Radiation Safety & Health Physics Blog

Does Weapons-Grade Uranium Pose a Health Risk When Handled?

Dear Dr. Zoomie – I was watching The Man in the High Castle and there was a bit about weapons-grade uranium posing a health risk to people around it. Is this true?

I’ve been watching this series too and I just watched that episode myself. I have to admit I was happy to see one of the “bad guys” who was concerned about the health of the public. On the other hand, I was disappointed that the writers (and researchers) got this part wrong. The short version is that uranium – even highly enriched uranium – is simply not very radioactive. I can confirm this from personal measurements – I’ve made radiation dose rate measurements on depleted uranium, natural uranium, and enriched uranium and none of them are very radioactive. Here’s why:

There are a couple of ways to approach this question. The easiest one is to do a calculation using something called a gamma constant – the gamma constant tells us the radiation dose rate from a given activity of a radionuclide at a given distance. For U-235 (the isotope of uranium used to make nuclear weapons) the gamma constant is only about 0.176 mR/hr from 1 curie of radioactivity at a distance of one meter). So now we just have to figure out how many curies of U-235 there are in a nuclear weapon.

The Little Boy nuclear weapon used highly enriched uranium – about 64 kg (141 pounds) of it. This is significantly more than what’s used in modern weapons, but it was our first one and the designers still needed to figure out some of the tricks we use today. Since the uranium in The Man in the High Castle was also intended for a country’s first nuclear weapons we’ll assume they were using this same amount of uranium. OK – this gets us a weight, but we need an activity to use the gamma constant. So a little more work is in order.

Every nuclide also has what’s called a “specific activity” – the amount of radioactivity (in curies or in the international unit of Becquerel). This is the amount of radioactivity in 1 gram of that radionuclide. For U-235 the specific activity is 91 microcuries per gram, so 1 kg will have a thousand times as much, or 91 mCi and the 64 kg in Little Boy would contain 5.8 Ci – to make the math easy, let’s call it 6 Ci.

So – if 1 Ci gives a dose rate of 0.176 mR/hr at a distance of 1 meter, 6 Ci will produce a dose rate of 0.176 x 6 = 1.056 R/hr at a distance of 1 meter. The actual dose rate from the Little Boy bomb was probably lower than this because it wasn’t 100% U-235, and the other nuclide present (U-238) has an even lower specific activity. But let’s use a dose rate of 1 R/hr at a distance of 1 meter – again, to make the math a little easier.

Now we’re to the final part – what health effects do we expect to see from this level of radiation exposure?

The lowest radiation exposure that’s been shown to cause short-term health effects is about 25 rem – this will cause your blood cell counts to drop for a few months due to damage to the blood-forming organs. It takes about 100 rem to cause radiation sickness, about 400 rem to give someone a 50% chance of death (without medical treatment), and nearly 1000 rem to be fatal. With a dose rate of 1 R/hr at a distance of 1 meter this part’s easy – it’ll take 25 hours of exposure to cause a change in blood cell counts, 400 hours to give a 50% risk of death, and 1000 hours to cause death. At a speed of 60 mph it takes about 50 hours to cross the US – not even enough time to develop radiation sickness. And that’s for a person sitting for that whole time at a distance of 1 meter from the uranium – a person in the next row (or the next seat) further away would receive only half (or less) that amount of radiation.

So – when we put all of this together it seems fairly safe to say that even a person sitting right next to all that uranium on a cross-country trip wouldn’t even get radiation sickness. Which means that The Man in the High Castle is overstating things a bit – nuclear weapons are bad when they explode, but they don’t give off dangerous levels of radiation.

Can Hospitals Refuse Patients Who’ve Been Contaminated with Radiation?

Hi, Dr. Zoomie – I’ve heard that sometimes hospitals don’t want to admit patients if they’re contaminated with radioactivity. There’s always a chance that one of my workers might need medical attention and they could be contaminated. How can we make sure that our people get the medical attention they need, even if they’re contaminated? I know it’s sort of far-fetched, but you never know.

You know, this isn’t as far-fetched as you might think. I won’t say it happens all the time, but workplace accidents happen all the time and it’s certainly not unreasonable to believe that you could end up with a contaminated injured person. One scenario that comes to mind almost happened to me a few times – a person’s carrying radioactive liquids and trips and falls down. Just falling on a level surface can hurt someone, especially if they hit their head. But a person can also fall down a stairway or brain themselves on a piece of machinery – the possibilities are endless, as we all know. In any event, you have to know that all of your injured people will get prompt medical attention, even if they’re contaminated with radioactivity.

The first thing is to call whatever hospital your people will be sent to as well as whoever will be taking them there – local EMTs, ambulance service, fire department, or whoever it is that makes these runs. All of you need to meet so that you can all talk through what needs to be done so that your people get the medical care they need with the fewest delays possible. This will probably require that you frankly discuss with the others the type and amount of radioactivity your folks might be contaminated with, the risk that it would pose, and how to work with it safely. And what you need to make sure they understand is that a contaminated patient poses little to no risk to medical caregivers – in fact, there’s virtually no plausible circumstance I can think of in which a person at an industrial, medical, or research facility can be contaminated badly enough that it would pose a risk to medical caregivers.

What the ambulance company needs to know is how to keep their drivers, medics, and ambulances from becoming contaminated; or when this contamination might be warranted. When the patient is critically injured and every minute counts, the most important thing is to try to stabilize the patient and get them to the hospital as soon as possible. We can always decontaminate an ambulance, but if a person suffers irreparable harm or if they die…these can’t be un-done. This means that we do whatever decontamination is possible – but only to the extent that it doesn’t delay any medically necessary care or attention.

If time does permit, there are some things that can be done to reduce the spread of contamination to an ambulance. Removing outer clothing will remove up to 75% of the contamination. Wrapping a person in a blanket or sheet reduces contamination even further, as does putting them in a Tyvek or disposable “bunny suit” to contain the contamination on their clothes and body. If there’s even more time, you can work on decontamination – wipe them down with a damp sponge or washcloth – but only if time permits. Something else you can do to limit the spread of contamination to an ambulance is to cover as much of the ambulance’s interior as possible. Also, remember that any nuclear medicine patient contains more radioactivity than virtually any contaminated worker, and many of them will also have a fair amount of skin contamination as well.

OK – this gets your person into the ambulance and on their way to the hospital, but you still have to persuade the hospital to let your contaminated workers into the emergency room.

As I mentioned earlier, if the patient is critically injured – if every minute counts – there is neither the time nor the need to decontaminate them prior to treating them. In this case, standard hospital precautions will suffice to keep the medical caregivers safe. So as long as they’re wearing gloves, a mask, and maybe a surgical gown – taking precautions to keep the contamination off of their skin – they should be OK. Having said that, even if they DO get some contamination on their skin it’s not the end of the world – I used to do water chemistry on nuclear reactors and I had skin contamination a number of times; every time it cleaned up with soap and water fairly quickly. I think of radioactive contamination as being like changing a diaper – I don’t want to get anything on my hands but, if I do, I just wash my hands and go on with my day. So – if their condition is critical – the patient can be taken directly to a trauma bay and worked on without posing a risk to the medical staff.

Having said that, it can take days, weeks, even months to decontaminate an emergency room and you don’t want to do that unless it’s necessary. If the hospital has a chance to prepare, there are some things that can be done to reduce contamination of their facilities. Most effective is to put down floor coverings – plastic (preferably textured to prevent slipping) or plastic-backed paper. They can also cover the examination table with plastic, and can even put a plastic covering over the lights, trays, and anything else that might come in contact with a contaminated patient. Even better is if the floor is covered with a seamless floor covering, but this obviously can’t be done on the spur of the moment.

You can see a lot of this in the photo below, which I took at the Fukushima University Medical Center a few weeks after the reactor accident – this is the same trauma bay where the two workers who had radiation burns were initially treated.

A Trauma Bay at the Fukushima University Medical Center

A Trauma Bay at the Fukushima University Medical Center

I could go into a lot more details, but space doesn’t permit. So for the purposes of this article, let it suffice to say that the risks to medical caregivers are well-known, they are very low, and can be managed. While it’s best to prevent contamination in either the hospital or the ambulance, if the patient is in urgent need of medical attention, the patient must come first. And for any medical responder, taking standard safety precautions will help to keep them from being contaminated.

So…. If you are concerned that one of your people might be contaminated with radioactivity AND might need medical attention you need to work out the details with both your local hospital(s) and whoever will be transporting the patient to the hospital. Make sure that they understand the (lack of) risks a patient might pose them and, between you, come to an agreement as to what everyone needs to do in order to ensure your people get the medical care they need, without undue delay if their condition is critical. And the time to do this is now – before one of your people is hurt.

Are Radiation Levels at Fukushima High?

Dear Dr. Zoomie – I heard that radiation levels have gone sky-high at Fukushima. What gives? Do we need to worry that it’s still melting down or giving worse? Should I avoid the Pacific Ocean and the West Coast? Help!

Yeah…this was pretty interesting. And of course the question is why the radiation levels went up and what that means. But first, let’s talk a little bit about the radiation level that the story talks about.

No way around the fact that 530 Sieverts per hour (Sv/hr) is a whopping radiation dose rate. A dose rate of 10 Sv (1000 rem) is lethal 100% of the time, so this dose rate would give you a fatal dose of radiation in about a minute. So – yes – this is a serious dose rate. And let’s face it, if even a robot can only handle it for a few hours then we know it’s a high dose rate! For what it’s worth, I’ve been involved in radiation safety for 35 years and this is far and away the highest dose rate I’ve ever heard of. So there is no doubt that the dose rate reported is serious. The question we have to ask is whether this is a new dose rate (that is, did something change within the core to cause dose rates to go up) or was it like this all along and it was just found.

The Fukushima I Nuclear Power Plant after the 2011 Tōhoku earthquake and tsunami. Reactor 1 to 4 from right to left.

The Fukushima I Nuclear Power Plant after the 2011 Tōhoku earthquake and tsunami. Reactor 1 to 4 from right to left.

If this dose rate represents a change in core conditions then there might be cause for concern – it could indicate that something’s changed. For example, maybe some of the fuel dropped down to a new location. If it’s the latter then it could indicate that conditions might still be unstable. There are those who have speculated that perhaps the melted fuel has somehow achieved criticality again – this is highly unlikely. The reason is that it takes a great deal of engineering to achieve criticality in a nuclear reactor; the possibility that the melted fuel somehow rearranged itself to become critical is vanishingly unlikely.

It is possible that the components of the wrecked core have shifted and, in the rearrangement, a high-dose rate piece (or pieces) ended up near the instruments. This is more likely than a criticality, but given some other facts (I’ll get to these in a moment) this is also less likely than are other possibilities.

The key piece of information in this story was that TEPCO was pushing radiation instruments into a part of the plant that hadn’t been investigated before. As their instrument-bearing robot pushed into new territory it encountered new conditions – including parts of the ruined core. So it’s almost certain that the increased radiation levels are due to moving the instruments into new – and far more radioactive – territory. Think of moving your hand over a candle flame – as it passes over the flame you feel your hand heat up. This isn’t because someone just lit a candle – it’s because you moved your hand into the hot air above the candle that was already burning.

Interestingly, the robot took a number of photos as it was making its rounds, giving us an idea of what the core and reactor vessel now look like. Needless to say, it’s a mess – but that’s to be expected. There are lumps of what we can speculate are solidified fuel, a place that looks as though molten fuel melted its way through the floor grating, and so forth. It’s evident even to an untrained eye that there’s been a lot of damage – unfortunately, without knowing what the plant looked like before the accident (and being unfamiliar with this particular reactor plant design) it’s hard to know if anything non-obvious has changed.

The bottom line is that, while the newly reported radiation levels are dangerously high they probably don’t represent any changes in the conditions at the Fukushima reactors – much more likely is that they represent the first push into an area that has had extraordinarily high radiation levels every since the accident. So you don’t need to avoid the Pacific Ocean!

Myth or Fact? – Will Alcohol Help Protect Against Radiation?

Dear Dr. Zoomie – I was watching a movie about a Russian submarine that had a reactor accident. In the movie they told the crew to drink vodka to help protect against the radiation. Is this BS or is it real?

I saw the movie you’re talking about – I think it was called K-19, the Widow-maker. Not a bad movie, and the incident it refers to actually happened. A Soviet nuclear submarine had catastrophic reactor accident not far off the American coast. The movie took some liberties with the science and engineering of course, but it was a fun one to watch.

This picture is said to be the photo the U.S. NAVY had of the K-19

A U.S. NAVY photo of the actual K-19 submarine of the 658 class of submarines

As far as your question goes, there’s a specific way to look at it and more general way. Let me try to tackle both.

The specific question is “Will alcohol help protect against radiation damage, or will it just keep me from caring as much?”

The answer is a little of both – but more of the latter. But let’s backtrack a little bit and talk about how radiation harms the body. Then we can see how alcohol (and other measures) can – or cannot – help.

When radiation interacts with our cells it can do one of two things – it can strip an electron off of an atom, creating a pair of charged particles (the negatively charged electron and the remaining positively charged atom, now called an ion) that we call an ion pair. This ion pair can recombine, or it can go on to cause chemical changes in the cell that lead to the formation of active (and potentially damaging) molecules called free radicals. These free radicals can then go on to damage the DNA. Alternately, the radiation might hit the DNA directly, causing one of the two strands of DNA to break. Our bodies have ways to repair both of these types of damage – there are many sources of free radicals besides radiation, and DNA is under attack all the time. But there’s only so much capacity for our DNA repair mechanisms – eventually they’ll be overwhelmed and damage will start to accumulate. And if too much damage accumulates too rapidly then we start to see the ill effects – we might have a higher risk of cancer over the next few decades, or if we’re really blasted with a huge dose of radiation (as happened on the Soviet sub) we can see changes in our blood cell counts, we can experience skin burns, develop radiation sickness, or even die.

Now – before you worry too much, it takes a LOT of radiation to get to the point of seeing physical damage – a minimum of 25 rem in a short period of time to see changes in blood cell counts, over 100 rem to start to feel ill, and over 400 rem before we really start worrying about death. So these are things that CAN happen – but they usually don’t. But let’s get back to the main question: If I’m blasted with high levels of radiation exposure, will a glass of vodka save my life? The answer here is no. Having said that, there is some science that alcohol can help to scavenge free radicals. But it’s not a strong scavenger and if we’re exposed to high levels of radiation – high enough to cause these short-term health risks – we’re way beyond the free radical-scavenging stage. At this point, there is so much radiation that’s causing so much DNA damage that a couple of shots of vodka just won’t help out at all. Sorry.

Vodka won't help with radiation

Vodka won’t help to protect against radiation, sorry.

OK – so that’s the specific question. But what about the more general one? And I guess I haven’t stated this yet – the general question is “Are there any drugs or treatments that can help reduce the effects of radiation exposure?” And here the answer is a qualified “yes.”

Remember – the first physical symptom that shows up is a drop in blood cell counts. This is because the blood-forming organs (for reasons too involved to get into here) are among the most sensitive in the body to the effects of radiation. So as radiation dose increases, we see faster and more precipitous drops in red and white blood cell counts. This can leave a person weak and susceptible to disease. So if we can build up – or find a way to stabilize – the blood-forming organs then we can help to avert this problem. Interestingly, cancer cells have many of the same characteristics of the cells in our blood-forming organs – in fact, cancer therapy takes advantage of these vulnerabilities, which is one reason that so many cancer therapies make us feel so bad. In order to help mitigate these effects, a number of drugs have been developed, and they also show promise in helping to protect the blood-forming organs from radiation as well as from the effects of radiation. So administering these drugs might well help to protect us from the effects of radiation. That being said, this is still an area of research and clinical trials – the drugs are approved for cancer patients but not yet (to the best of my knowledge) for radiation victims. Also, these drugs are only useful to help protect against short-term effects from blood cell loss – they don’t mitigate radiation sickness (the nausea and vomiting), skin burns, and so forth. But it’s a good start!

One other thing we worry about is that inhaling or ingesting radioactivity might cause harm from internal exposure. The worry here is that the internalized radioactivity will continue irradiating us from the inside out for days, weeks – up to decades if the radioactivity lodges in our bones or in an organ where it might reside for long periods of time. Americium, for example, will go into the bone and will remain there for the rest of your life, irradiating your bone, bone marrow, and surrounding tissues. But even shorter-lived radionuclides (I-131 for example) can still cause problems if they come to rest in sufficient quantities in a sensitive organ. This is why we worry about iodine – it’s easily absorbed by the thyroid, a radio-sensitive organ. Luckily, protections here are somewhat more advanced.

First, there’s iodine. What we can do here is to saturate the thyroid with non-radioactive (stable) iodine so there’s no place for the radioactive I-131 to find a home. So we can take potassium iodide (KI). There’s iodine in iodized salt, in seafood, and in some forms of water treatment tablets also, but the quantity is variable and uncertain. Plus, simply chugging salt (or salt water) can have dangerous health effects so we don’t want to do that. But if (and only if) somebody’s about to be exposed to radioactive iodine then taking stable iodine can certainly help to protect you. Taking iodine after the fact can help too, but it’s got to be within a few hours of exposure.

Another protective agent in the news is Prussian blue – an industrial dye that also happens to scavenge cesium from the body. So if a terrorist sets off a “dirty bomb” that uses cesium-137 (Cs-137), taking Prussian blue can help reduce your exposure by speeding the excretion of the radionuclide. A word of caution – it turns your stools blue, so you’ll have Smurf-poo while you’re taking it. But that’s a small price to pay, I would think!

An infographic detailing how the medical treatment prussian blue works. Provided by the Centers for Disease Control and Prevention. More information can be found at http://emergency.cdc.gov/radiation

An infographic detailing how the medical treatment prussian blue works. Provided by the U.S. Centers for Disease Control and Prevention.

And then there are a bevy of other of what are called “decorporation agents” for other radionuclides. If you’re exposed to americium, for example, a doctor might infuse you with a compound called DTPA; and there are a number of compounds that help to reduce the absorption of strontium by the bone (aluminum hydroxide, for example, or barium sulfate). But many of these drugs have never been approved for use in humans and some, in fact, might not have even been administered to humans so their effectiveness and safety have not yet been demonstrated. They’re certainly not FDA-approved! So – yes – there are drugs that, in theory, can help reduce the health effects of exposure to radioactive materials. But in practice, while we’re developing and testing new ones all the time, it’s more hit-or-miss in this category. The reason for this is that every element behaves differently, chemically and when it’s in the boy, so each one requires a different protective compound. We simply haven’t had the time, or the money, to develop protective drugs against every element out there so we’ve started with the most important and the easiest.

OK – so – getting back to your original question! We do have a number of treatments for exposure to radiation or for the ingestion of inhalation of radioactivity. Sadly, vodka is not one of them – it might make you feel better, but only until the hangover hits.

What Should Be in a Response Plan for Skin Contamination?

Dear Dr. Zoomie – I’ve got a hot lab and I was told I need to develop a response plan in case someone gets skin contamination. I was thinking soap and water; is there anything else I should include?

Skin contamination doesn’t happen often but if you work with enough radioactivity – especially in liquid form (as in a hot lab) it’s going to happen from time to time. And it doesn’t mean that people are being careless and sloppy (well…sometimes it does, but not always); sometimes we just make mistakes. I’ve had skin contamination myself at least a couple dozen times – mostly just random splatters here and there – and every time it’s cleaned up fairly quickly with soap and water. But let’s back up a little bit and talk about what goes into dealing with skin contamination. Specifically, you need to have a procedure to follow, you need to know how to clean up the contamination (and how to know when you’re done cleaning up), and you have to know how to tell if any follow-up is required. Let’s take these one at a time.

Skin Contamination

Commonly missed areas of the hand during decontamination

Your skin contamination procedure doesn’t have to be very complicated; in fact, it only needs to have a couple of parts. It should:

  1. Define what’s meant by skin contamination. For example, you might define skin contamination as the presence of any contamination above background or you might decide that contamination levels have to exceed a certain limit (100 cpm above background, for example).
  2. Describe the steps to be taken when a person is contaminated. For example:
    1. Contact the Radiation Safety Officer at the earliest opportunity.
    2. Perform a count rate survey over the contaminated area and write down the number of CPM.
    3. Start to clean the contaminated skin in the nearest sink or at the nearest decontamination station.
  3. Discuss cleanup techniques (more on this in a moment).
  4. Determine when to call for outside assistance and/or follow-up (more on this later as well)
  5. Document what’shappened.

Cleaning up contaminate skin isn’t always simple, but it can be. For example, most cases of minor skin contamination can be cleaned up with soap and warm water. In fact, every time I’ve had skin contamination, soap and water has worked for me. It’s also possible to wipe down the contaminated skin with baby wipes or other cleaning-type wipes. Wiping down with a damp rag or sponge will often do the trick as well, and other specific circumstances (or specific compounds that you might be using) might call for more specialized products. No matter how you choose to decontaminate a person there are a few rules of thumb to keep in mind.

  • Don’t do anything painful or uncomfortable. For example,
    • Don’t use hot or cold water – keep it cool to warm.
    • Don’t scrub with harsh substances (e.g. steel wool, scrub pads, wire brushes, etc. – and don’t laugh; I’ve seen all of these used).
    • And above all, don’t do anything that will draw blood. Your skin acts as a pretty good barrier, keeping contamination out of your bloodstream – if you do something that breaks the skin then you’re simply scrubbing contamination into the blood, which is never a good idea.
  • Count for contamination every several washes or wipes. As long as contamination levels are dropping then whatever you’re doing is working and you should keep doing it. If contamination levels stop dropping then what you’re doing is no longer working and it might be time to try something else.

You also have to understand when it’s time to follow-up or call for help. And “call for help” is not necessarily as dramatic as it might sound – that can simply mean calling a consultant. There are a number of possibilities in this category – here are a few of the more common.

  • For example, you might consider performing a thyroid count for every case of skin contamination with radioactive iodine, or performing urine bioassay if skin contamination exceeds, say, 10,000 cpm (you’ll have to determine what these “trigger” levels are for the nuclides you’re using).
  • You might also consider contacting a consultant to determine the possibility of uptake and/or to calculate skin dose if skin contamination exceeds a given count rate.
  • You (or, more likely, your consultant) might have to calculate radiation dose to the skin if contamination levels are sufficiently high. Duke University has an online calculator to help you with this. For more complicated cases, you can also use a program called Varskin, which is quite possibly the best software available for this purpose.
  • You’ll also have to contact your regulators if you (or a consultant) determine that a person has exceeded 50 rem to the skin.

Finally, you’re going to have to document what happened and how you responded to it. Start with a short description of the circumstances causing the skin contamination (e.g. liquid splashed on the skin) and write down the number of counts you measured as well as the instrument used for the measurement (e.g. 45,000 cpm measured with a GM pancake probe). You should also briefly describe the decontamination procedure (e.g. washed with soap and water for five minutes) and the results (e.g. contamination reduced to less than 100 cpm above background). And note any follow-up measures or samples that were taken (e.g. performed urinalysis to check for uptake) and the results.

decontamination

Finally, let’s put all of this in perspective. There are times that skin contamination can be damaging – the skin can be harmed from a sufficiently high radiation dose. But most of the time skin contamination is more of a nuisance than a risk. You have to take it seriously; you need to decontaminate the affected area, you need to try to get an accurate count rate to see how bad it might be, you need to document everything, and you need to know when to call for someone to give you a hand. But you don’t have to panic! Take a deep breath, break out your procedures and your supplies, and work methodically and you (and the person who was contaminated) should be OK!