Design considerations for instrumentation to monitor the enrichment of gaseous UF{sub 6}
The measurement of the enrichment of gaseous UF{sub 6} presents unique measurement problems. The well-known uranium enrichment meter is not applicable. For solid samples of uranium, including metal, and oxide and fluoride compounds, the infinite thickness is {approximately}1 cm. Gaseous UF{sub 6}, at a pressure of tens of Torr, has an infinite thickness on the order of 350 m. This is a physically and operationally unrealistic situation for an operating facility. Pipe dimensions and composition also strongly influence the applicable measurement technique. Fundamentally, the definition of enrichment is the ratio of {sup 235}U to total uranium. The amount of {sup 235}U is determined by measuring the intensity of the 185.7-keV gamma ray from the decay of {sup 235}U. There are two methods that have been implemented to determine the amount of total uranium in the gas: X-ray fluorescence (XRF) and gamma-ray transmission. The technique used to measure the amount of total uranium is dependent on the pressure of the gas in the header pipe. The transmission measurement is applicable for higher pressures, generally pressures {lt}40 Torr. The XRF measurement can be used for pressures greater than a few Torr. An XRF measurement at pressures lower than a few Torr becomes very difficult. Two other constraints strongly influence the implementation of the measurement technique--pipe diameter and material composition. These two techniques have been implemented. The XRF technique is an approved measurement by the International Atomic Energy Agency (IAEA) for inspections at gaseous centrifuge facilities. The XRF technique has also been implemented at the Portsmouth Gaseous Diffusion Plant for the IAEA verification experiment during the period December 1997 to October 1998 to verify the downblending of US highly enriched uranium (HEU) to low-enriched uranium (LEU). The transmission technique was originally developed to verify the downblending of Russian HEU to LEU. This instrument was demonstrated at the Paducah Gaseous Diffusion Plant from April 1998 to July 1998 and installed at the Urals Electrochemical Integrated Plant, Novouralsk, Russia, during January 1999.
- Research Organization:
- Los Alamos National Lab., NM (US)
- OSTI ID:
- 20005812
- Journal Information:
- Transactions of the American Nuclear Society, Vol. 81; Conference: American Nuclear Society 1999 Winter Meeting, Long Beach, CA (US), 11/14/1999--11/18/1999; Other Information: PBD: 1999; ISSN 0003-018X
- Country of Publication:
- United States
- Language:
- English
Similar Records
On Line Enrichment Monitor (OLEM) UF6 Tests for 1.5" Sch40 SS Pipe, Revision 1
Blend Down Monitoring System Fissile Mass Flow Monitor and its Implementation at the Siberian Chemical Enterprise, Seversk, Russia