[en] The initial three production reactors and their support facilities were designated as the 100-B, 100-D, and 100-F areas. In subsequent years, six additional plutonium-producing reactors were constructed and operated at the Hanford Site. Among them was one dual-purpose reactor (100-N) designed to supply steam for the production of electricity as a by-product. Figure 1 pinpoints the location of each of the nine Hanford Site reactors along the Columbia River. This report documents a brief description of the 105-B reactor, support facilities, and significant events that are considered to be of historical interest. 21 figs