LOS ALAMOS NATIONAL LABORATORY

KEY FACILITIES

Los Alamos Critical Experiments Facility - TA-18

The Los Alamos Critical Experiments Facility (LACEF) was located at TA-18, which sat adjacent to Pajarito Road, at the confluence of Pajarito and Three-Mile Canyons.

There were approximately 40 structures at TA-18. TA-18 had three 1950s-era laboratory buildings housing five critical assemblies that were remotely controlled. The three remote laboratory facilities were the Critical Assembly and Storage Areas (CASAs) buildings: CASA 1, CASA 2, CASA 3, formerly known as KIVA I, KIVA II, and KIVA III. The CASAs were remote-controlled laboratories in which criticality experiments were performed. The assemblies included two general-purpose platform lift machines (Planet and Comet), one highly reflected spherical benchmark assembly (Flattop), one unreflected fast-burst assembly (Godiva IV), and one solution high-energy burst assembly (SHEBA). All five assemblies were capable of delayed-critical operations.

The Solution High-Energy Burst Assembly (SHEBA) facility's principal use was to simulate criticality accidents for a uranium enrichment plant. Like the CASAs, it was located on the periphery of TA-18. It also served as a source for skyshine measurements. While it was designed to permit prompt supercritical (burst mode) experiments, SHEBA operated only in delayed critical mode. The Accelerator Development Laboratory (ADL) was also within the LACEF complex.

The other main buildings were Building 127, Building 227, and Building 30. Building 127 was originally constructed to house a Cockcroft-Walton accelerator to produce neutrons from reactions of deuterium and tritium. The building featured a false floor and light walls to provide a low room return, allowing the facility to be used for those measurements that require a "clean" radiation environment. Building 30, the centrally-located main office building, housed the control rooms for these laboratories.

TA-18 was originally established during World War II as an explosives test facility for the Manhattan Project. After World War II, TA-18 became the site of the LANL CEF. Following fatal accidents in 1945 and 1946, LANL constructed remote-controlled facilities so that criticality experiments did not have to be performed by hand. These facilities became the CASAs. The experiments supported emergency response, safeguards and weapons program activities.

In the 1990s, the principal mission of LACEF was the design, construction, research, development, and application of critical experiments. In addition to construction of new critical assemblies, the facility provided teaching and training in criticality safety and applications of radiation detection and instrumentation. LACEF was the only site in the DOE complex where general-purpose research and hands-on training could be conducted into nuclear safeguards, criticality safety and emergency response using Category 1 level nuclear materials.

In August 1998, LANL placed TA-18 on stand-down mode after a criticality safety infraction. On March 31, 2004 the NNSA made the decision to begin moving Special Nuclear Material (SNM) from TA-18 to the Device Assembly Facility at the Nevada Test Site. The National Nuclear Security Administration issued a decision to accelerate relocation of the facility's mission to the Nevada Test Site starting in September 2004. TA-18 was downgraded from a Hazard Category 2 nuclear facility to a Radiological Facility. Under the TA-18 Early Move Project, removal of CAT I/II SNM was completed on October 28, 2005. In January 2006, disassembly of the Godiva Critical Assembly, or Godiva IV, was completed after starting in December 2004, for shipping to the Nevada Test Site. It was one of the three fast burst reactors in the country. It was the fourth assembly in the LANL Godiva series. It included a stack of six interlocking uranium rings and plugs, held together with steel clamps.

On April 5, 2007, NNSA LASO approved the start of non-nuclear operations at TA-18. It has a nuclear material inventory tracking program. TA-18 operates only to complete residual material clean-up in preparation for eventual wholesale facility decontamination and demolition.