Dr. Noel de Nevers, a retired professor of chemical engineering at the University of Utah, Blaine Howard, a retired health physicist, and Dr. John Contreras, an epidemiologist with the state Department of Health, explained what DU is and the risks associated with it to an audience of about 50 people at the Tooele County Emergency Operations Center.
The trio left attendees with the impression that DU, while not without risks, can be safely stored by EnergySolutions.
“The county decided to hold the information meeting because we have been fielding a lot of phone calls from the public about depleted uranium,” said Colleen Johnson, Tooele County Commission chairwoman, who recruited the speakers. “We did not plan the meeting to be a debate and were not planning on changing anybody’s mind about depleted uranium. We just wanted to provide information from informed sources.”
Nevers, who was granted emeritus status from the University of Utah in 2002 after serving on the faculty for 40 years, described the process of creating DU from uranium ore mined from the ground.
Three different forms of uranium, or isotopes, are found in the material extracted from the earth. Only one of the three, U-235, is useful in power plants or for producing weapons, and natural uranium contains only 0.7 percent U-235. In the enriching process, the bulk of the U-235 is removed to make enriched uranium. What is left over becomes depleted uranium.
DU also contains other radioactive materials called “daughter products,” which are the result of the natural decaying process of the uranium. DU triples in radiation after its first three years and then increases again by six fold to reach a peak in radioactivity after a million years and its half-life is 4.5 billion years, according to Nevers.
Nevers described DU as “mildly radioactive.” It would take the radioactivity of 500 smoke detectors to equal about a full pound of DU, he said.
The most dangerous hazard created by DU as it decays is one of the daughter products produced: radon, a radioactive gas. However, with proper storage, including maintaining the soil cover and clay water barrier used by EnergySolutions in its storage cells, by the time the radon gas reaches the surface it would already have turned back into a solid product, Nevers said.
“We can’t make depleted uranium non-radioactive and we have to do something with it,” Nevers said. “It seems like burying it in an appropriate spot is the least worse solution.”
Nevers said his experience has been largely in the field of chemical engineering and he has no connection with EnergySolutions.
Howard, a Grantsville resident who received a masters degree in physics from Brigham Young University in 1964, discussed the nature of the radiation produced by DU compared to the radiation present in the environment.
“Radiation is present everywhere,” said Howard. “The amount depends on where you are.”
The average U.S. citizen is exposed to 375 millirems of radiation per year. Howard cited a 2005 study of EnergySolutions workers where 536 dosimeters — devices worn by the workers to measure their exposure on the job to radiation — were checked. Out of all the dosimeters, 418 recorded no exposure. The remaining 188 dosimeters averaged 17 millirems per year. The highest dosimeter measured was 414 millirems per year. Visitors to the Clive facility measured no detectable exposure, Howard said.
“No amount of depleted uranium stored at Clive will change these results,” Howard said.
To put the exposures in perspective, Howard cited the Health Physicists Society, a professional organization of people working in the radiation safety field, as stating that exposures below 5,000 to 10,000 millirems produce no measurable effects.
Howard also stated that the radiation produced by DU comes in the form of alpha particles, which are so low in energy they can be stopped by a sheet of paper.
“There is no possibility of any harm to the public from DU stored in any quantity at Clive,” Howard said.
Howard once worked as a health physics specialist for Envirocare, the precursor company to EnergySolutions.
Contreras, an epidemiologist with the Utah Department of Health, was back for his second county-sponsored health presentation in the past eight months. Last August, when community groups were raising concerns over the possible negative health effects of electric and magnetic fields associated with Rocky Mountain Power’s Mona-to-Oquirrh transmission line plan, Contreras gave a presentation contending power lines have not been proven to cause health problems.
At Tuesday’s gathering, Contreras tried to allay similar health fears over DU.
“With the possible exception of the kidneys, no conclusive epidemiological evidence has correlated DU exposure to specific health effects,” Contreras said.
Contreras had earlier in the meeting reported that some studies show possible renal kidney disease with acute exposure to large doses of DU, but when replicated the studies were not consistent.
But DU risks may not be as cut and dried as the picture painted by the three experts.“The Nuclear Regulatory Commission and the Utah Radiation Control Board obviously have some concerns or they would not both be in the process of developing rules for the safe disposal of depleted uranium,” said Christopher Thomas, policy director for HEAL Utah.
Thomas is concerned that the DU from the Savannah River site cleanup that the Department of Energy wants to send to Clive is not from the enriching of uranium for fuel but a by-product of reprocessing uranium from the inside of reactors to extract plutonium and uranium for making bombs. As a result, the DU comes with other radioactive elements that are not natural daughter products of decay and may exceed limits for Class A waste.
Thomas is also cautious about the suitability of Clive for long-term storage of a product that will not reach its peak of radioactivity for a million years.
The Utah Medical Association has submitted a letter to the Radiation Control Board in favor of a moratorium on depleted uranium. In the letter, Dr. Glen Morrell states on behalf of the UMA: “We strongly believe there are probable public health risks to any importation and storage of depleted uranium.”
Peter Burns, a current professor of civil engineering and geology at Notre Dame University, who is involved in research on DU and is a current member of a National Academy of Sciences study panel examining nuclear waste forms, has submitted his comments to the Radiation Control Board for their consideration in developing rules on DU storage.
Burns writes, “Shallow landfill disposal presents numerous pathways for release of radioactivity into the environment.”
In December 2009, the Department of Energy notified Gov. Gary Herbert that it had 15,000 barrels of depleted uranium from a federal weapons facility cleanup project in South Carolina. The DU was loaded for three train shipments to be sent to EnergySolutions’ Clive facility. On Dec. 21, with one DU train on its way to Utah, Herbert reached an agreement for the other two shipments to be held up and the DU on the way to be put into temporary storage while the state completed new regulations governing the disposal of the material.
In February, Herbert announced another agreement with the DOE. The two trainloads waiting in South Carolina will not come to Utah and the 5,400 barrels of DU already unloaded at Clive will be taken back by the DOE if a study reveals the material can not be safely stored at EnergySolutions’ facility.
In an informal, month-long poll on the Transcript-Bulletin’s Web site, 60 percent of respondents said Herbert was right to block the last two train shipments of DU that were headed to Clive, while 38 percent disagreed with Herbert’s decision.
The fate of the depleted uranium unloaded at Clive awaits the outcome of testing to verify that its contents do fit requirements for Class A waste, and the final development of rules for its disposal to be adopted by the Radiation Control Board. Both of those issues may be resolved at the Radiation Control Board’s April 13 meeting along with the proposed new rule requiring a site-specific study of Clive that may take up to a year to complete.
“I think the Tooele public deserves a much more robust discussion of these issues,” said Thomas.
Tim Gillie: tgillie@tooeletranscript.com
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