Land Of Enrichment

A 3.402Mb PDF of this article as it appeared in the magazine—complete with images—is available by clicking HERE

Just across the New Mexico border northwest of Midland, Texas, lies Eunice. The Midland area is known for being a longtime hotbed of petroleum production in the United States. Little known is the fact that Eunice hosts the only uranium enrichment plant currently using centrifuge technology in the United States. Centrifuges are often in the news because the international community has been trying–without success–to get Iran to stop using centrifuges to enrich uranium.

This facility, owned by URENCO USA, is the first nuclear of its kind in nearly 30 years to receive its Nuclear Regulatory Commission (NRC) licensing. When running at full capacity, URENCO USA will be able to enrich enough fuel to supply power to 10 percent of the United States. Nuclear energy accounts for about 20 percent of the total energy production in the United States. By contrast, France gets nearly three quarters of its total from nuclear reactors. The history of centrifuges in the United States goes back to the 1940s when Oak Ridge, Tennessee and Hanford, Washington used centrifuges to produce the fissionable material for Fat Man and Little Boy, the atomic bombs dropped on Japan to end World War II.

When uranium is mined, 99.3 percent of the product is in U-238 form. This has a larger atomic mass than the U-235 version. Turning the U-238 isotope of uranium to the less dense and more desirable U-235 isotope is called enrichment. Once enriched, the uranium can produce two to three million times the energy equivalent of oil per kilogram. A large cylinder of enriched uranium can sell on the market for around 2.5 million dollars.

URENCO has enrichment facilities globally with more than 1,400 employees. Centrifuge technology is the most cost effective way to enrich uranium, using an evacuated casing with a cylindrical rotor that spins in a highly engineered environment. In 1990, Stable Isotopes was formed as a subsidiary to URENCO and has used the centrifuge technology to separate isotopes of different elements for commercial, medical and industrial applications.

Uranium mining in the United States currently produces between four to five million pounds of uranium concentrate per year, approximately 80 percent coming from Utah. New Mexico has been identified as having the second largest uranium ore reserves in the country, but it hasn’t been mined since 1998. During the late 1940’s to early 1950’s, the United States was the number one uranium mining country in the world, but mining tailed off around the 1980’s when better deposits of sandstone were found in Australia and Canada. Uranium is mined mainly through chemical leaching. It comes out in a "yellow cake" form and is sold on the market as Triuranium Octoxide (U3O8).

The Enrichment Process
The uranium arrives in cylinders at URENCO USA in solid form and is taken to the plant’s UF6 area, which is designed with hot boxes that heat the uranium to a high tempurture.. This process turns the solid uranium into a gas. The gas is then transported to the cascade hall, which is made up of individual centrifuges that spin the gas at a very high speed. The gas must pass through a very intricate  piping system and multiple centrifuges, becoming more and more enriched. The heavier U-238 isotope presses against the walls of the centrifuge, and the less dense form is left in the middle for extraction. After the uranium is enriched, it must be cooled in cool boxes, which turns the enriched uranium back to a solid. The product is then checked by heating it to a liquid in an autoclave. Once small samples are drawn out, the product is cooled once again, returning it to a solid form. The liquid product is taken to onsite labs and tested for quality. The uranium is then weighed to ensure that it complies with international safeguards. All of uranium coming in or going out is accounted for to very small quantities.. The depleted uranium is stored on a large concrete pad called the UBC on site. It then can go through the enrichment process again. The enriched uranium is shipped in cylinders with highly protective casings to a fuel fabrication facility where it can be converted into a pellet form and inserted into fuel rods. The fuel rods are loaded into a nuclear reactor which generates electricity.

Creating the facility
Before the complex process of enrichment could occur, URENCO USA  had to construct this complex facility. The project commenced in the summer of 2006 and WTC, Inc. arrived shortly after. WTC began a site survey and laid out initial building corners under Project Manager Alonso Juarez. WTC, Inc. is an Engineering firm based out of Andrews, TX that offers a wide variety of services throughout the Southwestern United States. WTC, Inc. also offers services in three new Texas locations in Houston, Lubbock and Pecos.

The highly technical surveying took part inside the building. WTC, Inc. has assigned this task to its Construction and Engineering Survey Project Manager and co-author Robert T. Loane III. The base plate layout inside the UF6 area was extremely critical and required an accuracy to within a millimeter. For this, WTC used a NIST certified Trimble S-6 robotic total station. The instrument was not capable of consistently laying out to that accuracy, so the surveyors had to use other methods to achieve these results. They set up using a resection method off of five control points to get the best possible accuracy the S-6 could offer. They laid out the outside corners of the plates with the S-6 and then used a chalk line and measuring tape to put in the intermediate points. Then the surveyors went back and checked the locations of the points with the instrument to make sure the tolerance restrictions were met. The surveyors also laid out the hot boxes and cool boxes mentioned earlier in the article.

The WTC surveyors also had the difficult task of bringing control to the second level of thebuilding.. The upper steel in that area was designed based off a crucial subfloor necessary for stabilizing the centrifuges. The WTC surveyors created an arbitrary coordinate system based off the  geometry of the subfloor. They shot control from the first floor Assay hall through a series of small 1′ by 1′ windows on the second floor. They then set up using a resection method on the second floor and used points located on the first floor for the basis of stationing and alignment. Most of the plans were commercially sensitive , so the surveyors had to perform real-time layout calculations. It was a difficult process that required a great deal of skill and patience.

WTC also worked directly with Site Survey Manager and co-author John A. Hoover, PS to align the subflooring in the Assay halls. John and his team have had the task of establishing the controls for the centrifuge halls.. The subfloor placement is  extremely critical, so it is set as close to design as theoretical possible. The WTC surveyors also provided a third-party check on all subflooring and set control for the installation of gantry rails on the edge of the UBC Pad, which is used for storing the tails (depleted uranium). They used the NIST certified Trimble S-6 to traverse out to the UBC Pad from existing control and once new control was established the existing pad corners were shot in. The gantry rails run parallel to each other and fit outside the UBC Pad on concrete footers. WTC created a best-fit centerline from the existing pad corners and set control at a specific offset from centerline on each side of the pad. They also checked locations of the rails and made appropriates adjustments. The gantry rails were installed to move the cylind
ers of depleted uranium to a specific location on the UBC Pad.

The WTC team mentored two interns from Core Construction/URENCO USA  throughout the process, Peter Zelkowski and Marcus Ortiz. These college students were carefully selected by Mark Woods from Core Construction from a large applicant pool. Peter is studying Civil Engineering at New Mexico State University and Marcus is working towards his Bachelor’s in Construction Management at the University of New Mexico. Both of them really enjoyed the process of learning from the WTC surveying team.

WTC would like to thank Denise Shultz and David Huffman from URENCO USA for their hard work and cooperation, as well as, Mark Woods from Core Construction and Jacqueline Venable from 3P Writing.

Robert T. Loane III, LSIT received his Bachelors of Science in Geomatics Engineering from Florida Atlantic University and his AA and AS from Indian River State College. Robert was a multiple scholarship award winner at FAU and holds ESRI GIS certifications. He has worked on a great deal of large construction and engineering projects from Florida to Alaska, most specifically the Port of Miami Tunnel. Robert plans on taking his PLS exam in New Mexico this October. He currently manages and oversees all construction and engineering projects for WTC, Inc.

Thomas Walker Jr, PS also received his Bachelors of Science in Geomatics Engineering from Florida Atlantic University, as well as, his minor in GIS. Thomas is currently a Project Manager for Avirom and Associates, Inc. located in Stuart, FL.

John A. Hoover, PS is the Site Survey Manager at the NEF and directs multiple survey crews. John has over 40 years of experience in the surveying industry and is responsible for reviewing Civil, Architectural, Structural and Mechanical drawings for constructability and conflicts. He also reduces site survey data and produces as-built drawings.

A 3.402Mb PDF of this article as it appeared in the magazine—complete with images—is available by clicking HERE