Perseverance pays

Posted: July 16, 2012 - 3:55pm | Y-12 Report | Volume 9, Issue 1 | 2012

Enriched uranium button quality has increased dramatically, as can be seen in the difference between the buttons at left and right

Restoring the quality of enriched uranium metal buttons is crucial to Y‑12 missions.

During the Cold War era, Y‑12 produced enriched uranium “buttons” to provide high-purity metal for the manufacture of weapon components. Today, buttons are still needed to accomplish mission goals. In addition to their use in manufacturing components for weapons refurbishment, buttons can be used to adjust impurity levels in Naval reactor fuel, research reactor fuel and targets for medical isotopes production.

Although Y‑12 produced large quantities of buttons for many years, achieving a consistent high level of quality in the past decade has been challenging. In the 1990s, button production was greatly curtailed and then halted because of a chemical containment issue followed two years later by a safety-driven plant stand-down. Although the ensuing tougher requirements improved safety, new practices and some replaced equipment presented difficulties to decades-old processes, and ultimately button production.

“Applying modern safety standards to dated processes necessitated changes that impacted the efficiency of making a high-quality button product,” said a production chemical engineer who is a veteran of uranium production. “Y‑12 has had to re-evaluate and adjust the button production process to achieve quality similar to that of the past while operating within tighter constraints.”

“Bomb reduction” is the final stage of a purifying chemical recovery process that reclaims enriched uranium from filters, personal protective equipment, casting operation oxide and even mop heads. The enriched uranium is converted to a metal button form. High-purity buttons can be melted with other enriched uranium recycled metal, such as parts from dismantled weapons, to make “new” products. This blending controls the overall level of impurities, ensuring that products meet customer specifications.

Even though a complete enriched uranium recycle loop was re-established after the stand-down, the buttons produced did not consistently meet previous quality levels. Specialists, engineers, supervisors and chemical operators began focusing on bomb reduction and upstream processes. Adjustments were made until the right combination was found.

“A lot of things that affect button quality had changed,” said a process engineer. “We didn't realize how much until we restarted the processes. We had to adapt to the new operating conditions. Instead of trying to do what was done in the past, we had to find our sweet spot.”

“It is remarkable what this group of people has done,” said the chemical engineer. “I'm impressed every day with how they adapt to the ever-changing demands. It has taken a tremendous amount of determination and dedication.”

While regulations and equipment change, Y‑12's commitment to high-quality products remains. Button efficiency is now significantly closer to historical values, and work continues toward producing an even more consistently high quality product. “Everyone is here to serve the mission,” said the chemical engineer. “People are the key — not equipment. It is the people's understanding of uranium and their sense of mission that allows us to excel in this work.”