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Nuclear Fuel Assembly

Control rod and replica fuel assembly from Wisconsin's first nuclear power plant.
(Museum object 1997.56.13-14)

If this nuclear power plant fuel assembly had actually been used, the Wisconsin Historical Museum staff would be dead. The object shown at left is actually a replica fuel assembly - minus the radioactive fuel - built by Museum staff from spare parts. The accompanying control rod (at bottom in image), though never put into use, is the real thing. Together these two components represent the heart of Wisconsin's first atomic power plant, the La Crosse Boiling Water Reactor, built by the Dairyland Power Cooperative outside of Genoa, Wisconsin.

As the name implies, the La Crosse Boiling Water Reactor (LACBWR) produced electricity by boiling water using heat from a nuclear chain reaction and its resulting steam to drive a turbine connected to an electric generator. The LACBWR reactor core contains 72 nuclear fuel assemblies like these and 29 control rods. Each fuel assembly is composed of 100 seven-foot long stainless steel tubes (bundled in a ten-by-ten matrix) filled with enriched uranium dioxide pellets. Inside the core, the fuel assemblies are separated by control rods, which are X-shaped in cross section. The vanes of the control rods are filled with neutron-absorbing boron carbide, which acts as a brake on chain reactions. Operators control the rate of the reaction by moving the control rods into or out of the reactor core.

How did a relatively small, rural electrical co-operative come to build Wisconsin's first atomic power plant? The powerful appeal of atomic energy in the 1950s was crucial, but the lingering and contentious politics of rural electrification also played a role.

By the mid 1950s, atomic power was rapidly becoming the pre-eminent symbol of American progress, modernity, and technological know-how. Even small utilities hoped to participate in this energy of the future. Dairyland's managers were optimistic that atomic power would provide a low-cost alternative in a region where coal was expensive and power had to be transmitted long distances to scattered rural consumers. Perhaps more importantly, a nuclear power plant would provide prestige and legitimacy to a company and an industry – rural electrical cooperatives – whose right to exist was still disputed in some quarters.

The roots of the Dairyland Power Cooperative go back to 1935, when the Rural Electrification Administration was founded to bring electricity to areas not served by private utilities. In response, several communities in northern and western Wisconsin formed power cooperatives in the late 1930s, which eventually merged into the Dairyland Power Cooperative in 1941.

During the 1930s and 1940s, rural electrical cooperatives faced considerable opposition from those who felt they were examples of New Deal "socialism" as well as from neighboring private utilities. While those utilities did not yet find it profitable to run lines into rural areas, they did not want to lose a potential future customer base to the cooperatives. Before they could develop their own generating capacity, many rural cooperatives including Dairyland were forced to buy power from commercial utilities, which sometimes found ways to make this difficult and expensive. Dairyland Power resolved to expand its own generating capacity both to serve its members better and to insure its independence from private utilities.

In June 1954 Dairyland Power officially began seeking a pilot atomic power plant, and in January 1961 the Atomic Energy Commission finally accepted Dairyland's proposal to build a 50,000-kilowatt demonstration plant on the Mississippi River. Dairyland would own the generating plant while the AEC retained ownership of the nuclear reactor. Construction of the La Crosse Boiling Water Reactor began in May 1963.

The Allis-Chalmers Manufacturing Company of Milwaukee designed and built the nuclear portion of the plant. A leading manufacturer of electric power equipment, Allis-Chalmers had been deeply involved in the U.S. Army's Manhattan Project, and the company was eager to develop atomic expertise in order to supply the power technology of the future.

LACBWR was projected to be completed in late 1965 and to generate power commercially a year later. Although the conventional portion of LACBWR was completed on schedule, the reactor itself encountered repeated setbacks. After many repairs and design changes, the reactor first went critical on July 11, 1967, but testing revealed yet more problems. Additional testing, repairs, and upgrades took another three years.

LACBWR finally began generating electricity commercially at its full capacity in February 1971, nine years after the project was approved and four years past its planned operation date. Dairyland remained committed to nuclear power despite these disheartening delays, and bought the nuclear portion of the plant from the AEC in 1973 for one dollar.

By 1979, however, Dairyland's managers had concluded that LACBWR no longer represented the power of the future. They announced the plant would close before 1990. Growing public opposition to nuclear power - heightened by the accident at Three Mile Island in March 1979 - was a factor, but the real reasons were economic. From 1980 to 1985, LACBWR's fuel costs per million BTU generated had remained lower than those of Dairyland's coal-fired plants, but the signing of new long-term contracts for cheap coal and the looming costs of mandatory safety upgrades changed the equation. As the smallest operating nuclear power plant in the United States, LACBWR had great difficulty absorbing increased regulatory costs. The final decision to close LACBWR, which by then produced less than 5% of Dairyland's generating capacity, came in 1986. Though the plant was licensed through 2001, Dairyland closed LACBWR down on April 30, 1987.

Allis-Chalmers had left the nuclear field twenty years earlier. Rapidly escalating costs and frequent design changes made managing nuclear projects increasingly difficult, and Allis-Chalmers managers concluded that potential profits were small. LACBWR was the last complete nuclear plant that the company built.

[Sources: Driscoll, David B. "Slow Boil: The Story of Wisconsin's First Nuclear Reactor," Wisconsin Magazine of History (Autumn 2001), available online at; Schermerhorn, Harvey. The Dairyland Power Story (La Crosse, WI: Dairyland Power Cooperative, 1973); details concerning construction, operation, and closure of LACBWR are reported in Dairyland Power Cooperative's employee newsletter, Current Matters, and in its Annual Reports, both available at the Wisconsin Historical Society Library; the Wisconsin Historical Society holds two archival collections related to the Dairyland Power Co-operative: the papers of DPC public relations officer Harvey Schermerhorn and those of DPC board member John E. Olson; the current status of LACBWR is documented by Dairyland Power and the Nuclear Regulatory Commission.]


Posted on October 18, 2007

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