WASHINGTON, July 15 — George J. Tenet, the director of central intelligence, is expected to testify before a Senate panel on Wednesday about the reliability of intelligence indicating Iraq tried to obtain uranium, as administration officials raised new concerns about information his agency gave the White House on the matter last fall.
On Oct. 1, the nation's intelligence agencies circulated to senior administration officials and to Congress a classified "National Intelligence Estimate" that described how Iraq might have been seeking uranium in Niger, Somalia and Congo. 

That reference has become the center of a controversy.
According to White House and some intelligence officials, four days after the report was issued and was in the hands of a number of lawmakers, Mr. Tenet called a Bush aide and asked that any reference to allegations that Iraq had sought to obtain 500 metric tons of uranium yellowcake in Niger be removed from a speech President Bush was to give in Cincinnati.

That is a central question Mr. Tenet appears likely to face in the closed session with the Senate select committee on intelligence on Wednesday.
The warning, administration officials said, came in several phone calls to the deputy national security adviser, Stephen J. Hadley. 

Mr. Tenet told Mr. Hadley that the C.I.A. was not sure about the credibility of the information.
The White House, asked tonight whether Mr. Hadley had read the National Intelligence Estimate before Mr. Tenet warned him that the section on Niger might be unreliable, declined to comment. But one administration official said that it appeared that Mr. Hadley had not read the report before he spoke with Mr. Tenet, or finished reviewing the Cincinnati speech.
While that call was disclosed last weekend, White House officials were asking today why the information about uranium from Niger had been published in the intelligence estimate at all. The White House has said repeatedly over the past eight days that the estimate was one of the reports that they relied upon as evidence that Iraq had a global program to get an atomic weapon in the president's State of the Union speech.

"This report was supposed to be the gold standard of our intelligence about Iraq," said one senior administration official. Asked why the agency backed away from it days after it was circulated, the official replied, "Who knows?"
C.I.A. officials explain the discrepancy by saying that classified intelligence reports sometimes include information that does not necessarily rise to the level of certainty required of a public address by the president. The report contained a footnote that made clear that there were doubts at the State Department about the uranium evidence.
"It's one thing to have information in a classified document with caveats and footnotes, and another to have the president flatly assert something," an intelligence official said.
Intelligence officials have also said that the intelligence estimate, which provided an overview assessment of the status of Iraq's programs to develop weapons of mass destruction, was put together hastily and only at the request of Senate Democrats, who wanted to see the report before they voted on a war resolution.
The document was assembled in just three weeks, "record time" said one official, who added that it included imprecise language on the Niger uranium reports.
C.I.A. officials now acknowledge that the estimate should have included more complete caveats about the quality of the information. The C.I.A.'s inspector general has begun an investigation of the C.I.A.'s handling of the Niger information, officials said.
When Mr. Tenet arrives on Capitol Hill on Wednesday, he may encounter suspicion from conservative Republicans who charge he has undermined the president and from liberal Democrats who say his warnings underscore the degree to which the White House sought to twist information to fit its arguments.

Democrats sought today to keep the pressure on President Bush, saying the issue extended beyond the statement over the uranium, which Senator Carl Levin of Michigan, a Democrat, said had been "calculated to create a false impression."
"Even more troubling," he added, "is the fact that the uranium statement appears to be but one of a number of questionable statements and exaggerations by the intelligence community and administration officials that were issued in the buildup to the war." Mr. Levin has pressed for a more open inquiry into the use of American intelligence leading up to the war.
Looting at Iraqi Nuclear Site

UNITED NATIONS, July 15 — Looting at the Tuwaitha nuclear power complex in Iraq was less damaging than initially feared, the International Atomic Energy Agency reported to the United Nations Security Council in a letter dated July 14.
The I.A.E.A. inspected the complex last month and reported that about 10 kilograms of "uranium compounds" remained unaccounted for, adding, "The quantity and type of uranium compounds dispersed are not sensitive from a proliferation point of view." The letter did not address what use might be made of the missing material. 

Uranium Enrichment

Related Information

The uranium enriched in uranium-235 (U235) is required in commercial light-water reactors to produce a controlled nuclear reaction. Several different processes may be used to enrich uranium, as described on this page:

For additional information, see the Related Information (below) or the Fact Sheet on Uranium Enrichment.

Enriching Uranium

Enriching uranium increases the proportion of uranium atoms that can be "split" by fission to release energy (usually in the form of heat) that can be used to produce electricity. Not all uranium atoms are the same. When uranium is mined, it consists of about 99.3% uranium-238 or U-238 (U238), 0.7% uranium-235 or U-235 (U235), and < 0.01% uranium-234 or U-234 (U234). These are the different isotopes of uranium, which means that while they all contain 92 protons in the atom’s center, or nucleus (which is what makes it uranium), the U238 atoms contain 146 neutrons, the U235 atoms contain 143 neutrons, and the U234 atoms contain only 142 neutrons. (The total number of protons plus neutrons gives the atomic mass of each isotope — that is, 238, 235, or 234, respectively.)

The fuel for nuclear reactors has to have a higher concentration of U235 than exists in natural uranium ore. This is because U235 is "fissionable," meaning that it starts a nuclear reaction and keeps it going. Normally, the amount of the U235 isotope is enriched from 0.7% of the uranium mass to about 5%, as illustrated in this diagram of the enrichment process.

Gaseous diffusion is the only process currently being used in the United States to commercially enrich uranium. Gas centrifuges and laser separation can also be used to enrich uranium, as described below.

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Gaseous Diffusion

Gaseous Diffusion Uranium Enrichment Process
The gaseous diffusion process uses molecular diffusion to separate a gas from a two-gas mixture. The isotopic separation is accomplished by diffusing uranium [which has been combined with fluorine to form uranium hexafluoride (UF6) gas] through a porous membrane (barrier), and using the different molecular velocities of the two isotopes to achieve separation.

Process: In the gaseous diffusion enrichment plant, uranium hexafluoride (UF6) gas is slowly fed into the plant's pipelines where it is pumped through special filters called barriers or porous membranes. The holes in the barriers are so small that there is barely enough room for the UF6 gas molecules to pass through. The isotope enrichment occurs when the lighter UF6 gas molecules (with the U234 and U235 atoms) tend to diffuse faster through the barriers than the heavier UF6 gas molecules containing U238. One barrier isn’t enough, though. It takes many hundreds of barriers, one after the other, before the UF6 gas contains enough U235 to be used in reactors. At the end of the process, the enriched UF6 gas is withdrawn from the pipelines and condensed back into a liquid that is poured into containers. The UF6 is then allowed to cool and solidify before it is transported to fuel fabrication facilities where it is turned into fuel assemblies for nuclear power plants. The diagram to the right illustrates this gaseous diffusion enrichment process.

Hazards: The primary hazard in gaseous diffusion plants include the chemical and radiological hazard of a UF6 release and the potential for mishandling the enriched uranium, which could create a criticality accident (inadvertent nuclear chain reaction).

Plants: The only gaseous diffusion plant in operation in the United States is in Paducah, Kentucky. A similar plant is located near in Piketon, Ohio, but it was shut down in March 2001. Both plants are leased to the United States Enrichment Corporation (USEC) from the U.S. Department of Energy and have been regulated by the NRC since March 4, 1997.

Gas Centrifuge Uranium Enrichment ProcessTo top of page

The gas centrifuge process uses a large number of rotating cylinders in series and parallel configurations. Gas is introduced and rotated at high speed, concentrating the component of higher molecular weight toward the outer wall of the cylinder and the lower molecular weight component toward the center. The enriched and the depleted gases are removed by scoops.



Gas Centrifuge

The gas centrifuge uranium enrichment process uses a large number of rotating cylinders in series and parallel formations. Centrifuge machines are interconnected to form trains and cascades. In this process, UF6 gas is placed in a cylinder and rotated at a high speed. This rotation creates a strong centrifugal force so that the heavier gas molecules (containing U238) move toward the outside of the cylinder and the lighter gas molecules (containing U235) collect closer to the center. The stream that is slightly enriched in U235 is withdrawn and fed into the next higher stage, while the slightly depleted stream is recycled back into the next lower stage. Significantly more U235 enrichment can be obtained from a single-unit gas centrifuge than from a single-unit gaseous diffusion stage. The diagram to the right illustrates this gas centrifuge enrichment process.

One gas centrifuge commercial production plant, the URENCO USA facility owned by Louisiana Energy Services (LES), is currently operating in Eunice, NM. A license was issued to AREVA Enrichment Services, LLC in October 2011 to construct and operate the Eagle Rock Enrichment Facility, a gas centrifuge commercial facility, in Bonneville County, ID. The construction of the facility is currently on hold. USEC Inc., in Piketown, OH, was issued a license in April 2007 to construct and operate the American Centrifuge Plant (ACP). Construction of the ACP began in 2007 but was placed on hold in 2009. In addition, USEC Inc. was granted a license in February 2004 for a demonstration and test gas centrifuge plant, the Lead Cascade facility, that is in operation.

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Laser Separation

Isotopic separation of uranium can be achieved based on photoexcitation principles (exciting the molecules using laser light). Such technologies have been named Atomic Vapor Laser Isotope Separation (AVLIS), Molecular Laser Isotope Separation (MLIS), and Separation of Isotopes by Laser Excitation (SILEX). In general, the enrichment process entails using three major systems, which are the laser systems, optical systems, and separation module system. Tunable lasers can be developed to deliver a highly monochromatic radiation (light of a single-color). The radiation from these lasers can photoionize a specific isotopic species while not affecting other isotopic species. The affected species is then physically or chemically changed, which enables the material to be separated. AVLIS used a uranium-iron (U-Fe) metal alloy as its feed material, while SILEX and MLIS use UF6 as its feed material.

No laser separation uranium enrichment plants are currently operating in the United States. However, in July 2007, General Electric - Hitachi submitted a license amendment request to the NRC, seeking approval for research and development associated with laser enrichment to be conducted at its Global Nuclear Fuels-Americas, LLC, facility in Wilmington, NC. The NRC approved the amendment on May 12, 2008, and GE-Hitachi is currently constructing the test loop with the intention of beginning operations in the near future. In addition, in June 2009, GE-Hitachi submitted a license application to construct a commercial laser enrichment plant in Wilmington, NC. The NRC staff is currently reviewing that application.

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Page Last Reviewed/Updated Tuesday, October 21, 2014