Piqua Nuclear Generating Station
The Piqua Nuclear Generating Station was a single-unit, experimental nuclear power plant that operated outside of Piqua, Ohio, from 1963 to 1966. The plant’s organically cooled reactor, which utilized terphenyl in lieu of water for both cooling and power moderation, was rated at an installed capacity of 45.5 MW. Operated by the Atomic Energy Commission, the site was selected in 1956 and developed as a joint venture between the AEC and local utilities, with North American Aviation’s Atomics International division’s bid chosen for the design of the plant. Though at one point it supplied the town of Piqua with up to 40% of its energy needs, the plant’s reactor was permanently deactivated at the beginning of 1966 following a series of technical problems. Today its reactor vessel is permanently entombed in concrete, and the associated work spaces and facilities have been turned into an office park.
Though the research and development of both pressurized and boiling water nuclear reactors was well underway by the time the Piqua site was selected as part of an AEC program to develop small nuclear power plants, there was some interest during the period in the use of oils similar to biphenyl as both a reactor coolant and power moderators. In theory, such an organically cooled reactor would control its power by adjusting the flow of oil into the vessel, thereby moderating its thermal status directly. In practice, however, it was found that biphenyl-related oils such as terphenyl would foul easily during reactor operations as a result of neutron-induced crystallization. Such problems plagued the Piqua reactor as well as other organically controlled units, such as General Electric’s WR-1.
Though the Piqua Nuclear Generating Station never experienced an incident that led to injury or the release of radioactive particles, it did suffer a variety of malfunctions during its short lifespan. Between 1963 and spring 1965, it was shut down several times to repair malfunctioning fuel rod control units or to rearrange in-vessel components. On May 6, 1965, a “scram” was initiated when an error led to a drop in the level of reactor coolant that disrupted circulation among three fuel components. Though these damaged elements were removed to the spent fuel containment area, a subsequent restart found the reactor operating at excessive temperatures. This necessitated the removal of more fuel and a reduction of the reactor’s power to 24 MW until its decommissioning in 1966.
Though it operated for only a short time, the Piqua Station was built during a time when asbestos use was high in the United States. Nuclear power plants such as Piqua generate an enormous amount of heat in the course of operations and require machinery and facilities to be well-insulated to prevent the risk of fire and other heat damage. While asbestos served this purpose, it also put workers at risk for mesothelioma and other asbestos-related diseases.