Industry Watching Supply of Lithium-7 for US PWRs
Dec. 19, 2013—The importance of monitoring all aspects of the nuclear supply chain is underscored by a recent report on a critically important component of that chain―lithium-7.
To help regulate the nuclear reaction in the 65 pressurized water reactors in the United States, boric acid is dissolved in the cooling water. But that makes the water more acidic, which would cause pipes and other reactor components to corrode. To counteract this, lithium hydroxide is added to the water.
The isotopic form of lithium in this addition must be lithium-7 and not lithium-6, which would interact in the reactor core to form undesirable tritium, a radioactive form of hydrogen.
Lithium-7 also is added to demineralizers to filter contaminants out of the cooling water.
Two countries―Russia and China―currently produce and export lithium-7. It is a byproduct of enriching lithium-6, which is used in the production of nuclear weapons. The United States ceased producing lithium-6 in 1963, and the U.S. Department of Energy sold most of its stockpile of lithium-7 on the open market. Approximately 2,860 pounds remains, but that supply has become contaminated and would need to be purified before it could be used in a PWR.
Earlier this year, Rep. Dan Maffei (D-N.Y.), ranking member of the oversight subcommittee of a House science panel, asked the Government Accountability Office to review the supply-and-demand situation for lithium-7 in the United States.
In its report, the GAO found that the total demand from U.S. pressurized water reactors is approximately 660 pounds and that China and Russia are producing enough to meet that demand. However, the GAO said, the Chinese supply could be reduced because of growing demand stemming from the 25-plus PWRs that are scheduled to begin operating there by 2015.
In addition, China is developing molten salt reactors, which would require thousands of pounds of lithium-7 as primary coolant. China also has purchased lithium-7 from Russia for enrichment, possibly making the country a net importer of the material.
Russia is believed to have little demand for lithium-7, and the country’s supply may thus be largely available for export. However, supply cannot be assured, the GAO said, noting that one lithium-7 broker had difficulty obtaining supply from Russia this year―although the reason was not known.
No supply issues have arisen to date, but the risk of relying on so few producers leaves U.S. PWRs “vulnerable to supply disruptions,” the GAO said.
The GAO identified three options to address possible near- and long-term shortages, such as building a domestic reserve, building a domestic production facility or reducing the reliance of PWR reactors on lithium-7. The latter would be a long-term solution that may require years of research and changes in how reactors are operated.
The agency noted that DOE is taking steps to mitigate a potential shortage, such as setting aside a reserve of about 440 pounds.
The Electric Power Research Institute is working with DOE to gain an accurate understanding of the total amount of lithium-7 used in the U.S. industry and to evaluate any options for managing potential shortages, said Tina Taylor, director of EPRI’s nuclear sector.
The nuclear energy industry is following EPRI’s activities, said Suzanne Phelps, NEI’s director of fuel cycle policy and programs. “We want to understand the supply-and-demand situation—how much do we need and what are the best projections of supply,” she said. “We will act in the future if it’s deemed necessary.”