Rock formations that contain fossil fuel resources also contain uranium, thorium and their decay products in concentrations that can be significantly higher than the levels that raise concerns regarding tritium. When companies seeking to extract oil or natural gas drill into those formations, a large quantity of material (US total is about 260,000 metric tons per year) is pulverized by the drill bits and brought to the surface, releasing isotopes that include Rn-220, Rn-222, Ra-226, Pb-210, Ra-228, and Th-228.
Though these isotopes are part of the natural rock formations, like the oil and natural gas that is the target of the extraction effort, the drilling process frees them from their sealed, underground condition and puts them into the human environment where they have the potential for increasing exposures. There is a term for naturally occurring radioactive materials (NORM) and one for Technologically-Enhanced, Naturally-Occurring Radioactive Materials (TENORM). Internationally, the second one is often referred to as Technologically Enhanced Natural Radiation (TENR). (I think that the international term was coined by people who did not like the warmer, fuzzier acronym of "NORM" as in "normal".)
Under most conditions, the exposure levels are not something that should concern anyone, but it is not uncommon for workers in some oil and gas extraction efforts to be routinely exposed to enough radioactive material to increase their annual exposure by .03-.5 mSv (3-50 mrem) if they are doing maintenance work on pipes and valves associated with drilling and by 0.3 to 7 mSv (30-700 mrem) for workers involved in recycling oilfield drilling equipment. (Source: Radiological Impact On Man And The Environment From The Oil And Gas Industry by F. Steinhausler, Radiation Safety Problems in the Caspian Region, 129-134 2004. Kluwer Academic Publishers.)
There is a current court case in which employees at a facility owned by ExxonMobil are charging that they were not informed that they were working with radioactive material and thus were not trained on the precautions that radiation workers should take to minimize exposures. They claim to be worried that they might develop cancer as a result of the exposure, though none of the claimants currently have the disease.
The concentration of radioactive isotopes that can be released by drilling activities will vary depending on the composition of the formation; some locations have produced little radioactive material while others have had much higher doses because of the high concentration of uranium in the drilled rock. The Marcellus Shale formation will most likely be at the high end of the spectrum; that kind of shale contains enough uranium that it is possible to profitably mine for that material if the world market price for uranium is high enough.
Not only is there a certain amount of increased exposure to oil field workers and those who handle used equipment, but some of the isotopes listed are gaseous and will mix with the extracted gas. When that happens, the gas will carry those isotopes all the way to the point of use. The gases, like radon, will not oxidize in the burning process, but they will be released into the environment - which might be inside homes if the end use of the gas is for a stove.
My intent here is certainly not to scare anyone; the levels of exposure are low enough that moderate protective measures can keep human doses well under the range that would cause health impacts. As ExxonMobil's attorney has stated with regard to the worker lawsuits:
“The real level of exposure was far less that what would increase the risk of cancer,” he said. “There is no increased risk of developing cancer.”My intent, instead, is to try to generate some rational conversation about the decisions surrounding the construction of new nuclear power plants and the continued operation of existing plants like Vermont Yankee, Indian Point and Oyster Creek that have been accused of being potentially hazardous merely because it is possible to detect a moderate amount of tritium on the plant site that appears likely to have come from degraded or cracked piping systems.
“They don’t have an injury,” Woolf said about the Plaintiffs. “You cannot award damages on speculation.”
“Did these men have a right to be angry at Exxon?” Woolf asked. “You bet. Did they suffer any damages that they are seeking to recover in this case? Absolutely not.”
Shutting down those plants will increase the demand for natural gas, and that increased demand might be supplied by increased drilling activity in tight gas formations like the Marcellus Shale. Though nuclear plants certainly contain far more radioactive material than natural gas or coal plants do, the real question for those who are honestly concerned about radioactive exposures is how much does each form of energy RELEASE to the environment where it might cause additional exposure to humans and other living creatures.
Nuclear plant operators work very hard to keep radioactive material under tight control - though they are not perfect, the record is very good. In contrast, oil and gas operators often do not even bother to keep records of the material that they handle or release to the environment.
Rational decision making processes would compare the actual or potential doses from small leaks of tritiated water from systems that have nothing to do with reactor plant safety against the actual or potential doses from thousands of tons of natural gas well drilling wastes, oil field service equipment and radon contained in the distributed natural gas.
If radiation exposure to the general public is the primary concern, natural gas has a higher measured risk than nuclear power plants with small tritium leaks. It also produces a lot more CO2, CO and NOx, but that has always been obvious. I am fairly certain that few people know much about the radiation exposures that are a routine part of using extracted fossil gas.
Here is a quote from that paper I referenced earlier that might provide some explanation for why the radiation implications of oil and gas production are not well publicized:
It is emphasized that in many countries the oil and gas industry represents a powerful concentration of capital and is frequently one of the main providers of a large number of jobs. Therefore this industry is able to exert also significant lobbying power at the political level. For example, in Brazil until recently a single company had the monopoly to extract oil in all of Brazil, making it the largest Brazilian commercial and industrial enterprise. Such a concentration of power can pose a significant hurdle in enforcing the implementation of any TENR-relevant legislation, as in the case of Brazil. The situation is still worse in many other countries with large oil and gas extraction industries, which have not even yet finished their internal discussion on how to adopt a common regulatory structure with regard to TENR. This is the current situation for: Argentina, Azerbaijan, Australia, Bolivia, China, Ecuador, India, Indonesia, Kazakhstan, Malaysia, Mexico, Saudi Arabia, United Arab Emirates, and Venezuela.
(Note: I would add the United States and Canada to that list of countries that do not have a common regulatory structure that treats TENR in a manner even remotely similar to isotopes associated more closely with nuclear energy production.).
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