In scenarios, nuke cleanup costs reach into billions

Wednesday, Aug. 9, 2000 | 11:10 a.m.

In a worst-case scenario, a traffic accident involving high-level nuclear waste on Las Vegas' busy highways could cost taxpayers billions of dollars, state and federal scientists say.

If high-level nuclear waste cargo were involved in an accident similar to the tandem gasoline tanker wreck last week on U.S. 95, radiation would contaminate an area within a 3-mile radius of the scene, a state computer study shows.

In the computer model, the contaminated area could take at least a year to clean up, and businesses and residences would be sealed off.

Truckloads of highly radioactive waste could be shipped from power plants and defense facilities nationwide to Yucca Mountain, 90 miles northwest of Las Vegas, as soon as 2010 if the site is declared scientifically suitable for a nuclear waste repository.

Most of the 77,000 tons of waste would likely be transported through the Las Vegas Valley by trucks using federal highways, although the state can request alternate routes.

State scientists say that should one of those shipments be involved in an accident as severe as last week's, the cost of cleaning up the contaminated area could reach $20 billion.

Federal experts, who use a less severe nuclear accident model, say the cleanup cost would be just $1 billion.

Both state and federal officials say the chance of an accident involving high-level nuclear waste is more than one in a million, but they also agree there is a definite risk involved with shipping the waste to Yucca Mountain.

While DOE and Nevada transportation consultants use the same technique for estimating deaths, dollar losses and injuries from a high-level nuclear waste accident, their results differ.

The methods used and the results of the two studies are significant because the DOE is responsible for establishing that high-level nuclear waste can be safely transported to Nevada and safely stored in a Yucca repository. State officials are trying to keep the waste out.

DOE's accident scenario assumes a breach of the shipping cask along a seal, a fire that burns for eight hours and no wind, which would expose more residents to higher levels of contamination. But it also placed the scenario in a sparsely populated area on Las Vegas' outskirts, as opposed to the dense residential neighborhoods surrounding the U.S. 95 accident.

The DOE uses RADTRAN and RISKIND as its computer models for analyzing environmental effects after accidents involving high-level waste on the way to Yucca.

However, the federal models assume lower levels of radioactive waste than the state's analysis, though they assume the waste escapes over a longer amount of time. The DOE results were not as deadly as the state's.

The state duplicated the DOE's analysis on the same computer models, evaluating the same accident and replicated the results.

Then scientists started considering varying conditions -- such as high winds, which are common to the valley -- and winds blowing from different directions, to come up with the state's simulation.

The consultants used a truck carrying more highly radioactive waste -- 10-year-old spent nuclear fuel that represented the highest radioactive hazard that would likely be shipped, as opposed to the DOE's assumption of waste 26 years old, which is not the worst possible case, state experts Marvin Resnikoff of New York and Robert Halstead of Wisconsin said.

They also used 1999 population figures -- the DOE used 1990 Census figures -- for the area surrounding Interstate 15 and Blue Diamond Road where the simulated accident occurred.

Both models used a tractor-trailer truck carrying the high-level waste going at least 60 mph that slams into a highway bridge. A single-tank gasoline truck hits the waste vehicle and bursts into flames.

In the state's simulation, the fire burns for about two hours, and the cask cracks.

The state contends that up to 199 people would contract a fatal cancer based on its assumptions, including the more recent population figures.

The DOE model predicts five people would die from cancer after one day of exposure to radiation from an accident that burned eight hours.

But Steve Maheras, a health physicist who worked on the federal analysis, said the DOE included much worse conditions in an accident than the state.

The DOE believes that the shipping canisters would survive under almost any circumstances, but if they did not, the "accident is bad," Maheras said.

Applying the DOE's scenario of a high-level nuclear waste accident to the accident last week, the damage to the nuclear waste cask would be far less than the state's worst-case scenario, Maheras said.

The Las Vegas accident under the federal analysis would result in one death from cancer caused by radiation exposure, Maheras said. State consultants estimate the accident would result in 199 cancer deaths.

The death rate for the federal simulation of last week's accident was adjusted down because the fire burned for less time than the DOE's eight-hour example where five people died from cancer, Maheras said.

"Our analysis did assume that the cask seals failed, but it is not like the cask (carrying the nuclear fuel) is going to crack open on the ground. It's more likely the seals will fail from the fire," he said.

"We looked at accidents that were much worse than the accident in Las Vegas," Maheras said. "The fire was longer."

The state did not adjust its estimate of 199 deaths because its original simulation assumes a two-hour fire and that the cask would fail earlier than in the federal model, scientists said.

The state also added other environmental factors, Resnikoff said.

While the DOE counts only radiation from inhaling the air during the accident, the state includes exposure from radioactive particles on the ground.

The immediate risk from radiation and future exposure to radiation in the soils add to the higher death rates, he said.

"It (contaminated soil) would essentially become an X-ray machine that you can't turn off," Resnikoff said.

The state also estimates that 9,000 people would seek medical help, Halstead said, noting that he considered 90,000 to 100,000 people living under and on each side of a plume of smoke from the fire.

The DOE does not estimate how many people might seek medical aid.

The state also looks at economic effects of a cleanup, something not in the DOE analysis.

Total costs soar when the losses of business, use of homes and open spaces near the accident are added into the mix. These costs are for a typical urban area, not a crowded resort street such as the Las Vegas Strip or people packed into high rises, Resnikoff said.

"We have extensively reviewed the range of health effects, and we have confidence of the range of health consequences," Halstead said. He is still in the process of evaluating the economic portions of the model, which Resnikoff produced.

The costs could go higher, Halstead said.