Tuesday, April 21, 1998
Experts disagree on safety of gaseous emissions
One of the most contentious controversies at Yucca Mountain has been over the release of radioactive gas from the repository.
Because no metal will last for 10,000 years, the storage canisters and casks shielding the waste will corrode and fall away to expose the nuclear materials to air inside the mountain. A chief component of that air would be radioactive carbon 14, which is released as the waste decays.
In 1992, after it was discovered that there would be 10 times more carbon 14 to be released from the repository than EPA regulations allowed, Congress threw out the carbon 14 standard and asked the NAS to recommend new standards to EPA. Congress also conveniently barred any further studies of carbon 14 releases as a repository regulatory issue.
"Congress has decided in its wisdom that the release of carbon 14 is inconsequential to public health and safety," complains Robert Loux, who heads Nevada's repository program.
Before that happened, the EPA had concluded that 6,000 premature cancer deaths per year would result globally from carbon 14 releases under the original health standard, according to Loux and Ray Clark, head of EPA's standard-setting team. However, the carbon 14 health threat was dismissed by the NAS and the DOE as too "negligible" to matter.
"Six thousand is not negligible," acknowledges Clark.
"It's a ludicrous number," counters Abe Van Luik, DOE's senior technical adviser at Yucca Mountain, who faults the EPA's methodology. He says the repository would release its carbon 14 in tiny doses, far lower than natural background radiation over 10,000 years, so it poses little real risk to humans.
"Even the DOE conceded that the repository could not meet that standard," contends Loux. "It was the reason the standard was thrown out. The reason no one cared is that it would disqualify Yucca Mountain, and we can't have that for God's sake."
Loux warns that if waste is put in Yucca Mountain, the gas will seep out of it because "it's so fractured that air and gases move freely through the whole mountain."
"The air is not the problem, it's the water," counters Allen Benson, DOE's Yucca Mountain Project spokesman.
But Loux insists that the only reason carbon 14 isn't a problem is because Congress says it isn't.
In 1994 the NAS proposed a new repository standard. This one relied on calculating doses of maximum tolerable human exposure to radioactivity from the repository.
But DOE persuaded Congress not to accept the recommendations in the new standard either, Loux says. The House of Representatives eventually dictated a permissible maximum dose that allows four times more human exposure than the NAS recommended, or 100 millirem per year, while the Senate prefers 30 millirem. (A millirem is one-thousandth of a rem; a rem measures one dose of ionizing radiation. A human traveling round trip by plane between Seattle and New York is exposed to 5 millirem.)
Inexplicably, at Carlsbad, N.M., where DOE plans to bury less dangerous but very long-lived wastes such as lab equipment, the law forbids human exposure to more than 25 millirem per year.
Where the truth lies in all the contradictory safety assertions is hard to say. But one thing can be said: Such widely varying expert opinions do not instill public confidence that any of these people know what they're doing.
As Van Luik cheerfully notes: "All of this we have no experience with. We have to wait a few thousand years" to see if it works.
'We" won't be here to answer for the consequences if "we" are proven wrong.
The scientists who so confidently make 10,000-year guesses about safety rely on probability and statistics to predict the future.
Given this unprecedented challenge, that's a pitiful tool kit.
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