[ RadSafe ] Spallation Neutron Source Amazing Science Facts

Susan Gawarecki loc at icx.net
Thu Dec 29 16:47:29 CST 2005

Spallation Neutron Source Amazing Science Facts

OAK RIDGE, Tenn. Dec. 22, 2005 -- The New Year is bringing the science 
community a grand present: The Spallation Neutron Source at Oak Ridge 
National Laboratory. On schedule for completion in 2006, the Department 
of Energy's new science facility will provide researchers with the 
world's most powerful and most advanced tool for analyzing a host of 
materials with neutrons.

As they home in on the fruition of seven years of construction, SNS 
staff members have compiled the following list of SNS Amazing Science 
Facts to illustrate what's in store for the neutron science community 
once this state-of-the-art, world-class materials research facility 
starts up around mid-year. Read on and prepare to say "Wow."

Around the world: The energy of the SNS's proton beam, expressed in 
terms of voltage, is 1 billion electron volts. That is equivalent to 666 
million 1.5-volt D-cell batteries joined end to end. Such a string of 
these batteries would nearly reach around the Earth!

Fast off the line: The proton beam accelerates through the linear 
accelerator (linac) from a standstill to approximately 90 percent of the 
speed of light in two microseconds!

Now that's cold: The SNS's linac takes advantage of superconducting 
technology: Approximately two-thirds of the linac's total 1000 feet is 
at superconducting temperature, chilled with liquid helium to 2 degrees 
above absolute zero, or 2 Kelvin. How cold is that? By comparison, a 
December night-game spectator at the Green Bay Packers' Lambeau Field 
should dress to endure a comparatively toasty 275 Kelvin!

Flurry of punches: Following 1,060 turns around an accumulator ring, 150 
trillion accelerated protons (150,000,000,000,000) strike the target in 
a pulse that lasts only one millionth of a second. These pulses strike 
the target 60 times per second!

Ouch: The pulses strike the target vessel at enough energy to release 
neutrons from atoms--neutrons that are then used for research. That 
energy is similar to a 200-pound block of steel hitting the vessel at 50 

Over the horizon: The SNS requires the tuning of the beam lines to be so 
precise that the Earth's curvature was factored into the construction of 
the linear accelerator—a tiny but critical difference of 7 millimeters 
from one end of the 1,000-foot linac to the other!

Fine as frog's hair: All components on the SNS that comprise the 
accelerator and the target, independent of size, shape and weight, are 
installed to specifications within a mite-sized 2/10 of a millimeter!

Plugged in: Beam power in the linac is 1.4 megawatts, enough juice to 
power 1,400 homes. It will require 42 megawatts of electricity to 
generate those 1.4 megawatts of beam power. The total SNS electric bill 
will be, at current rates, $10 million a year, or enough power to serve 
a town of roughly 30,000!

Admiration from afar: The SNS will increase the number and intensity of 
neutrons for research by factors from 10- to 100-fold. So intense that, 
once the SNS is operational, no one will ever again enter the target 
bay. All maintenance operations inside the target--even changing light 
bulbs--will be performed remotely, with state-of-the-art robotic 
manipulators Because they have to be performed robotically, all 
anticipated remote operations inside the target facility, for the 
40-year design life of the SNS, have been planned and practiced beforehand!

Thick as a brick: Shielding over the tunnel into the target facility 
"monolith" consists of 7 feet of steel and 2 feet of concrete. The 
target facility floor is 5 feet thick. There are 12 million pounds of 
steel shielding in the monolith alone, and 4 million pounds of concrete!

Chock full o'neutrons: The SNS is the first facility to use pure mercury 
as a target material. Why? The liquid mercury can be continuously 
circulated, thus dissipating the enormous heat and energy. Mercury is 
also rich in neutrons--the average mercury nucleus has 120 neutrons--and 
consequently, has a very large mass. The target's 20 tons of mercury is 
only one cubic meter in size!

Come together: Five Department of Energy Office of Science 
laboratories--Argonne, Berkeley, Brookhaven, Jefferson and Los 
Alamos--participated with Oak Ridge in the design of the SNS project. 
The $1.4 billion Basic Energy Sciences project has been constructed on 
time and on budget with an excellent safety record.

But the most remarkable aspect of the SNS is the science that will be 
performed there in the years ahead. Researchers from the United States 
and abroad--an estimated 2,000 a year--are poised to come to the SNS to 
study materials that will form the basis for new technologies in 
telecommunications, manufacturing, transportation, information, 
biotechnology and health. This broad range of scientific impact will 
strengthen the nation’s economy, energy security and national security.

Oak Ridge National Laboratory is a multiprogram laboratory managed for 
the Department of Energy by UT-Battelle.

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