Plutonium levels in waste may delay shipments
By N.S. Nokkentved
TWIN FALLS -- Some barrels of radioactive waste slated for disposal in New Mexico have been rejected because they might contain too much plutonium.
Since 1994, officials at the Idaho National Engineering and Environmental Laboratory have rejected 47 barrels of plutonium-contaminated waste because they could contain more than 200 grams of plutonium, INEEL spokesman Tim Jackson said.
Two hundred grams is a little more than seven ounces, about the weight of two compact discs and their cases.
The barrels with high levels of plutonium could in turn slow shipment of waste out of Idaho. The INEEL is under a court-enforced deadline to ship all plutonium-contaminated waste out of the state by the end of 2015.
And the amount of plutonium in a 55-gallon barrel of waste is of concern because of the possibility of starting a spontaneous, uncontrolled nuclear chain reaction -- known as a criticality. Too much of the leadlike metal, concentrated in a small area, could trigger such a reaction.
Test data this summer gathered from a radioactive waste disposal pit at the INEEL suggests that some buried waste also might contain plutonium above the levels of concern.
The U.S. Environmental Protection Agency is concerned about the possibility of a criticality. Site officials are confident, however, that the buried waste doesn't present such a risk.
The rejected barrels were slated for shipment and disposal at the Waste Isolation Pilot Plant near Carlsbad, N.M. The amount of plutonium in WIPP-bound waste barrels is limited to avoid a criticality risk if two barrels with a lot of plutonium in them are stacked too closely together.
The 47 barrels were rejected because the system used before 1994 to analyze them was less accurate than the one now in use, Jackson said.
The rejected barrels will be studied again, using newer, more accurate equipment. If they still show more than 200 grams of plutonium, they might still be shipped to WIPP, but they might have to be shipped by themselves in a shipping container that otherwise can hold 14 drums.
Meanwhile, the barrels are being carefully stored to avoid any danger of starting any accidental nuclear chain reactions, Jackson said.
But INEEL officials still are trying to meet the milestones of the 1995 agreement between the state and the federal government, which requires the INEEL to ship 108,500 cubic feet of waste by the end of 2002.
To meet the deadline, the INEEL is trying to send only full shipping containers, containing the maximum 14 barrels of waste. But shipping restrictions allow only a total of 325 grams of plutonium per shipping container, so some containers may have to be sent with only a single barrel.
With three containers to a truck, each shipment could carry up to 42 barrels.
The INEEL plans to ship 40,600 cubic feet by October 2001 to meet the milestone, Jackson said.
Times-News writer N.S. Nokkentved can be reached at 733-0931, Ext. 237, or by e-mail firstname.lastname@example.org