Correction: (Posted at 6:43 on 6/16/2013) I made a boneheaded error in the below computation and dropped an important prefix in my units. That error resulted in my final number being off by a factor of 1000; I wrote 0.001 mrem when it should have been 0.001 rem. I apologize for the math error. I have made corrections in the below that should appear with a single line out so you can still see the original words. I stand by my overall conclusion that the amount of tritium that leaked from Vermont Yankee was never a human health risk. End Correction.
In his review of Pandora’s Promise (which is opening this weekend in about 20 cities in the United States), Ed Lyman, senior scientist for the Union of Concerned Scientists, picked a nit by extracting a single line and attempting to show how wrong it was.
My hand got tired trying to jot down all the less-than-half truths put forth by the talking heads in the film, which could have benefited from some fact-checking. Here’s just one example. Gwyneth Cravens, when prompted by the interviewer about the leak of tritium from the Vermont Yankee nuclear plant, stated that someone would get more radiation from eating one banana than from drinking all the water coming out of the plant. Well, I thought I would double-check this one. The dose from eating a single banana is about 0.01 millirem. Entergy, Vermont Yankee’s owner, estimated in a 2011 report to the NRC that the leak detected in early 2010 released 2.79 curies of tritium into groundwater. Assuming someone consumed all of this tritium in the form of tritiated water, that person would receive a dose of 185,000 millirem. Ms. Cravens was only off by a factor of twenty million. Perhaps she was referring to the actual amount of tritium that would end up in the wells of the plant’s neighbors, given dilution effects—but that isn’t what she said. These sloppy soundbites greatly diminish the film’s credibility.
In making that statement, Lyman questioned the credibility of the film and insulted one of my frequent Atomic Show guests, who happens to be one of the most concerned human beings I know. According to a correction posted on his blog entry, Gwyneth Cravens has responded.
Gwyneth Cravens pointed out that I missed part of the quote that I attributed to her. She writes that her actual quote was “If you ate one banana which has a potassium isotope that’s a little hot, you would get more radiation exposure than you would if you drank all the water that comes out of the plant in one day.” I had missed the phrase “in one day.” However, her statement is still wrong by a large factor.
Lyman goes on to modify his assumptions a little to claim that Gwyneth was off by a factor of 25,000. She is standing her ground and added the following comment on his blog:
In regard to Mr. Lyman’s mistaken quote of my remark in the film about the tritium leak, thanks for posting my correction.
In regard to Mr. Lyman’s second attempt, I stand by what I said in the film. This information was fact-checked by one Nobel-prizewinning particle physicist, a health physicist, and by four radiation-protection experts. Apart from my own wish only to say what I knew to be the case, Robert Stone wanted to make sure everything in the film was accurate.
Lyman’s response at that point was to demand that Gwyneth and her checkers show their work so that it can be compared to the work done by the UCS. I’m an old school commissioned officer and gentleman (CDR, USN (Ret.)) so I jumped in to help a fine lady being wrongly accused of misleading people. Here is the comment that I added to the UCS blog post. (Note, I have made some editorial changes; continual proof reading is one of the annoying habits I picked up as the son of a high school English teacher.)
The method I am using can be found in many basic texts. One that is available online is LLNL Environmental Report 1998 Appendix A Methods of Dose Calculations.
In that document, you can find the following conversion factor for a whole body dose from consuming tritiated water. The document has a fully referenced method for producing the final number, so I will not reproduce it on your blog.
6.4 × 10–8 mrem/pCi
Therefore dose from consuming 2.79 curies = 6.4 x 10-8 mrem/pCi x 2.79 x 10+12 pCi = 178,000 mrem
So, it looks like your number is close enough – on the surface.
I will admit that Ms. Cravens’s comparison is a little off, but the key element remains true. Even in the entirely impossible instance of a single person consuming every single drop of a leak of tritiated water that had a concentration of 2.5 million picocuries per liter, the total dose to that one individual would be about 178 Rem. That dose is in the range that might result in mild radiation sickness, but is unlikely to lead to any immediate consequences worse than a mild flu.
The recipient MIGHT contract cancer that they otherwise would not have gotten, but the average American has a 30-40% lifetime risk of cancer anyways.
In order to get that dose, however, the person would need some rather special capabilities that are not normally found in human beings. They would have to be able to consume, in a single sitting, roughly one MILLION liters of water.
If, instead, the person was closer to an average human and consumed their normal intake of 8 liters per day, their dose rate would be 0.001
mremrem per day.
Perhaps the comparison that Ms. Cravens was attempting to make in the film and the one that was checked by her eminent sources was to note that human beings could obtain ALL of their daily water intake DIRECTLY from the water that Vermont Yankee was leaking into the ground underneath the plant and they would STILL receive a daily dose that
is less than the one received from eating a single bananawell below the level at which there is any measurable increase in lifetime cancer risk.
Even that situation is absurd, since water that leaks into the ground underneath a power plant cannot be consumed by any human without going through a rather effective filter consisting of thousands of feet of soil with a delay measured in years, since there is little driving head pushing that water towards wells used for drinking water.
Ms. Cravens and Robert Stone are perhaps guilty of making a statement that is attempting to illustrate risk in terms that people can more readily understand and goofing up the wording of the comparison a little bit. What they are NOT guilty of is harming people and the planet by making people tremble in fear about a minuscule risk.
Living in continuous fear can cause debilitating health effects all its own. Focused efforts aimed at shutting down emission free electrical generating plants because of “tritium leaks” can cause an elevation in real risks like climate change, fires and explosions, and economic consequences from rising power prices caused by having to replace an adequately safe nuclear plant that is already built and paid for.
I am accusing you and your organization of failing to help the public make reasonable evaluations about one of the most important energy decisions they can make – whether or not to allow the safe, reliable, cost effective operation of nuclear power plants INSTEAD of having to produce the power they would otherwise have produced by burning hydrocarbons or damming up rivers.
Here is the statement that I think Gwyneth was trying to make in Pandora’s Promise: “If you ate one banana which has a potassium isotope that’s a little hot, you would get more radiation exposure than you would if you drank all of your water directly from the place where Vermont Yankee was leaking tritium.” That is an accurate statement that. The extremely low level of radiation risk, even if people drink water directly from a the leak source, should make people ask Arnie Gundersen and his friends at the UCS the following questions:
“What was all of the fuss about? Why have you worked so hard to discredit a fine company and spread fear, uncertainty and doubt about the best available energy alternative? Why are we supposed to be more afraid of tritiated water coming from nuclear power plants than of the possibility of contaminated ground water from natural gas fracking, carbon and other nasty waste products from coal plants, continued dependence on oil imported from abusive regimes, or the potential of massive forced relocations for hydro electricity (along with occasional risk of dam failures.)?”
The shared motivation caused all of Robert Stone’s stars to change their mind about nuclear energy was not an unrealistic belief that nuclear energy is a perfect solution. It was a recognition that a world that needs energy needs to make reasonable choices among available energy alternatives. There is no perfect power source that is fueled by “unobtainium”. Nuclear power plants do not have to be perfect in order to be acceptable. They just have to be better than other available choices.
Stone’s protagonists have decided that we must chose to accept pretty darned good power sources fueled by small quantities of uranium and plutonium, even if they have a few complexities, costs and imperfections. The alternative to accepting nuclear energy is to burn more coal, natural gas and oil and to dam up more rivers. Wind and solar are expensive distractions that are only available at the whim of the weather; they are never going to be players in the vital enterprise of supplying reliable power.
Note: I brought Arnie Gundersen into this post because he was one of the main protagonists in the saga about Vermont Yankee and its highly publicized tritium leaks.