotope created within the fuel it self that is undergoing fission). There are many more than that, but this example should do.
Radioactivity: Refers to the capacity of a radioactive material to emit radiation.
For an example: The media continualy refers to radiation “leaking” from the plant, or a radiation cloud or plume. They have even refered to it as “Explosive Radiation leaking from the damaged reactor"
Radiation does not “leak” out of anything. Radioactive Material can leak out or be released. There is no such thing as a plume of radiation, there IS such a thing as a plume of radioactive material which in turn emits Radiation. And that radiation is NOT explosive!
Radiation Exposure, US Federal Limits, Threshold limits and associated damage to human beings
Radiation Exposure: Radiation exposure is basically a measurement of energy that was deposited within your body as a result of exposure to Ionizing Radiation. This exposure is denoted in the unit REM (Radiation Equivalent Man). Because of the variying types of radiation and how they affect our cells in a different manor from each other, we must use a quality factor (damage potential factor) that can be related to a single term that refers to the damage in the human body. RAD(Radiation Absorbed Dose) is a general term that relates the effects to any type of material, REM is a conversion from RAD that specifically speaks to the damage (potential) to human cells.
A persons exposure to radiation can not be measured by a hand-held instrument. If you receive a radiation exposure or “dose”, there is nothing left behind (inside you or on you) to measure. The way a persons radiation exposure is measured is by wearing a TLD (Thermo-luminescent Dosimeter or film badge), Whole body gamma counts (very sensitive, stationary counter) to measure how much radioactive material your body has taken in, Bioassay sample (fecal, urine or other that is gamma counted to quantify the type and amount of radioactive material inside the body), and dose estimates based on how long a person was in a certain area compared to the known radiological conditions in that area. A persons total exposure is a combination of exposure to outside sources of penetrating radiation (Gamma, Neutron, and Beta which generally only gives dose to the skin and lens of the eyes when exposed externally, but can effectively equate to deep dose in higher energy ranges similar to Gamma) and internal exposure from radioactive materials that have been taken into the body (Alpha, Beta and there is usually Gamma as well
What are the limits for expoure to ionizing radiation, and what are dangerous levels that can actually do harm? In the United States, trained and monitored nuclear workers are held to a several limits. The different organs of the human body have different tollerances for exposure to radiation. There is a whole body limit that refers to external dose plus internal organ dose (where the different organs are assigned a “weighting factor” based on their individual radio-sensitivity). That Whole Body Anual Limit is 5000 millirem. The most radiosensitive areas of the body are blood-forming organs like the large bones, liver etc. and the sex organs. Some of the lesser radiosensitive areas are extrmities like the arm below the elbow to the fingers, the legs below the knee to the toes, skin, and believe it or not, one of the least radiosensitive areas...the brain and nervous system. Below I will list the federal limits for us and then the thresholds for noticable damage to the body up to death from Acute Radiation Sickness
Annual Federal Limits for trained/monitored Radiation Workers in the US:
Whole Body (Internal plus External dose): 5,000 Millirem or 5 Rem
Extrmities (below the elbows, below the knees) and skin: 50,000 Millirem or 50 Rem
Lens of the eyes : 15,000 millirem or 15 Rem
Any internal organ: 50,000 millirem or 50 Rem
Fetus of a monitored worker: 500 millirem or .5 Rem total gestation period.
Unmonitored members of the public: 100 millirem from licensed facilities.
Note: all of the above are annual besides the fetus limit
For conversion to international units that are being reported: 1 milliSevert equals 0.1 Rem or
100 milliRem
Threshold limits where damage to human cells can be observed up to Death from Acute Radiation Sickness
There are two different definitions when it comes to radiation exposure and how it can potentially cause damage.
Chronic exposure: Relatively small doses of exposure over longer periods of time.
Acute Exposure: Large doses of exposure over short periods of time.
Acute exposures are the ones that cause immediate damage to the extent you can observe evidence of damage to the body. So that is the exposure I want to outline. Acute exposure is what people are exposed to in an accident like Chernobyl or the one in Japan and is of the highest concern. Chronic exposure from contamination left over after the accident may or may not relate to health problems years down the road. If interested, search the net for Hiroshima/Nagasaki radiation exposure studies that detail the long term effects of chronic exposure.
These are numbers that are ballpark. Remember that 1000 milliRem is equal to 1 Rem. For the sake of saving zeros, I will use Rem. Also remember that the average American receives around 350 milliRem/yearly from natural sources and medical procedures such as dental x-rays. Nuclear workers like myself recieve an average of around 500 – 1000 MilliRem/yearly additional dose from chronic, occupational exposure
Acute Exposure Thresholds
50 Rem: Noticeable blood changes, will most likely have no other short term effects
100 Rem: Vomiting along with the blood changes. Still a very good chance of long term survival assuming medical care
150 Rem: Mortality threshold. Still a majority chance of long term survival assuming medical care.
320 – 360 Rem: This is the known 50/60 threshold where it is expected that 50% of the exposed people will die within 60 days of the initial exposure. This is assuming limited or no medical care.
480 – 540 Rem: This is the known 50/60 threshold where it is expected that 50% of the exposed people will die within 60 days of the initial exposure. This assumes advanced medical care.
800 Rem: This is the 100% fatality threshold where all exposed are expected to die from Acute Radiation Sickness.
Can taking potassium iodide really help?
The answer is yes. One of the most immediately damaging isotopes released in an accident is I-131(RadioIodine). This isotope really likes the thyroid gland and tends to settle there. This was the most impactfull thing to the public right after the Chernobyl accident. Particularly the youngest people. Taking Potassium Iodide prior to exposure to I-131 will saturate the thyroid gland and help prevent the thyroid from taking in I-131, allowing the body to eliminate it and not retain significant amounts that can lead to Thyroid cancer.
RadioIodine or I-131 is a radioactive isotope that is extremely abundant during fission. It has an 8 day half life and is really only a hazard for a few weeks after a release. During an accident like Chernobyl, it is one of the most abundant isotopes released.
So how does Radiation hurt the body?
There are a few things that could possibly result from radiation exposure at all levels, but of course the potential increases along with the dose recieved. The radiation could pass through your body and never interact with any of your cells.
The radiation could damage a cell/cells and then the cell/cells could repair themselves. This is the most common scenario for chronic exposure within the federal limits.
The radiation could damage the cell and kill it.
The radiaiton could damage the cell and then the cell mutates (cancer basically)
How ionizing radiation damages our cells is through depositing energy to the atoms of the cell and ionizing them by removing electrons. As many of you already know, we are mostly made up of water (H2O). When ionization occurs within your cells, it can create a variety of combinations. Most of the time you will have a ion pair combination of H2 and O which will most likely recombine to H2O and effectively be repaired, no harm no foul. One of the combinations that could occur is Hydrogen Peroxide, which is a poison to our cells and will make it die. Free radicals can also be formed which can promote cancer and can damage DNA.
There are two different types of effects to humans from damage after exposure to Ionizing radiation.
Somatic effects: A term used to describe the effects on the person that was actually exposed to the radiation.
*Genetic Effects: A term used to describe the passed down, genetic effects to the off-spring of the person that was actually exposed.
*Note: Genetic effects are purely theroretical. There has never been a proven case of genetic mutations in the offspring of a human that was exposed acutely or chronicly to Ionizing Radiation. The children of Chernobyl who had deformities or thyroid/other cancers related to the exposure from the accident were still Somatic effects. Their health issues stem from being directly exposed to the radiation while in the womb. Same goes for the Hiroshima/Nagasaki bombs.
Ok, now that you have a little information about Ionizing Radiation and its effects, lets talk about the accidents.
Chernobyl:
On April 26, 1986 the worst nuclear accident in history occurred in the Ukraine Republic of the Soviet Union. The plant was operating at the time, there were safety systems that were bypassed and a lot of human error involved in the accident, really not important for this. What is important to know are the differences between US (and Japan) nuclear plants and the Chernobyl nuclear plant? The biggest difference is the total lack of a containment building. Our US plants (and Japan) ALL have a primary containment building that is typically a web of re-bar surrounded by concrete, 4+ feet thick. Inside of this circular building are all of the most vital parts of the plant including the reactor pressure vessel which of course contains the nuclear fuel that is undergoing fission. This is also a very formidable chuck of metal several inches thick that is capable of slowing the progression of melted fuel. This is the same type of containment that contained the hydrogen blast, fuel melting and ultimately prevented a massive disaster at Three Mile Island in Harrisburg Pennsylvania. We'll get to that later.
Chernobyl was basically built in a pole barn. So when the accident happened, the reactor went super-critical, blew the HUGE reactor head into the air and released Millions of Curies of assorted radioactive isotopes into the atmosphere. One of the most immediately damaging isotopes released was Radioactive iodine-131. This isotope has an affinity for the thyroid gland. It only has an 8 day half life so the threat is right after the release and up to a couple of months, after which time it will have effectively decayed off to negligible levels. The ones most impacted were children, infants and fetus. Due to the fast rate of cell division in younger people, the chance for cell mutation is much higher than in adults. Their government did very little to help these communities in the short term after the accident. Had people been evacuated in a more timely manor, given potassium iodide, and prevented from coming back for a time, it would have saved many from Thyroid cancer. There are lots of other things that get released as well. Transuranics (isotopes with a higher atomic number than Uranium), generally produced in a nuclear reaction. These are typically Alpha emitters and pose significant health risks internally. Americium and Plutonium are a couple you may recognize.
The total radioactive release of the Chernobyl accident was hundreds of times more than the atomic bombs dropped on Hiroshima or Nagasaki, however, they are really different animals and hard to compare. Atomic bombs generally have shorter lived isotopes released making the affected land area inhabitable in a shorter period of time. The explosion associated with a bomb is what causes most of the damage and loss of life which is exponentially more than a reactor accident of any magnitude. Most all of the impacted areas from the Chernobyl accident are now inhabitable and have had residents since the accident.
So how many people actually died from the worst nuclear accident in history? It’s hard to put a firm number on that. We know that in the initial accident and response, <span>237 people suffered from acute radiation sickness, 31 of the diagnosed actually died within the first three months. Most of these were fire and rescue workers trying to bring the accident under control. There were no further deaths identified, in the general population affected by the disaster, as being caused by ARS (acute radiation sickness). It is also thought that there may be as many as 4000 total deaths from cancer related to the accident of the 600,000 people considered to be the highest exposures due to the accident. Not to downplay the impact of this accident, but consider that this represents a .6% increase in Thyroid cancer over the course of about 20 years. This increase is due to the acute, short term exposures to I-131 right after the accident and mostly in the youngest of the population. This also outlines the importance of government response to an accident like this. Getting people out of the immediate affected areas and distributing Sodium Iodide to reduce the impact of Radioiodine on the Thyroid gland. While even one person lost is one too many, I think when looked at in terms of percentages, the overall impact on human life in this “worst-case” accident demonstrates how over-blown the media makes it sound. Again, it is horrible either way and I don’t want to take away from that fact, it just needs to be put in context.
For comparison, just in the United States, nearly 500,000 people die each year from illnesses related to smoking. The percentages of people who died related to the nuclear accident vs the population exposed to the radiation is far less than the expected mortality rate for people who smoke. Still doesn't make me feel any better about the people who died because of the Chernobyl accident, just wanted to draw that comparison.
Three Mile Island
In a nutshell, because there is simply not much to talk about in terms of impact on human life or health.
In 1979, one of the units at Three Mile Island in Harrisburg, PA underwent a Loss of Coolant Accident. Much like the issues in Japan right now, the core of the operating reactor was unable to be cooled due to a relief valve that was stuck open. This allowed much of the primary coolant to escape resulting in a partially melted core, hydrogen buildup and explosion and release of up to 13 million curies of I-131. The plant was brought under control pretty quickly which prevented a full blown meltdown. The impact to the surounding public was exactally...zero. No one died, no one got sick. With the exception of the one unit that had the accident, Three Mile Island is safely generating power to this day.
The events that are unfolding in Japan are very significant, but even if all of the units undergo a complete meltdown, it will pale in comparison to the Chernobyl accident. Chernobyl literally exploded due to super-criticality, sending millions and millions of curies into the atmosphere unchallenged by any containment structures. Unlike the plants in Japan and the US, Chernobyl was a Graphite moderated reactor (we use water). The Graphite ignited during the accident and blazed for 10 days, this was a significant contributer to the total radioactive release of the accident. Because of containment structures that are in place (Japan), and the fact that all fission automatically stopped when the earthquake happend (auto scram), there was no super-critcal explosions. Even if there would have been, it would not have had the same outcome as Chernobyl. Once fuel starts to melt, it looses its very important geometry and can no longer sustain a chain reaction (fission). This means that there is no way that these (Japan) plants can release quantities of radioactive isotopes that Chernobyl did, not even a significant fraction. Most of the activity that will be released from this accident will be short lived gases. There will be a release of some of the heavier isotopes, but not anything like Chernobyl because there was no super-critcal explosion sending the actual core into the atmosphere. People in the United states should not have a single worry about what the impact will be in our country. By the time any I-131 could reach us, it will have gone through at least a few half-lifes along with being diluted by the massive volume of our atmosphere. There is no reason to take Potassium Iodide or take any other action to protect yourself from radioactive fallout. We will see environmental increases in radioactivity, but they will be so miniscule that they are not worth mentioning in terms of human health in our country.
I hope that this helped.
Brett LaVigne