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Vol. 56, No. 21                October 15, 2004
[Sandia National Laboratories]

Albuquerque, New Mexico 87185-0165    ||   Livermore, California 94550-0969
Tonopah, Nevada; Nevada Test Site; Amarillo, Texas

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Sandia's Z Machine fires

Officials cut ribbon on weapons-testing facility Sandians play big role in ARG exercise
Z refurbishment to advance machine’s
Officials mark opening of WETL building
at Pantex
Sandians play role in nuclear weapon

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Z refurbishment to advance machine’s capabilities

By Neal Singer

Sandia’s Z machine has received approval from NNSA to proceed with a $61.7 million refurbishment. The project is called ZR, for Z-Refurbished.

“The advance will support the weapons program and materials work not only at Sandia but at Livermore and Los Alamos,” says Nuclear Weapons Senior VP Tom Hunter (9000), who managed the funding that made the new installation possible. “I give credit to the Sandia project team and NNSA for making this a reality.”

Tom describes “a sense of excitement in the discoveries we will make in X-ray production, using these increased [electrical] current flows, for the nuclear weapons program, material science studies, and in our inertial confinement fusion program that plays a strong and complementary role to other NNSA investments like NIF [the National Ignition Facility in Livermore, Calif.]. This significant upgrade and investment will allow us to move to a new level of insight of z-pinches and their relationship to fusion.”

Eight years ago, the Z machine startled the scientific world when a technical advance produced an increase in output that made a graph of X-ray power (Y-axis) over time (X-axis) rise the way investors want their stocks to move: straight up. Output for Sandia’s pulsed power projects, which had increased only slowly for more than a decade, rose dramatically. For the Saturn machine, a smaller prototype similar to Z, output rose from 20 to 75 terawatts. For Z itself, just coming on line, an expected output of 50 terawatts rose to 150 tera- watts. Over the next two years, Z’s usable output rose to 230 terawatts. This made the machine more valuable as a data provider for nuclear weapons simulations and showed that z-pinches were a candidate for peacetime fusion that would provide electricity from, essentially, sea water.

Articles noting this change appeared in the popular press ranging from the New York Times to Esquire Magazine, and from the Washington Post to Scientific American. The photo of Z firing became the most widely published picture in Sandia’s history, appearing (among myriad newspapers, magazines, TVs, and textbooks) as the centerfold of a National Geographic issue celebrating “Machines of the Future” and even in a recent issue of the “men’s” magazine Maxim.

Theory and fact

Last year, Z researchers announced at the March meeting of the American Physical Society that Z had generated thermonuclear neutrons by imploding a small capsule filled with deuterium. This emission signaled that the machine had joined a select group of machines capable of executing high-quality inertial confinement fusion implosion experiments.

The coming upgrade can only increase neutron emission, say Z researchers.

In the next two years, 36 new Marx generators (read, large capacitors) will be installed. Exactly the size of their 20-year-old predecessors, the devices’ newer technology will store twice the energy as the original installation.

Thirty-six very rapid switches, formerly bathed in water and operated en masse by a single signal, will be upgraded to a system — oil-bathed for greater insulation — which alerts each switch individually when to turn on. Each switch controls the electrical current proceeding down one of 36 transmission lines, thus enabling researchers to shape the machine’s electrical pulse. The trigger upgrade and expected improvement in pulse shaping should make the already-overbooked machine even more valuable to researchers from Sandia, LANL and LLNL, whose calculations depend upon shape-controlled electrical current flows and X-ray outputs.

“This is a pretty significant engineering-and-logistics tailoring job,” says Ed Weinbrecht (1635), manager of the ZR project. “We have about a year and a half to complete the design and fabricate the parts we need.” Plans then are to dismantle the accelerator, move the oil-water separation wall to meet the insulation needs of the very fast switches, and install new pulse power systems “in what will be a hectic six-month period,” says Ed.

The overall Z architecture, looked at from the roof, resembles a wagon wheel. Marx generators form the outer rim of the wheel, power transmission lines imitate spokes, and a central vacuum chamber holding the target functions as a kind of hub.

ZR’s form will be unchanged, but the working numbers will be significantly different.

Instead of 18 million baseline amps bathing the target, 26 million amps will make the journey. The X-ray usable peak emissions will rise from 230 to 350 terawatts — more than 100 times the entire world’s output of electricity for a few nanoseconds. The [X-ray] energy output will rise from 1.6 to 2.7 megajoules.

Says Doug Bloomquist (1630), “There will be more data produced for classified experiments. The more energy-rich environment will bring higher fidelity to nuclear test simulations.”

Jeff Quintenz, Director of Pulsed Power Sciences Center 1600, says the project has already increased the facility’s precision. “We’ve been able to produce only the same pulse shape each time, when operating with a particular experimental configuration,” he says. “Without investment, experimentalists got what we had. Now we can dial a pulse; we have 36 switches that can be timed separately instead of 36 under one control.”

Less downtime

The machine also is expected to be lower-maintenance, with less downtime between shots. Current capacity is 200 shots/year, says Jeff; the refurbished machine will be capable of 400 shots/year, if funding is available.
Finally, in terms of capability, Jeff says, “Z was originally optimized to produce a 50-nanosecond short pulse, with high voltage to accelerate [lithium] ion beams. When we converted to Z, we had to live with a machine designed to drive ion beams. The refurbishment is optimized for high current to suit a z-pinch.”

Z-pinches employ high amperages to vaporize tungsten wires thinner than human hairs, creating particles imploding at a million miles an hour (500km/s). These, when colliding, give up their energy in the form of X-rays. Researchers also use the intense magnetic field created by the current either to accelerate particles outward or test the strength of materials.

A less obvious but no less important reason for the new upgrade, says Jeff, is “to exercise our pulsed-power engineering capability so we don’t lose it.” The last big pulsed-power upgrade was for Sandia’s Hermes III facility in 1988, he says.

-- Neal Singer

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Officials mark opening of WETL building at Pantex

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By Chris Burroughs

Officials from Sandia, BWXT Pantex, and NNSA snipped a ribbon last week, marking the completion of the new Weapons Evaluation Test Laboratory (WETL) located at the Pantex Plant near Amarillo, Texas.

The new $22 million state-of-the-art facility replaces the current 39-year-old laboratory, constructed when some of the early nuclear weapons were first built. It will house more than $90 million worth of testing equipment that will conduct systems-level, non-nuclear tests on nuclear weapons and components. WETL is the only US facility that performs these types of tests.

“This is such an important facility,” said VP 2000 John Stichman, one of the “snippers” at the ribbon cutting ceremony. “It will have the capability to support data acquisition technology so that we can not only tell whether a system works, but tell how well it’s working.”

Others participating in the ceremony included Mike Mallory, general manager of BWXT Pantex, and Martin Schoenbauer, acting assistant deputy administrator for NNSA Military Applications and Stockpile Operations.

Money for the new facility came from a congressional project approval four years ago and follow-on appropriations.

WETL is part of Sandia’s Stockpile Evaluation Program that monitors the reliability and safety of the nuclear weapons in the stockpile as required by DOE and the DoD. This assessment program, called “surveillance,” relies heavily on testing and evaluation of samples from the stockpile and contributes to the required Annual Assessment Report to the President.

Sandia has 80 people in its surveillance-related departments. Eighteen work at WETL where they test nuclear weapons components, without nuclear materials, using equipment designed and built at Sandia/New Mexico.

Annually the WETL crew conducts hundreds of tests on the different weapon systems in the stockpile, looking for anomalies. Some of these tests are conducted at the coldest and hottest temperatures for which the system is designed to verify proper operation in those conditions.
The new facility will not only allow for this testing to be done in an environment better suited to modern technologies but also provides expanded capability. It has modern office and lab facilities, a state-of-the-art video conference and training room, and new work areas. These work areas will allow the future integration of shock/ vibration testing as well as chemistry and explosives test laboratories.

WETL Manager Ted Frederiksen (2953), who will be retiring at the end of the month, says the move from the old building will take about a year and will begin sometime in the next few months. WETL, he says, has nine testers (testing equipment), and it will take six to eight weeks to move each one.

“The challenge will be continuing test capabilities between the two locations as we move the testers to the new WETL,” he says. “We have committed to NNSA that we will maintain our test schedules during the move.”

He adds that “most of the equipment has been designed to be flexible and will move easily. It’s all on rollers. We don’t anticipate much of a problem since the equipment was built in Albuquerque and shipped here.”

The most difficult pieces of equipment to move will be the 50,000-pound underground centrifuge that simulates portions of a weapon’s flight environment. The first centrifuge was moved to the new building in April. The roof panels had to be removed, and the centrifuge was lifted out in pieces. The new facility has two large skylights that allow for the centrifuges to be lowered into the building with a crane. The second centrifuge will be moved in the same manner.
Bill Norris (2950), Level II Manager of Sandia’s Surveillance group, calls the new facility “a real step forward” for the program.

“There will be no leaky roofs, open areas for birds to come in [yes, that has happened], or snakes to creep in [that happened too],” he says. “It will be a good place to work that will be flexible and allow for changes as technologies change.”
-- Chris Burroughs

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Sandians play role in nuclear weapon exercise

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By Michael Padilla

John Hoffman (12345) gave good news following an explosion involving a fuel tanker and a military transporter carrying a nuclear weapon.
“The weapon has burned itself out,” he told members of the media and others during an afternoon mock news briefing. “Without the explosive, the weapon is effectively nonfunctional.”

John, serving as a senior scientific advisor, was one of 650 participants in a nuclear weapon accident response full-scale exercise titled Diligent Warrior 04. The three-day exercise was sponsored by the Defense Threat Reduction Agency (DTRA), and held at the 341st Space Wing, Malmstrom Air Force Base in Great Falls, Mont.

John, serving as part of DOE’s Accident Response Group, said the high explosive that encapsulated the warhead’s plutonium pit likely was consumed in the fire.

His next step in the exercise was to assist the Air Force and the National Command Authority on a transportation plan to remove the remains of the nuclear weapon.

The exercise was designed to test and validate nuclear weapon accident response procedures and to test the contingency plans and procedures if a similar situation ever occurs. Federal, state and local agencies participated in the exercise, including DTRA, Air Force Space Command, FBI, DOE/NNSA, DOD, National Transportation Safety Board, Environmental Protection Agency, and the Federal Emergency Management Agency.


The exercise began early Monday, Sept. 13, when a simulated fuel tanker collided with a military transporter carrying a nuclear weapon. The weapon involved was simulated as part of a re-entry system for a Minuteman III Intercontinental Ballistic Missile.

In the scenario, the drivers of both trucks were killed instantly and eight individuals were taken to the local hospital for radiation and medical evaluation. A passenger in the military vehicle was treated for a broken arm.

The next couple of days focused on the recovery of the weapon, clean-up of the accident site, public reaction, and other issues.
The site of the accident was cordoned off during the investigation and a detour was created for traffic.

About 25 anti-nuclear protesters demanded answers about the wreckage and were met by hundreds of military police to ensure that they did not get close to the wreckage site. Three protesters crossed the line and were taken down by force.

A temporary claims office was opened for anyone who felt they were entitled to a claim. In addition, Air Force chaplains were available to provide moral support to those affected by the accident.

Several news conferences and briefings were held throughout the exercise, in which all players were able to interact with mock media. A newspaper documented the media and joint information center interactions.

The exercise does not reflect an increased likelihood that a real accident might occur.

Organizers maintain the highest nuclear safety standards, and continue to apply stringent precautions to prevent an accident.

Sandia’s role

Several Sandians participated in the exercise as part of the Accident Response Group. They included Ramon Pacheco (2112) as well as Hans Oldewage, Erica Sanchez, Ralph Carr, Al Horvath, and Richard Stump (all from 12345).

They worked closely with other officials in determining the condition of the weapon, and helped render the device safe.
John says the exercise helps validate that effective plans, policies, and technical procedures are in place to respond to real-world events involving nuclear ordnance.

(Michael Padilla, a member of the Lab News staff, participated in the exercise playing a news reporter.)

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Last modified: October 14, 2004

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