Salt Wells Pilot Plant

The Salt Wells Pilot Plant was a facility established by the Manhattan Project at the Naval Ordnance Test Station (NOTS) at Inyokern, California, where non-nuclear explosive components of nuclear weapons were manufactured. The first explosives were melted, mixed and poured on 25 July 1945. Between 1945 and 1954, it manufactured explosive components of the Fat Man, Mark 4, Mark 5 and Mark 12 nuclear bombs. The Salt Wells Pilot Plant also helped design, equip, and train workers for the Burlington AEC Plant in Iowa and the Pantex Plant in Texas. The Salt Wells Pilot Plant closed on 30 June 1954.

In the early 1930s, an emergency landing field was built by the Works Progress Administration in the Mojave Desert near the small town of Inyokern, California. Opened in 1935, it was acquired by the United States Army Air Forces (USAAF) in 1942 after the United States became involved in World War II, and became part of the Muroc Bombing and Gunnery Range. In 1943, the Office of Scientific Research and Development (OSRD) contracted with the California Institute of Technology (Caltech) for the testing and evaluation of rockets for the Navy.

A suitable test area was required for this convenient to Pasadena, California, so the area was transferred from the Army to the Navy in October 1943, and commissioned as the Naval Ordnance Test Station (NOTS), Inyokern, on 8 November 1943, under the command of Captain Sherman E. Burroughs, Jr. Workshops, laboratories and facilities were constructed for over 600 men. During 1944, NOTS worked on the development and testing of the 3.5-inch, 5-inch, HVAR and 11.75-inch (Tiny Tim) rockets.

By late 1944, rocket development and testing work began to taper off, and production models started to reach the Navy and USAAF in quantity. The director of the OSRD, Vannevar Bush, saw an opportunity to use some of the expertise at Caltech on another secret wartime project he was involved with, the Manhattan Project. Bush arranged for Charles C. Lauritsen, the head of the rocket team at Caltech, to visit the Los Alamos Laboratory, and meet with the project director, Major General Leslie R. Groves, Jr., the laboratory director, Robert Oppenheimer, and senior scientists.

Oppenheimer and Lauritsen knew each other well, as Oppenheimer had worked at Caltech before the war. In addition to its scientists, Caltech also possessed an experienced procurement team, headed by Trevor Gardner. This group worked closely with its counterpart at Los Alamos, which was headed by Lieutenant Colonel Robert W. Lockridge. All the work done at NOTS on behalf of the Manhattan Project came under the codename Project Camel. The name is said to have come from a remark by a Los Alamos scientist that once a camel (meaning Caltech) gets its nose under a tent flap it is hard to dislodge.

The Los Alamos Laboratory was engaged in the development of an implosion-type nuclear weapon, codenamed Fat Man. This used explosive lenses to focus an explosion onto a spherical shape using a combination of both slow and fast high explosives. The design of lenses that detonated with the proper shape and velocity turned out to be slow, difficult and frustrating. Various explosives were tested before settling on composition B as the fast explosive and baratol as the slow explosive. The final design resembled a soccer ball, with 20 hexagonal and 12 pentagonal lenses, each weighing about 80 pounds (36 kg).

The explosive lenses required by the Fat Man had to be fabricated. A small explosive plant was established at Los Alamos known as Site S, as it was a former sawmill. Groves was appalled at the work practices and safety at Site S, and considered it only a matter of time before it blew up. Graves expressed his concerns about Site S to Captain William S. (Deak) Parsons, a Navy officer who was in charge of O (for ordnance) Division at Los Alamos. Parsons recommended establishing another explosives plant. While Site S had the capacity to produce enough explosive lenses for one or two bombs per month, more might be required.

Parsons suggested that NOTS might be a suitable location. It was remote and easy to secure, and Caltech had experience with pilot plants, such as the ones at Eaton Canyon and China Lake, where rocket propellants were manufactured. Groves had some misgivings about this, because he thought that the Navy might err too far on the side of workplace safety when time was of the utmost importance.