The Saga of the Californium Flux Multiplier

Kodak is one of the nation’s iconic brands, forever associated with camera equipment, photographic film, and related materials and services. The idea of capturing a “Kodak moment” is a familiar one to many Americans, especially those of a certain age.

Based in Rochester, N.Y., and known more formally as the Eastman Kodak Co., its origins date to 1889, when George Eastman founded the firm. In recent years, Kodak has sought to keep pace with changing consumer demand by transforming itself into a digitally oriented company and, as part of this shift, has made a number of changes.

It was against this backdrop that the Rochester Democrat and Chronicle newspaper reported in early May that Kodak had, for more than three decades, operated a small nuclear research reactor, unbeknownst to the public. More about that last part in a moment.

But one element of the story that needs clarifying is that the device – known by the elegant name of Californium Flux Multiplier – was a “reactor.” In the truest sense of the word, it did not qualify as one.

While the Kodak device, which was decommissioned and removed in 2007, made use of plates containing highly enriched uranium, it was incapable of sustaining the fissioning, or splitting, of atoms. In nuclear power reactors, atoms are fissioned to release large amounts of heat that can then be tapped to produce power for the grid.

This unique piece of equipment was used to conduct chemical and radiological analyses on manufacturing processes. It also was used to investigate new chemicals and explore new technologies that might be of interest to any of the company’s various operating divisions.

Enriched uranium contained in the Californium Flux Multiplier was in the form of fuel plates clad in aluminum alloy. The plates formed a sub-critical (or below the point of fissioning) assembly that surrounded a Cf-252 (Cf stands for Californium) source. The U-235 (U stands for uranium) fuel was able to multiply the neutrons coming from the Cf-252 source, which fissions spontaneously.

The device was designed to remain always sub-critical, but it nevertheless yielded sufficient neutrons for neutron activation analysis.

After the Californium Flux Multiplier was shut down, all of the fuel plates were removed from the facility and transferred back to the U.S. Department of Energy in late November 2007.

So even though media outlets might use the shorthand reference of “reactor” to refer to the device, in this case a reactor by any other name is not a reactor.

The Democrat and Chronicle reported that it learned of the device from a Kodak employee and emphasized the lack of public awareness regarding it over its many years of operation. But a lack of awareness should not be confused with an effort to keep information about the Californium Flux Multiplier under wraps.

Indeed, a quick check of the NRC’s web site yields numerous documents regarding the device. One area of exception would be details related to security, including shipments of the special nuclear materials used in the device. There are thousands of NRC-licensed devices containing nuclear materials in use across the U.S. Some, it could be said, are easier to picture than others.

Neil Sheehan
Public Affairs Officer, Region I

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
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