How much tritium leaked from Vermont Yankee before the leak was stopped?
A good friend asked me the title question for this blog during the week. The question intrigued me enough to encourage some digging and computations. I would be interested in any questions that you have about the assumptions.
Based on reading a number of different articles and checking through the tables provided by the Vermont Department of Health, the fluid that was leaking into the ground contained tritium at a concentration of approximately 2.5 million picocuries per liter. That is equal to 2.5 x 10^-6 curies per liter. The rate that it was leaving the pipe was roughly 100 gallons (370 liters) per day. If the leak had been going on for a year before being detected and stopped, the total quantity of fluid that left the pipe would equal 138,000 liters. The total activity released would be 0.35 curies.
If a single person consumed every drop of that water, their whole body radiation dose would equal roughly 30 rem. According to a 1977 UNSCEAR study, the LD-50 (lethal dose for 50% of the population receiving the exposure) for tritium in adult rats was determined to be 1000 Rad. For the kind of low energy beta emissions that are produced by tritium, a rem is equal to a Rad. A dose of 30 rem received over a 1 year period would be unlikely to cause any immediate health effects, though it might add an additional risk of developing cancer sometime during the person’s life. The magnitude of that risk could be computed using the conservative linear, no-threshold dose assumption.
Of course, a person who tried to drink 378 liters per day for a year would have problems more immediate the possibility of increasing their lifetime risk of cancer.
I also was asked to put this discharge into some kind of perspective, so I decided to compare it to the allowable and measured releases from a well operated and safe CANDU reactor in Ontario. Pickering B has a Derived Release Limit (DRL) for tritium of 490,000 terabecquerels each year. That is 4.9 x 10^17 Bq or 13 million curies. Here is how the Canadian regulators determine the DRL for a facility:
The CNSC requires nuclear facility operators to closely monitor and report tritium releases into the environment. The releases of tritium into the environment are controlled, and do not pose a health risk.
The CNSC sets the limit for the radiation dose for the public arising from the activities of nuclear facilities at 1 mSv per year. In addition, to minimize the environmental impact of tritium releases, the CNSC uses the ALARA principle, which means that licensees are required to keep exposures “As Low as Reasonably Achievable”.
All authorized releases to the environment – known as Derived Release Limits (DRLs) – are calculated using a methodology that considers the various ways in which radionuclides, such as tritium, can impact members of the public.
For instance, the methodology must take into account the impact of tritium releases on locally-grown food, water supply and air quality. The methodology used is conservative and assumes, for instance, that individuals live, work and stay in their community for extended periods of time.
DRLs are specific to each facility, and take into account various regional factors such as meteorological and geographical conditions, as well as the population density near the facility.
Through careful management and application of ALARA (as low as reasonably achievable) actions, the plant managed to keep its releases in 2008 to just 200 TBq or 5,400 curies, just 0.04% of its allowed limit. At that rate, Pickering B released almost 15 curies per day, about 40 times as many curies as Vermont Yankee’s infamous leak released in an entire year.
Now can you see why I so strongly believe that the protesters and politicians in Vermont have been stirring up a tempest over a shot glass sized swirl? As one of my mentors used to say – no sense reacting if you cannot overreact.
Very insightful post! I believe the original monitoring well where the tritium was detected is sampled once per month. Depending on where the sample point is in relation to the leak, and the transport time, it seems likely the leak was discovered within a few weeks of initiation.
The NRC web site says emergency exit signs contain up to about 25 curies of tritium PER SIGN. Your calculation puts into perspective the insignificance of the leak: all the tritium that leaked from Vermont Yankee was about 1/100 the of the amount in one exit sign.
Was the tritium in the form of hydrogen gas dissolved within water? Or was it in the form of water?
When tritium (H2O) is mixed with regular water, what happens? Does it dissipate quickly, sinks, floats, etc?
In a BWR, steam from the reactor goes directly through the turbine to the condenser. Steam is condensed and the water is returned to the reactor.
Some water in the reactor exposed to high energy neutron flux is converted to H2 &O2 which are non-condensible gases. These gases are removed from the condenser by the off gas system along with any trace fission product gases. The off gas system has a hydrogen recombiner to form water again. This water is drained and recovered.
Tritiated water is chemically the same regular water. Since it has a relatively long half life, it represents an occupational dose to workers because it builds up with time.
Kit – you may understand chemistry and physics, but I recommend a review of biology. Human bodies process water; they do not build it up with time.
Who said anything about drinking the water. It builds up in the primary coolant and fuel pool.
Kit – forgive my misunderstanding of the following “. . .it represents an occupational dose to workers because it builds up with time.”
The ONLY way I know of that tritium can contribute to the occupational dose of anyone is for them to ingest it. It is a low energy beta emitter; it does not penetrate human skin and does not contribute to the whole body dose of any workers unless they breathe or drink it.
Rod has anyone told you that you are an idiot today? It is think like yours that gets nuke plants shut down. I do have some experience with that.
One day I discover an unmonitored release path at the nuke plant that existed for 15 years. I documented the problem only to have it rejected as not being a problem rejected by management. On the third try I walked the paper through. Again, they told me it was not a problem. I said that they were right. I told I was just collecting their signatures so I could take their rejects to the NRC to see if I could get them banned from working in the nuclear industry. Or they could forward the problem to the environmental group who would attach the calculation we had already done. This would go into the monthly report to the NRC showing attention to detail. Nobody would accuse us of covering up anything and the FBI would not have to investigate (again) perceived criminal behavior.
In any case, 100 gpd leak from the off gas system is a big deal on a BWR. The problem with accepting small problems is that they build up and cover up big problems. If people reporting problems are forced to run a gantlet to identify a problem, problems stop being reported.
I am not saying this is the case at VY but it is unacceptable regardless of public risk that you calculate.
Kit – When someone like John Wheeler writes “Very insightful post” and an anonymous commenter who insists on using a pseudonym tells me I am an idiot just a few minutes later in response to exactly the same post, I have to celebrate the freedom of speech.
Oops, I forgot, John also graduated from an Academy, so he must also be an arrogant idiot – in your oh so humble opinion.
Rod try not to prove my point about being an idiot. You suggested that I was arrogant for thinking I am right. There are a great number of people who went to the naval academy that I respect, you just do not happen to be one of them. College was a long time ago.
I did read John W’s post. I made not comment. Rod seems to think that naval academy provides some insight to something or other in the practical world outside the navy.
Kit – just to be clear, John did not attend the Naval Academy, though he did attend an Academy.
You have often implied that I stopped learning and experiencing the world nearly 30 years ago when I graduated. Yes, I am proud that I earned an appointment to one of the more selective colleges in the country and that I graduated with honors. I am also proud of the way that school taught me to learn and gave me some humility by putting me into situations that were tough, new and uncomfortable.
Despite what you think, I have learned a bit and seen a bit through serving two engineering tours on submarines, one of them as the Engineer. During a six year break from my active duty service, I ran two small companies, one of which competed head to head with Chinese manufacturing firms in making plastic products.
During my naval career, in addition to doing 11 patrols, I have taught engineering, ethics and writing at the Naval Academy, and have served in Navy Headquarters staff billets for the past 8 years.
You defend smoking and believe that low levels of tritium deserve a “cost is no object response”. You like biomass better than small nuclear power and you think that John Rowe is the cats meow.
Stop the name calling or I will take my platform away from you.
Kit – are you telling me that you have not defended smoking or that you honestly want us to believe that pointing out its negative health effects is lying? I am actually confused and not trying to trick you.
Since my father engineered systems that delivered electricity for more than 35 years and the company that he worked for still provides my mother with a pension, I have no reason at all to criticize the PEOPLE who produce electricity. I can point out – without demeaning their difficult and important jobs – when the leaders in their company continue to make technology decisions that are not in anyone’s best interest. The company leaders are the ones that choose what fuels to burn, what kinds of systems to buy, and where to put their plants. The people working there simply do the best job they know how to do with the tools they are provided.
If I have ever made any comments that were critical of the PEOPLE who operate electricity plants reliably and contribute so much to the general welfare of the country I apologize. I did not mean to do that.
On my old submarine, we worked hard to inspect and conduct preventive maintenance. Normally we were successful in preventing leaks, but we were not perfect. Sometimes piping fails in between required inspections. It is impossible to inspect continuously, especially when the the 1960s era designers chose to put things in inaccessible locations. Stuff happens. My point is not that operators should ignore potential issues or paper over real problems; it is that there should be a sense of perspective in the responses.
Finally – why is someone in a public position who has no problem pontificating about whether or not he thinks a revival of nuclear energy considered to be above criticism? Nothing in my submarine force training led me to believe that somehow people in high ranking positions were immune from mistakes or always had the right answer. Maybe the surface navy is different.
Of course, my belief that all men are created equal has gotten me in some amount of hot water in the presence of flag officers who thought that their stars prevented their stuff from smelling. Maybe those run ins explain why I remain an O-5 after so many years.
Rod I have never smoked not counting second hand smoke from being one of the few non-smokers in the navy in 1970. I neither have to worry about the health effects of smoking or drinking tritiated water because there is not good reason to do either.
Where I disagree with you is you thinking you have insight to deciding things ‘that are not in anyone’s best interest’. All large power project must demonstrate a public interest and insignificant risk.
The commercial nuke are way past preventive maintenance and into reliability centered maintenance. Not letting ‘stuff happen’ is good business. It is also good business at coal and gas plants too.
Without getting into things that I assume are still classified ‘confidential’, your old submarine is different from a stationary power plant. A lot fewer neighbors.
Finally I have no problem with criticism. It is healthy. Questioning the motives of people without foundation however is unethical.
Kit – The only motive I questioned about Rowe is one that is his fiduciary job. I think it is important for people to fully understand that company CEO’s are SUPPOSED to be focused on the profits that their company makes. That focus can conflict with the interests of the customers that the company serves, especially in a situation where there is limited competition.
Rowe’s belief that there is no good reason to build new nuclear power plants or to restore the operation of Zion is solely based on what is good for his company. It is not based on the best interests of his customers or the people who have to breathe the output from the coal fired power plants that still provide 50% of the electricity consumed in the territories that his plants serve.
We will always disagree on the continued use of coal. It is a dirty fuel that is fine when there is no other choice for producing reliable, affordable electricity. The nuclear option has been available for more than 50 years; coal should have retired at least a decade ago. It is kind of like an aging ball player who simply does not know when to quit.
Sorry Rod you have your facts wrong. It is not that you are a liar but you are just mistaken. To use your analogy, Zion was the ball player who retired 10 years before with knees so bad that he could not run to first base. Rod wants to blame the new coach, Rowe. It sure looks like the Rowe is doing a fine job of keeping the old nukes he has running. I have worked at 4 of the reactors.
Furthermore, right now coal is the backbone of the team. It has just been in the last decade that nukes have proved they can take care of their knees and compete with coal. Some of us old guys hope to teach a new generation how to build new nukes before retiring. With 30+ nukes in the pipeline, the challenge is getting that job done not bashing others who are doing an excellent job of carrying the load.
Yes, Kit, a tiny bit of tritium leaked from VY. Yes, it did violate regs. Yes, some folks can use it to stir the public into a panic and pretend they are in mortal fear of contamination of their precious bodily fluids. Yes, it does matter to the people at VY. If they had known about the leak, then I’m sure they would have sent a welder down there to weld it. First, it’s in violation of regulations, and if the regulators regulate something that you own and value, then if the regulator says jump, you ask “how high?” Second, it costs less to arrest a problem before it leads to a bigger one than it does to allow it to grow to the point where it consumes you. NRC investigations, witch-hunts by the legislature, anti-nuclear fear-mongering by fear-mongerers, all of this places the plant in danger far more than a tritium leak does.
No, in the grand scheme of things it does not matter one whit. People are far more likely to be endangered by smoking, or by that old coal plant down Mount Tom way than by a few picograms of tritium leaking from a very secondary system at a reactor kept in fine condition in the prime of its life.
You are not arrogant for thinking you are right. You are arrogant for the way in which you think you are right – by calling others “idiots”. Even if you are right, you don’t make yourself “righter” by calling people you disagree with idiots. All you do is piss them off. This forum is not the Plant Maintenance Forum. We don’t talk about the importance of complying with regulations here; compliance with regulations is expected, just like compliance with the law is expected. Compliance is a given; it is necessary; it is done.
Here, we talk about the larger systemic context within which those regulations are made, whether those regulations are appropriately scaled to the risk posed by that which is regulated, whether those regulations deserve to be changed, and the larger, systemic context within which nuclear power operates and flourishes in greater society, its merits and demerits, how to preserve what we have, and expand for the future, what challenges to broader society nuclear energy might have the power to solve, and how to convince people that nuclear power can help them in their personal challenges, or help their society in its broader societal challenges. We discuss interesting and powerful new concepts, such as small modular reactors, which will offer fixed costs, delivered on time and within budget, as well as more precise matching of electrical and heat output to the desired application, and evolutions of older designs that have a tremendous amount of potential for offering major cost savings, improvements in safety, and improvements in performance.
You can’t seem to see the forest for the trees. You don’t seem to be able to see nuclear power in its systemic context within the greater scheme of things and understand that there are greater things out there than tritium leaks. There are ‘grandfathered’ coal plants poisoning the air that we breathe. There are fossil fuel monopolists plotting and planning and making America less safe while raking in the filthy lucre. There is the threat of global warming. We are in an economic depression, there is a need for new jobs, and a need for more electricity, cleaner electricity, and more orders of more American stuff to jump-start the economy. Compared to these, tritium is not even a blip on the radar screen. And to all of these problems save for nanogram-scale leaks of tritium, Vermont Yankee – and nuclear power – is the solution.
If I were you, I would question my constructions and question my assumptions. Because the only constant is change, and assumptions made once upon a time might be worthy of re-evaluation in the light of operational data and experience as well as changes in paradigms.
Otherwise, your arrogance will be your downfall, Kit.
Which risks get excessive attention and which get overlooked depends on a hierarchy of factors. Perhaps the most important is dread. For most creatures, all death is created pretty much equal. Whether you’re eaten by a lion or drowned in a river, your time on the savanna is over. That’s not the way humans see things. The more pain or suffering something causes, the more we tend to fear it; the cleaner or at least quicker the death, the less it troubles us. We dread anything that poses a greater risk for cancer more than the things that injure us in a traditional way, like an auto crash. In other words, the more we dread, the more anxious we get, and the more anxious we get, the less precisely we estimate the odds of the thing actually happening. It’s called probability neglect, and it is one of the reasons a small release like this is given more weight in the public mind that the tons and tons of greenhouse gases that will be produce by the gas-fired plant that will replace VT if it is shut.
DV82XL – If what you say is correct, how do you account for the millions of people who still start smoking cigarettes each year, knowing what we all know about the risk of cancer, heart disease and emphysema that the habit brings. All of those are potentially lingering, painful illnesses that can take years to kill someone.
If what you say is correct, why do people save themselves a few pennies per gallon and choose to pump their own gasoline when every self service pump includes a warning about the science findings that indicate that exposure to gasoline has caused cancer in laboratory rats?
If people are really fearful of exposure to radiation, why do they choose to bring natural gas into their home for cooking since it can very well be coming from underground reservoirs with naturally occurring radioactive materials and include enough radon gas to give them an average dose of 9 mrem per year – which is about 8 times as much as they would get from drinking water at the legal limit of 20,000 picocuries per year?
No, I think that people are not as afraid of cancer or far away risks as nukes have been taught to believe. I do not think that people are as afraid of nuclear energy as we have been repeatedly taught that they are. I do believe that there are some people who have fully accepted the lies that they have been taught, so they are vocally afraid of radiation. I also believe that there are people who recognize that the only way they can compete against nuclear energy is to spread as much fear, uncertainty and doubt as they can afford – and since some of the competitors are the world’s richest companies, they can afford a lot of FUD.
First, I’m certainly not suggesting that there is any logic at work here, and I think you know I am convinced that there has been an active FUD campaign prosecuted against nuclear energy for years by fossil-fuels and their fifth-column green puppets.
However what I was trying to point out is that there is a physiological trait in humans that these forces are exploiting. Understanding HOW our opponents are working their propaganda, is a necessary step in countering it.
Yes people still smoke tobacco, but many have given up that filthy, disgusting, expensive, and thoroughly enjoyable habit, because we recognized that there was a possibility that it could kill us, and many that never started for the same reason. The fact is that the truth will out, but it needs to be spoken, and lies faced down.
Rod, I think the greatest dread comes from things they don’t understand. An automobile accident – in its horrible violence – is easy to understand. Smoking is easy to understand. Gas and a resulting explosion/fire for heating is easy to understand.
Radiation on the other hand people have only a very vague idea what it is. To sound like your average teenager… “It’sm like, rays and stuff… things you can’t see… and they, like, give you cancer but you don’t really notice when it happens, and then you get sick and die”
That is about as far as the general public’s understanding of what radiation is goes. They don’t know what it is. The understanding of radiation is intangiable to them, and therefore they are frightened.
Education is the answer. Teach them what it is.
You are right, we do not accumulate water. We consume water and expel water. With the litres of water that each of us consume each day, any molecule of water that enters the body would likely not stay there very long.
Tritium in the form of HTO (water) has a biological half-life of approx. ten days, which is, incidentally, the same for any molecule of water in your body. Organically bound tritium (ie a tritium atom replacing a hydrogen on a hydrocarbon / fat) has a longer biological half life (if I recall, around the order of sixty days for most species).
Accumulation implies no elimination, which is certainly not the case. Elimination comes through biological processes, compounded with radioactive decay. For tritium, the elimination process is dominated by the biological end, as H-3 has a radiological half-life of 12.3 years.
Tritium in the environment will invariably oxidize, whether in a water system or open air. What you are seeing at VY is most likely molecules of HTO in H2O (ie hydrogen-oxygen-tritium atom, vs. hydrogen-oxygen-hydrogen as in normal water).
HP – you are right to bring up the topic of organically bound tritium as being different from HTO, but the likelihood of that kind of tritium being associated with a nuclear plant is essentially zero.
There is some free hydrogen produced when H2O is exposed to a neutron flux, and some of that may, in fact be converted into tritium. Before that H2 (or HT) would ever be released, it is oxidized to become HTO. Once that process has occurred, the tritium is tightly bound to oxygen in one of the tighter chemical bonds formed. Water is essentially never broken up in biological processes – the H in carbohydrates comes from other sources.
Correct me if I am not correct.
I would think that any radioactive water spilled, touch and wiped off a person posses very little risk.(Beta decay) There is no risk of any employee drinking water containing tritium. If you breath in radioactive water vapour, you will breath it out with the next breath.
If small amounts of tritium gets into a river or lake it would be instantly be diluted to normal background levels.
If tritium gets into the ground water, first it would be diluted by 1000 times with the ground water. It would likely take 100 to 1000 years to migrate outside the plant property through the ground. After the first 100 years it would have decayed by 1000 times. If next to nothing (radiation wise) leaks, by the time it comes into contact with someone there would be a million times less then next to nothing in exposure. It does not matter how you look at it. If the tritium migrates through the ground faster, it would also get diluted faster so the results would be the same.
The decay is something that other toxins in water does not do. You can not treat tritium the same way as heavy metals (from coal emissions) that do not decay and does accumulate in certain organs.
Ted Rockwell: “The radioactivity of a liquid is measured in picocuries per liter (a liter is a little more than a quart). The proposed US regulatory limit for the radium level in tap water, for example, is 5 picocuries/liter, and 300 picocuries/liter for radon in tap water. Nuclear plant discharge water is only about 10, in contrast. Whiskey (1,200 picocuries/liter), beer (1,300), milk (1,400), and salad oil (5,000) all have far greater radioactivity levels than one might expect. And the natural radioactivity levels of some health spa waters can be as high as 300,000!”
I understand VT is the nation’s leader in craft breweries. Whereas the tritiated water has only appeared in test wells within the plant boundaries, it is highly likely that radioactive beer is being consumed throughout the state. I hope that the legislature understands the importance of stopping all beer sales and shutting down all breweries ASAP. And dairies, too.
On a lighter note, I guess these calculations mean I can keep my Tritium night-sighted Kimber Compact 1911 in .45 ACP? (Sigh of relief!)
Becquerel is not a good unit to discuss in media – it does not tell the reader anything of the risk. Of importance though is the dose, which the most affected person close to the NPP receive. Is the dose low, such as in this case, there is no danger. The nuclear risk hype has grown too large in the US and elsewhere.
As sixteen thousand children die every day of hunger one can wonder if the attention this incident has received is justified.
As someone who lives six miles from the plant and a student of physics, I appreciate your rational approach. The part I don’t have confidence in, however, is recommissioning a plant that was designed to run for so many decades.
Furthermore, the state has had to jump through all kinds of hoops to get Entergy to prove it had the funds sufficient to eventually close down the plant, pay for the long term storage of the nuclear materials, and other promises made when the plant was first contracted to be built. It would not surprise me at all that when the plant eventually closes (and of course, eventually it must) that Entergy could claim bankruptcy and leave the state tax payers with the tens of millions of dollars in bills.
There are indeed rational criticisms of the plant, some that are relevant to the type of power generation, while others are unrelated.
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