By Raam Wong, Journal Staff Writer
Sunday, August 26, 2007
LOS ALAMOS— Earthquakes pose a greater risk to Los Alamos National Laboratory than previously believed, according to a new study that's forcing lab officials to re-assess whether they're ready for the big one.
Over the next two years, the lab intends to analyze two dozen of its nuclear and non-nuclear facilities in light of the study's finding that seismic hazards are as much as 50 percent higher than once thought.
In the meantime, LANL this month received the National Nuclear Security Administration's permission to continue normal operations, asserting that there's only a 1 in 700 chance of a significant earthquake in the next two years.
"LANL is asking the NNSA to accept the risk of continued operation until a quantitative assessment of each facility is performed," LANL stated in a so-called justification for continued operations recently released to the Journal.
The lab has until Sept. 21 to inform NNSA of how it plans to complete a seismic analysis for the facilities by June 2009.
Any facility found to be not up to snuff with Department of Energy requirements could be strengthened or see changes in its operation or use.
Already, LANL officials have identified a few needed improvements. For instance, the lab plans to reduce the allowed inventory at its Weapons Engineering Tritium Facility to limit how much tritium would be released during an earthquake-induced fire.
The increased risk assessment is largely the result of a better understanding of the 50 kilometer-long Pajarito fault system that extends along the western end of the lab. Seismologists have found evidence of more past surface-faulting than once believed.
"What it means is that the (perceived) hazards have increased," said LANL structural engineer Michael Salmon.
The Department of Energy has set goals for how certain types of buildings should hold-up during an earthquake based on what goes on inside.
An office building, for example, should protect worker safety when things start shaking, while a nuclear facility should also confine hazardous materials and ensure that operations are not interrupted.
DOE requires that these high-value buildings, of which LANL has 19, have less than a 1 in 10,000 chance of suffering unacceptable damage during a seismic event in any given year.
But the potential earthquake that officials have been planning for turns out to be larger.
When the lab first assessed its seismic risk in 1995, seismologists believed that a one in 2,500-year quake would shake the ground with a peak acceleration of 0.33g, where a "g" represents the force of gravity.
Now, seismologists believe a 2,500-year quake is as high as 0.5g.
Lab seismologists have said that magnitude earthquakes of 7.0 on the Richter scale have occurred in New Mexico in prehistoric times. A 1906 earthquake knocked down chimneys on the Socorro County courthouse and caused plaster to fall from walls in Santa Fe. In May 1918, a quake knocked people off their feet in Cerrillos.
Smaller quakes regularly hit New Mexico— for instance, a series of temblors measuring up to 4.4 near Raton in 2004.
The question for LANL officials is whether lab buildings can still perform as needed during a larger quake.
Lab officials have known for years that one important facility— the 550,000-square-foot Chemistry and Metallurgy Research Building— wouldn't survive a significant earthquake.
LANL spokesman Kevin Roark noted the facility no longer holds significant quantities of nuclear material. The building is set to be replaced, though the project faces mounting skepticism in Congress.
The lab's plutonium facility, Technical Area-55, is thought to be safe in a large earthquake "We're confidant that 55 is fine," said LANL's Salmon.
Greg Mello, an arms control activist with the Los Alamos Study Group, said LANL has a number of underlying safety problems that are only compounded by the heightened seismic risk. "Just to say everything's going to be fine is just whistling in the dark," Mello said.