The chemical treatment of uranium is a mandatory stage in the nuclear fuel cycle, at both its front and back ends. It primarily comprises converting the mined natural uranium ore into UF6 (uranium hexafluoride), a preliminary process before uranium enrichment.
Conversion of the uranium concentrate extracted from mines, stored here at the COMURHEX plant at Malvesi (Aude Département), is effected by a two-stage chemical process. In the first stage, the uranium ore is converted into UF4 (uranium tetrafluoride).
The COMURHEX plant at Pierrelatte (Drôme Départment) converts the UF4 (uranium tetrafluoride) transferred from the COMURHEX plant at Malvesi into UF6 (uranium hexafluoride, also called "hex"). This is the second and final stage in uranium concentrate conversion before enrichment.
The conversion of UF4 into UF6 necessitates the electrolysis of hydrofluoric acid. This operation, carried out in these cells at the COMURHEX plant at Pierrelatte (Drôme Département), separates the acid's hydrogen molecules from its fluor molecules.
The chemical reaction converting UF4 (uranium tetrafluoride) into UF6 (uranium hexafluoride) takes place at a very high temperature in a flame reactor such as this the COMURHEX plant at Pierrelatte (Drôme Département).
The chemical conversion of uranium is very closely checked in a laboratory at every stage of the process. All the sites of AREVA's Chemistry Business Unit possess triple certification in regard to the environment, quality, and health and safety in the workplace.
The defluorination of depleted UF6 is carried out to obtain uranium oxide (U308). Uranium can be stored in this form in optimal conditions regarding safety and respect of the environment, as shown here at AREVA's Pierrlatte plant (Drôme Département).
The installations at AREVA's Pierrelatte plant (Drôme Département), like this TU5 oxide conversion furnace, are used to chemically treat uranium recycled from spent fuel.
December 16, 2010
AREVA has successfully completed ultrasonic inspection testing (UT) of 1,088 baffle bolts at Surry Power Station in Virginia as part of its license renewal requirements. The Non-Destructive Examination (NDE) is the first inspection of baffle bolts at a U.S. nuclear power plant under the stringent new protocol of the “Materials Reliability Program: Pressurized Water Reactor Internals Inspection and Evaluation Guidelines (MRP 227/228).”
Baffle bolts number in the thousands in the reactor vessel and hold baffle plates together. The baffle plates allow a cylindrical vessel interior to accommodate the fuel which is in square bundles. They also provide a boundary between incoming cold reactor coolant and the heated reactor coolant flowing on the outside and inside of the cylinder. Before MRP 227/228, the protocol for baffle bolt inspections was visual inspection testing (VT).
The exam was completed 17 hours ahead of schedule, under dose by 40 mrems, and with zero foreign material exclusion (FME) incidents. “We were pleased with the AREVA team’s performance on this first-of-a-kind inspection in the U.S.,” said Jerry Bischof, Site Vice President - Surry Power Station.
The newly formed AREVA NDE Solutions combines technical, human resources and NDE equipment from France, Germany and the United States. The Surry baffle bolt inspections brings to the U.S. nuclear fleet innovative NDE technologies already field proven within the European fleet, including utilization of a state-of-the-art German-designed SUSI (Submarine System for Inspections) that provides an extremely fast, stable and accurate platform for VT and UT data collection.
”The Surry inspection is another example of world-class technology and innovation that AREVA provides to help our customers reduce outage time and improve operations,” said Craig Ranson, AREVA NDE Solutions NA Vice President.