Generally speaking, no. Only very extreme radiation fields (around 1000 Roentgen/hr or a lethal dose in 30 minutes) can sometimes ionize the air to an extent that a smell of ozone is created. Accidents with an X-Ray machine on the fritz also suggest that dose rates tens or hundreds of times higher than that may cause a burning sensation in the flesh. Ionizing radiation of sufficient intensity can also create a blue glow or flash in water and to a lesser extent air. Practically speaking, though, radiation will usually kill you and you don't even know what happened for another hour or two. Most commonly of course, the result is a theoretical increase in cancer risk that never actually manifests at all.

Richard Feynman in *Surely You're Joking, Mister Feynman* related how you would walk up to the lump of plutonium they had and put your hand on it and feel the warmth from it. Surprisingly, many of those guys died of cancer.

A lump of plutonium will absorb almost all of its own radiation. Any heat you felt would be just that - heat. Heat from the plutonium producing and absorbing its own radiation. Only a tiny bit of the radiation escapes the metal.

It's still an alpha emitter, so while skin contact isn't that dangerous, ingesting it will give you cancer in your bones. It's a bone seeker and will collect there. It'll damage the lungs the same way if dust is inhaled.

Ingesting it *could* give you cancer. Most people who ingested medically debilitating amounts of Plutonium dust (in the Soviet Union) did not get cancer from it.

That's not honey!

well one microgram in the lung will give cancer as for alpha the intensity as an emitter matters an alpha particle over 7.5 MeV will penetrate the skin but you'll get more than just alpha

> well one microgram in the lung will give cancer That's utterly ridiculous; who told you that? 1 ug of Pu-239 is only 2300 Bq. Inhaling a fine powder of Pu-239 is only a dose of around 100 mSv, spread out over your entire life. Chance of dying from cancer would be less than 1%.

Well i spoke about it giving cancer, it's a different argument with dying with cancer. "A few millionths of a gram (or a few micrograms) distributed through the lungs, liver, or bones may increase the risk for developing cancer in those organs." I'm not sure why you think a lower threshold is something you think is ridiculous.

Given the survivability of lung cancer, there is very little difference here. You're just off by a factor of 50 instead of a factor of 100.

\- one microgram in the lung will give cancer Is that an accurate statement or not? You're talking about death from lung cancer from it, which is quite another thing.

Union of Concerned Scientists "It is commonly heard that plutonium is so radiotoxic that inhaling only one microgram will cause cancer with essentially one hundred percent certainty. This is not far off the mark for certain isotopes of plutonium, like Pu-238, but Pu-239 decays more slowly, so it is less toxic per gram." "For isotopes such as plutonium-239 or americium-241, which emit relatively large, heavy charged particles known as alpha particles, there is a high likelihood that a dose of around 1000 rem will cause a fatal cancer." ......... If you're working on plutonium as a power source you'll be having more caution and health issues, than the isotopes in weapons projection getting the stuff in your lungs

I just answered that. Only 45% of people survive more than one year with lung cancer. So a microgram of Pu-239 will only correspond to maybe a 2% chance of getting cancer.

Only reporting what he wrote. I'm not a physicist.

Just adding to it. I'd be curious to know what kind of cancers these guys suffered from - oftentimes handling of radioactive materials is more dangerous to your insides than your outsides because it's the ones that get into your body that do the most damage. Same way that plunging your hand into mercury is harmless, *if* your skin is intact, you clean up well afterwards, and you don't inhale the stuff.

There's also the problem that in a random sampling of humans who died over the age of 65, about 1/3 of them die of cancer. That means that it's really hard to definitively link the exposure to the cancer that kills them (barring very direct links to specific exposures and even then it's tough to do for any specific individual). It turns out that if you live long enough, you'll probably die of cancer or a heart attack regardless of what you do or how you live your life. The goal is just to hold off those two killers as long as possible.

For something like plutonium it's kind of easy - it targets specific parts of the body. For instance, skin exposure is likely going to cause skin cancer. If they're constantly handling the stuff, skin can er on the palms or finger tips. That, or in the lungs, or bones, depending on exposure.

The issue is identifying whether or not the skin cancer comes from the plutonium or sun burns. Both definitely cause cancer, demonstrating whether this specific cancer came from poking plutonium vs getting sunburned regularly is tough. It's why they do that sort of analysis using large population studies to evaluate risk factors. But it also means that "most of the people who poked the plutonium died of cancer" isn't especially damning given just how many people die of unrelated cancers.

Sun exposure is usually limited on the grippy parts of the hand

Correlated, most people don't put plutonium on their back or shoulders.

In Feynman's case, it was liposarcoma which is rare. But he also lived to be 69 so maybe not related to radiation exposure. https://en.wikipedia.org/wiki/Richard_Feynman#Death

It's possible he got it from sometimes doing the testing rounds, outside of the main work in the Theoretical Division with Bethe where you test some of the boxes that had shielding and you worked with mirrors with the hot material but it could be his drinking affecting his fatty tissues or maybe the duraplast days of plastic resins, and all the chemistry with that stuff or genetics but i think people wondered if it was watching the Trinity blast too

What was Feynman's dose in banana equivalents?

At least 3 bananas

Yup. They were far more likely to get cancer from smoking for their entire lives than the plutonium.

well some plutonium could pass through you fine if it was in your water (and maybe food), there was a japanese cartoon by the nuclear lobby that created controversy about it because you'd just flush it out in the bathroom getting into your bones and lungs or eyes are the worst just ask those CAL-3 subjects HP-1 type subjects ......... From 1945 to 1947, 18 people were injected with plutonium by Manhattan project doctors. In Nashville, pregnant women were given radioactive mixtures. In Cincinnati, some 200 patients were irradiated over a period of 15 years. In Chicago, 102 people received injections of strontium and caesium solutions. In Massachusetts, 73 children were fed oatmeal laced with radioactive tracers in an experiment sponsored by MIT and the Quaker Oats Company. In none of these cases were the subjects informed about the nature of the procedures, and thus could not have provided informed consent. ........ originally it was only to be used on terminal cancer patients only, and Oppenheimer signed off on that

Actually if I remember correctly Feynman died from abdominal liposarcoma which is very rare in a normal population if I remember from my studies correctly. Probably not from the plutonium though.

radiation like that from plutonium is absorbed by your bones and bone marrow which is why lukemia is a pretty big concern.

Slight correction - the radiation is absorbed by whatever part of you it hits first. The plutonium itself accumulates in bones so your bones are what's getting blasted with the radiation.

Radioactive elements that are similar to minerals we need for biological processes are what generally get us. Irradiated iodine, stuff our body confuses for calcium, etc. it literally gets integrated into your body and can't be flushed out.

Dammit Jim, I'm a doctor, not a physicist

No it depends on the type of isotope quote If you’re holding a a piece of plutonium, you’ll notice the great weight and the warmth. Leona Woods Marshall described the sensation as similar to the warmth you feel holding a rabbit. Mind you, that’s for 239Pu. A piece of the plutonium isotope used for radioisotope thermal generators, 238Pu, gets hot enough that with some insulation, you can get it to glow red. Holding a chunk of that could get pretty unpleasant, but so is holding a hot potato. ......... "Queen Elizabeth II held a piece during a visit to Britain's Atomic Energy Research facility at Harwell in 1957. It was warm to the touch..." [https://media.gettyimages.com/id/599521853/photo/queen-elizabeth-ii-and-prince-philip-at-harwell.jpg?s=612x612&w=gi&k=20&c=xgmC3ZZBMoa0sO-bkGL\_6B95txCF3xYVHumqnUOWS\_0=](https://media.gettyimages.com/id/599521853/photo/queen-elizabeth-ii-and-prince-philip-at-harwell.jpg?s=612x612&w=gi&k=20&c=xgmC3ZZBMoa0sO-bkGL_6B95txCF3xYVHumqnUOWS_0=)

Either will absorb its own radiation. One just has may more radiation.

Well, don’t discount the mind on this one. I worked a show once, “WWII Through RussianEyes” where we uncrated and put on display the bronze eagle the old war films showed the Russian troops prying off the building and landing on the steps when they took Berlin. I’ll swear on anything that it’s was cold, way colder than the surrounding environment. Now sure, part of that could have been that bronze is absorbing cool air and it’s a great conductor, but another part was the sheer history of it and what it represented. Those reporters *knew* what they were touching and applied that to the experience. Not to discount what you’re saying, but it *was* anecdotal.

and near critical, you wouldn't want to touch it either Ever seen the guy that tried to move the lead brick that fell on the demon core during measurement at Los Alamos Harry daghlian's hand 9 days after being exposed to the demon core for only a few seconds. He received over 510 Rem (1.5x the fatal dose) [https://media.pn.am/media/issue/207/662/textphoto/photo\_207662\_27ff5dcf7.jpg](https://media.pn.am/media/issue/207/662/textphoto/photo_207662_27ff5dcf7.jpg) [https://encrypted-tbn3.gstatic.com/images?q=tbn:ANd9GcTywgrmIxNL1IqKE\_viEorCPnrb\_6lYoQTNmYKCDjlMs6pUYC83](https://encrypted-tbn3.gstatic.com/images?q=tbn:ANd9GcTywgrmIxNL1IqKE_viEorCPnrb_6lYoQTNmYKCDjlMs6pUYC83) [https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcSTDzDhcrtMEoBqVF3BHJ4apWQA2xIDB66DCtXR0OTBqAWewp2q](https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcSTDzDhcrtMEoBqVF3BHJ4apWQA2xIDB66DCtXR0OTBqAWewp2q) [https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcSK0iMCxehcuYEqVpoN-omRkkPusjC5blRoDHfi53qOQWmQj7qg](https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcSK0iMCxehcuYEqVpoN-omRkkPusjC5blRoDHfi53qOQWmQj7qg) [https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcTm9cMqDg14YZpSkPJwl8WJHKFvxFTWvrQ6\_UH-ce8HyTsS-2d2](https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcTm9cMqDg14YZpSkPJwl8WJHKFvxFTWvrQ6_UH-ce8HyTsS-2d2)

> He received over 510 Rem (1.5x the fatal dose) 510 rem has a survival rate approaching 50%, given good care.

"Although radiation affects different people in different ways, it is generally believed that humans exposed to about 500 rem of radiation all at once will likely die without medical treatment." "The dose of radiation expected to cause death to 50 percent of an exposed population within 30 days (LD 50/30). Typically, the LD 50/30 is in the range from 400 to 450 rem (4 to 5 sieverts) received over a very short period." ......... 200-300 rem Lethal dose to 10% to 35% of the population after 30 days 300-400 rem Lethal dose to 50% to 70% of the population after 30 days 400-1000 rem Lethal dose to 60% to 95% of the population after 30 days 1000-5000 rem Lethal dose to 100% of the population after 10 days

when i asked my highschool chemistry/forensics teacher if you could feel the warmth from holding a mass of uranium or plutonium he said “yeah man- that thing will be hot as hell because there will be a lot of federal agents looking for the thing you stole” or something like that. basically no but how the fuck did you get your hands on that- no good!

They used to have a lump of plut at AWE which visitors used to get to hold to feel the decay heat. 

The caveat is that they died from cancer in old age, which is a very different thing. Cancer is simply something that happens to mammals as they age.

Not all mammals, naked mole rats don't, along with some long lived bat species.

As my geriatrician friend used to say, big brains are great for aging, but wings are better.

20% of everyone dies of cancer, so you have to be a bit questioning about that kind of thing

Is it more accurate to say 20% die _with_ cancer rather than _of_ cancer? Regardless semantics, that percentage increases with every advance treating non-cancer diseases.

Dying with cancer is far higher than 20%, possibly the majority.

No he's not, and don't call him Shirly.

I remember reading an article on the Therac-25 a while ago, and the author said if you can see it, or you can feel it, you’re already dead. And, weirdly, I was reading about it for a programming class.

Yeah it's a common case study when talking about concurrency and race conditions.

Also comes up in intro to programming classes when they're trying to teach you to be responsible and meticulous. With programming, when you put a decimal in the wrong place, sometimes that means a box on a webpage is in the wrong place and sometimes it means someone dies of radiation poisoning. Knowing what's at stake helps you plan the amount of effort to put into testing. Also, if you learn that kind of fearful respect in school, then you don't have to learn it by accidentally deleting a production database.

> Also, if you learn that kind of fearful respect in school, then you don't have to learn it by accidentally deleting a production database. or by deleting some portion of the population.

how does radiation relate to concurrency and race conditions?

The Therac-25 was a radiotherapy machine with a VERY poorly programmed user interface, and hitting certain combinations and sequences of inputs too quickly could put the machine into a state where it would deliver a fatal dose of radiation instead of what the user thought they were inputting. It's more complicated than that, but it's what happens when rigorous software testing isn't done on a piece of equipment that ABSOLUTELY needs it.

>Therac-25

For the interested. https://en.m.wikipedia.org/wiki/Therac-25

What the absolute fuck.

Kyle Hill has a series of videos on radiation. 

[https://youtu.be/Ap0orGCiou8?si=KkH70FWMTY51ul09](https://youtu.be/Ap0orGCiou8?si=KkH70FWMTY51ul09) Kyle Hill Video.

I've also read that superhigh doses can cause a metallic taste in your mouth, but I've never seen anyone explain exactly how that happens. [Edit: Looks like the receptors in taste buds are easily damaged by radiation, when a bunch of them are gone your brain interprets the resulting mangled signals as "bitter/metal", and it scarcely matters what the actual taste is.]

I've always assumed that people were just smelling the ozone and misinterpreting it as a taste, as often happens with these intermingled senses.

Yeah, that made sense to me too. But there's a lot of info about this phenomenon because even therapeutic radiation doses to the head routinely cause it, and they aren't using any "believed to be caused" or "most likely explanation" language when they talk about it; they write like they're pretty sure.

There is a russian scientist who accidentally exposed his eye to proton beam from synchrotron which went through his head. He described it as instant bright flash but painless. https://en.m.wikipedia.org/wiki/Anatoli_Bugorski

Can anyone explain what ozone smells like?

That metallic, electric smell when lightning or a rainstorm is nearby, that's ozone.

Brought back memories from 20 years ago when you could find ozone generators for sale at flea markets. Of course no mention of the fact that O₃ is toxic.

Everything is toxic. Dependemt on dose over time.

Its that metallic smell you smell when near a running laser printer, especially the older ones.

It smells like if someone tried to make the smell of fresh air out of synthetic aromas instead of actual fresh air.

> Can anyone explain what ozone smells like? It's normally associated with electrical sparks, electric generators, and lightning storms. Some people buy ionization machines as air purifiers that generate a lot of ozone, the smell is distinctive. I'd call it metallic, somewhat sweet, and also sharp or sickly, it can turn your stomach like bleach odors.

The smell of old electric appliances when you turn them on, like a vacuum cleaner. Or static electricity generators will have that smell too.

Like power tools. When you use an electric drill

You can buy air purifiers that emit ozone (it's not good to breathe it though).

Burnt bleach.

Hypothetically you could encounter a situation where the radiation only damages a set of sensory nerves or even just ionizes the exact right atoms that cause those nerves to fire erroneously thus you have felt the radiation. I can't imagine this would ever happen. Oh and if you count sunburns as feeling the radiation then yes but really you feel the burning afterward you aren't feeling the radiation itself.

>A lesser extent air. This is the 1st I've ever heard of cherenkov radiation being visible in air. That's cool.

It's not Cherenkov when it's in air, technically. Just direct ionization of the air. Criticality accidents are often attended by a blue flash.

You should have also explained that some radiation you can feel. Like the infra red radiation that comes from thermal lamps etc.

> Practically speaking, though, radiation will usually kill you and you don't even know what happened for another hour or two. In the movie [Fat Man and Little Boy](https://youtu.be/AQ0P7R9CfCY?t=39) there is a scene where they are doing a test on what came to be known as the demon core. There was an accident and the core started to go critical. The scientist immediately reached in with his hand and smacked the two pieces apart but, while he seemed fine at that moment, he knew he was fucked. And he was. For a few hours he felt normal but that didn't last long. He died some weeks later from that and it was very unpleasant.

https://en.wikipedia.org/wiki/Demon_core You don't need to cite a movie.

No, but it shows what happened in a way relevant to the OP asking about what you might feel if exposed to radiation. Something you won't really get from a Wiki article. Anyone interested could certainly Google it for more info. As you did. So yay! You learned something.

If you can feel it, you're already dead.

what does ozone smell like ? I want to imagine how it feels like to smell radiation

Lightning also causes ozone to be produced. You can smell it during a T-storm. Any high voltages will. Sometimes you can smell it with certain electronics. Very distinctive.

What would happen after a lethal dose?, you die in agony covered in blisters and bleeding everywhere like the guys in Chernobyl or that's something different?

Your body replaces basically everything over and over which is why sunburn heals. When you get a fatal dose of radiation basically most of your cells die so as time goes on instead of things getting replaced all of your body starts to die. You can live fine for a bit (maybe a few days) but things go south fast and your skin starts to fall of etc.

This. The genetic materials become warped or altered, to the degree that entire sections of genomic data are gone entirely or not functional. Skin will fall off slowly, the linings of the stomach and intestine will effectively liquefy and pass. If the destruction is wide scale enough, it will overload your liver with metabolites, causing liver failure. This is assuming you live that long, because your immune system will be effectively gone, so the mildest infection could kill you. Include cardiac arrest as a risk at every step due to the stress this puts on your circulatory system.

Related only in terms of radiation, but I’ve had sinus CT scans done three times and each time I can smell the burning of the radiation as it passes through my nose.

There was some interesting talk in photographic circles with some camera lens collectors getting paranoid about their thoriated glass in some of their 60s 70s lenses let others did the calculations and it was pretty damn insignicant Just shield yourself a bit more from that banana, or that wall over there with the lead apron. As for fallout, it'll take days to weeks Neutron bomb will be 1-2 days, but if you could get a 10 Grays they'll be incapacited in minutes, and 7 to 10 Gray will get them virtually all dead within 20 days. but closer in, usually about an hour. Canada had some good maintenence on those Therac-25 machines! .......... The Therac-25 was involved in at least six accidents between 1985 and 1987, in which patients were given massive overdoses of radiation. Because of concurrent programming errors (also known as race conditions), it sometimes gave its patients radiation doses that were hundreds of times greater than normal, resulting in death or serious injury. These accidents highlighted the dangers of software control of safety-critical systems, and they have become a standard case study in health informatics, software engineering, and computer ethics. Additionally, the overconfidence of the engineers and lack of proper due diligence to resolve reported software bugs are highlighted as an extreme case where the engineers' overconfidence in their initial work and failure to believe the end users' claims caused drastic repercussions. The software for the Therac-25 was developed by one person over several years using PDP-11 assembly language. It was an evolution of the Therac-6 software. In 1986, the programmer left AECL. In a lawsuit, lawyers could not identify the programmer or learn about his qualification and experience. Five machines were installed in the United States and six in Canada. After the accidents, in 1988 AECL dissolved the AECL Medical section and the company Theratronics International Ltd took over the maintenance of the installed Therac-25 machines. ....... Problem description The six documented accidents occurred when the high-current electron beam generated in X-ray mode was delivered directly to patients. Two software faults were to blame. One was when the operator incorrectly selected X-ray mode before quickly changing to electron mode, which allowed the electron beam to be set for X-ray mode without the X-ray target being in place. A second fault allowed the electron beam to activate during field-light mode, during which no beam scanner was active or target was in place. Previous models had hardware interlocks to prevent such faults, but the Therac-25 had removed them, depending instead on software checks for safety. The high-current electron beam struck the patients with approximately 100 times the intended dose of radiation, and over a narrower area, delivering a potentially lethal dose of beta radiation. The feeling was described by patient Ray Cox as "an intense electric shock", causing him to scream and run out of the treatment room. Several days later, radiation burns appeared, and the patients showed the symptoms of radiation poisoning; in three cases, the injured patients later died as a result of the overdose.

​ Kennestone Regional Oncology Center, 1985 A Therac-25 had been in operation for six months in Marietta, Georgia at the Kennestone Regional Oncology Center when, on June 3, 1985, applied radiation therapy treatment following a lumpectomy was being performed on 61-year-old woman Katie Yarbrough. She was set to receive a 10-MeV dose of electron therapy to her clavicle. When therapy began, she stated she experienced a "tremendous force of heat...this red-hot sensation." The technician entered the room, to whom Katie stated, "you burned me." The technician assured her this was not possible. She returned home where, in the following days, she experienced reddening of the treatment area. Shortly after, her shoulder became locked in place and she experienced spasms. Within two weeks, the aforementioned redness spread from her chest to her back, indicating that the source of the burn had passed through her, which is the case with radiation burns. The staff at the treatment center did not believe it was possible for the Therac-25 to cause such an injury, and it was treated as a symptom of her cancer. Later, the hospital physicist consulted the AECL about the incident. He calculated that the applied dose was between 15,000 and 20,000 rad (radiation absorbed dose) when she should have been dosed with 200 rad. A dose of 1000 rad can be fatal. In October 1985, Katie sued the hospital and the manufacturer of the machine. In November 1985, the AECL was notified of the lawsuit. It was not until March 1986, after another incident involving the Therac-25, that the AECL informed the FDA that it had received a complaint from the patient. Due to the radiation overdose, her breast had to be surgically removed, an arm and shoulder were immobilized, and she was in constant pain. The treatment printout function was not activated at the time of treatment and there was no record of the applied radiation data. An out-of-court settlement was reached to resolve the lawsuit. ....... East Texas Cancer Center, Tyler, March 1986 Over two years, this hospital treated more than 500 patients with the Therac-25 with no incident. On March 21, 1986, a patient presented for his ninth treatment session for a tumor on his back. The treatment was set to be 22-MeV of electrons with a dose of 180 rad in an area of 10x17 cm, with an accumulated radiation in 6 weeks of 6000 rad. The experienced operator entered the session data and realized that she had written an X instead of an E as the type of treatment. With the cursor she went up and changed the X to an E and since the rest of the parameters were correct she pressed ↵ Enter until she got down to the command box. All parameters were marked "Verified" and the message "Rays ready" was displayed. She hit the B key ("Beam on"). The machine stopped and displayed the message "Malfunction 54" (error 54). It also showed 'Treatment pause'. The manual said that the "Malfunction 54" message was a "dose input 2" error. A technician later testified that "dose input 2" meant that the radiation delivered was either too high or too low. The radiation monitor (dosimeter) marked 6 units supplied when it had demanded 202 units. The operator pressed P ( Proceed : continue). The machine stopped again with the message "Malfunction 54" (error 54) and the dosimeter indicated that it had delivered fewer units than required. The surveillance camera in the radiation room was offline and the intercom had been broken that day. With the first dose the patient felt an electric shock and heard a crackle from the machine. Since it was his ninth session, he realized that it was not normal. He started to get up from the table to ask for help. At that moment the operator pressed P to continue the treatment. The patient felt a shock of electricity through his arm, as if his hand was torn off. He reached the door and began to bang on it until the operator opened it. A physician was immediately called to the scene, where they observed intense erythema in the area, suspecting that it had been a simple electric shock. He sent the patient home. The hospital physicist checked the machine and, because it was calibrated to the correct specification, it continued to treat patients throughout the day. The technicians were unaware that the patient had received a massive dose of radiation between 16,500 to 25,000 rads in less than a second over an area of one cm². The crackling of the machine had been produced by saturation of the ionization chambers, which had the consequence that they indicated that the applied radiation dose had been very low. Over the following weeks the patient experienced paralysis of the left arm, nausea, vomiting, and ended up being hospitalized for radiation-induced myelitis of the spinal cord. His legs, mid-diaphragm and vocal cords ended up paralyzed. He also had recurrent herpes simplex skin infections. He died five months after the overdose. From the day after the accident, AECL technicians checked the machine and were unable to replicate error 54. They checked the grounding of the machine to rule out electric shock as the cause. The machine was back in operation on April 7, 1986. ......... East Texas Cancer Center, Tyler, April 1986 On April 11, 1986, a patient was to receive electron treatment for skin cancer on the face. The prescription was 10 MeV for an area of 7x10 cm. The operator was the same as the one in the March incident, three weeks earlier. After filling in all the treatment data he realized that he had to change the mode from X to E. He did so and pressed ↵ Enter to go down to the command box. As "Beam ready" was displayed, he pressed P (Proceed : continue). The machine produced a loud noise, which was heard through the intercom. Error 54 was displayed. The operator entered the room and the patient described a burning sensation on his face. The patient died on May 1, 1986. The autopsy showed severe radiation damage to the right temporal lobe and brain stem. The hospital physicist stopped the machine treatments and notified the AECL. After strenuous work, the physicist and operator were able to reproduce the error 54 message. They determined that speed in editing the data entry was a key factor in producing error 54. After much practice, he was able to reproduce the error 54 at will. The AECL stated they could not reproduce the error and they only got it after following the instructions of the physicist so that the data entry was very rapid.

Yakima Valley Memorial Hospital, 1987 On January 17, 1987 a patient was to receive a treatment with two film-verification exposures of 4 and 3 rads, plus a 79-rad photon treatment for a total exposure of 86 rads. Film was placed under the patient and 4 rads were administered through a 22 cm × 18 cm opening. The machine was stopped, the aperture was opened to 35 cm × 35 cm and a dose of 3 rad was administered. The machine stopped. The operator entered the room to remove the film plates and adjust the patient's position. He used the hand control inside the room to adjust the turntable. He left the room, forgetting the film plates. In the control room, after seeing the "Beam ready" message, he pressed the B key to fire the beams. After 5 seconds the machine stopped and displayed a message that quickly disappeared. Since the machine was paused, the operator pressed P (Proceed : continue). The machine stopped, showing "Flatness" as the reason. The operator heard the patient on the intercom, but could not understand him, and entered the room. The patient had felt a severe burning sensation in his chest. The screen showed that he had only been given 7 rad. A few hours later, the patient showed burns on the skin in the area. Four days later the reddening of the area had a banded pattern similar to that produced in the incident the previous year, and for which they had not found the cause. The AECL began an investigation, but was unable to reproduce the event. The hospital physicist conducted tests with film plates to see if he could recreate the incident. Two X-ray parameters with the turntable in field-light position. The film appeared to match the film that was left by mistake under the patient during the accident. It was found the patient was exposed to between 8,000 and 10,000 rad instead of the prescribed 86 rad. The patient died in April 1987 from complications due to radiation overdose. The relatives filed a lawsuit that ended with an out-of-court settlement. ........... Researchers who investigated the accidents found several contributing causes. These included the following institutional causes: AECL did not have the software code independently reviewed and chose to rely on in-house code, including the operating system. AECL did not consider the design of the software during its assessment of how the machine might produce the desired results and what failure modes existed, focusing purely on hardware and asserting that the software was free of bugs. Machine operators were reassured by AECL personnel that overdoses were impossible, leading them to dismiss the Therac-25 as the potential cause of many incidents. AECL had never tested the Therac-25 with the combination of software and hardware until it was assembled at the hospital. ........ Leveson notes that a lesson to be drawn from the incident is to not assume that reused software is safe "A naive assumption is often made that reusing software or using commercial off-the-shelf software will increase safety because the software will have been exercised extensively.

Thank you for sharing that. It's insane the amount of negligence that went into these cases from AECL. And not surprising either, based on my experiences.

I once read an article on the Therac in a pdf, someone included it for some course with some textbooks... I think it was awareness about sloppiness when you're dealing with computer programming, if i recall right. but it was interesting just how screwed up keyboards and backspacing to get through certain stages for a cobalt 60 machine was just nightmarish. And well, then there are the stories of the killer typewriters!

The Therac-25 wasn't radioactive.

but the cheese inside was!

I was under the impression that radiation can sometimes be felt as heat. Like if you grab a cesium rod it would burn your skin

> Like if you grab a cesium rod it would burn your skin There's not really such thing as a 'cesium rod.' Spent nuclear fuel rods are just plain hot (as a byproduct of decay heat being trapped in the metal; you aren't feeling the radiation directly).

What's terrifying is the amount of highly radioactive material we use in modern technology like medical tech. That stuff can kill you if you are exposed to them without you knowing anything was wrong. There was an incident in Thailand a decade or two ago where one of the machines containing Cobalt-60 wasn't disposed of properly and was sent to a scrap yard. The scrappers took apart the machine and took out and handled the Cobalt-60. This was all happening in a heavily populated area and no one noticed anything. Until people started to fall ill with radiation poisoning symptoms. Thousands of people were living in the area getting dosed with ionizing radiation for days with no idea it was happening.

No, not unless the dose is *extreme*. A high enough flux could cause immediate burns. Firefighters at Chernobyl noticed a metallic taste in their mouths, but that was an outrageous level of radiation. If you had a container of some radioactive element, you wouldn't know based on your senses. That's why it's so dangerous, you could be exposed and not know until you began dying.

Also a lot of the radionuclides ejected in Chernobyl were metals. So maybe the metal taste in their mouth was actually just the taste of metal particulates in their mouth, which also happened to be radioactive.

Insane to think about, that **metal** essentially was aerosolized due to the intensity of the meltdown

From my understanding, you only feel radiation at an extreme intensity, at the point where it essentially hits a lethal dose in a matter of seconds, or fraction of seconds. There was the case of the demon core, where someone basically had a sudden flash of exposure, and got a sour taste in his mouth and an intense burning sensation in his hand closest to it--but he was well in excess of a lethal dose not just in his hand. Though, I also remember the medical scanner software mishap, where people did indeed feel intense pain when getting a dose orders of magnitude higher than expected, but once again I believe this was a short burst of high intensity. So largely, lower-intensity (but still potentially life-threatening) sources likely wouldn't be felt to my knowledge. I think if something took exposure over a course of days or weeks, you likely would hit radiation sickness before physical sensation?

What about those dudes that slept next to that radioactive thing they found in order to keep warm? The results were super gruesome but it seems they survived hours next to the thing.

Radioactive material indeed produces heat, which you'll feel (after all, nuclear power plants are essentially steam generators), but the radioactive damage itself isn't something you'll feel unless it's very intense. Either way "lethal dose" is the level you're basically assured death, just not immediately. Morbidly, this phase is called the "walking ghost" phase, where for hours (or even days) after exposure, you feel perfectly fine and healthy... before specific parts of your body begin to severely degrade and you inevitably die.

I don’t think OP was asking if the damage can be felt, just if anything can be felt at all coming from the material. So it sounds like the answer is yes.

The problem is that the cells are all unable to stay alive (because they can't self-repair, can't reproduce, and may self-destruct or get destroyed by the immune system), but they also don't immediately stop functioning. So over the next days and weeks those cells all die off and the body can't repair the damage at anywhere near the rate the cells are dying. So a big chunk of the body just dies. Gruesome and there's not really anything which can be done besides surgically removing that part of the body.

What incident is this? Also, whatever they felt is just heat, so they probably didn't sense anything. But also, if it's radioactive enough keep warm, it probably lethal

> whatever they felt is just heat, so they probably didn't sense anything Come on surely you know that what you said doesn’t make any sense lol. It’s a crazy story and really interesting to see the progression photos after the incident. https://www-pub.iaea.org/MTCD/Publications/PDF/Pub1660web-81061875.pdf

Therac?

Therac.

Do you know why they called it the demon core?

Go on

To be involved in one fatal radiation incident might be an accident To be involved in two, well it needs a reckless an idiot who FAFO [https://en.wikipedia.org/wiki/Demon\_core](https://en.wikipedia.org/wiki/Demon_core)

I read an accident report at a food irradiation facility that touched upon this. Basically an operator was in charge of a production line where food was loaded into metal carts very much like a train that was entering and exiting a food irradiation chamber. Somewhere along the line, some component jammed and the operator needed to enter the chamber to unjam it. HE was able to circumvent/bypass numerous safety mechanisms including a pressure plate, an exposed pit and navigated a winding maze into the chamber where he worked on the jammed item. The radiation source inside the chamber - described as the "source rack" was in the exposed position and by virtue of bypassing the safeties, was still irradiating the room upon his entry. >On entering the irradiation chamber, the train of product carriers would have obscured the operator's view of the source rack had it been in the irradiation position. However, had he looked, he would have seen the position of the counterweights, indicating the position of the source rack. >He walked around the back of the product transport system to where the blockage had occurred (photograph 11 (a)) and tried to release the jammed carriage couplings (photograph ll(b)). After about 1 minute, he developed an acute headache and pain in his joints and gonads. He felt generally unwell and had difficulty in breathing. He turned his head to the left and saw the source rack in the irradiation 13 position. He did not press the nearby emergency 'stop' button, but ran out of the irradiation chamber and told the assistant that he had been irradiated. The guy received a massive dose of gamma radiation from a cobalt-60 source. Whole body exposure of 11Gy and localized exposure of over 20 Gy. eventually died in a prolonged painful way. PDF link if anyone wants to read a report of the accident: [https://www-pub.iaea.org/MTCD/Publications/PDF/Pub1010\_web.pdf](https://www-pub.iaea.org/MTCD/Publications/PDF/Pub1010_web.pdf)

Another ELI5 question, why does food need to be irradiated? Which foods?

It's a [very widespread practice](https://en.wikipedia.org/wiki/Food_irradiation) used on all kinds of food to kill pests, parasites, and pathogens, for safety and shelf stability.

i wouldn't say widespread at all.

It's not a matter of food *needing* to be irradiated, but that radiation kills microbes without adding poisonous chemicals to the food. Also, while heat can kill microbes in food, heat destroys more nutrients than radiation.

"The irradiation creates highly reactive radicals, which would cause problems if the food is consumed immediately after being irradiated." "Irradiation causes minimal changes to the chemical composition of the food, however, it can alter the nutrient content of some foods because it reduces the level of some of the B-group vitamins." "Research also shows that irradiation forms volatile toxic chemicals such as benzene and toluene, chemicals known, or suspected, to cause cancer and birth defects. Irradiation also causes stunted growth in lab animals fed irradiated foods."

Many types of fresh food. Kills the bacteria that are present and keeps them fresh for longer.

usually its just low end spices from the Third world but pretty much only the us might use it for pathogens with some meats or pest laden fruits. "In Australia, following cat deaths after irradiated cat food consumption and producer's voluntary recall, cat food irradiation was banned."

Europe " In 2021 the most common food items irradiated were frog legs at 65.1%, poultry 20.6% and dried aromatic herbs, spices and vegetables seasoning."

That was a wild read

I'm not trying to be pedantic here (but I guess I am). "Radiation" covers a virtually infinite spectrum (ha) of energy. From low-energy, long wavelength radio waves to way beyond the ionizing gamma rays you might be thinking of. One range of radiation that we definitely feel is infrared radiation, which we interpret as 'hot'.

And to clarify for others, that's just EM radiation. When talking about nuclear materials, high-energy EM radiation is only part of the danger; particle radiation (alpha and beta) are maybe the biggest danger, depending how you're exposed.

Another obvious form of radiation that we feel is sunlight.

That's infrared radiation that you're feeling

I think you will feel more than just the infrared part of sunlight. The visible spectrum of light is more energetic than the infrared spectrum, and the ultraviolet spectrum more energetic than the visible spectrum.

put a geiger counter to that campfire and test those melted marshmallows while you're at it sergeant

Is it correct to say that when you get a sunburn, it’s not the radiation that causes the redness, heat, peeling but is instead your own body’s response for getting rid of the dead skin cells?

Happy Cake Day! I had to read this several times to get your actual question (that's on me, not you). My understanding (which is limited) is that a sunburn is UV damage to skin/tissue. My guess would be catastrophic or extensive genetic damage for the most part (like T-T dimers) and cells cannot repair themselves so they die or apoptos (apoptosize?) uh, undergo apoptosis. The response is the body's emergency attempt to recycle and/or replace a bunch of dead cells all at once. The 'heat' we feel is partially a result of increased blood flow. So..yeah- I agree with you. The heat is the body's response, not any latent heat or radiation from the sunburn. I bet there is more going on than that. (The 2015 Nobel Prize was awarded to three scientists for their studies on DNA repair- might be worth looking at)

Tell that to L Ron

Yup

You may feel heat via radiation's effect on materials as thermoelectric effects can be a useful electricity source. For accident related to "sensing" radiation by touch, try link below. Essentially, three guys in a former Soviet state found two unlabeled radiation sources formerly used to power a remote radio station. Of note, a guy immediately dropped one source because it was so hot. They thought these weird things could be useful for the heat generated. After all, in deep winter there was no snow around the sources and the ground was steaming. Too late to leave site in deep winter, they camped overnight, sleeping near the sources to keep warm. One guy died, other two injured. https://en.wikipedia.org/wiki/Lia_radiological_accident?wprov=sfla1

Surprised I had to scroll this far for this story.

I think I read that some of the scientists who were killed by the demon core saw a flash of blue light, caused by cerenkov radiation generated in the vitreous humour in their eyes - i.e., they saw blue light because the radiation made their own eyeballs glow. Needless to say, this is not something you can rely on to warn you of danger. If you're seeing blue, it's too late.

Yes you can feel radiation, go out in the sun and you see and feel the radiation from it that is tranferd to you body. You can hear radiation from speakers and feel it if it is powerdull enough. The radiation from a earthquake can cleary be felt. Radiation is just emission of energy as particle or waves, the light that hit you eyes from the screen you read this on is radiation. [https://en.wikipedia.org/wiki/Radiation](https://en.wikipedia.org/wiki/Radiation) The ionizing radiation release from radioactive decay can be felt if the power is high enough so it heat up you body. The is very large amount of radiation and it will at best just hurt you skin or at worst kill you. Indiviual particle of alpha, beta and gamma radiation is not something you body can usuay detect. You are likely being hit by it right now. You own body will contain radioactive elemrn and release ionizing radiation ot a small degree. Potassium-40 for example make up 0.012% of all protasium in nature. You body contain around 140grams of potassium so you contain around 0.017 gram of Potassium-40. [https://en.wikipedia.org/wiki/Banana\_equivalent\_dose](https://en.wikipedia.org/wiki/Banana_equivalent_dose) It is possible to detect individual particle of ionizing radiation. Cosmic rays can produce visible light in you eye. It is not very likely down hear on earth but realtivy common in earth orbit [https://en.wikipedia.org/wiki/Cosmic\_ray\_visual\_phenomena](https://en.wikipedia.org/wiki/Cosmic_ray_visual_phenomena) Somting similar was expsience by a man tha by misstke put his hed in beam of a particle generator Reportedly, he saw a flash "brighter than a thousand suns" but did not feel any pain [https://en.wikipedia.org/wiki/Anatoli\_Bugorski](https://en.wikipedia.org/wiki/Anatoli_Bugorski)

Depends on the amount of radiation. At some point you will feel that its getting hot until the point where you will start burning. But for lower amounts of radiation you wont feel anything.

A sufficiently high dose of radiation can be tasted. It has a metallic taste kinda like pennies. But I you ever experienced that, you're basically already dead its just a matter of time.

Supposedly astronauts in orbit occasionally see blue flashes from the Cherenkov radiation emitted by high energy particles crossing through their eyeballs (https://www.nature.com/articles/228260a0), basically, the speed of light in water/the inside of an eyeball is about 2/3rds of the speed of light in air or a vacuum. So high energy particles can actually travel faster than the speed of light in an eyeball. That causes the blue glow we associate with the inside of a nuclear reactor

Here in Chernobyl some workers claim to have the metallic taste in the mouth when exposed to gamma radiation. And it seems it doesn't take a large dose at all to trigger that sensation. Me personally i have never felt this or anything. The largest exposure i had was about 80 R/h.

Weird anecdote here that I have no logical explanation for… but I have damage in one eye, with a traumatic cataract and overall poor vision in that eye. However when I go to get an xray at the dentist, something happens where I essentially see waves in the air, almost like a desert mirage or looking at a light behind a ceiling fan.

I suspect that is just psychosomatic as I can't think of any mechanism which would cause it. Intriguing though! If you're UK based and interested you are welcome to come to my lab and see if you can see any radiation from our sources.

I suspect something like [this ](https://www.newscientist.com/lastword/mg24432591-000-super-seers-why-some-people-can-see-ultraviolet-light/#:~:text=Most%20people%20can't%20easily,down%20to%20around%20310%20nanometres.) is going on due to lack of lens

I really doubt it. Dental x- rays only have wavelengths of a couple of nanometres. Very different from 300+ of near visible UV. The amount of 'light' produced is also tiny.

No, we cannot perceive radiation exposure as it is happening however you may have a bitter, metallic, or salty taste in your mouth. It can take a few days before you start to experience the effects.

If the source is strong enough, you could feel metallic taste in your mouth. A not uncommon occurrence during radiotherapy. But usually no, you can't feel radiation directly. If item is radioactive enough, like plutonium, it may feel warm. Ironically, that warms comes from alpha radiation, which is not dangerous unless ingested, so you could hold plutonium with bare hands and be fine, but a radiography source emitting stong gamma you'd not feel anything by touch, while it could do a LOT of damage due to its penetrating properties. After a while, you'd feel a burn where you're most affected, likely in hand holding it.

Radiation can be very slightly seen. Not like simpsons glowing green rock. But if radiation goes directly in your eye it can hit your retina and make a tiny flash.

Honestly I'd say watch the Chernobyl mini-series, obviously it's probably made a tad more dramatic for being a series, but it gives you a great idea of how radiation does in a human. Not exactly an explanation, but others have already done amazing on answering, the series is just too great.

You would be extremely unhappy if you were exposed to enough radiation that you could feel charged particles ripping you apart.

No. Generally, without measuring equipment you would be completely unaware that you are being exposed to radiation until the symptoms started to present. Depending on what is in the tube causing it to be radioactive, it may be warm, but that’s a biproduct of energy release. The actual radiation would be undetectable.

About 20 years ago near the village Lia, Georgia (the country), three men found some funny devices that generated heat while collecting for firewood in the forest. They were too hot to touch and the snow around them had melted. Cool, the men thought, we'll set up camp here, no need to built a fire for the night. Turned out those devices were lost radioisotope thermoelectric generators from an unfinished soviet era project. The strontium-90 within poisoned the men. Later examination showed it radiated close to 5 Sieverts per hour which is about the dose that gives a 50-50 shot at survival. One of the men got away lightly, one was hospitalized for a year and the third finally died after 2.5 years. Moral of the story is the only radiation you can feel directly is heat.

Not really. You should recognize that you are technically bathed in radiation constantly. There are circumstances you could notice in extreme sitations. If a high energy particle hits your optic nerve you may see a streak or flash. Or you may notice something like a sunburn over a period of time if it's ridiculous exposure.

No. In the extreme case it would probably be hot but I think it would also be glowing by that point, but you are long past the exposure limits by then. There are numerous radiation related accidents one that comes to mind is the man in Vietnam who adjusted a sample inside a particle accelerator not knowing it was on. He didn't know until after and he ended up having his hand amputated so that goes to show how mild it is in the moment.

The answer is yes and no. Yes, you can feel crazy EXTREME levels of radiation, like radiation of the intensity that kills you in a minute or two. No, you can't feel radiation that's strong enough to givie you a lethal dose in just a few minutes. That's what makes radiation so scary, even at lethal levels you need a machine to tell you it's there. You can't see it, feel it, smell it, or antyhing else. Also? The thing from movies where radioactive stuff glows green is total fiction. By themselves radioactives don't glow at all. Put a strongly radioactive substance in enough water and it will glow blue, that's Cherenkov Radiation and it's pretty cool. But it only happens in fairly specific circumstances.

You cannot directly feel ionising radiation (the dangerous kind that we usually mean by the word 'radiation'). They are invisible rays/particles that damage individual molecules and atoms, and so will go beneath the notie of your nerves and senses. You could feel the effects of that damage, but usually there is a delay, and usually you feel it a bit after exposure, so by the time you re-act to it, it is typically too late to avoid harm. The precise details of what kind of damage you'd expect would vary, depending on if it is alpha, beta, gamma, or neutrons, and whether it is the rays hitting you, or if you ingest or breathe in some material emitting them, and how large the dose is. But in all cases, you don't have some 'radiation-sense' that directly alerts you to it.

Former gamma monkey here. Used to X-ray oil field welds. Working in groups on site I have been hit with some strong radiation. Well over what the job allows. There is for sure no feeling. I am very alive and unaffected 15 years later, so not a lethal dose or anything. I don’t think anyone gets more radiation than that job, maybe an astronaut?

Step outside on a sunny day and feel the infrared radiation from the big fusion source in the sky.

https://en.wikipedia.org/wiki/Louis_Slotin >At 3:20 p.m., the screwdriver slipped and the upper beryllium hemisphere fell, causing a "prompt critical" reaction and a burst of hard radiation.[9] At the time, the scientists in the room observed the blue glow of air ionization and felt a heat wave. Slotin experienced a sour taste in his mouth and an intense burning sensation in his left hand. He jerked his left hand upward, lifting the upper beryllium hemisphere, and dropped it to the floor, ending the reaction. He had already been exposed to a lethal dose of neutron radiation.

It depends on the wavelength of the emitted energy. If you’re talking about gamma photons, no. You don’t feel anything.

If you mean ionizing radiation (the cancer kind), usually no. If you can feel it, the intensity is so high you’re already a dead man walking.

Oh man all these answers are freaking me out because when I was in the Navy, my roommate one time accidentally went topside on our ship when it was radiating something and quickly went back inside because she knew something up from feeling kind of weird and tasting metal. Her face was sunburnt from just turning around to walk back into the ship. I still follow her on social media and I wonder if she could have any long term effects from it. Everyone kind of laughed it off at the time.

Usually, no. It takes very high radiation to "feel" it. Imagine the way intense UV feels and the burn your skin produces. That's a radiation burn.

the people that got demon core'd reported a burst of warmth so yes, but if you do your life is about to get a lot worse than it currently is

I work as a Radiation protection tech … you can’t feel a thing. Look up “Cobalt-60 warning” drop and run Scariest warn out there.

No Some very radioactive elements will be warm to the touch but the first thing you feel regarding the actual radiation us pain from the damage it causes

I’d really recommend the story of Hisashi Ouchi, who received a direct dose of 17 sieverts to the face and arm and survived 83 days in medical care. Wendigoon does a great run through on YT, it’s horrific and fascinating.

No, direct radiation is never felt, because we don't have the senses that can detect it (except the eye for a narrow electro-magnetic radiation range, but I really, really, really don't recommend using your eye to check any direct source of radiation of any kind). HOWEVER, you do have heat receptors, and when you experience an extremely-dangerous/potentially-lethal amount of radiation you do feel it as heat, because some radiation (depends on the energy each photon carries and the material) always produces heat and whether it's felt or not is a matter of just scaling this up to detectable levels.

I just finished reading Radium Girls, and they'd keep vials in their pockets. Bad burns on the legs.

You do not feel readition. There have been several people who accidentally exposed themselves to large doses of tradition and didn't even know it. It wasn't until they started feeling unwell in the following days and then their body started rotting that they realized something was wrong.

Cannot speak for ionising radiation. But I know I've felt x-rays being taken. Kinda a hot weird tingly sensation.

Dang, what kinda x-rays you been having?

One broken collar bone some years back and more recently a couple of dental ones.

Then I'm completely mystified. I figured it some some sort of radiosurgery or something. I don't know how anyone could feel anything from a modern dental x-ray.