The Challenge of Decommissioning a One-of-a-Kind Reactor

The spent fuel cask will be moved from the dome-shaped reactor building using a heavy-duty overhead crane. A special “crawler” vehicle (not pictured) will move the fuel cask to a secure storage pad.

Correction: Allis-Chalmers build three reactors – Elk River (operated 1964-68), PathFinder (never achieved full power) and La Crosse (operated 1967-1987). They were all designed as commercial nuclear plants but La Crosse was the only one that operated for a significant amount of time.

Early nuclear power plants in the United States were custom designs, but the LaCrosse Boiling Water Reactor in Wisconsin was truly unique in both its design and construction. That uniqueness has carried over into the work to decommission and dismantle the plant.

Owned by the Dairyland Power Cooperative, the facility on the Mississippi River near Genoa, Wisconsin, is very small — producing just 50 megawatts of electricity — compared to 1,000 or more megawatts from later reactor designs. It was one of several demonstration reactors funded, in part, by the Atomic Energy Commission, the predecessor to the NRC. The plant was completed in 1967 and operated until April 1987. It was the only reactor built by Allis Chalmers, a company best known until the mid-1980s for its tractors and farm equipment.

In the 25 years since the plant was shut down, the NRC has monitored and inspected activities at the plant to assure continued protection of public safety and the environment. NRC requirements have also remained in place to maintain security at the facility.

Since shutdown, the plant has been maintained in a safe and secure condition until the plant can be fully decommissioned. In 2007 the 310-ton reactor vessel was removed from the plant and shipped to South Carolina for permanent disposal.

Spent fuel from the reactor’s 20 years of operation has been safely housed in the plant’s spent fuel storage pool. The Dairyland Power Cooperative has been developing plans over the past several years to transfer that fuel into five concrete and steel storage casks for interim storage on a specially constructed concrete pad at the site. Similar dry cask storage systems are in use at about 65 sites across the country.

Moving that fuel, however, has posed special challenges for this unique facility. The pool holding the spent fuel is too small to accommodate the cask used to load and transfer the spent fuel. Faced with the lack of space in the spent fuel pool itself, LaCrosse engineers devised a unique solution of converting the structure that formerly housed the reactor into a cask loading pool. The former reactor structure, which adjoins the spent fuel storage pool, will be filled with water for the cask loading. Once the cask is loaded, the loading pool will be drained and a gateway opened. A heavy-load overhead crane will move the cask outside the loading area.

Throughout the process, NRC engineers and inspectors have evaluated each step, including review of the construction of the storage pad and modifications to form the cask loading pool. All activities are assessed to assure that the unique concepts can be safely implemented for workers, the public, and the environment.

Before actually loading and moving the spent fuel, plant personnel are performing “dry runs” without actually loading the fuel assemblies to assure that the cask loading and transport equipment and procedures are ready for safe movement of the fuel. NRC inspectors have been on site to inspect these “dry run” activities.

The actual fuel movements will begin later this summer and NRC inspectors will be on hand to inspect the loading and movement of at least the first of the five casks.

Christine Lipa, Chief
Materials Control, ISFSI and Decommissioning Branch
Region III

Channeling da Vinci: The Competition to Create the NRC Seal

U.S. Army Institute of Heraldry seal designs

When it comes to creating a seal, most federal agencies keep it simple: show what you do. The Forest Service: A pine tree. The Bureau of Reclamation: A lake. The Federal Communications Commission: Telephone lines. It’s usually not complicated. But for the NRC, the eagle-centered seal reflected the controversies that caused its creation out of the former Atomic Energy Commission (AEC).

Even before the NRC opened its doors on January 19, 1975, the U.S. Army Institute of Heraldry produced a number of seal options for the agency. The Institute’s key symbols were the atom to represent nuclear R&D and five pointed stars or similar figures to represent the five Commissioners, and usually had a circle to “symbolize complete control for peaceful purposes.” AEC counsel Marcus Rowden, soon to be one the NRC’s first five commissioners, was “somewhat underwhelmed” by the choices and suggested soliciting employee submissions.

In early 1975, employees, family members, and contractors submitted about 70 designs. While some employees simply wanted the old AEC seal superimposed with the new agency name, others were unconventional, including one attempt at Leonardo da Vinci’s The Vitruvian Man. Many reveal what the first NRC employees imagined their agency should be by using symbols depicting a broad agency mission of public safety, environmental protection, and fairness in the regulatory process. A selection committee picked a number of finalists and sent them to the Commission.

The Vitruvian Man design option

But none of the finalists got the nod. The NRC was created in part because of the perception that the AEC favored promoting nuclear power over ensuring its safety. The AEC’s seal had prominently displayed an atom at its center. Any submission that reminded the public too much of the NRC’s link to the AEC was a non-starter.

Additionally, some NRC retirees recall that federal agencies questioned whether the NRC, a regulatory agency with considerable independence, could represent the federal government on export licensing issues. It seems that the agency needed a seal that broke with its past but clearly linked it to the federal government.

The Commission opted for a bald eagle featured on the seals of the President and several agencies. Benjamin Huberman, the director of the Office of Policy Evaluation, put his engineering drafting skills to work. He pulled a dollar bill out of his wallet and used its eagle as a model. He eliminated the dollar’s cluster of 13 stars, as well as the ribbon clutched in its beak. He added the NRC’s name and five stars to represent the agency’s five Commissioners. It was approved.

The NRC’s selection of a seal reflects a regulatory agency seeking to distance itself from a promotional past while also clarifying its new place firmly within the federal government.

Tom Wellock, NRC Historian

SATAN’s Code: The Early Years of Accident Models

The IBM 650 circa 1950s

When the first mass-produced computers hit the stage in the 1950s, nuclear engineers saw the opportunity to use them to help run accident scenarios. It was a good idea that took decades to become reality and the computer limitations created early uncertainty about reactor safety.

In 1954, Westinghouse experts put together a homemade digital computer that read punch tape. With a practiced ear, you could tell from the computer sounds which program was being run.

In 1959, Battelle Memorial Institute developed an early Loss-of-Coolant-Accident model for a heavy-water plutonium reactor. The program was run on an IBM-650/653, the first mass production computer ever developed. The 650 weighed more than a 1955 Cadillac Deville, had vacuum tubes, and used a punch-card reader. Even if it had the memory and someone willing to load the 50 million cards, it would take six months to boot up Microsoft Windows 7.

Fortunately, Battelle’s code was a mere 166 cards. It calculated the behavior of just one fuel rod (modern reactors have thousands of rods) and took minutes to produce one data point.

For the sake of speedier results, gross simplifications were made. For example, an ideal accident code would have broken a reactor cooling system into many small volumes and done extensive calculations on each one to accurately simulate the complex conditions that existed throughout the reactor core and piping. But to run it on mid-1960s computers could take days. As a result, Westinghouse’s FLASH code used just three volumes to represent the whole reactor system.

At least they had computers. Neither the Idaho National Labs, a center for accident-code development, nor the Atomic Energy Commission had them. INL relied on weekend visits to the University of Utah. At the AEC, engineer Norm Lauben begged time from the National Bureau of Standards. Norm drove to the Bureau’s headquarters in Gaithersburg, Md., in the morning to submit his job on the 12,000-line RELAP-3 code, and returned after lunch to pick up the results.

Engineers were confident that the codes would prove reactor designs were overly conservative. Their optimism proved unfounded.

When Westinghouse proudly unveiled its 70-volume SATAN code in 1970, AEC staffers discovered errors in the code indicating that the company’s Emergency Core Cooling System might fail in an accident. The problems of the SATAN code helped lead to a major rulemaking hearing in 1972 on the adequacy of both emergency cooling system designs and accident codes. Those hearings revealed just how embarrassingly uncertain and rudimentary the early codes were about what happened during an accident.

The AEC and later the NRC had to make a huge investment in creating more robust – and accurate – codes. Additional research that produced the RELAP-5 Code is still used today as an industry standard worldwide.

Tom Wellock
NRC Historian

Putting the Axe to the ‘Scram’ Myth

The NRC glossary defines a “scram” as “the sudden shutting down of a nuclear reactor usually by rapid insertion of control rods.” But where did the word come from? One deeply engrained legend about the origin of the word dates to the first sustained chain reaction on December 2, 1942, at the Chicago Pile (CP-1), the first atomic reactor developed for the Manhattan Project. According to the legend, Enrico Fermi created the acronym, Safety Control Rod Axe Man, for Norman Hilberry. It was Hilberry’s assignment that day to kill a possible runaway reaction by using an axe to cut a rope to allow the backup safety control rod to drop into the pile.

The axe-man story now has a life of its own. A search on Google for “scram” and “axe” yields 124,000 hits. Even the NRC’s glossary attributes scram’s etymology to the axe man story. Eleven years ago, Oak Ridge National Laboratories reported a fanciful variation of this story where Fermi, presumably unimpressed with the physical prowess of his fellow physicists, recruited a lumberjack from the Pacific Northwest to do the job. That version has now spread on the internet, and the acronym itself has mutated into Super-Critical Reactor Axe Man and Start Cutting Right Away, Man.

Hilberry, as it turns out, only learned the story second-hand years later, which lends doubt to the axe-man version, and Hilberry’s own recollection of the event didn’t accord with the memories of several other participants. Leona Marshall Libby, the only female physicist present that day, wrote in her memoir that it was Volney “Bill” Wilson who called the safety rods “scram rods.” She didn’t explain why, but her crediting the term’s invention to Wilson was supported by others involved in CP-1, including Warren Nyer.

I contacted Nyer recently, and he was eager to tell the “scram” story, one that squares well with Wilson’s reported version of events. Nyer’s job that day was to be Hilberry’s backup. If all safety systems failed, he and the other members of the “suicide squad” were to dump a liquid cadmium solution on CP-1 to poison the reaction. The axe-man story is, he recalls, “a bunch of baloney.” But he did offer another explanation for the word. His recollection was that Wilson was assembling a panel that included a big red button. According to Nyer, someone asked Wilson the reason for the red knob. Wilson replied you’d hit it if there was a problem. “Well, then what do you do?” he was asked. Wilson reportedly replied “You scram … out of here.” The word appears to have stuck.

And so it seems likely that scram switches all over the world owe their names not to the nuclear industry’s later penchant for acronyms, but to the slang of twentieth-century America.

Tom Wellock
NRC Historian

Why Does The NRC Have an Official Historian?

Historial photo of President Carter
Historical photo

As the relatively new historian for the NRC, I am interested in blogging so I can talk directly with the public about the history of nuclear power regulation. In this first post, I’ll introduce you to the agency’s history program, give a little of my background, and offer my plans for future posts.

Established in 1977, the NRC’s history program is almost as old as the agency itself. Many federal agencies employ historians for a variety of archival and public outreach tasks, but the NRC set itself apart by committing its historians primarily to research and writing accurate, scholarly histories of the agency and its predecessor, the Atomic Energy Commission.

To meet the standards of the history profession, the Commission made it clear early on that its historians were to “be free to express scholarly opinions.” It is a commitment that has worked well. Under my predecessor, J. Samuel Walker, the history program produced numerous well-regarded articles and five books, including a widely popular account of the Three Mile Island accident.

The NRC historian also provides historical background for reports, responds to Commissioner, staff, and public inquiries, and is available for public presentations on agency history.

Although new to the position, I’m not new to history or nuclear power. After receiving my B.S. in mechanical engineering, I tested nuclear reactors on submarines for General Dynamics in Groton, Connecticut, and worked as an engineer at the Davis-Besse Nuclear Power Station near Toledo, Ohio.

My career then took a different, but not unrelated, professional direction. I earned a Ph.D. in U.S. history from the University of California, Berkeley in 1995. To understand the citizens protesting outside of the power plant fence, I wrote my first book on the history of the antinuclear movement, Critical Masses: Opposition to Nuclear Power in California, 1958-1978 (University of Wisconsin Press, 1997). Before coming to the NRC, I was a history professor and wrote on the history of nuclear power and environmental issues.

I am currently researching the history of the AEC and NRC in the 1970s. In future blog posts, I’ll mark the anniversaries of key agency events, discuss material from my ongoing research, and respond to reader inquiries. Let me know if you have a topic you’d like me to address by commenting on this post.

Tom Wellock
NRC Historian