NRC Science 101 — Different Types of Radiation

Donald Cool
Senior Radiation Safety Advisor

science_101_squeakychalkIn earlier Science 101 posts, we talked about what makes up atoms, chemicals, matter and ionizing radiation. In this post, we will look at the different kinds of radiation.

There are four major types of radiation: alpha, beta, neutrons, and electromagnetic waves such as gamma rays. They differ in mass, energy and how deeply they penetrate people and objects.

The first is an alpha particle. These particles consist of two protons and two neutrons and are the heaviest type of radiation particle. Many of the naturally occurring radioactive materials in the earth, like uranium and thorium, emit alpha particles. An example most people are familiar with is the radon in our homes.

The second kind of radiation is a beta particle. It’s an electron that is not attached to an atom (see previous blog post). It has a small mass and a negative charge. Tritium, which is produced by cosmic radiation in the atmosphere and exists all around us, emits beta radiation. Carbon-14, used in carbon-dating of fossils and other artifacts, also emits beta particles. Carbon-dating simply makes use of the fact that carbon-14 is radioactive. If you measure the beta particles, it tells you how much carbon-14 is left in the fossil, which allows you to calculate how long ago the organism was alive.

The third is a neutron. This is a particle that doesn’t have any charge and is present in the nucleus of an atom. Neutrons are commonly seen when uranium atoms split, or fission, in a nuclear reactor. If it wasn’t for the neutrons, you wouldn’t be able to sustain the nuclear reaction used to generate power.

The last kind of radiation is electromagnetic radiation, like X-rays and gamma rays. They are probably the most familiar type of radiation because they are used widely in medical treatments. These rays are like sunlight, except they have more energy. Unlike the other kinds of radiation, there is no mass or charge. The amount of energy can range from very low, like in dental x-rays, to the very high levels seen in irradiators used to sterilize medical equipment.

fordoncools101As mentioned, these different kinds of radiation travel different distances and have different abilities to penetrate, depending on their mass and their energy. The figure (right) shows the differences.

Neutrons, because they don’t have any charge, don’t interact with materials very well and will go a very long way. The only way to stop them is with large quantities of water or other materials made of very light atoms.

On the other hand, an alpha particle, because it’s very heavy and has a very large charge, doesn’t go very far at all. This means an alpha particle can’t even get through a sheet of paper. An alpha particle outside your body won’t even penetrate the surface of your skin. But, if you inhale or ingest material that emits alpha particles, sensitive tissue like the lungs can be exposed. This is why high levels of radon are considered a problem in your home. The ability to stop alpha particles so easily is useful in smoke detectors, because a little smoke in the chamber is enough to stop the alpha particle and trigger the alarm.

Beta particles go a little farther than alpha particles. You could use a relatively small amount of shielding to stop them. They can get into your body but can’t go all the way through. To be useful in medical imaging, beta particles must be released by a material that is injected into the body. They can also be very useful in cancer therapy if you can put the radioactive material in a tumor.

Gamma rays and x-rays can penetrate through the body. This is why they are useful in medicine—to show whether bones are broken or where there is tooth decay, or to locate a tumor. Shielding with dense materials like concrete and lead is used to avoid exposing sensitive internal organs or the people who may be working with this type of radiation. For example, the technician who does my dental x-rays puts a lead apron over me before taking the picture. That apron stops the x-rays from getting to the rest of my body. The technician stands behind the wall, which usually has some lead in it, to protect him or herself.

Radiation is all around us, but that is not a reason to be afraid. Different types of radiation behave differently, and some forms can be very useful. For more information on radiation, please see our website.

Don Cool, who holds a Ph.D. in radiation biology, advises the NRC on radiation safety and for 30 years has been active on international radiation safety committees.

Author: Moderator

Public Affairs Officer for the U.S. Nuclear Regulatory Commission

45 thoughts on “NRC Science 101 — Different Types of Radiation”

  1. According to the National Radon Defense, radon is the second leading cause of lung cancer in the US; yet, few people know about it because it is a colorless, odorless, radioactive gas. Common indications of radon poisoning include persistent or recurring respiratory infections, cough, hoarseness, breathing difficulties. Although these symptoms do not guarantee long-term exposure to the carcinogen, they require medical attention.
    Interested can these links for more information on lung cancer:,-Screening,-Rates,-Treatment.html

  2. Hello, this article is surely informative. Whether from radioactive material or produced by devices like x-ray machines can be harmful. Radiation can kill cells in our body. Some of the cells can grow back fine but others are permanently damage and will not be able to function.

  3. The NRC is hiding the fact that hundreds of thousands of pounds of deadly, highly radioactive used/spent nuclear trash, called spent nuclear fuel, is stored in defective GE Mark 1 fuel pools in unsafe containments with no overhead protection; as the song says, “Who do you think you are fool’n?”

    The public has a right to know how much dangerous, highly radioactive spent nuclear fuel is stored in fuel pools. The GE Mark 1 fuel pools are a serious health, and security threat to our nation. It is your responsibility NRC to keep the public accurately informed of the threat, regulate and offer protection as our regulator. You have failed, you appear to offer protection to the nuclear industry, not the citizens in regards to spent nuclear fuel.

    Inappropriate secrecy and deceit will not resolve the serious national problem of spent nuclear fuel. Particularly in the case of the lacking overhead containment in the GE Mark 1 nuclear facilities.

    The entire situation relating to spent nuclear fuel has been allowed to grow to a serious health and security threat.

  4. The NRC requires licensees that possess nuclear fuel to keep an accounting of their inventory and report to us on any changes. This information is sensitive and is not available to the public.

    Maureen Conley

  5. We are not aware of any similar sources of radionuclide inventory data for MOX fuel. This report was prepared for the Department of Energy as part of its Yucca Mountain program to characterize materials that require geologic disposal. MOX fuel is not used in the U.S. for power production in commercial nuclear reactors.

    Maureen Conley

  6. The fuel pool inventory emits ionizing radiation and if uncovered will burn, thus emitting deadly levels of ionizing radiation into the air, land, water and atmosphere such as occurred at Fukushima.

    Is the NRC saying they do not know the amount in weight and radionuclide content of current radioactive material in the fuel pools which they are supposed to be regulating which is contained in spent fuel pools and in dry storage at the various nuclear power plants across the nation? Could you please explain where the current weight and radionuclide inventory of each fuel pool and dry storage may be found, link etc. Again, the key word is current inventory.

    The info document you listed is from 1992, it is appreciated but surely there is a current listing of fuel pool weight and radionuclide inventory which you track as our regulator? Help us out here please.

  7. Maureen I did a review, and thank you so much, this is a great resource, and they do a simple list of the primay fission products 1 year after burn, and for various enrichments and degree of burn. Perfect for what I need to do.

    Sorry to ask another favor, but can you find a similar resource that would depict fission products and neutron production from various MOX mixes? Thanks!

  8. thanks Maureeen, I will review the doc later. I had found some others where they list fission product, but like 22 years after the burn….would prefer to have data on the year of burn stoppage.

  9. I was asked to respond to your question.

    The NRC does not track the isotopic inventory in each spent fuel assembly at nuclear power plants. The following is a link to a public document titled “Characteristics of Potential Repository Wastes”: It contains physical, isotopic, and thermal characteristics of all type of commercial spent nuclear fuel assemblies. For example, in the middle of Table 2.4.13 on Page 2.4.17, the most dominant (i.e., >1%) isotopes, in terms of curies/Metric Tons of Initial Heavy Metal (MTIHM), for a typical Pressurized Water Reactor (PWR) spent fuel assembly enriched up to 4.42%, burned up to 40,000 MWD/MTIHM, and cooled for 10 years are shown. These numbers are still valid to date. The number for each isotope should be multiplied by 0.45 MTIHM/assembly, which is a typical number for a PWR assembly, in order to obtain the isotopic inventory in a single PWR fuel assembly.

    Maureen Conley

  10. It appears that those who attack any type of anti-radiation comment get free reign to use false arguments, ad hominems, and be generally rude. Since the NRC is tasked with promotion of the nuclear industry, I guess this is expected.

  11. The blog is checked multiple times a day so that comments are approved and posted frequently. As stated previously, we try to be liberal in our application of the comment guidelines so as to allow as much dialogue as possible, although at times we will remove direct, personal attack verbiage while still posting the remainder of the comment. We also try to limit our moving of topics to the Open Forum for the same reason.


  12. Attention NRC Moderators!

    If we have to wait so long to get normal comments posted then please explain why you allowed:
    Dan Williamson’s April 17, 2014 at 8:23 am (see above) comment to be posted at all, since “halitosis and warped floors.” has no place in this NRC blog…

    BTW if you delete the above comment you are welcome to delete this comment about it.

  13. Slightly off topic, but one I have spent a few hours trying to ferret out.

    Can Doc Cool or anyone here provide realistic radiation inventory data for spent fuel based on an average burn up rate? I am looking for not just the Ur, Pu and higher transuranics, but the fission products such as Cs, Sr, and all the usual suspects.


  14. I see, then why does Plutonium have a W(r) multiplier of 115,000 when most internal radiation gets a W(r) of around 20 to 50. Radon in areas subject to it, can be greatly controlled by a simple radon system around $1000. One of the greatest lies of the radiation industry is that background is high (even if they made it high), therefore don’t worry about a little more.

    Uh, and that little point about Plutonium ALSO killing as a Heavy Metal, and one that goes to the liver and pretty much will kill you will liver cancer, except that the lung cancers will likely kill you first. 255 of 255 Beagles were killed directly by Pu inhalation.

  15. Gary – Great comment that speaks to the heart of the NRC’s radiation reporting problem, the industry and probably many within the NRC don’t want the public to understand radiation…

    Now with low cost radiation monitoring instrumentation that automatically uploads measurements to the web their is no good reason for radiation monitoring to be done in real time especially around all nuclear power plants and other nuclear Gov’t. facilitates.

  16. Consider that radon and its progeny have multiple alpha emissions in a commonly equilibrium ambient environment. Nearly all these alphas are higher in energy than all plutonium isotopes. We are bathed in ambient and deep lung concentrations every hour of our lives. The federal radon exposure limits (10CFR20) are 1000 times higher than for plutonium with some evidence that 1) the original dosimetry testing was flawed, and 2) there was conscious attempts to make it so that the public would have all nation-states end nuclear weapons (the Mueller assertions and the genesis of LNT). A good place to start the knowledge process is and the open letter to journal editors.

  17. To: Moderator RE: Comment posted April 17, 2014 at 4:07 pm and the NRC Chairman

    Dr. Donald Cool, your efforts to expand our knowledge base just earned you a SALUTE!

    Please continue to moderate and/or help US explore these and other issues since they may very well be important both now and/or in the future!

    I’d like to suggest that the NRC Chairman immediately establish an Office of Information Confirmation (OIC) which answer directly to the Chairman and would serve as an informational request portal for those seeking answers to radioactive related questions that may very well affect our health. The OIC knowledge base could then be expanded as needed, as additional blog comments are posted along with their moderated replies.

    The OIC would fill the large vacuum which now exists between the general public and the experts that work for the NRC. Since radiation safety is a primary NRC safety concern, the OIC would allow interested non-NRC personal to post questions to the NRC that they feel need to be answered. Once a question/topic has been posted the discussion would then be educational both for the NRC and the general public, since the OIC knowledge base could be searchable and/or used by the public. I envision the OIC as new resource that would provide the NRC with a powerful new outreach tool that will allow them to better fulfill its mandate of providing transparency to the public.

    I’d be very interest in speaking to you about the formation of the OIC, so if you are interested you can contact me through the Office of the Chairman who has my contact information on file.

  18. We can Make Radiation Visible from nuclear facilities in real time. The questions are: Will the regulator require it? Will nuclear facility operators be transparent?

    Current monitoring and publishing of ionizing radiation contamination surrounding nuclear facilities is not transparent and is outdated. Plus, current radiation monitoring requirements are akin to the “fox guarding the hen house;” monitoring activity is conducted based on averaging with quarterly computations reported annually to the regulator and certainly not timely in reporting to the public.

    Current radiation monitoring and reporting to the public surrounding nuclear facilities appears to protect the operator, and is not adequate to protect the public. NRC personnel have stated in Region 2, at Nuclear Facility Inspection Public Meetings, that the public would not understand if the data was displayed in real time. It is not a wise decision for NRC supervisory staff to assume the public does not understand.

  19. CaptD — Buckyballs are generally considered to fall under the realm of nanotechnology, and in this case the manipulation of carbon at a molecular level. The National Nanotechnology Initiative ( ), part of the National Science Foundation, has some information on the subject. The NRC staff in the Office of Nuclear Regulatory Research are following developments in the general area of nanotechnology, and I have let them know of your comments.

    Don Cool

  20. @ Dan Williamson

    I see, your opening salvo is an Ad hominem false argument, followed by the standard nuker deflection of FUD

    And then finally the “you can’t prove it” argument, similar to the you can’t find it fallacy.

    I am amazed you didn’t retort with eating a banana while flying….LOL

    Moderator Note: Some verbiage removed to adhere to comment guidelines

  21. Radioactive dosages are very important but what is even more important is getting truthful factual information and data, especially about radiation releases.

    If the NRC started to release data about all releases then those in the public with scientific training could better judge what is happening but because this in not the case the public is left having to trust others that may not have the technical expertise they do to make health related decisions for the public at large!

    Somewhere i the past the nuclear industry got permission to keep all information secret from the public and that decision should be reexamined because to continue to withhold key safety and/or health information is no longer acceptable in the 21 Century!

    Here is just one example of why the public needs to be concerned:

    Estimated radiation doses of Fukushima returnees withheld for half a year

    Here is another :

    Contamination of USS Ronald Reagan During Fukushima Response Underreported

    and another
    DOE To Do WIPP Mine Reentry On April Fools Day

    and one more:
    5 Types Of Plutonium Released From WIPP; Officials Not Informing Public – Dr. Caldicott: Inhaling A Millionth Of A Gram Of Plutonium Will Induce Lung Cancer

    As I post on the above:

    Attention NRC, EPA & WIPP Officials:

    When something happens, show US all the Data and stop talking to us like we have no scientific training!

    If you will N☢T, then we are Calling You Out (CYO) , because the only real reason that you will not share ALL THE DATA is that it shows something VERY BAD has happened and you are afraid of a public panic…!

    Experts from:

  22. Again:
    Dr. Donald Cool I am sure we would get a much more professional and timely reply if you were the one asking the question, since you are in a position to talk to them as one professional to another! If you are not interested in pursuing this , then just let me know, the Chairman has my contact info.

    BTW: If what I believe is accurate then I think the NRC should be VERY interested in finding out much more about it, and who better to find out about it for them since you advise the NRC on radiation safety and for 30 years has been active on international radiation safety committees.

  23. “nukeprofessional.blogspot” eh? The only things missing from their list are halitosis and warped floors.

    So you fellows must lay awake at night sweating about that 300 mrem you’re getting every year just being on earth. The FUD specialists count on the inability of the typical citizen to quantify risk and their proclivity to be stampeded into irrational fear by buzzwords. You’re right….the risk of detrimental effects from exposure to ionizing radiation is not zero. But you don’t know what it is. And studies of the occurrance of cancer in radiation workers indicates no higher rate than that in the general population….showing that the risk is vanishingly low.

  24. Bill, regarding my question 4 – I would suggest our esteemed experts study the history of the National Academy’s Bier VII Report and understand that this statement is a true statement: “There is no safe level of exposure and there is no dose of (ionizing) radiation so low that the risk of a malignancy (cancer) is zero.” Dr. Karl Morgan, the father of Health Physics -BIO –

    When nuclear corporate lobbyists become embedded into the regulatory process we have what is called, “a corrupted system.”

    Bier VII Report’s conclusion National Academy of Sciences BEIR VII, Phase 2, 2006 study, pg 15: There is a “no-threshold dose-response relationship between exposure to ionizing radiation and the development of cancer in humans.”

    “The chapter on DNA repair and processing concludes that it is likely that exposure of humans
    to low doses and low dose rates does result in permanent alterations in DNA sequences,
    which points away from a threshold.” Richard Wakeford, Review of Evaluation of the Linear-Non-threshold Dose-Response Model for Ionizing Radiation (National Council on Radiation Protection, NCRP Report No.136), Journal of Radiological Protection, 2002, Vol. 22 No.3

    No threshold means that any dose of radiation can lead to cancer. Wakeford states, “The report begins by examining the way in which radiation energy is deposited in cells. It concludes that at low doses and low dose rates the relevant biological damage would be produced by a ‘single hit’ because of the spatial and temporal sparseness of the events causing the damage. Since cancer is considered to be monoclonal (single cell) in origin, this suggests that the dose-response is linear at low doses with no threshold.” Again, no threshold means that any dose of radiation can lead to cancer which means that there is no safe dose of radiation. Nuclear industry supported health physicists attack the evidence as it is financially advantageous for them to do so. Money before health and citizen welfare has long been the driving value of the trillion dollar multi-national nuclear corporation.

  25. yeah arent those the nice folks who jacked up the “allowable” radiation in food by 1000% after Hillary went to chat with the Japanese. Spread the love Hillary.

  26. The NRC link doesn’t really provide any usefulness for CPM in an airplane. I would like average CPM based on altitude and lattitude. I have scoured the web and come up empty handed.

    Some people are saying that post Fukushima, that airplane doses are way way up compared to back in the day. 900 CPM sure seems high to me, I have it on video. Airline personnel could be at extreme risk, it would be nice to facts, any further help you could provide would be great.

    How does one calculate body dose from Cosmic, is it mostly all Gamma, and at what energy levels. Some Xray too? Other stuff?

  27. the EPA & DOE….you mean the pollution enablers? a true answer from them is about as likely as the truth in your article. monsanto/GE lovers they are & you are.

  28. It’s an interesting question, but not one that I can answer for you. You could ask the Environmental Protection Agency, or the Department of Energy, which is responsible for the National Laboratories.

    Don Cool

  29. That’s a very interesting question, but it’s out of my area of expertise. You might ask the National Weather Service or the Environmental Protection Agency, perhaps, among others.

    Don Cool

  30. In response to your questions:

    1) The tritium produced through nuclear fission is identical to natural tritium. The EPA has a good fact sheet on tritium, including its potential health effects.

    2) The risk posed by various radioactive materials is largely a function of the type of radiation, and how much you get, as discussed in the post. Whether a particular source has a beneficial use or not, it is important that we take precautions, minimize exposures, and use it safely. That’s what the NRC and effective regulation are all about.

    3) Probably not. There are naturally occurring amounts of different radioactive materials that are always in our food and water. Like the tritium example in the blog, all water has small quantities of tritium, and this is not a problem. The Environmental Protection Agency, and the Food and Drug Administration have levels for food and water.

    4) Frankly speaking, we don’t know. The information we have on radiation risks comes from much higher levels of exposure. Since we can’t know for sure, we control radiation assuming there could be some risk even at very low levels, even though it could well be that there is really no risk. This is an overstatement of the so-called “linear non-threshold” view of radiation, which holds that any exposure to radiation, no matter how low, increases one’s risk, however slightly, of eventually contracting cancer.

    Don Cool

  31. There is quite a lot of information out there on the web about cosmic radiation in flights. For example, the NRC’s web page on calculating your radiation dose ( ) gives 2 mrem per year from cosmic radiation living at 1000 feet above sea level; 2000 miles in an airplane also gives you 2 mrem. An average flight across the Unites States would be somewhere between 2 and 5 mrem. Cosmic radiation levels vary, generally being greater as you go towards the poles.

    Don Cool

  32. Howdy Gary,

    While not being qualified to answer any of your questions I will attempt to address them anyway(because this is the internet.)

    Question 4. (Because of how you ordered your questions, it makes more sense to address four first.) Is this a true statement? “There is no safe level of exposure and there is no dose of (ionizing) radiation so low that the risk of a malignancy (cancer) is zero.”

    The answer depends on the models used for radiation and the effects of radiation. As you are most likely aware, the current model (used for almost everything but cancer therapy, cell research, and various tissue research) is the linear no-threshold (LNT) model. This model assumes that there is no threshold below which radiation causes no increase risk of cancer. While the risk of cancer is 44% for males and 38% for females in the United States, it is difficult to get data to validate or refute the LNT model. Because of how slight the model predicts the increase in cancer from low doses and low dose rates of radiation, a barbaric animal study of at least 2 million mice/rats would be needed to get the statistics desired to say with certainty whether or not the LNT is valid or invalid.(or at least if there is enough evidence to refute or not refute the LNT model) Whether or not the LNT model is correct is inconsequential in that, it is a useful tool. All models are wrong, but some are useful. While I personally feel that the LNT model is false, since cells do regularly repair damage from radiation within hours of exposure, I appreciate the value it brings in the absence of data from a project that would need to be on the order of the Megamouse experiment. The statement is true and false, depending on what model you choose.

    Question 3. If alpha or beta particles are ingested via water, air or food should I be concerned?

    Your question is concerning weakly penetrating radiation. While these types do not get past the dead skin(mostly) from the external exposure side, they do present a hazard to the internal environment of your body. While I would like to answer your question with a simple yes, keep in mind there are radioactive elements in all of the food we eat.

    Question 2. Does this mean that some alpha, beta and gamma emitters are not useful and are dangerous?

    While your question was specific to alpha, beta, and gamma emitters, ingrained in it was the assumption that the radioactive properties are what makes something useful or dangerous. Many times the chemical nature of an element presents a larger hazard than its corresponding radioactive isotopes. Barium for example, or mercury comes to mind. Usefulness and dangerousness is in the eye of the beholder. Dimethylmercury is extremely dangerous but still used. (hopefully it will be phased out soon.) There are about 3000 isotopes that are known to exist, some are dangerous(maybe because of their chemical nature), some are not useful(maybe we haven’t had a need for that isotope yet), most are shortlived, some are alpha, beta, and gamma emitters. So yes, there are some that are dangerous and are not useful.

    And finally your Question 1. Is the tritium which is produced and discharged into our environment by nuclear fission safe?

    I have never felt that the lines from Rudyard Kipling, “If,” had more application, “if you can bear to hear the truth you’ve spoken twisted by knaves to make a trap for fools.” (I am including this also because of how the other comments weren’t even about this specific article, they appeared to be from individuals seeking to have someone from the NRC make a comment about the ongoing incident at Japan, so that it could be cited for further debate). I think what you are really asking about is, what are the health hazards of releasing tritium into the environment, and does releasing tritium into our environment present a unique hazard that is different from the tritium that is naturally produced. While I am in no way qualified to answer this question either, I would indicate A) How water is/should be tested for tritium contamination, B) How the public would be informed if the water didn’t pass said test, C) Why we believe said test is a good way of determining risk to the public. D) How slowly groundwater moves from some release point to the pumps that retrieve it. (depending on where you are from or how you get your water) E) What error is associated with that test, and what would cause a false positive.

    I wish you good luck in finding the complete answers you seek as you take charge of your health and the health of your family and friends.

  33. This blog post is biased and misleading, and says nothing at all about what radiation does to DNA — the main concern of all who read it.

    For example, the sentence on tritium in the paragraph on beta particles should be amended as follows:


    “Tritium, which is produced by cosmic radiation in the atmosphere and exists all around us, emits beta radiation.”

    Suggested rewrite:

    Tritium, which is produced by cosmic radiation in the atmosphere and exists all around us IN MINUTE QUANTITIES in surface water and in trace quantities elsewhere in the biosphere except around nuclear power plants (which are allowed to routinely emit hundreds of Curies of tritium every year), emits beta radiation.”

    Instead you’ve misled people into thinking “tritium is all around us.” Naturally-occurring tritium is NOT a substantial concern for anyone; but Canada’s CANDU reactors are particularly bad, and NO tritium level is good for you: Tritium is extremely hazardous to humans because it can go anywhere in the body and is a DNA disrupter, as well as (usually) creating HO molecules inside the body, which are extremely hazardous as well (these oxidants are created because tritium is usually absorbed by the body as one atom of an “HTO” (instead of H2O) water molecule).

    The rest of that paragraph, about Carbon-14 dating, should also be amended to mention that C-14 dating will never be a reliable method of dating anything in the Nuclear Age (it will still work for dating artifacts from before 1945). This is because nuclear power plants and weapons produce vast quantities of the isotope and therefore, the levels of C-14 in the biosphere that exists now varies from place to place, and what percentage of C-14 a living object will be made of can no longer be relied on for dating purposes. Events such as Chernobyl, Fukushima, or any dry cask spent fuel fire release C-14 and many other radioactive nasty things, which then pollute the planet in uneven (and unfair) ways.

    The paragraph on neutrons may appear to the uninformed as being fairly neutral, but in reality, neutrons continue to be emitted by the spent fuel for tens of thousands of years and are a significant danger because they go through just about everything until they finally randomly smack hard into a nucleus, at which point, of course, they can do significant damage including causing other emissions. Neutron emissions are one of the reasons spent fuel is so dangerous and difficult to handle. Additionally, the neutron flux from spent fuel from reactors which are shut down permanently in mid-cycle is especially strong. And most reactors end up shutting down mid-cycle, because it’s more profitable to keep them running until something too expensive to fix finally breaks than to retire them any other way.

    The last comparison, that x-rays and gamma rays “are like sunlight, except they have more energy” is absurd, unless a 1-mile-per-hour collision is like a 10,000-mile-per-hour collision. X-rays are about 10,000 times more powerful than visible light, and gamma rays are about a million times more powerful. You could have at least said “a lot more energy” instead of just “more energy”. And describing dental x-rays as “very low” amounts of energy is likewise raising the bar. ALL types of ionizing radiation are very strong forms of energy emissions, whether they are “like” photons that the sun puts out (but with “a lot more energy”) or high-speed helium atoms without their electrons (alpha particles), or high-speed electrons (beta particles), or penetrating but short-lived neutrons (about 15 minutes before they decay by beta emission into hydrogen, on average).

    Claiming that an alpha particle “doesn’t go very far” because it is heavy is not only counter-intuitive, it’s wrong (at least according to Newtonian physics, to the extent it applies at the sub-atomic level). I presume what the author intended to refer to is that the “large” alpha particle has a cross-section (as measured in barns, for example) which interacts with the nuclei of other atoms much more than, for example, a beta particle would. The “very large” charge is, of course, the main thing that interacts with other atoms and molecules: it ionizes them (for example by knocking off an electron). One alpha particle — what you refer to as “low energy” — can ionize thousands of molecules in the human body. A DNA molecule consists of a specific unique chain of approximately 13 billion atoms. Nearly every cell in the human body has a DNA chain (red blood cells being one exception). DNA damage from a single ionizing radioactive emission can cause THOUSANDS of separate cancers to develop!

    When discussing beta particles, you state they “can go a little further than alpha particles.” This again is rather imprecise and in many ways dreadfully inaccurate. High energy beta particles can go nearly a centimeter through tissue (for example, all the way through a fetus’s heart or a baby’s pinkie). Lower energy beta particles don’t penetrate so much, but oddly enough, most of the damage from beta emissions is done as it runs out of energy because at higher energy levels, it whizzes by things and is slightly slowed by them, but does not damage them because it goes by too fast to have much effect. So both “low-” and “high-” energy beta emissions do roughly the same level of damage, and in approximately the same volume of space — though that pocket of damage is generally further away from the source for a high-energy beta emission.

    Your discussion of the effects of radiation on the human body didn’t mention DNA damage at all, it sticks almost entirely to discussing the benefits of medical radiation, and then assures us that “radiation is all around us.” Well, yes, it is, but there’s no reason to increase the level of radiation that is already there. You seem to forget that your whole job is to make sure that level doesn’t go up “significantly” but clearly, you’ve lost sight of what level of radiation is significant, and of DNA damage is significant. Even very low levels of radiation can be harmful to DNA and if a clean alternative exists, it should be taken, and if not, perhaps the whole process should be reevaluated. For energy needs, there are clean alternatives such as solar, wind, wave, geothermal, biomass, and so on. For medical diagnostics and treatments, there are also alternatives to many of the radioactive procedures, but cost of the installed radiation equipment (such as CT-SCAN machines) must be amortized over thousands of patients, and the cost of buying an entire different diagnostic device in addition to the CT machine is prohibitive, especially because some things will still probably need to be diagnosed with a CT-SCAN for many decades to come.

    But in general, medical doses have been significantly reduced over the past few decades because radiation is so incredibly dangerous, and because better and better radiation detectors are now available.

  34. Well we know that Fukushima “signature” radiation was detected in Lithuainia. Even as the WIPP plutonium release in New Mexico, we heard officials telling us “don’t worry, those are heavy metals, they can’t go far”. Makes me say hmmmmmm………………….

  35. Aloha Doc Cool

    I tried hard to find background levels for airplane flight radiation. Couldn’t come up with any.

    On a recent trip I measured 9 to 15 CPS with my Radiation Alert Inspector Geiger Counter, per SECOND. That is up to 900 CPM, which is 35 times my average background.

    That is at 30000 to 35000 feet. What is historical normal ranges for in flight?

  36. Dr. Donald Cool – I’d like to ask you, Has Fukushima radiation has been detected in the Upper Atmosphere and if so, what effect if may be having upon our weather/climate since radioactive particles are highly charged?

  37. A key issue about radiation is that while many people in a crowd may receive only minimal dosages someone standing next to them may inhale a single tiny highly radioactive particle sometimes known as a “fuel flea” which would result in serious health effects.

    The same thing is true for measuring radiation, since especially after explosive releases like Fukushima, radiation is not the same everywhere, so that a reading taken in one part of a city could be dramatically different that one taken just a short distance away. Since the wind and other environment factors move radioactive particles great distances, there is no guarantee that health thresholds are not being exceeded without personal dosimeters and even then they do not measure radiation that has been inhaled, unless it is a large amount.

  38. We will be doing a future NRC Science 101 on how a nuclear power plant works.


  39. Please explain how nuclear power plants make tritium.
    What are the radioisotopes that are routinely released?

  40. Yeah, just keep smiling, and no amount of radiation can harm you, at least that is what the Dr in Japan said.

    Different type of radiation behave differently, and some can be very harmful.

    And plutonium is roughly 5000 times more dangerous than Radon. Plutonium is what was being pumped out of WIPP

  41. Four Questions

    Quote: “Tritium, which is produced by cosmic radiation in the atmosphere and exists all around us, emits beta radiation.” 1) Is the tritium which is produced and discharged into our environment by nuclear fission safe?

    Another quote: “Radiation is all around us, but that is not a reason to be afraid. Different types of radiation behave differently, and some forms can be very useful.” 2) Does this mean that some alpha, beta and gamma emitters are not useful and are dangerous?

    3) If alpha or beta particles are ingested via water, air or food should I be concerned?

    4) Is this a true statement? “There is no safe level of exposure and there is no dose of (ionizing) radiation so low that the risk of a malignancy (cancer) is zero.”

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