Author Archives: Dr. Zoomie

What’s the Deal with Yucca Mountain?

So, Dr. Zoomie:  what’s the deal with Yucca Mountain?

North Portal of Yucca Mountain

North Portal of Yucca Mountain

In the mid-1990s I was on a technical advisory committee to the organization that was working to find a location for a low-level radioactive waste disposal facility that was to service several states in the Midwest. Even with stringent siting criteria there were a number of locations that would have been acceptable; what stopped the process was that the Midwest Compact decided to pull the plug – changes on the national level made it more attractive to continue using existing sites than to start up a new one. At present, there are a number of sites for the disposal of low-level radioactive waste, but the nation is still struggling to answer a question that many nations have already satisfactorily addressed – where to put the nation’s high-level radioactive waste. This process has recently come up in the news again. This is an important topic – one that warrants more than a single posting – so I’d like to discuss various aspects of the science behind high-level radioactive waste disposal in general, and of Yucca Mountain in particular, over the space of a couple of postings. But first I’d like to start with an overview of where high-level radioactive waste (HLW) comes from and a little bit of history on this topic. So history this week, then we’ll get into the science.

By definition HLW is “highly radioactive material produced as a byproduct of the reactions that occur inside nuclear reactors.” It includes both spent reactor fuel (fuel removed from the reactor because it no longer has enough fissionable U-235 to easily sustain a chain reaction) and waste produced during the reprocessing of spent fuel. HLW can be hot – both thermally and radioactively – and it has to be handled with care. Not only that, but some of the nuclides remain hot for decades to millennia so it has to be kept secure for at least as long as the Pyramids have been standing. There are a lot of factors that enter into storing HLW safely – too many to go into here, but I’ll try to cover them in future postings as well.

All nuclear reactors produce HLW during their operation – a typical reactor will be refueled every year or two; during a refueling outage much of the fuel is shuffled around in the core and the remainder is removed. In other nations the spent fuel is reprocessed – plutonium that was produced during reactor operations is removed and residual fissionable U-235 can be removed as well; whatever’s left over is disposed of as HLW. Until recently plans were to dispose of HLW beneath Yucca Mountain, located in the Nevada desert, but those plans have been on hold for several years. Here’s what happened.

In 1982, realizing that the US needed a long-term plan for high-level waste, the Nuclear Waste Policy Act was enacted into law. This law tasked the Department of Energy (DOE) with developing a repository, the Environmental Protection Agency was instructed to develop environmental safety standards and to evaluate a repository’s safety, and the Nuclear Regulatory Agency was told to develop appropriate regulations. DOE started a long process that led them to Yucca Mountain. Without getting into the details, Yucca Mountain, by 1987 the DOE was beginning to investigate its suitability as a deep geologic repository and Congress approved it in 2002. Instead of solving the issue, though, this only seemed to serve as incentive to those opposed to the site – both inside and outside of Nevada. Both scientific studies and legal/political opposition continued until 2011, when Congress pulled the plug on Yucca Mountain. And there’s where the issue seemed to rest until just recently, when the issue came up yet again. At present it seems the issue isn’t settled after all – but who knows what will happen next year.

At the same time, all of our nuclear power plants are continuing to operate and to produce HLW. At first it was stored on-site in wet storage – immersed in water. As the spent fuel pools began to fill up the nuclear power plants got permission to re-rack their fuel (the spacing of the spent fuel rods is carefully controlled to prevent the possibility of a criticality). With pools continuing to fill up – and still no place to permanently take the waste – the NRC authorized dry cask storage – taking the spent fuel out of the swimming pool and putting it into land-based casks. And that’s where matters stand today – over 50 individual reactor sites are storing their HLW on site in a combination of dry casks and re-racked swimming pools.

All this being said, Yucca Mountain is hugely controversial. There’s not space here to go into all of the controversy – it gets into geology, transportation, groundwater and surface water, and more – but if there’s an interest I’ll try to cover some of the controversy in future postings.

Staying Safe in a Radiological or Nuclear Attack

Dear Dr. Zoomie: Last week a big nuclear terrorism exercise made the news, and I can’t help but wonder “What do I do if something like this happens for real? How do I keep myself and my family safe?”

I’ve been working on this, and related topics for some time and can say, first off, that most of our immediate instincts are wrong. If you can do the right thing – and do it quickly – even a nuclear attack can be survived. But in the case of a nuclear attack, it’s what you do in the first few minutes – before the first public service announcement – that will save your life. Or not. Anyhow – I can’t promise that following the steps listed here are guaranteed to save your life in the case of a nuclear attack. But I can tell you that following these steps will maximize your chance of survival. Oh – I’ll also point out that much of this (sheltering, for example) is simply sound advice for any major attack; not just radiological or nuclear, but also for chemical, biological, bombs, and even most cases of active shooters.

  1. Don’t try to evacuate – go into the nearest (and largest) safe building and wait until the fallout pattern can be mapped so that we know where it’s safe to go outside versus where it’s dangerously radioactive. If you’re outside and in the wrong place (the fallout plume) you will die – if you shelter in a building (as far away from the walls and roof as possible) you will survive. As soon as the plume footprint is known, the government will let us know who should continue sheltering, when it’s safe to evacuate, and the route to take that will give the lowest radiation dose. As the Brits say – Go in, Stay in, Tune in.
  2. Don’t pick your kids up from school or day care! If you are in the fallout plume then radiation levels will be dangerously high. If you go outside, you will pick up a fatal dose of radiation. If you get your kids out of school then they will also receive a fatal radiation dose. The safest thing for everybody is for all of you to shelter indoors.
  3. Prepare – not just for this, but for any big bad thing that might happen. What’s the best building for you to shelter in near work? Around your favorite hangouts? Near home? Where will you find water for the 1-3 days you might have to shelter (for example – you can drink the water in the toilet tank, fruit juice and beer will keep you hydrated, bottled water, etc.)? How about a few days’ worth of food (might finally get around to eating those canned yams!)? You can’t starve to death in a few days, and probably won’t die of thirst either – but we also want to have the strength to evacuate when the time comes.
  4. Make up a family communication and reunion plan – do you know how you’ll let your kids, spouse, etc. that you’re OK? Where will you meet up when the sheltering order is lifted? Figure this out now because an emergency is not the time to be winging it. Even if you can’t find each other right away, you can at least know that everyone is OK. And remember – you might not have to talk directly! Having everyone call in to grandparents, good family friends, etc. will also let everyone know that everyone else is OK.
  5. Radiation and pregnancy – it takes a lot more radiation to cause problems with pregnancy than most people think. Also, most physicians don’t know as much about the reproductive effects of radiation as one might think – after Chernobyl there were at least 100,000 women who had unnecessary abortions because their doctors gave them poor medical advice. Before making any decision about terminating a pregnancy – or letting a pregnancy proceed – talk with someone who can help you to figure out how much dose your baby received and whether or not it’s enough dose to cause problems. THEN you can take this information to your OB/GYN to see if the risk from the radiation – combined with other risk factors (age, alcohol and tobacco use, health problems, etc.) – is unacceptable. You can find a knowledgeable professional by contacting the Health Physics Society ( and then clicking on “Public Information” and “Ask the Experts.” Choose the “Pregnancy and Radiation” topic area.

One other thing – a lot of people might want to buy their own radiation detectors so they can find out for themselves if they’re safe. There’s no problem with this – but they need to buy a GOOD detector (not a cheap and inaccurate one) that will give accurate readings up to dangerously high levels. Some types of detectors overload at levels that are still safe – you want to avoid these. In addition, some kinds of radiation detectors are good for measuring radiation dose and others are designed to measure contamination – you can’t just use any radiation detector for all purposes. Two radiation detectors I’ve used and think highly of are the Dosime and the Ludlum Model 25. Both are solid radiation detectors that give accurate dose rate readings anywhere from normal natural radiation all the way to dangerously high levels. Both are affordable, and both are made by companies that make professional-quality radiation instruments.

Finally, learn how to use the detector, learn what normal “background” radiation levels are in your area, and use the meter every now and again to make sure it’s still operating properly and to remind yourself how to use it. Otherwise you might end up with an inoperable meter, the wrong type of meter, or one you don’t know how to use. Using the wrong instrument (or the right instrument, but improperly) can be more dangerous than performing no survey at all because it can lead to a false sense of safety. And – by the way – most “Geiger counters” are NOT the right instrument to use for something like this!

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

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.


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!

My Wife Is Pregnant – Will an X-ray Hurt the Baby?

Dear Dr. Zoomie – my wife is pregnant and she needs to have an x-ray. Is this going to hurt the baby? Or should she wait until after she delivers? How does radiation affect pregnancy?

My kids look perfectly normal – in my humble opinion maybe even a tad better than normal. This became an issue, actually, in the months following the 2002 arrest of Jose Padilla on charges he was plotting to set off a “dirty bomb.” How it became an issue is that I was interviewed by a reporter interested in the reproductive effects of radiation – she was wondering if we could expect to see legions of children born with birth defects in the aftermath of a radiological attack. I spent a fair amount of time helping her to understand the basic science behind why this was unlikely to happen and then, to lighten the conversation a tad, threw in the line “let’s face it – if parents have strange-looking kids they should probably blame the in-laws and not the radiation.” Guess what quote she used. For a few weeks I was getting e-mails from colleagues around the world asking to see photos of my kids. And I’m happy to say that in spite of my years working around radiation, my kids look perfectly normal. At least as close to normal as we can expect from teens….

The point here is that the reproductive effects of radiation are exaggerated to the point of irrationality – more so than most other reproductive hazards. True – radiation can cause birth defects and it has been shown to induce mutations in animals. But the amount of radiation required to cause birth defects in humans is substantial (at least 5 rem or 50 mSv to the fetus) and the medical literature has not noted a single instance in which pre-conception radiation exposure to humans has caused birth defects when the woman eventually conceives. And if more people – physicians included – really understood these points there would be far fewer worries.

Consider – the BBC documentary Nuclear Nightmares (which was about radiation phobia) stated that the Soviet government performed a few hundred thousand abortions on women exposed to radiation after the accident and others have stated that there were at least 100,000 abortions conducted in Europe due to fears about the reproductive effects of radiation exposure. It is almost certain that few – if any – of these abortions could have been justified by the radiation exposure alone. I understand that the numbers cited are not from the peer-reviewed literature and that they might be high. But the 2006 report by the World Health Organization concluded that after 20 years there had been fewer than 100 deaths attributable to radiation exposure from the accident (including radiation-induced cancers) and projected that as many as 10,000 people might eventually develop cancer from the accident – even if the WHO’s worst-case estimates come to pass and even if the abortion numbers are over-stated by a factor of 10 we will still find that fear, ignorance, and misinformation was deadlier than the accident itself. This is tragic.

As a radiation safety officer I calculated nearly 100 fetal dose estimates, usually when a pregnant woman was involved in a car crash and, while unconscious, received the “trauma series” of x-rays from head to foot, possibly followed by CT or even fluoroscopy. Sometimes when the woman woke up she told the doctor she was pregnant, sometimes she didn’t know this herself for another few weeks. In either case, our policy was that I was to be informed so that I could perform fetal radiation dose calculations and write a letter explaining the results to the woman’s OB/GYN. There was not a single case in which the fetal dose estimate was high enough to warrant taking any actions at all, even though some of the women had been advised they might need to terminate their pregnancies. And I was not alone in this – the Health Physics Society runs a wonderful feature on their website (Ask the Experts) that has a section for radiation and pregnancy. Over the last decade or so they have accumulated hundreds of inquiries on this topic and almost none of them warranted any concerns at all. Sadly, many physicians in the US are taught that radiation can cause problems with pregnancy, some of them might vaguely remember a dose of 5 or 10 rem (50-100 mSv) but don’t know the fetal radiation dose from the radiation they might prescribe, and are then told little more. Is it any wonder they sometimes give bad advice?

For the record, the Centers for Disease Control and Prevention maintains a web page that includes information on the impact of prenatal radiation exposure aimed at parents and at physicians. CDC includes a table that summarizes the impact of prenatal radiation exposure based on the post-conception age and the fetal radiation dose – they conclude that for any radiation exposure that occurs less than 2 weeks into the pregnancy and for any fetal radiation exposure of less than 5 rem (50 mSv) there is no need to take any actions at all. To put this number in perspective, it can take tens of x-rays or a few CT scans that image the uterus (the exact number depends on the x-ray machine being used, the amount of tissue between the x-ray beam and the fetus, and a number of other factors) to reach this level of fetal exposure. And for x-ray exposures that do not image the uterus – a chest or head x-ray for example – the dose is even smaller. But believe it or not, I even took a call from a woman who had dental x-rays wondering if she should take her physician’s advice to have a therapeutic abortion.

Having said all of this I don’t want to make it sound as though I’m advocating throwing caution to the winds – according to the ALARA principle (to keep radiation exposure As Low As Reasonably Achievable) we should not simply run up the dose through unnecessary medical imaging – I agree with the goals of the Image Gently initiative to help reduce pediatric (and prenatal) radiation exposure. But I would suggest that if the mother’s health or life are at stake then physicians should avail themselves of the tools they have without letting unwarranted fears deny them access to valuable diagnostic information. And the physicians need to remember that – before giving any medical advice about the pregnancy – fetal radiation dose should be calculated by a qualified and competent health physicist or medical physicist. Radiation health effects depend on the radiation dose – absent a solid radiation dose estimate it simply is not possible to give good, informed advice to the prospective parents.

The sad fact is that the programs that train our physicians – not just in the US by the way, remember the numbers from Europe – are not doing a good job of teaching their students about the impact of radiation on their patients. I discussed this in an earlier blog, where you can find references on this point. This is ironic given that, according to the National Council on Radiation Protection and Measurements, our exposure to medical radiation had increased dramatically in the last few decades. Given our society’s heavy reliance on radiation in industry, medicine, research as well as our dependence on nuclear power I would like to think that our physicians can be better prepared to give good advice to their patients about the effects of the radiation to which they are unavoidably exposed, just as I would like to think that the public can be provided with solid information so that they can participate more fully in the process of making decisions about radiation exposure.

To wrap this all up – and bring us back to your original question – a single x-ray, even a single CT scan, doesn’t give enough radiation dose to the developing baby to cause birth defects. Remember, too, that there’s a reason the doctor is prescribing an x-ray for your wife – he needs diagnostic information to help keep her healthy. There is a risk to your wife – and your developing child – from not having this information. Since your baby’s health depends on that of your wife, there’s a risk in NOT getting this diagnostic information. Chances are that the risk from not having an x-ray or CT scan (due to lack of diagnostic information) is higher than the risk from the x-ray images. In other words, if the doctor feels that an x-ray is needed then it makes sense to follow the doctor’s advice.

Mixed Oxide (MOX) Explained

Dear Dr. Zoomie – every now and again there’s something in the news about something called MOX. Some people seem to like it and it seems to make others unhappy. Can you tell me what the story is?

This is one of those issues that, like you, most people don’t know much about – in fact, most of the population probably doesn’t know anything about it at all. Those who do follow the controversy tend to come down heavily in favor or vehemently against – not many are on the fence. With that as a bit of a prelude, here’s what the facts are – I’ll let you decide how you feel about the issue.

To start, MOX stands for Mixed Oxide. What this refers to is the fact that MOX fuel contains both uranium and plutonium mixed together with each metal in a chemical form called an oxide (rust, for example, is iron oxide). Since the uranium and plutonium are both fissionable, the reactor generates power by fissioning both of these elements instead of just the uranium.


Mixed oxide, or MOX fuel, is a mix of plutonium and natural or depleted uranium which behaves similarly (though not identically) to the enriched uranium feed for which most nuclear reactors were designed. MOX is an alternative to low enriched uranium (LEU) fuel used in the light water reactors which predominate nuclear power generation.

This plutonium can come from one of two sources. One possibility is that plutonium from former nuclear weapons – or from plutonium stockpiles – can be mixed in with standard uranium fuel. Alternately, plutonium can be extracted from spent reactor fuel (more on this in a moment) and mixed in with fissionable uranium to form reactor fuel. In either case, this is sort of like blending ethanol in with gasoline – they both burn so you can mix them together and still fuel your car.


As for where plutonium is created…well, this gets interesting. Whether the plutonium in the MOX fuel comes from weapons or weapons stockpiles, or from spent reactor fuel it was produced in the same way – inside a nuclear reactor. In fact, every operating reactor produces plutonium during its operation. Every nuclear reactor generates power by nuclear fission and the atoms most likely to cause these fissions are the lighter isotope of uranium, U-235. But if reactor fuel is, say, 6% U-235 (at the upper range for commercial reactor fuel) then the other 94% is U-238. The core of a reactor has a lot of neutrons flying around (the neutrons come from fission) and many of those neutrons will be captured by U-238 atoms to form U-239. U-239, in turn, is radioactive and it emits beta radiation to become fissionable plutonium (Pu-239). So normal fission results in the formation of Pu-239 in every single nuclear reactor on the planet. The question is what happens to the Pu-239 after it’s formed.

Some of the Pu-239 fissions as the fuel continues to produce energy. Some of it will capture another neutron to become Pu-240 (which also fissions) or can even capture more neutrons to form heavier forms of plutonium. But not all of the Pu-239 will fission or capture neutrons – a lot of it simply remains in the fuel until it’s removed from the reactor as spent fuel. And this is where some of the controversy starts to arise – since all spent reactor fuel contains Pu-239, a nation (or a sophisticated terrorist group) can chemically process the spent fuel to extract the plutonium. In truth, much of this will be marginally useable for nuclear weapons because of the Pu-240 and heavier isotopes. But the fact remains that it’s still there and it can be extracted by anyone with access to the right chemistry, handling equipment, and the rest of the necessary technology. This is, in fact, one reason that the US gave up reprocessing spent reactor fuel – since the plutonium presents a possible proliferation risk if the fuel is reprocessed, deciding not to reprocess the fuel means that the Pu-239 remains locked up in the fuel rods alongside the highly radioactive fission products, rather than being extracted for possible theft or diversion into nuclear weapons.

Another approach – no matter where the Pu-239 comes from (reactor fuel or nuclear weapons stockpiles) – is to deliberately mix the Pu-239 in with uranium fuel and to use it to produce energy. The thinking here is that, if the Pu-239 is sequestered away inside of spent fuel, it still exists and can be extracted at some time in the future; or if it’s locked in a secure bunker it still exists and can be stolen or formed into weapons by a nation that has decided it’s time to make new weapons again. On the other hand, according to this line of thought, if the Pu-239 is used to make reactor fuel, the actual atoms of Pu-239 are split and can never be fissioned again – if the plutonium is fissioned then it no longer exists; no more than carbon dioxide and water vapor can be reconstituted into the gasoline that they once were. When the Pu-239 is fissioned it is forever gone from this world and it will never again be a proliferation risk.

On the other hand, groups that oppose MOX fuel point out that, until the fuel is inserted into a reactor and fissioned, it poses even more of a security risk. The thinking here is that, normally, Pu-239 is either locked up inside of secure storage vaults or is locked up within dangerously radioactive spent fuel rods (which are, themselves, locked up behind multiple barriers). Either way, the plutonium is fairly secure.

By comparison, those who are opposed to the use of MOX fuel point out that it makes the plutonium much easier to steal. First, it’s already been separated from the dangerous fission products (if the source is spent reactor fuel). Second – and even more important – the fuel itself can be stolen when it’s in transit to the reactor in which it will be used. Typically, the most vulnerable time for any dangerous material is during shipping, when it is outside the normal security barriers and safety systems. No matter how much security is in place, materials in transit are never as secure as when they’re locked up behind multiple barriers in a hardened facility.

So this is the situation – we have (quite literally) tons of plutonium in various places around the world, and every nuclear reactor is producing more all the time. It doesn’t matter whether you are pro- or anti-nuclear power – the fact is that the world we live in has this material in it. That being the case, the question – and the controversy – is what to do with this material. Do we lock it up to achieve maximum security (but the plutonium continues to exist)? Or do we add it to uranium to form MOX so that it can be destroyed forever (but introducing potential vulnerabilities during transit)? There is logic to both positions – the question is whether the ability to gain useful energy, as well as removing the plutonium from the face of the Earth, is worth the added risk of theft.

How Do You Respond to a Radioactive Spill?

Dear Dr. Zoomie – I run a radiation safety program at a small laboratory and I’m working on our emergency response procedures. I was wondering if you can tell me what goes into responding to a radioactive spill.

How Do You Respond to a Radioactive Spill?

How Do You Respond to a Radioactive Spill?

Good question – and a very good topic! I ran an academic radiation safety program for several years and spills were most common type of incident we had; on average, about one spill a week. Most of these were fairly minor – a researcher with a leaky pipette for example, or a little spray from around the cap of a stock vial when you open it up. Of course you can have larger spills too – we had a researcher once drop 100 ml of radioactive solution on the floor, and (in our hospital) had an incontinent patient who urinated on the floor – nearly a liter of radioactive urine. Anyhow, what it means is that you are likely to have spills ranging from nearly invisible to fairly significant, and you have to know how to respond.

The acronym we learned in the Navy was SWIMS – it stands for:

•    Stop the spill
•    Warn other people
•    Isolate the spill area
•    Minimize radiation exposure
•    Stop ventilation if possible and if it will help

Here’s what that means….

Stop the spill doesn’t mean cleaning it up so much as stopping it from getting worse. So you want to pick up (wearing gloves so your hands don’t get contaminated) the bottle or vial or whatever you might have dropped or knocked over (if that’s what happened) and put some absorbent materials over whatever spilled to keep it from spreading further.

Warn other people about the spill. Let the RSO know about it so he or she can send help. Let people in the vicinity know about the spill so that they don’t walk into your spill area (also so that people who might be contaminated – anybody closer than about a meter away – stay put so they don’t spread contamination around). Even if it’s a minor spill you have nothing to lose by warning others – especially Radiation Safety.

Isolate the spill area to keep people from wandering in and getting contaminated. This means putting up physical barriers – rope, tape, even a table across a doorway – something that people have to physically move in order to cross. What you should do is to give yourself enough room to work – at least a meter past the furthest droplet you can see. Once a spill boundary is put up, you shouldn’t let anybody enter the spill area unless they have proper protective equipment (PPE) – at the least, gloves, shoe covers, and a lab coat. And once somebody is inside the spill area, only Radiation Safety should be permitted to survey them out of the area.

Minimizing radiation exposure is not so much a procedural step as a way to approach the incident. Remember – there is nothing life-endangering about a spill and you don’t have to rush in, unthinking, to save the day. Take a moment – give yourself the luxury of thinking about what’s happened and the best way to deal with it. Do you need respiratory protection? Do you have your gloves on? Do you have the right materials on-hand to clean it up? Or do you need to wait until you can get the right materials to clean it up safely? By doing this you’ll be minimizing everybody’s exposure.

Stop ventilation if possible and if desirable – but this isn’t something that needs to be done every time. First – running the ventilation can spread radioactivity through the ventilation system, which can cause problems. In addition, air blowing on a spill – especially if it’s volatile – can cause the activity to go into the air, turning it into an inhalation concern. So if you can turn off the ventilation then it will keep these things from happening. On the other hand, if you don’t know how to turn off the ventilation or if you have to stand in the middle of the spill to do so then you might want to leave it be for the moment. Oh – also, don’t forget to stop ALL the sources of ventilation if you make this decision. This includes, say, refrigerators and freezers (the compressor blows out air), pumps (the motors usually have vents), and even computers or projectors that have vents that might blow onto your spill.

Another quick comment about these actions – SWIMS is a mnemonic to help you remember these steps – they do not have to be done in that order. Just make sure you remember to do them!

Once you’ve got through these actions you’ve earned the right to take a short break – at this point things aren’t getting better, but they’re also not getting any worse. So take a minute to think about what you’ve got and the best way to clean it up and restore the area. Cleaning up is part of this – here’s a little on that.

•    First, work from the outside of the spill area towards the inside, and to work from the top to the bottom (if the spill is, say, on a table or countertop and has dripped onto the floor).

•    Most of the time, commercial cleaners will work just fine; although you might want to use a specialty cleanup product if you have radioactive metals (cobalt, cesium, etc.) in the spill – this is mostly at nuclear power plants, though, and not so much at universities.

•    As you clean, you should put the cleaning materials (paper towels, bench pads, or whatever you’re using) into a plastic bag as you use them. If someone is holding the bag they should be wearing gloves to keep from being contaminated. And every now and again, survey the cleaning materials to make sure your cleanup is having an effect – if you start finding that no contamination is coming off on the paper towels (or whatever you’re using) then either the area is fully decontaminated OR the contamination is fixed to the surface and you should move on to another location.

•    Finally, you’ll have to survey the entire spill area when you think cleanup is completed in order to show that contamination levels are acceptable. Usually this means less than 1000 dpm per 100 square cm, but these vary depending on the radionuclide and the type of radiation it emits. A good reference is a document called RegGuide 18.6 – it’s a Nuclear Regulatory Commission regulatory guidance document that, even after nearly 40 years, is still the standard reference on the issue.

There’s a lot more on this topic than what I’ve got here, but what I’ve got here will get you off to a good start. Hopefully you won’t have to use this often but, if you do, I hope this helps out.