Lawrence Livermore National Laboratory Site 300
Contained Firing Facility
The Site 300 Firing Facilities are used for "hydrodynamic testing" of HE. The term hydrodynamic testing refers to the fact that when HE is detonated, such high pressures are produced that solid materials (even when not melted) flow like fluids. The firing facilities capture the dynamics of material in motion at ultrahigh speeds using x-ray and electro-optic pictures. Firing tests are run from control bunkers associated with each firing facility. There are observation posts near the firing facilities to spot people, animals, aircraft, and other things that might interfere with testing. Although the firing facilities continue to be principally used for nuclear weapons research, tests of conventional weapons are also conducted. Facility improvements have focused on adding capabilities to record test data (flash x-ray machines, high speed optical cameras, the gamma ray camera, and multi-beam laser velocimeter.)
Building 801, built in the early 1950s, supports explosives tests for the nuclear weapons program. This facility has a flash x-ray for recording HE detonation tests. This one-of-a-kind machine produces high-resolution x-ray pictures of high density objects. It can penetrate more than a foot of steel, and its digital imaging camera can record the material structure of an explosively driven implosion. In 1985, Livermore completed the Bunker 801 project at Site 300. The newly refurbished bunker became a fully modernized hydrodynamic test facility to gather data crucial for assessing the operation of a nuclear weapon's primary stage (a pit). Until project completion, weapon designers relied largely on technologies from the 1960s for much of their hydrodynamics experimentation. After the upgrade, Bunker 801 contained the most modern diagnostics available, including a 18-megaelectron-volt Flash X Ray (FXR) machine. Continual upgrades to Bunker 801 since 1985 have kept the facility equipped with the most modern capabilities. For example, in the 1990s, the beam quality of the FXR was improved, and a gamma-ray camera system was installed-70 times more sensitive than the radiographic film it replaced. With these upgrades, in 1998 the first "core punch" experiments were carried out on mock pits for two stockpiled weapons-the W76 submarine-launched ballistic missile warhead and the B83 strategic bomb.
The Contained Firing Facility (CFF) was built on the site of Building 801's open-air firing table, adding almost 3,200 square meters to the building between April 1999 and 2000. This concrete-reinforced, 28,000-square-foot facility allows explosives tests to be conducted indoors, thus minimizing minor blast pressure, emissions, and noise. It has a permanent, state-of-the-art firing chamber, slightly larger than half a small gymnasium (16 by 18 meters and 10 meters high); the firing chamber contains the blast overpressure and debris from detonations of up to 60 kilograms (kg) of cased explosive charges. The inside surfaces of the chamber are protected from shrapnel traveling as fast as 1.5 kilometers per second with 55-millimeter-thick mild steel plates. To permit repetitive firings, all main structural elements of the firing chamber are required to remain elastic when subjected to blast. Detonations are conducted above a 150-millimeter-thick steel firing surface (the shot anvil) embedded in the floor. All main structural elements of the firing chamber must be able to withstand repetitive firing as well as meet design safety standards. These criteria require the structure to withstand a 94-kg TNT blast, which is the equivalent to 60 kg of high explosives. A staging area and diagnostic equipment rooms with ports into the firing chamber are included in the facility, along with a support area, offices, a conference room, diagnostic equipment area, and a control room from which the shot is fired.
During the testing phase of the project, "overtests" were run using 75 kg of high explosives to assure that the building can withstand planned 60-kg detonations. A key aspect of the new facility is that the rectangular concrete firing chamber was made with low-cost, conventional reinforcement, as opposed to the labor-intensive, laced reinforcement commonly found in many blast-resistant structures. From a materials standpoint, a spherical chamber shape is more blast efficient, but a slightly heavier, rectangular shape is cheaper to construct, provides easier and more desirable setup and working surfaces, and encompasses existing diagnostic systems. The thickness of the reinforced concrete walls, ceiling, and floor of the chamber will be 1.2, 1.4, and 1.8 m, respectively.
Building 812 is a backup firing facility in used since the 1960s that is also used for storage. Building 851 supports explosives tests, including most of the experiments for the advanced conventional weapons program. It has the same type of diagnostic capabilities as Building 801, and includes the new multi-beam velocity systems. The Building 851 Firing Table has been used for high-explosives research since 1982.
Building 850 is a backup firing facility also used for camera repair. High explosives (HE) experiments have been conducted at the Building 850 Firing Table since 1958. Between 1963-1978, tritium was used in the experiments. To remedy contamination, excavation of the contaminated soil was done. A Five-Year Review was scheduled for 2009.
Bunker 851 housed a 100-MeV LINAC and had open-air firing tables.
|Join the GlobalSecurity.org mailing list|