[ RadSafe ] Spallation Neutron Source Amazing Science Facts
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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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