What the document says
This volume is part of the official history of the Manhattan District. It covers the design, engineering and purchase of equipment for the Electromagnetic Plant from June 1942 to January 1947. The job of the design group was to turn laboratory research on electromagnetic separation, a method that splits uranium isotopes using magnets, into a working industrial plant. A presidential directive authorized the design of a plant to produce 100 grams per day. Stone and Webster Engineering Corporation acted as architect and engineer and was directly responsible for the design of the project.
The document describes how the separation worked. Uranium tetrachloride feed material was heated until it vaporized, then passed through an electric arc that turned the atoms into charged particles called ions. A high voltage field accelerated the ions into a beam, and a magnet bent the beam so that lighter ions curved more sharply than heavier ones, letting separate receivers collect them. The tanks that held this equipment, called bins, sat inside oval structures known as racetracks, which were housed in process buildings. The plant ran in stages, Alpha first and Beta second, with chemical buildings that recovered and purified material after runs.
Design kept changing while the plant was going up. Development work continued after buildings were already under construction, and in some cases buildings were put up to house equipment before that equipment had been designed. As a result, the Alpha process buildings ended up in three different designs. Procurement brought its own trouble. The vacuum system called for diffusion pumps at twice the capacity of any built before, so Stone and Webster designed them and an outside manufacturer was picked to build them. Special materials such as silver, graphite and liquid nitrogen were needed in amounts unusual for plant work.
Key points
- 01A presidential directive authorized the design of a plant to produce 100 grams per day, which the design group had to build out of laboratory research results.
- 02Engineers first estimated that 2000 single source units would be needed to reach the output target.
- 03Improvements found through actual operation meant the Alpha process buildings were built to three different designs instead of one.
- 04Redesigned sources carried four ionization chambers and ran at high voltage, while the original sources operated at ground potential.
- 05Work was split among three electrical manufacturers: General Electric for power supply equipment, Allis-Chalmers for magnet excitation coils, and Westinghouse for process bins.
- 06Yearly national output of some vacuum tubes could not keep even a monthly stock of replacements on hand, so new plants had to be built and the supply watched closely.
Source: U.S. Department of Energy, OpenNet declassified document archive, OSTI ID 1129023, document number D00030960. The summary is written from the document’s own text. Old scans can be hard to read, so check the original for anything you plan to cite.